APPARATUS AND PROCESS WITH AN ANGLED VIBRATING PLATE AND / OR FIXED HORIZONTAL PLATE FOR FORMING FIBER-REINFORCED CEMENTITIOUS PANELS WITH CONTROLLED THICKNESS

Abstract

A production line (10) and a process including a movable carrier frame (14) for transporting the panel, and a device (93) for controlling the thickness of a fiber-reinforced cementitious panel grout formed, but not yet set, on the frame. The thickness control device (93) may include an angled rigid plate (95) for contacting a downstream end (202) of the angled plate (95) with the grout on the movable carrier frame (14) and a mounting bracket (97) for mounting the angled rigid plate (95). The thickness control device (93) may also include a flat horizontal plate (201) at a fixed height above the movable carrier for contacting the entire underside surface of the horizontal plate (201) with a coating (444) in the grout on the movable carrier frame (14).Or, the thickness control device (93) may include the angled plate (93) and include the horizontal plate (201) that comes into contact with the coating (444).

Description

APPARATUS AND PROCESS WITH AN ANGLED VIBRATING PLATE AND / OR FIXED HORIZONTAL PLATE FOR FORMING FIBER-REINFORCED CEMENT-BASED PANELS WITH CONTROLLED THICKNESS FIELD OF INVENTION This invention relates to a continuous process and related apparatus for producing structural panels by the use of settable grout, and more specifically to a thickness control device for controlling thickness to reduce thickness variation during the manufacture of fiber-reinforced cementitious panels (FRC panels) in which fibers are combined with rapid-setting grout to provide flexural strength. These FRC panels are also referred to herein as fiber-reinforced concrete panels or structural cementitious panels (SCP panels). BACKGROUND OF THE INVENTION Fiber-reinforced concrete panels (FRC panels) can be formed by placing alternating layers of reinforcing glass fibers and cementitious grout. A thin layer of grout is deposited on the line. A fiberglass chopper then deposits a layer of crushed glass on top of the grout. A double-disc embedding roller then embeds the glass fibers into the grout, as described. For example, the process may include four grinding stations. Ref. 334434 layering, which are placed in series on a conveyor belt, after which the product reaches an overall average thickness. Two vibrating plates of the screed then rub against the top of the panel while the mass being layered is still somewhat fluid, providing a smoothing effect on the upper surface. An illustrative process is described in U.S. Patent No. 7,794,221 to Dubey. This process is repeated several times until the panel reaches the desired thickness. U.S. Patent No. 7,445,738 to Dubey et al. describes a multi-layer process for producing fiber reinforced concrete (FRC) panels, which are referred to as cementitious structural panels, including: (a.) providing a moveable web; (b.) one of (i) depositing a first layer of loose individual fibers over the web, followed by depositing a layer of settable grout over the web, or (ii) depositing a layer of settable grout over the web; (c.) depositing a second layer of loose individual fibers over the grout; (d.) actively embedding the second layer of loose individual fibers in the grout to distribute the fibers throughout the grout; and (e.) repeating steps (ii) through (d) until the desired number of layers of fiber-enhanced settable grout are obtained and the fibers are distributed throughout the panel. ηζααηη / ζζηζ / Ε / γίΛΐ U.S. Patent No. 8,038,790 to Dubey et al. describes structural cementitious panels employing one or more layers of a continuous phase resulting from the curing of an aqueous mixture of alpha calcium sulfate hemihydrate, hydraulic cement, coated expanded perlite particle filler, optional additional fillers, activated pozzolan, and lime. The coated perlite has a particle size of 1500 microns, an average diameter of 20-150 microns, and an effective particle density (specific gravity) of less than 0.50 g / cc. The panels are reinforced with fibers, e.g., alkali-resistant glass fibers. US 2018 / 0036912 to Dubey et al. describes a single-layer process for producing grout for cementitious panels having high concentrations of reinforcing fibers. These fiber-reinforced cementitious panels are made with edges wrapped in a surface reinforcement web, such as a nonwoven fiber mat, on the panel production line, where the nonwoven fiber mat can be a polypropylene mat or a fiberglass mat. The process applies a first nonwoven fiber mat onto the surface of a moving endless belt and a second nonwoven fiber mat over the setting fiber and grout mixture. Other aspects of single-layer processes for producing grout for cementitious panels having high ηζααηη / ζζηζ / Ε / γίΛΐ concentrations of reinforcing fiber are described by the following: Published U.S. patent application No. 2018-0036912 Al to Dubey et al., entitled Methods of making fiber reinforced concrete panels using a continuous process; U.S. Patent No. 10,272,399 to Dubey et al., entitled Method for producing fiber reinforced cementitious slurry using a multi-stage continuous mixer (also published as US 2018-0036693 A1); Published US patent application no. 2018-0036911 Al to Dubey et al., entitled Continuous mixer and method of mixing reinforced fibers with cementitious materials; Published U.S. patent application No. 2018-0036909 Al to Dubey et al., entitled Headbox and forming station for fiber reinforced cementitious panel production; These structural FRC panel manufacturing processes involve two separate production lines: the forming line and the finishing line. During panel formation on the forming line, the panel thickness is greater than that of the finished product. This extra material is provided so that the entire panel, including thickness variations, meets a desired minimum thickness to ensure there are no thin spots in the finished panels. However, the extra material is removed as the panels pass through the finishing line to ensure that the entire panel meets the desired minimum thickness without thickness variations. Therefore, typically, the final thickness and surface of structural fiber-reinforced cementitious panels (also known as FRC panels) are the result of a separate sanding and finishing process. This practice has several disadvantages.The product is thicker than the desired thickness due to limitations imposed by the forming process. Sanding must be added to the panel finishing line to achieve the correct panel thickness. The formed product has dimensions (length and width) greater than the desired final product dimensions. This requires adding a processing step to the panel finishing line to cut the panel to the final dimensions. Panel production efficiency is reduced due to the additional time and finishing steps. It would be desirable to form the panels thinner, because a later stage of the process will grind the panels to the desired thickness, and the material that is ground off is waste. However, when attempting to shape a thinner average, there will be localized areas that are less than the desired thickness, and this results in complete panels that cannot be sold. Therefore, it is currently more economical to shape an excessive thickness and then grind to the desired thickness. US 6,702,966 to Suzuki et al. describes a thickness control apparatus 4 having a vibrating leveler 2a on a smooth forming pressure plate 2b for smoothing the surface of the slurry A'. The smooth forming pressure plate 2b is tiltable and inclined downward and is configured to have an angle of incidence between 5 and 10 degrees, preferably 7 degrees. Angles of less than 2 degrees cause the formation of bubbles (see Col. 4, 11, 3658). US 8,163,352 (US2009 / 0043780) to Jones describes a production line having a smoothing device, also referred to as a vibrating edge bar, for gently smoothing an upper surface of the deposited slurry layer before depositing the next respective fiber overlay. US 8,038,915 (20100132870) to Stivender describes a flexible curved smoothing sheet or cover, which is arranged transversely to the travel direction of a fiberboard slurry being formed, where the flexible sheet is designed to float over the surface of the panel being formed without tearing or otherwise damaging the surface of the heavily fiber-reinforced surface layers of the panel (see Abstract). However, there is still a need for additional thickness control in the production of fiber-reinforced cementitious panels. SUMMARY OF THE INVENTION The invention provides a thickness control device and a method for reducing thickness variation during the formation of fiber-reinforced cementitious panels. By minimizing or eliminating edge grinding, sanding, and / or finishing, there will be significant cost savings in raw materials and other operating costs, such as labor and maintenance. Specific cost savings will include reduced raw material usage, less scrap handling, less wear and tear, and increased production speed on the finishing line. There may also be other advantages, such as a reduction in the amount of warping during the panel curing process, which will further reduce scrap costs. The present invention features a thickness control device having an adjustable but fixed position for applying uniform pressure to the entire upper surface of a fiber-reinforced cementitious panel being formed as it exits a headbox and / or exits an embedding device of a grouting station and / or further downstream of the headbox and / or an embedding device. The thickness control device levels and smooths the surface of the FRC panel and controls the thickness of the panel without damaging the FRC panel. As used in this description and depending on the context, one skilled in the art will understand that the term "panel" may include a panel precursor which is a cementitious product that is not yet formed or cut into discrete panels. The invention provides a production line for fiber-reinforced cementitious (FRC) panels comprising: a movable carrier web, a support frame for supporting the movable carrier web, wherein the panel is transported on the movable carrier web having a direction of travel relative to the support frame, and a thickness control device for controlling the thickness of a fiber-reinforced cementitious structural panel that is formed but not yet set or cut, comprising a fiber-laden cementitious slurry comprising cementitious material and chopped fibers embedded in the movable carrier web, wherein the thickness control device comprises a rigid angled plate and a mounting frame for mounting the rigid angled plate onto the support frame for the movable carrier web, and a rigid, flat support bed under the rigid angled plate, which is adapted and configured sufficiently to support the fiber-laden slurry and preferablyresisting the downward force exerted by the rigid angled plate with a deflection of less than 0.03 inches, preferably less than 0.01 inches, preferably less than 0.003 inches, the rigid angled plate having an upstream transverse rear wall, a downstream transverse bottom wall extending downstream from a lower end of the upstream transverse rear wall, open side walls and an open top, wherein the bottom surface of the bottom wall has a flat horizontal profile, the upstream transverse rear wall meets the downstream bottom wall to form a bent transition section that is aligned transversely to the travel direction of the movable carrier frame, and the upstream transverse rear wall meets the downstream transverse bottom wall to form an angle in a range of 60 to 120 degrees,preferably from 70° to 110°, and most preferably from 80° to 100°, the upstream transverse rear wall being directed from the upwardly bent transition section away from the movable carrier frame, the downstream transverse bottom wall being directed from the downwardly bent transition section towards the movable carrier frame, the angled rigid plate transverse to the upstream ηζααηη / ζζηζ / Ε / γίΛΐ rear wall being mounted on the mounting bracket to be transverse to the direction of travel of the movable carrier frame, a vibrator being attached to the angled rigid plate transverse to the upstream rear wall, the mounting bracket for fixedly but adjustable maintaining the height of the angled plate above the movable carrier frame and for fixedly but adjustable maintaining the angle of the angled plate relative to the movable carrier frame of 5° to 30°, typically the angle being in the range of 10° to 25°,to fixedly locate a downstream end of the transverse bottom wall at a height of 0.1 to 2 inches, preferably 0.2 to 1.1 inches, above the movable carrier web, wherein the downstream end of the transverse bottom wall is transverse to the direction of travel of the grout and the movable carrier web, wherein the downstream end of the transverse bottom wall extends transversely across the movable web, and wherein the downstream end of the transverse bottom wall is capable of contacting the fiber-laden cementitious grout when carried on the movable carrier web. The flat, rigid support bed beneath the angled rigid plate may be located under or above the carrier frame. The carrier frame is typically an endless belt. A deviation of less than 0.03 inches, preferably less than 0.01 inches, or preferably less than 0.003 inches, is a deviation in a vertical direction relative to the horizontally movable carrier frame. Therefore, the downstream end of the transverse bottom wall extends transversely through a path for grouting in the moving frame. Furthermore, the angle of the angled plate relative to the moving carrier frame places the downstream end of the transverse bottom wall lower than the upstream end of the transverse bottom wall. The mounting bracket mounts the angled rigid plate on or around the support for the traveling carrier frame, typically in a position after the carrier frame exits a headbox and / or an embedding device of a grout forming station. The rear wall of the angled rigid plate (vertical leg) and the bottom wall (horizontal leg) are made, for example, of light metal, which is relatively short and as wide as the fiber-reinforced cementitious grout panel being formed. The horizontal leg of the angled rigid plate is generally arranged transversely to the direction of travel of the panel on the carrier frame. The ηζααηη / ζζηζ / Ε / γίΛA vibrator is mounted on the upper surface of the rear wall to impart vibration to the angled rigid plate that will cause the surface of the angled rigid plate to vibrate during use. With respect to the angled plate, the term rigid means that it has sufficient strength to resist bending or flexing when it comes into contact with the grout according to the invention. The transverse bottom wall (also known as the horizontal leg) of the angled rigid plate is adjusted, relative to the moving frame and relative to the grout moving beneath, at a small, fixed lead-in angle, e.g., 5° to 30°; typically, the angle is in the range of 10° to 25°. Thus, only the downstream end portion of the angled rigid plate contacts the upper surface of the grout to form the panel. This allows firm, controlled contact with the fiber-laden grout as the angled rigid plate levels and smooths the grout surface. The height of the angled rigid plate and the adjustment and support system are configured such that the height of the angled rigid plate and the contact angle of the angled rigid plate with the fiber-laden grout are fixed, but adjustable, during this contact. The shape of the angled plate may be L-shaped, but it need not be a perfect L-shape, i.e. the angle Θ between the upstream transverse rear wall and the downstream transverse bottom wall may not necessarily always be 90°. The angle between the rear wall and the bottom wall is fixed, but may vary from obtuse to acute. For example, the angle between the two walls may vary from 60° to 120°, preferably from 70° to 110°, and most preferably from 80° to 100°. Furthermore, the transition geometry between the rear wall and the bottom wall may be acute or curved. The upstream transverse rear wall and the downstream transverse bottom wall may be a single piece forming the angle Θ or two pieces that are joined in a fixed manner, for example by welding, forming the angle Θ. The invention also provides a continuous process for controlling the thickness of a formed, but not yet set, fiber-reinforced cementitious panel comprising a fiber-laden cementitious slurry comprising cementitious material and embedded chopped fibers, in the fiber-reinforced cementitious panel production line described above comprising the steps of: conveying the panel on a movable carrier web having a direction of travel relative to a support frame for supporting the movable carrier web, contacting the formed but unset fiber-reinforced cementitious panel comprising grout and embedded chopped fibers with a downstream end of a thickness control device, wherein the thickness control device comprises a rigid angled plate and a mounting frame for mounting the rigid angled plate onto the support frame for the movable carrier web, and a rigid, planar support bed beneath the rigid angled plate, which is sufficiently adapted and configured to support the fiber-laden grout and preferably resist a downward force exerted by the rigid angled plate with a deflection of less than 0.03 inches, preferably less than 0.01 inches, preferably less than 0.003 inches,the rigid angled plate having an upstream transverse rear wall, a downstream transverse bottom wall extending downstream from a lower end of the upstream transverse rear wall, open side walls and an open top, wherein the lower surface of the bottom wall has a flat horizontal profile, the upstream transverse rear wall meets the downstream bottom wall to form a bent transition section that is aligned transversely to the direction of travel of the movable carrier frame, and the upstream transverse rear wall meets the downstream transverse bottom wall to form an angle in a range of 60 to 120 degrees, preferably 70° to 110°, and most preferably 80° to 100°, the upstream transverse rear wall is directed from the bent transition section upwardly away from the movable carrier frame,the downstream transverse bottom wall is directed from the folded-down transition section toward the movable carrier frame, wherein the angled plate transverse to the upstream rear wall is mounted to the mounting bracket to be transverse to the direction of travel of the movable carrier frame, a vibrator being attached to the angled plate transverse to the upstream rear wall, the mounting bracket fixedly but adjustable maintains the height of the angled plate above the movable carrier frame and fixedly but adjustable maintains the angle of the angled plate relative to the movable carrier frame at less than 30°, typically the angle is 5° to 30°, preferably in the range of 10° to 25°, to fixedly locate the downstream end of the bottom wall at a height of 0.1 to 2 inches, preferably 0.2 to 1.1 inches, above the movable carrier frame,wherein the downstream end of the bottom wall comes into contact with the fiber-laden slurry carried on the moving carrier frame to control the thickness of the fiber-laden slurry. The flat, rigid support bed beneath the angled rigid plate can be located under or above the supporting frame. The supporting frame is typically an endless belt. Quite unexpectedly, it has been discovered that a more uniform panel surface profile across the width of the panel is obtained when the outer edge of the bottom wall of the angle plate assembly is positioned lower than the top surface of the panel being formed. Accordingly, the outer edge of the bottom wall of the angle plate assembly is positioned from about 0.01 inches to 0.25 inches lower than the top surface of the panel being formed. Typically, the thickness control device comprising the angle rigid plate and the mounting frame can be used in a multi-layer process or a single-layer process to produce fiber-reinforced cementitious panels (FRC panels). In a first version of the multi-layer process, the process makes an initial deposit of loose, chopped, distributed fibers or a layer of cementitious slurry onto a moving web and then deposits fibers onto the slurry layer. An embedding device thoroughly mixes the newly deposited fibers into the slurry so that the fibers are distributed throughout the slurry to form a fiber-laden cementitious slurry, after which additional layers of slurry and chopped fibers are then added, followed by further embedding by additional embedding devices. The process is repeated for each layer of the panel, as desired. The thickness control device is employed downstream of one or more of the embedding devices to contact the fiber-laden cementitious slurry layer to level and control the thickness of the layer.A device is located downstream to cut the set grout in the FRC panels. In a second version of the multi-layer process, the first version of the process is modified by depositing an additional layer of loose fibers onto the existing fiber-laden cementitious slurry after an embedding device, followed by a layer of slurry and then another layer of fibers. The fiber / slurry / fiber combination is then embedded to thoroughly mix the fibers into the slurry. A thickness control device is employed downstream of one or more of the embedding devices before the additional layer of loose fibers is deposited onto the existing fiber-laden cementitious slurry. It therefore comes into contact with the existing fiber-laden cementitious slurry layer to level and control the layer thickness. In the single-layer process for making fiber-reinforced concrete (FRC) panels, fiber-laden slurry (ηζααηη / ζζηζ / Ε / γίΛΐ) is mixed upstream of a headbox (slurry feed station) of a panel production line. This fiber-laden cementitious slurry is then fed to a slurry feed apparatus (referred to as a headbox) and deposited directly by the headbox onto the moving carrier frame of the panel production line evenly as a 0.125 to 2 inch thick, preferably 0.25 to 1 inch thick, typically 0.40 to 0.75 inch thick layer to produce the fiber-reinforced cementitious panel.In the process for producing cementitious panels from fiber-reinforced grout mixtures of the present invention, panels having at most a single layer of fiber-reinforced cementitious grout are preferably produced. The moving surface preferably moves at a speed of 1 to 100 feet per minute, more preferably 5 to 50 feet per minute. Other speeds above 100 feet per minute are also contemplated, as would be understood by one skilled in the art. Apparatus is located downstream for shearing the set grout into the FRC panels. Therefore, the thickness control device of the present invention may be employed downstream of the headbox as part of an apparatus for producing a cementitious panel having at most a single layer of fiber-reinforced cementitious composition including a conveyor-type frame supporting a movable web; a ηζααηη / ζζηζ / Ε / γίΛA mixing system for mixing water, cementitious material, and fibers in operative relationship with the frame and configured to feed the resulting fiber-grout mixture to the headbox in operative relationship with the frame and configured to deposit a layer of settable fiber-containing cementitious slurry onto the movable web. In particular, the thickness control device of the invention comprising a rigid angled plate can be applied downstream of the headbox, preferably immediately downstream of a headbox, in a continuous process for depositing a uniform layer of a cementitious slurry containing reinforcing fibers of the headbox in a traveling pattern comprising: depositing the cementitious slurry containing reinforcing fibers on the inner surface of the headbox which is rigidly mounted, depositing the cementitious slurry containing reinforcing fibers from the headbox as a continuous layer on a displacement frame; wherein the cementitious slurry containing reinforcing fibers being deposited from the headbox has a slump of 4 to 11 inches as measured according to a slump test using a 4 inch high, 2 inch diameter pipe, the resulting cementitious slurry containing reinforcing fibers further has a viscosity of less than 45,000 centipoise, preferably less than 30,000 centipoise, more preferably less than 15,000 centipoise, and most preferably less than 10,000 centipoise when measured using a Brookfield Viscometer, Model DV-II+ Pro with an HA4 Spindle accessory operating at a speed of 20 RPM. Typically, the resulting fiber-grout mixtures have a viscosity of at least 1500 centipoise; and the formed, but not yet cured, fiber-reinforced cementitious panel is contacted withcomprising the cementitious grout containing reinforcing fibers with a downstream end of a thickness control device, wherein the thickness control device comprises a rigid angled plate and a mounting frame for mounting the rigid angled plate on the support frame for the movable carrier frame, and a rigid, planar support bed under the rigid angled plate, which is adapted and configured sufficiently to support the fiber-laden grout and preferably resist the downward force exerted by the rigid angled plate with a deflection of less than 0.03 inches, preferably less than 0.01 inches, preferably less than 0.003 inches, the rigid angled plate having an upstream transverse back wall, a downstream transverse bottom wall extending downstream from a lower end of the upstream transverse back wall,open side walls and an open top, wherein the lower surface of the bottom wall has a flat horizontal profile, the upstream transverse rear wall meets the downstream bottom wall to form a folded transition section that is aligned transversely to the direction of travel of the movable carrier frame, and the upstream transverse rear wall meets the downstream transverse bottom wall to form an angle in a range of 60 to 120 degrees, preferably 70° to 110°, and most preferably 80° to 100°, the upstream transverse rear wall is directed from the folded transition section upwardly away from the movable carrier frame, the downstream transverse bottom wall is directed from the folded transition section downwardly, towards the movable carrier frame,the angled plate transverse to the upstream rear wall being mounted to the mounting bracket to be transverse to the direction of travel of the movable carrier web, a vibrator being attached to the angled plate transverse to the upstream rear wall, the mounting bracket fixedly but adjustable maintains the height of the angled plate above the movable carrier web and fixedly but adjustable maintains the angle of the angled plate relative to the movable carrier web at less than 30°, typically the angle is 5° to 30°, preferably in the range of 10° to 25°, to fixedly locate the downstream end of the bottom wall at a height of 0.1 to 2 inches above the movable carrier web, wherein the downstream end of the bottom wall contacts fiber-laden slurry carried on the movable carrier web to control the thickness of the fiber-laden grout., In another aspect of the invention, the invention may provide an FRC panel production line comprising a horizontal thickness control device comprising a horizontally oriented upper forming plate having an adjustable but fixed height for applying uniform pressure to the entire upper surface of a fiber reinforced cementitious panel being formed as it exits a headbox and / or an embedding device of a grout forming station and / or further downstream of the headbox and / or an embedding device for leveling and smoothing the surface of the panel and controlling panel thickness without damaging the panel. More specifically, the invention provides an FRC panel production line and a method for producing FRC panels that reduces thickness variation during forming of fiber reinforced cementitious panels, using a liner, such as a fiberglass mat, that is positioned across the width of the forming surface (tape / plate), and a rigid horizontal top forming plate. With the novel invention, a liner, such as a glass mat, is applied to one or both surfaces of the structural panel during the forming process. The rigid horizontal top forming plate, which is oriented horizontally, is then used to form the fiberglass / cementitious material slurry of the FRC panel to the desired thickness.The position of the entire rigid horizontal upper forming plate is fixed to provide a fixed gap between the bottom surface of the rigid horizontal upper forming plate and the movable carrier frame below. Therefore, it is not a floating plate. Due to its horizontal orientation, the entire bottom surface of the rigid horizontal upper forming plate, not just the downstream end as in the angled rigid plate described above, comes into contact with the fiber-laden slurry passing beneath the forming plate. This process produces panels with less variation (e.g., + / - 0.1 inch, preferably + / - 0.05 inch) in thickness, which then allows panels to be formed with a reduced average thickness, e.g., for a target average thickness of 0.80 inches, without having local thin spots (ηζααηη / ζζηζ / Ε / γίΛA below 0.72 inches.Therefore, it is possible to use fewer raw materials while producing the same finished product. Additional savings will come from reduced waste management costs, as well as from elements such as reduced equipment wear and increased manufacturing speed. As mentioned, one or two liners may be used in this invention. Furthermore, the one or two liners may be temporary, so that the liner(s) are removed before or during the finishing operation, or the liner(s) may remain on the finished product. The carrier under the horizontal forming plate should be a rigid carrier frame or a rigid, flat bottom forming plate, because the upper forming plate must be hard and flat, and the lining and fiber-laden cementitious slurry passing under the horizontal forming plate will exert pressure on the carrier below. If the fiber-laden cementitious slurry were to push against a weak support frame under the movable carrier frame, the thickness results would be poor. The invention therefore provides a production line for fiber-reinforced cementitious panels comprising: a movable carrier web, a support frame for supporting the movable carrier web, wherein the panel is transported on the movable carrier web having a travel direction relative to the support frame, and means for applying a coating, such as a glass mat, over a fiber-laden cementitious slurry on the movable carrier web, the means for applying the coating being positioned across the width of a forming surface of the movable carrier web, a horizontal thickness control device for controlling a thickness of a formed, but not yet set, fiber-reinforced cementitious panel comprising a fiber-laden cementitious slurry comprising cementitious material and chopped fibers embedded on the movable carrier web, wherein the thickness control device comprises a rigid horizontal upper forming plate,wherein the rigid horizontal upper forming plate has a planar bottom surface, an upstream end and a downstream end, and a forming plate mounting frame for mounting the rigid horizontal upper forming plate in a horizontal orientation on the support frame for the movable carrier frame, wherein the rigid horizontal upper forming plate is mounted to the forming plate mounting frame, and a planar and rigid support bed under the rigid horizontal upper forming plate, which is adapted and configured sufficiently to support the fiber-laden cementitious slurry and preferably resist the downward force exerted by the rigid horizontal upper forming plate with a deflection of less than 0.03 inches, preferably less than 0.01 inches, preferably less than 0.003 inches, the forming plate mounting frame to hold it fixedly, but adjustable,the height of the rigid horizontal upper forming plate above the movable carrier web and keeping the rigid horizontal upper forming plate parallel relative to the movable carrier web, to fixedly locate the flat lower surface at a height of 0.1 to 2 inches, preferably 0.2 to 1.1 inches, above the movable carrier web, wherein the upstream end of the flat lower surface extends through the movable web transversely, relative to the direction of travel of the movable web, wherein the downstream end of the flat lower surface extends through the movable web transversely, relative to the direction of travel of the movable web, and wherein the entire flat lower surface is capable of contacting the lining in the fiber-laden slurry when carried on the movable carrier web., The flat, rigid support bed beneath the rigid horizontal upper forming plate can be located under or above the supporting frame. The supporting frame is typically an endless belt. The invention also provides a process for making a fiber-reinforced cementitious panel comprising: conveying a fiber-laden slurry for a panel on a moving carrier web, the moving carrier web being supported by a support frame, wherein the panel is transported on the moving carrier web having a travel direction relative to the support frame, applying a coating, such as a glass mat, over a fiber-laden cementitious slurry on the moving carrier web, across the width of a forming surface of the moving carrier web to cover the forming surface, passing the forming surface covered by the coating under a horizontal thickness controlling device to control the thickness of a formed, but not yet set, fiber-reinforced cementitious panel comprising a fiber-laden cementitious slurry comprising cementitious material and chopped fibers embedded in the moving carrier web,wherein the thickness control device comprises a rigid horizontal upper forming plate (e.g., horizontal forming plate 446), wherein the rigid horizontal upper forming plate has a planar bottom surface, an upstream end and a downstream end, and a forming plate mounting frame for mounting the rigid horizontal upper forming plate in a horizontal orientation on the support frame for the movable carrier frame, wherein the rigid horizontal upper forming plate is mounted to the forming plate mounting frame, and a rigid, planar support bed beneath the rigid horizontal upper forming plate, which is conformable and configured sufficiently to support the fiber-laden cementitious slurry and preferably resist downward force exerted by the rigid horizontal upper forming plate with a deflection of less than 0.03 inches,preferably less than 0.01 inches, preferably less than 0.003 inches, controlling the thickness of the formed, but not yet set, fiber-reinforced cementitious panel, when the formed, but not yet set, fiber-reinforced cementitious panel, covered with the coating, comprising a fiber-filled cementitious slurry, comes into contact with a lower surface of the rigid horizontal upper forming plate; ηζααηη / ζζηζ / Ε / γίΛΐ the mounting frame to fixedly maintain, but adjust, the height of the rigid horizontal upper forming plate above the movable carrier web and keep the rigid horizontal upper forming plate parallel relative to the movable carrier web, to fixedly locate the flat lower surface at a height of 0.1 to 2 inches above the movable carrier web, wherein the upstream end of the flat lower surface extends through the movable web transversely, relative to the direction of travel of the movable web, wherein the downstream end of the flat lower surface extends through the movable web transversely, relative to the direction of travel of the movable web, and wherein the entire flat lower surface comes into contact with the coating in the fiber-laden slurry when carried on the movable carrier web. The flat, rigid support bed beneath the rigid horizontal upper forming plate can be located under or above the supporting frame. The supporting frame is typically an endless belt. If desired, the invention provides an FRC panel production line and method for producing FRC panels that reduces thickness variation during the forming of fiber reinforced cementitious panels, using the above-described angle plate, a liner, such as a glass mat, that is positioned across the width of the top forming surface, and a horizontal forming plate. Such an FRC panel production line and method would contact fiber-laden slurry with the above-described angle plate and then apply a liner, such as a glass mat, to the top surface of the FRC panel during the forming process, and then pass the fiber-laden slurry covered by the liner under the rigid horizontal top forming plate.Optionally, the production line and method may also apply a coating, such as a glass mat, to the bottom surface of the structural panel upstream of the headbox during the forming process. The invention also provides a process for using this production line. This invention also provides embodiments in which a panel has a fabric facing on one or both planar surfaces of the panel. The facing provides the panel with a significantly flatter surface profile and uniform thickness. It has also been unexpectedly discovered that the fabric facing improves the exterior weatherability of the final composite. Distinctive features of fabric-faced FRC panels may include, among other things: Superior outdoor weather durability performance Improved aesthetics and dust-free surface. Improved readability / visibility of printing on the panel surface Ability to provide two distinct usable surfaces for various applications and uses—one coated surface and the other uncoated surface. For example, the uncoated surface is best suited for bonding various types of roofing membranes and plastic foams. The uncoated surface is also suitable for applications where a simple, plain concrete appearance is desirable, such as interior wall and ceiling applications. On the other hand, the coated surface is particularly suitable for applications requiring superior bonding to cementitious underlayments and other coating materials. Interior and exterior walls and subfloors are some applications where having at least one panel surface coated may be desirable. Improves surface durability from impact loads Upper joining surface ηζααηη / ζζηζ / Ε / γίΛΐ Ability to differentiate products by using fabrics with different colors and / or patterns Enhanced flexibility for the application of value-added functional coatings, such as waterproof coatings, air and water barrier coatings, architectural coatings, etc. Unless otherwise indicated, all percentages in this description, if any, are by weight. BRIEF DESCRIPTION OF THE FIGURES Figure 1A is a schematic elevation view of an FRC panel production line of the present invention for producing a multi-layer FRC panel with an angled plate. Figure IB is a schematic view of a mixer feeding an input box of the FRC panel production line of Figure 1A. Figure 2 shows the thickness control device as used in contact with the grout in the plot. Figure 3 shows a perspective view of the thickness control device in its operating position over the direction of travel of the frame carrying the grout panel. Figure 4A shows the angled plate having a downstream end of the angled plate that is dipped into a slurry on a production line. ηζααηη / ζζηζ / Ε / γίΛΐ Figure 4B shows the angled plate with a curved corner having a downstream end of the angled plate being dipped into a slurry on a production line. Figure 5 shows another perspective view of the thickness control device in the upward position above the plot line. Figure 6 is a fragmentary vertical section through a cementitious structural panel, which panel is produced in accordance with the present procedure. Figure 7 is a schematic elevation view of a second version of an FRC panel production line plate of the present invention for producing a multi-layer FRC panel with an angled plate. Figure 8 is a schematic elevation view of a third version of an FRC panel production line for producing single-layer FRC panels with an angled plate of the present invention. Figure 9 is a schematic elevational view of a fourth version of an FRC panel production line of the present invention which is the production line of Figure 1A with an angled plate that is modified to apply a coating and employ a fixed forming plate. Figure 9A shows a first enlarged perspective view of a portion of the FRC panel production line of Figure 9 for applying the coating and employing the stationary forming plate. Figure 9B shows a second enlarged perspective view of a portion of the FRC panel production line of Figure 9 for applying the coating and employing the stationary forming plate. Figure 9C shows a forming plate mounting frame for mounting the rigid horizontal upper forming plate in a horizontal orientation on the support frame for the movable carrier frame for the fixed forming plate of the FRC panel production line of Figure 9. Figure 9D shows a beveled edge upstream of the horizontal forming plate. Figure 10A is a schematic elevation view of a fifth version of an FRC panel production line with an angled plate of the present invention that is modified to apply a coating and employ a fixed forming plate. Figure 10B is a schematic elevational view of a sixth version of an FRC panel production line with an angled plate of the present invention that is modified to apply a skin and employ a stationary forming plate and fold the edges of a lower skin under the edges of an upper skin to wrap the FRC panel. Figure 10C shows a perspective view of an FRC panel made by the production line of Figure 10B. Figure 10D shows a side cross-sectional view of a polymer fiber mat having a laminated composite structure of a layer bonded by spunbond fibers and a relatively impermeable layer melt-blown fibers. Figure 10E depicts a top perspective view of one embodiment of an FRC panel that is enclosed in a mat of facing material, showing an edge of the panel that is covered by the facing and showing an overlap of the back and front facings. Figure 10F shows a side view of a portion of a representative production line with side cleaners installed on each side of the line and before the forming plate to prevent slurry runaway. An optional vibrator attached to the side of a cleaner is also shown. An optional vibrator is also shown installed under the bed of the forming line plate just behind the forming plate to keep the slurry head active and fluid. Figure 11A schematically shows sample panels being formed from an example that is cut into four pieces after curing. Figure 11B shows the standard deviation in inches and the maximum and minimum thickness difference in inches of the ηζααηη / ζζηζ / Ε / γίΛA panels formed under different experimental conditions on the samples measured in the cross-machine direction with and without the angle plate thickness control device of the present invention. Controls #1 and #2 are experimental conditions without the present invention for an example of the present disclosure. Figure 11C schematically shows the sample panels formed from an example that is cut into eight pieces after curing. Figure 12 shows the cross-sectional thickness profile in inches of a cementitious panel formed in the cross-machine direction without the use of the angle plate thickness control device of the present invention. Figure 13 shows the cross-sectional thickness profile in inches of a cementitious panel formed in the cross-machine direction by using the angle plate thickness control device of the present invention. Figure 14 has information on panel thickness measurements in inches across the cross machine direction to show the standard deviation and difference of maximum and minimum thickness of panels formed under different experimental conditions on samples measured in the cross machine direction ηζααηη / ζζηζ / Ε / γίΛΐ with and without the angle plate thickness control device of the present invention, wherein control #1 and #2 are experimental conditions without the angle plate thickness control device of the present invention. Figure 15 has information on panel thickness measurements in inches along the machine direction to show the standard deviation and difference of maximum and minimum thickness of panels formed under different experimental conditions of Table 1 for an example of the present disclosure with and without the angle plate thickness control device of the present invention, wherein control #1 and control #2 are experimental conditions without the angle plate thickness control device of the present invention. Figure 16 shows the cross-sectional thickness profile in inches in the cross-machine direction of a cementitious panel formed without the use of the angle plate thickness control device of the present invention. Figure 17 shows the cross-sectional profile of a cementitious panel formed by using the angle plate thickness control device of the present invention for an example #R3 of the present disclosure of a control sample, made on an FRC panel production line with a normal method without thickness control device comprising the fixed horizontal forming plate. Figure 18 shows the cross-sectional profile of a cementitious panel formed for an example #R3 of the present disclosure which is measured in the cross-machine direction of a control sample, made on an FRC panel production line with a normal method without thickness control device comprising the fixed horizontal forming plate. Figure 19 shows the cross-sectional profile of a cementitious panel formed for an example #R3 of the present disclosure measured in the machine direction of a control sample, made on an FRC panel production line with a normal method without thickness control device comprising the fixed horizontal forming plate. Figure 20 shows the cross-sectional profile of a cementitious panel formed for an example #R4 of the present disclosure which is measured in the cross-machine direction of a control sample, made on an FRC panel production line with a normal method without thickness control device comprising the fixed horizontal forming plate. Figure 21 shows the cross-sectional profile of a cementitious panel formed for an example #R4 of the present disclosure which is measured in the machine direction of a control sample, made on an FRC panel production line with a normal method without thickness control device comprising the fixed horizontal forming plate. Figure 22 shows the cross-sectional profile of a cementitious panel formed for an example #R1 of the present disclosure which is measured in the cross-machine direction of a control sample, made on an FRC panel production line with a normal method without thickness control device comprising the fixed horizontal forming plate. Figure 23 shows the cross-sectional profile of a cementitious panel formed for an example #R1 of the present disclosure measured in the machine direction of a control sample, made on an FRC panel production line with a normal method without thickness control device comprising the fixed horizontal forming plate. Figure 24 shows the cross-sectional profile of a cementitious panel being formed for an example #T1 of the present disclosure being measured in the cross-machine direction of test specimens made on a production line with the thickness control device comprising the fixed horizontal forming plate of the invention. Figure 25 shows the cross-sectional profile of a cementitious panel being formed for an example #T1 of the present disclosure being measured in the machine direction of test specimens made on a production line with the thickness control device comprising the fixed horizontal forming plate of the invention. Figure 26 shows the cross-sectional profile of a cementitious panel formed for example #T2 of the present disclosure as measured in the cross-machine direction. Figure 27 shows the cross-sectional profile of a cementitious panel being formed for an example #T2 of the present disclosure being measured in the machine direction of test specimens made on a production line with the thickness control device comprising the fixed horizontal forming plate of the invention. Figure 28 shows the cross-sectional profile of a cementitious panel being formed for an example #T4 of the present disclosure being measured in the cross-machine direction of test specimens made on a production line with the thickness control device comprising the fixed horizontal forming plate of the invention. Figure 29 shows the cross-sectional profile of a cementitious panel being formed for an example #T4 of the present disclosure being measured in the machine direction of test specimens made on a ηζααηη / ζζηζ / Ε / γίΛA production line with the thickness control device comprising the fixed horizontal forming plate of the invention. Figure 30 shows glass mat-faced FRC panels in an outdoor weather exposure farm located in northern Illinois, USA. Figure 31A shows a close-up view (front surface) of an FRC panel without a coating after nine months of outdoor weathering exposure. Figure 31B shows a close-up view (front surface) of a glass mat-coated FRC panel after nine months of outdoor weathering exposure. DETAILED DESCRIPTION OF THE INVENTION I. Fiber cement mixtures for the present invention The invention works with a variety of fiber cement mixtures that are produced and that contain cement, water, and other cement additives. The fiber cement mixtures produced by the method and apparatus of this invention are aqueous slurries that can be a variety of settable cementitious slurries. For example, such aqueous slurries can be compositions based on hydraulic cements. ASTM defines hydraulic cement as follows: a cement that sets and hardens by chemical interaction with water and is capable of doing so underwater. ηζααηη / ζζηζ / Ε / γίΛΐ Examples of suitable hydraulic cements include Portland cement, calcium aluminate cements (CAC), calcium sulfoaluminate cements (CSA), geopolymers, magnesium oxychloride cements (sorel cements), and magnesium phosphate cements. A preferred geopolymer is based on the chemical activation of Class C fly ash. While calcium sulfate hemihydrate sets and hardens by chemical interaction with water, it is not included within the broad definition of hydraulic cements in the context of this invention. However, calcium sulfate hemihydrate may be included in fiber cement mixtures produced by the method and apparatus of this invention. Therefore, such aqueous slurries may also be based on calcium sulfate cements such as gypsum or plaster of Paris cements. Gypsum cements are primarily calcined gypsum (calcium sulfate hemihydrate). It is common in the industry to refer to calcined gypsum cements as gypsum cements. Fiber cement mixtures may contain pozzolanic material such as silica fume, a finely divided amorphous silica that is the product of manufacturing alloys of metallic silicon and ferrosilicon. Typically, it has a very high silica content and a low alumina content. Other additives, such as plasticizers or superplasticizers, have been mentioned to improve the fluidity of a hydraulic slurry. Such additives disperse molecules in the solution so they move more easily relative to each other, thereby improving the fluidity of the entire slurry. Plasticizers are commonly manufactured from lignosulfonates, a byproduct of the paper industry. Superplasticizers are generally manufactured from sulfonated naphthalene condensate or sulfonated melamine formaldehyde, or from polycarboxylic ethers. The water-reducing admixture may be present in an amount of 0% to 5%, preferably 0.5 to 5%, by weight of the wet finish fiber-slurry mix. U.S. Patent No. 6,620,487 to Tonyan et al., which is incorporated herein by reference in its entirety, discloses a reinforced, lightweight, dimensionally stable structural cementitious panel (SCP) employing a core of a continuous phase resulting from the curing of an aqueous mixture of alpha calcium sulfate hemihydrate, hydraulic cement, an active pozzolan, and lime. The continuous phase is reinforced with alkali-resistant glass fibers and contains ceramic microspheres, or a mixture of ceramic and polymeric microspheres, or is formed from an aqueous mixture having a weight ratio of water to reactive powder of 0.6 / 1 to 0.7 / 1, or a combination thereof.At least one external surface of the SCP ηζααηη / ζζηζ / Ε / γίΛΐ panels may include a cured continuous phase reinforced with glass fibers and containing sufficient polymer spheres to improve nailing ability or made with a ratio of water to reactive powders to provide an effect similar to the polymer spheres, or a combination of these. Various formulations for the composite grout used in the current process are also shown in U.S. Patent No. 7,841,148 to Tonyan et al. which is incorporated herein by reference. A typical formulation would comprise as the reactive powder, on a dry basis, 35 to 75% by weight (typically 45-65 or 55 to 65% by weight) of alpha calcium sulfate hemihydrate, 20 to 55% by weight (typically 25-40% by weight) of hydraulic cement such as Portland cement, 0.2 to 3.5% by weight of lime, and 5 to 25% by weight (typically 10-15% by weight) of an active pozzolan. The continuous phase of the panel would be uniformly reinforced with alkali-resistant glass fibers and would contain 20-50% by weight of lightweight, uniformly distributed filler particles selected from the group consisting of ceramic microspheres, glass microspheres, fly ash cenospheres, and perlite.An example of a formulation for the composite grout includes 42 to 68% by weight of reactive powders, 23 to 43% by weight of ceramic microspheres, 0.2 to 1.0% by weight of polymer microspheres, and 5 to 15% by weight of alkali-resistant glass fibers, based on the total ηζααηη / ζζηζ / Ε / γίΛA. 6 of dry ingredients. U.S. Patent 8,038,790 to Dubey et al. provides another example of a composite grout formulation including an aqueous mixture of a cementitious composition comprising, on a dry basis, 50 to 95% by weight of reactive powder, 1 to 20% by weight of coated hydrophobic expanded perlite particles uniformly distributed as a lightweight filler therein, the coated hydrophobic perlite particles having a diameter in the range of about 1 to 500 microns (microns), an average diameter of 20 to 150 microns (microns), and an effective particle density (specific gravity) of less than about 0.50 g / cc, 0 to 25% by weight of hollow ceramic microspheres and 3 to 16% by weight of alkali-resistant glass fibers to distribute them uniformly for reinforcement; wherein the reactive powder comprises: 25 to 75% by weight of alpha calcium sulfate hemihydrate, 10 to 75% by weight of hydraulic cement comprising Portland cement, 0 to 3.5% by weight of lime, and 5 to 30% by weight of an active pozzolan; and the panel has a density of 50 to 100 pounds per cubic foot. If desired, the compositions employed in the single or multi-layer processes of the invention may have a weight ratio of water to reactive powder of from 0.20 / 1 to 0.90 / 1, preferably from 0.25 / 1 to 0.70 / 1 or from 0.4 / 1 to 0.7 / 1. ηζααηη / ζζηζ / Ε / γίΛΐ The fibers may be discrete or chopped fibers made from various reinforcing fiber materials, including fiberglass; polymeric materials such as polypropylene, polyethylene, polyvinyl alcohol, etc.; carbon; graphite; aramid; ceramic; steel; cellulosic or natural fibers, such as jute or sisal; or a combination of these. The fiber length is approximately 2 inches or less, and most preferably 1.5 inches or less. For the single-layer process, fiber cement mixes contain sufficient water to achieve the desired slump test value and viscosity in combination with the other ingredients of the fiber cement mixes. PRODUCTION LINE AND METHOD WITH THICKNESS CONTROL DEVICE USING AN ANGLED PLATE II. First version of a production line Referring now to Figure 1A, there is shown diagrammatically an FRC panel production line, generally designated 10. The production line 10 includes a support frame or forming table 12 having a plurality of legs 13 or other supports. Included in the support frame 12 is a movable carrier 14, such as an endless rubber-like conveyor belt with a smooth, water-impermeable surface; however, porous surfaces are contemplated. As is well known in the art, the support frame 12 may be made of at least one table-like segment, which may include legs designated 13 or other support structure. The support frame 12 also includes a main drive roller 16 at a distal end 18 of the frame, and an idler roller 20 at a proximal end 22 of the frame.Also, at least one belt tracking and / or tensioning device 24 is typically provided to maintain a desired tension and positioning of the carrier 14 on the rollers 16, 20. The FRC panels are continuously produced as the movable carrier 14 advances in a direction T from the proximal end 22 to the distal end 18. In this production line 10, the carrier web 26 of Kraft paper, release paper or a plastic carrier to support a slurry before setting, can be provided and placed over the web 14 to protect it and / or keep it clean. However, it is also contemplated that instead of the continuous carrier web 26, 14 individual sheets (not shown) of a relatively rigid material, for example, polymeric plastic sheets, may be placed on the carrier. It is also contemplated that the FRC panels produced by the present line 10 may be formed directly on the carrier 14. In the latter situation, at least one belt washing unit 28 is provided. The carrier 14 is moved along the support frame 12 by a combination of motors, pulleys, belts or chains driving the main drive roller 16 as is known in the art. It is contemplated that the speed of the carrier 14 may be varied to suit the product being made. A. Picador In the present invention, production of fiber reinforced concrete (FRC) panel, also known as structural cementitious panel (SCP panel), is initiated by depositing a layer of loose chopped fibers 30 about one inch in size onto a plastic carrier in carrier web 26. The present line 10 contemplates a variety of fiber depositing and cutting devices. For example, a typical system employs a rack 31 holding a plurality of spools 32 of fiberglass rope, from each of which a length or strand 34 of fiber is fed to a chopping station or apparatus, also referred to as a chopper 36. Typically, a number of fiberglass strands are fed into each of the chopping stations. The chopper 36 includes a rotating knife roll 38 from which radially extending knives 40 extend transversely across the width of the carrier 14, and which is disposed in close, contacting, rotating relationship with an anvil roll 42. ηζααηη / ζζηζ / Ε / γίΛΐ Preferably, the knife roll 38 and the anvil roll 42 are arranged in a relatively close relationship such that rotation of the knife roll 38 also rotates the anvil roll 42, however, the reverse is also contemplated. Also, the anvil roll 42 is preferably covered with a resilient backing material against which the knives 40 chop the strands 34 into segments. The spacing of the knives 40 on the roll 38 determines the length of the chopped fibers. As seen in Figure 1A, the chopper 36 is disposed on the carrier 14 near the proximal end 22 to maximize productive use of the length of the production line 10. As the fiber strands 34 are chopped, the fibers fall loosely onto the carrier web 26. B. Grout mixer The present production line 10 includes a slurry preparation and feeding section 2 (Figure IB). The slurry preparation and feeding section 2 includes a slurry feeding station or slurry feeder or slurry headbox, generally designated 44 and a slurry source, which is a wet mixer 47. The slurry feeder 44 receives a supply of slurry 46 from the wet mixer 47 to deposit the slurry 46 onto the chopped fibers in the carrier web 26. It is also contemplated that the process may begin with initial deposition of slurry onto the carrier 14. Examples of some suitable grout mixers 47 are grout mixers commonly used in the cement mortar and concrete industry that may also be employed in the present invention. For example, mortar mixers described in ICRI Guideline No. 320.5R-2014, Technical Guidelines, Pretorial Atlas of Concrete Repair Equipment, International Concrete Repair Institute, May 2014, which are incorporated by reference, may be used in this invention to prepare the cementitious grout. These include horizontal shaft mixers, tumbling mortar mixers, stationary rotary drum mixers, pan mixers, rotary tub rotary paddle mixers, planetary paddle mixers, horizontal shaft mixer-pump combinations, and vertical shaft mixer-pump combinations. Horizontal shaft mixer-pump combinations and vertical shaft mixer-pump combinations are continuous mixers.C. Slurry feeding apparatus. Referring now to Figures 1A-1B, as mentioned above, one embodiment of a grout feeding apparatus, also referred to as a grout feed station, a grout feeder or grout inbox, generally designated 44, receives a supply of slurry 46 from the wet mixer 47. The slurry feeder 44 includes a main metering roller 48 which is arranged transversely to the direction of travel T of the carrier 14. A complementary or backup roller 50 is arranged in a close rotational relationship parallel to the metering roller 48. The slurry 46 is deposited at a nip 52 between the two rollers 48, 50. The slurry feeder 44 further has a gate 132 which is mounted on the side walls 54 of the slurry feeding apparatus 44 so as to be mounted adjacent to the surface of the metering roller 48 to form a clamping point 55 therebetween. As seen in Figure IB, the gate 132 is located above the metering roller 48 so that the clamping point 55 is located between the gate 132 and the upper portion of the roller 48. The rollers 48, 50 and the gate 132 are arranged in a close enough relationship so that the clamping point 55 retains a supply of the slurry 46 while the rollers 48, 50 rotate relative to each other. The gate 132 is provided with a vibrator (not shown). As seen in Figure IB, the metering roller 48 rotates from the clamping point 52 to the clamping point 55. While other sizes are contemplated, typically the metering roller 48 has a larger diameter than the complementary ηζααηη / ζζηζ / Ε / γίΛΐ roller 50. Also, typically one of the rollers 48, 50 has a smooth stainless steel exterior, and the other, preferably the complementary roller 50, has a resilient non-stick material coating its exterior. In particular, the gate 132 comprises a blade 132A that is mounted on a vibratory gate support rod / shaft (not shown) and, optionally, a reinforcing member (not shown) that is mounted on the vibratory gate support rod / shaft. The blade gate 132A is typically made of 16-12 gauge stainless steel sheet. The gate 132 is vibrated by means of a rotary vibrator (not shown) mounted on the opposite side of the blade from the reinforcing member. The reinforcing member is attached to the rear of the vibrating gate support shaft and the vibrating gate 132. If the reinforcing member is not provided, then the rotary vibrator may be attached to the gate support shaft or to another suitable portion of the gate 132. The vibration means is typically a rotating ball type pneumatic vibrator. The vibration level may be controlled with a conventional air regulator (not shown). The gate 132 may be mounted to the side walls 54 of the headbox 44 by a support system (not shown) to allow the position of the blade to be adjusted both horizontally and vertically. The support system includes a pivot pin which is attached, respectively, to each end of the gate support shaft and sits in an adjustable mount which is attached to a side wall 54 of the slurry feeding apparatus. One version of the adjustable mount has a pivot yoke which sits in a U-shaped member. Screws pass through legs extending upwardly from the U-shaped mount to allow fore and aft adjustment of the position of the pivot yoke and, in turn, of the gate 132.Also, bolts are provided through the holes in the U-shaped member to allow up and down adjustment of the position of the pivot yoke and, in turn, the gate 132. Preferably, the vibratory gate 132 can be pivotally adjusted to vary the gap D (Figure IB) between the gate 132 and the metering roller 48 by means of a pivot adjustment system (not shown). The vibrating gate 132 helps prevent significant buildup of the slurry 46 in the gate 132 and controls the thickness of the slurry 46 being deposited on the metering roller 48. Typically, the slurry feeder 44 has a pair of relatively rigid side walls 54 (one is shown), preferably made of or coated with a non-stick material such as TEFLON® material or the like. The side walls 54 prevent the slurry 46 being poured at the clamping point 52 from escaping off the sides of the slurry feeder 44. The side walls 54, which are preferably secured to the support frame 12 (Figure 1A), are in close relation to the ends of the rollers 48, 50 to retain the slurry 46. However, the side walls 54 are not excessively close to the ends of the rollers as to interfere with roller rotation. The grout feeder 44 deposits a uniform layer of grout 46 onto the moving carrier frame 26. Suitable layer thicknesses range from about 0.05 inches to 0.35 inches (0.13 to 0.9 cm), e.g., about 0.08 inches to 0.3 inches. However, with four layers preferred in the structural panel being produced by the production line 10, and a suitable building panel being about 0.75 inches, an especially preferred grout layer thickness is in the range of 0.15 to 0.25 inches. However, for a target panel forming thickness of about 0.84 inches, the standard layer thickness is typically closer to about 0.21 inches at each of the 4 forming stations. ηζααηη / ζζηζ / Ε / γίΛΐ Thus, the relative distance D (Figure IB) between the vibratory gate 132 and the main metering roll 48 may be adjusted to vary the thickness of the slurry 46 being deposited. The nip point distance D between the gate 132 and the metering roll 48 is typically maintained at a distance of about 1 / 8 to about 3 / 8 inch (about 0.318 to about 0.953 cm). However, this may be adjusted based upon the viscosity and thickness of the slurry 46 and the desired thickness of the slurry to be deposited on the web 26. Slurry 46 is supplied to slurry feeder 44 via a hose 56 or similar conduit having a first end 60 (Figure IB) in fluid communication with the outlet of slurry mixer or reservoir 47. A second end 62 of hose 56 is connected to a cable-actuated, laterally reciprocating, fluid-powered dispenser 64 (Figure IB) of the type well known in the art. Slurry flowing from hose 56 is therefore poured into feeder 44 in a laterally reciprocating motion to fill a reservoir 57 which is defined by rollers 48, 50 and side walls 54 of slurry feeder 44. Rotation of metering roller 48 draws a layer of slurry 46 from reservoir 57. Another feature of the present feed apparatus 44 is that the main metering roll 48 and the companion roller 50 are both driven in the same direction, thereby minimizing the chances of premature setting of the grout on the respective movable external surfaces. A drive system (not shown), including a fluid powered, electric, or other suitable motor, is connected to either the main metering roll 48 or the companion roller 50 to drive the roller(s) in the same direction, which is clockwise when viewed in Figures 1A and 1B. As is well known in the art, any one of the rollers 48, 50 may be driven and the other roller may be connected via pulleys, belts, chains and sprockets, gears or other known power transmission technology to maintain a common, positive rotational relationship. The slurry feeder 44 has a doctor blade 134 (Figure IB) which is located between the main metering roll 48 and the carrier web 26 to ensure that the relatively thin slurry 46 is completely deposited as a continuous curtain or sheet of slurry which is evenly directed to within a distance of about 1.0 to about 1.5 inches (2.54 to 3.81 cm) of the carrier web 26. The doctor blade 134 ensures that the slurry 46 evenly covers the fiberglass layer on the carrier web 26 and does not back up towards the clamping point 52 and the feed bin 57. The doctor blade 134 also helps to keep the main metering roll 50 free of prematurely setting slurry 46. The scraper blade 134 is mounted on a scraper blade support shaft (not shown) which is mounted to a scraper blade tension arm which is pivotally mounted to an adjustable pivot mount which is attached to the support frame or side wall 54 of the slurry feeder 44. A shaft or bar is attached to the side walls 54 of the slurry feeder 44 above the metering roll 48. The scraper blade 134 is biased toward the roll 48 by a tension spring having a first end which is attached to the shaft or bar and a second end which is attached to the free end of the scraper blade tension arm. The scraper blade 134 is thus held in a position adjacent the outer surface of the metering roll 48 by the tension arm and the tension spring.The position of the scraper blade 134 may be adjusted by adjusting the adjustable pivot assembly that is attached to the support frame or side wall 54 of the slurry feeder 44. The scraper blade 134 removes the slurry from the surface of the metering roll 48 and serves to collect the slurry 46 in an even layer or curtain and directs the slurry 46 downward in the direction of web movement to a point about 1.0 to 1.5 inches (92.54 to 3.81 cm) above the fiberglass layer in the web so as to uniformly cover the fiberglass layer with the slurry 46. The reciprocating dispensing mechanism 64, gate 132, and scraper blade 134 are explained in greater detail in U.S. Patent No. 7,754,052 to Frank, et al., entitled "Process and apparatus for feeding cementitious slurry for fiber-reinforced structural cement panels," and is incorporated herein by reference in its entirety. Other embodiments of slurry feeding apparatus may be used as are known in the art. One such apparatus is described in U.S. Patent No. 8,770,139 to Frank, et al., entitled "Apparatus for feeding cementitious slurry onto a moving web," and is incorporated herein by reference in its entirety. D. Processing downstream of the slurry feed apparatus Referring again to Figure 1A, the other operating components of the FRC panel production line will be briefly described, but are described in more detail in the following documents, all of which are incorporated herein by reference in their entirety: U.S. Patent No. 6,986,812 to Dubey et al., entitled Slurry feed apparatus for fiber-reinforced structural cementitious panel production; U.S. Patent No. 7,182,589 to Porter, entitled Embedment device for fiber-enhanced slurry; ηζααηη / ζζηζ / Ε / γίΛΐ U.S. Patent No. 7,445,738 to Dubey et al., entitled, Multi-layer process and apparatus for producing high strength fiber-reinforced structural cementitious panels; U.S. Patent No. 7,475,599 to Frank et al., entitled Wet slurry thickness gauge and method for use of same; U.S. Patent No. 7,513,768 to Porter et al., entitled Embedment roll device. U.S. Patent No. 7,513,963 to Frank et al., entitled Method for wet mixing cementitious slurry for fiberreinforced structural cement panels; U.S. Patent No. 7,524,386 to George et al., entitled "Method for wet mixing cementitious slurry for fiber-reinforced structural cement panels"; and United States Patent No. 7,670,520 to Dubey, entitled Multi-layer process and apparatus for producing high strength fiber-reinforced structural cementitious panels with enhanced fiber content. E. Embedding device A variety of embedding devices are contemplated, including, but not limited to, vibrators, sheepsfoot rollers, and the like. However, Figure 1A shows that the embedding device 70 includes at least one pair of generally parallel shafts 76 that are mounted transversely to the direction of travel of the carrier frame 14 in the frame 12. Each shaft 76 is provided with a plurality of relatively large diameter discs 76 that are axially separated from each other on the shaft by small diameter discs (not shown). During production of the SCP panel (FRC panel), the shafts 76 and discs 74 rotate together about the longitudinal axis of the shaft 76. As is well known in the art, either one or both of the shafts 76 may be powered, and if only one is powered, the other may be driven by belts, chains, gears, or other known power transmission technologies to maintain a direction and speed corresponding to the shaft being driven. The respective discs 74 of adjacent, preferably parallel, shafts 76 overlap and interlock with each other to create a kneading or massaging action in the slurry, which embeds the previously deposited fibers 68. Furthermore, the close, interlocking, rotating relationship of the discs 74 prevents buildup of slurry 46 on the discs and, in effect, creates a self-cleaning action that significantly reduces production line downtime due to premature setting of slurry clumps. The interlocking relationship of the discs 74 on the shafts 76 includes a close adjacent arrangement of the opposing peripheries of the small diameter separator discs (not shown) and the relatively large diameter main discs 74, which also facilitates the self-cleaning action. As the discs 74 rotate relative to each other in close proximity (but preferably in the same direction), it is difficult for slurry particles to become trapped in the apparatus and set prematurely. By providing two sets of discs 74 that are laterally offset from each other, the slurry 46 is subjected to multiple breaking acts, creating a kneading action that further embeds the fibers 68 into the slurry 46. F. Thickness control Once the fiber 68 has been embedded, a first layer 77 of the panel 92 is completed. Typically, the height or thickness of the first layer 77 is in the range of about 0.05 inches to 0.35 inches (0.13 to 0.9 cm). Preferably, the height or thickness of the first layer 77 is in the range of about 0.08 to 0.3 inches. This range has been found to provide the desired strength and stiffness when combined with similar layers in an FRC panel (SCP panel). However, other thicknesses are contemplated depending on the intended end use of the FRC panel (SCP panel). Then, the first layer 77 comes into contact with a thickness control device 93 of the present invention for controlling the thickness of the formed, but not yet set, first layer 77 of fiber-reinforced cementitious panel comprising a fiber-laden cementitious slurry comprising cementitious material and chopped fibers embedded in the movable carrier frame 26. The thickness control device 93 comprises an angled rigid plate 95 and a U-shaped mounting bracket 97 for mounting the angled rigid plate 95 onto the support frame or forming table 12 for the movable carrier frame 26.The mounting bracket 97 has opposing upright members 99 (one is shown in Figure 1A for clarity), a tiltable cross-mount member 101 having opposite ends that mount to respective upright members 99 at a fixed but adjustable angle relative to the movable carrier frame 26 and a fixed but adjustable height above the movable carrier frame 26. The mounting frame 97 further has a connector plate 103 having an upper end portion that is attached to the cross-mount member 101 and a lower end portion that is attached to a rear wall of the angled rigid plate 95. A vibrator (vibration motor) 105 is also mounted to the rear wall of the angled rigid plate 95. Figure 1A shows a forming table 12, an endless belt 14, and a carrier web 26 and optional lower support plates 46A, 46B. The production line 10 provides a rigid, flat support bed under each angled rigid plate 95 that is conformable and configured sufficiently to support the fiber-laden slurry and preferably resist the downward force exerted by the angled rigid plate ηζααηη / ζζηζ / Ε / γίΛA with a deflection of less than 0.03 inches, preferably less than 0.01 inches, preferably less than 0.003 inches. The rigid, flat support bed is provided to counteract the downward force of the fiber-laden slurry covered with the liner passing under the rigid horizontal upper forming plate 446 and may, for example, be any of the following: the forming table 12 if sufficiently rigid, the forming table 12 is further supported by the rigid lower forming plate 46A, which is provided under the carrier belt 14, rigid panels used on the carrier belt 14 under or instead of the carrier web 26, the endless belt 14 could be supported by sufficient rollers to be rigid, or there could be a break in the forming table 12 and the rigid lower forming plate 46A is placed at the break directly under the portion of the endless belt under the upper forming plate 446. As mentioned above, it is also contemplated that, instead of the continuous carrier web 26, 14 individual sheets (not shown) of a relatively rigid material, e.g., sheets of polymeric plastic, may be placed on the carrier. These may also provide the bed of rigid, planar support. Figures 2, 3, 4A, 4B and 5 show details of the construction of the thickness control device 93. Figure 2 is a schematic of the angled vibratory plate 95, typically made of metal, with a coupling unit 204 for attaching a vibrator (vibration motor) 105 (see Figure 1A) to impart vibration to the plate. The angled vibratory metal plate 95 has an angled cross section, with a back wall 200, a bottom wall 201, and a downstream functional edge 202 which, in operation, sits in the cementitious slurry to a certain depth (ID, see Figure 4A) and imparts vibrations to the slurry. Screws 203 are provided for attaching the coupling unit 204 to the back wall 200 of the angled plate 95. The angled plate 95 is typically made of metal. Figure 3 is a schematic figure of a typical U-shaped mounting frame 97 of the thickness control device 93 for installing the angled vibratory metal plate 95 and the vibrator (vibration motor) 105 (see Figure 1A) in the production line 10 for fiber reinforced cementitious panels. The U-shaped mounting frame 97 has vertical members 99 which are fixedly attached to a stationary frame cross member 220. The U-shaped mounting frame 97 further has the swinging cross mounting member 101 which is movably attached to the vertical members 99. The swinging cross mounting member 101 has opposite ends, each of which is rotatably mounted on a respective metal plate 206 with holes for angle adjustment. The typically rectangular U-shaped metal mounting frame 97, made from modular pieces of metal channels, typically 4 inches by 4 inches, which can be easily connected via slots and bolts or screws, is shown in Figure 3. A pair of screw jacks 212 with individual caster wheels 214 and handles, which are installed on each side of the forming surface, to adjust the height of the vibratory metal plate from the forming surface and level the plate parallel to the forming surface. A metal rod, typically 0.5 inches in diameter, which is locked in a specific angular position by holes in metal plates 206 which are mounted on the two sides of the mounting frame 97 in a plane perpendicular to the forming surface, to adjust the angle of the vibratory metal plate 95 with the forming surface, as shown in Figure 3.Therefore, each of the opposite ends of the tilting cross mounting member 101 is paired with a hole that is selected for adjusting the angle of the plate 206 to fixedly set the angle of the tilting cross mounting member 101 relative to the movable carrier frame 26, as well as relative to ηζααηη / ζζηζ / Ε / γίΛA the grout in the movable carrier frame 26. When the angle of the tilting cross mounting member 101 is adjusted and set, the angle of the tilting cross mounting member 101 of the 95 angle vibrating metal plate that is mounted on the tilting cross mounting member 101 is likewise adjusted and set to the angle a (alpha). Figure 3 also shows a location 205 on the coupling unit 204 for mounting the vibration motor. To assist in adjusting the angle, the tilting cross-mount member 101 is provided with a handle 208 for raising and lowering the vibratory plate. The handle 208 is typically metal in the form of a tube or rod, typically rectangular and 1 inch by 1 inch in cross-section, but may also be circular or other cross-sectional shape, which attaches to the center cross-member of the frame member 101 allowing rotation about the axis perpendicular to the forming direction in the forming plane, to disengage the replacement, cleaning, or maintenance mechanism for lifting the plate from the manufacturing line, as shown in Figure 3. The mounting mechanism 97 described above typically maintains the vibratory plate at a fixed height that is set from the forming surface (belt / plate) across the width such that the functional edge of the plate remains within the slurry surface at a depth of 0.05 inches or more, and that the plate does not adjust in height itself with the incoming flow of materials. Figure 4A shows the angle α (alpha) of the bottom wall 201 of the 95 angled rigid plate relative to the surface of the movable carrier frame 26. Figure 4A shows the angle β (beta) of the bottom wall 201 of the 95 angled rigid plate relative to the surface of the grout 77, if present, in the movable carrier frame 26. For the purposes of this description, the angle α (alpha) and the angle β (beta) are equal. Figure 4A also shows the depth DI, the downstream end 202 of the bottom wall 201 of the angled rigid plate 95 dips into the grout surface 77 in the movable carrier frame 26. The angled plate angle α (alpha) and angle β (beta) are from 5° to 30°, typically the angle α (alpha) and angle β (beta) are in the range of 10° to 25°. The metal plates 206 travel vertically up and down the vertical members 99 along the channels 210 of the vertical members 99 and the stationary frame cross member 220 of the frame 97. When the metal plates 206 travel vertically, the tilting cross mounting member 101 travels vertically with the plates 206. In order to raise and lower the height of the tilting cross mounting member 101, the U-shaped mounting frame 97 has screw jacks 212 and caster wheels 214 (one is shown) for moving the screw jacks 212. The angled vibrating metal plate 95 when mounted on the tilting cross mounting member 101 moves vertically with the tilting cross mounting member 101. Figure 5 shows a lightweight, stationary, vibrating metal plate configuration for reducing thickness variation during the forming of fiber-reinforced cementitious panels across the width of a forming surface. Figure 5 shows vibrator (vibration motor) 105 being attached to coupling unit 204. A rear end of coupling unit 204 is attached to the rear wall of vibratory metal plate at an angle 95°. Figure 4A shows that the top wall of the coupling unit is attached to a connector plate 103 having an upper end portion that is attached to cross-mount member 101 and a lower end portion that is attached to the rear wall of rigid plate at an angle 95°. An elastomeric damper 212A is located between the lower end of connector plate 103 and the top wall of coupling unit 204. This inventive thickness control device 93 solves the problem of producing cementitious panels with reduced thickness variation to decrease processing steps during forming. The inventive thickness control device 93 provides a mechanism that imparts vibrations to the forming slurry in a plane parallel to the forming surface (belt / plate) to evenly spread the materials on the surface in a manner that would reduce thickness variations. The invention provides a method for reducing thickness variation during the forming of fiber-reinforced cementitious panels, with the use of a lightweight, stationary, vibratable metal plate across the width of the forming surface to impart contact vibrations into the surface or into the cementitious slurry containing reinforcing fibers. G. The angled plate The 95 angle vibrating plate of the invention typically has the following characteristics: The 95 angle plate is typically made of metal, preferably magnesium alloy, although aluminum, titanium, steel and other metal alloys can also be used. The 95° angle plate cross section is generally angled, however, other cross sections can also be used to provide a flat or curved surface in contact with the grout and offer structural rigidity. The shape of the 95 angle plate may be L-shaped, but it need not be a perfect L-shape, i.e. the angle between the rear wall and the bottom wall may not necessarily always be 90°. The angle between the two walls may vary from obtuse to acute. For example, the angle between the two walls may vary from 60° to 120°, preferably from 70° to 110°, and most preferably from 80° to 100°. Furthermore, the transition geometry of the bent transition section between the rear wall and the bottom wall may be acute or curved. Figure 4B shows the 195 angle rigid plate which is a version of the 95 angle rigid plate that is modified to have the transition geometry between the rear wall 200 and the bottom wall 201 that is curved at a radius of curvature r. The radius of curvature of the transition bent section can vary between 0.05 inches and 2 inches. In other respects, the 195 angle rigid plate and the 95 angle rigid plate are the same. Beyond the bent transition section, the thickness of the bottom wall may be either uniform or tapered, with the thickness decreasing from the end of the transition section to the edge of the bottom wall. Furthermore, the lower surface of the bottom wall beyond the end of the transition section and in contact with the cementitious grout is in the form of a two-dimensional plane without any curvature. The upper surface of the bottom wall beyond the end of the transition section may either be in the form of a two-dimensional plane or take on any other curvilinear surface geometry, such as a surface that gradually tapers toward the edge of the bottom leg. Furthermore, the back wall and the bottom wall assembly may optionally be braced together, either continuously or intermittently, along the length of the assembly by using cross-bracing elements.When the assembly is braced continuously, the bracing element may be a single piece added externally to the angle element, or alternatively, it may be cast, extruded, or monolithically formed to the angle element. The continuous bracing element may take on different geometries to impart the desired rigidity to the vibratory assembly. Furthermore, the rear wall of the assembly may be in the form of a flat two-dimensional plane, or alternatively, it may be formed or bent into a three-dimensional shape to increase the material's rigidity. The 95 angle plate has one face in contact with the cementitious grout and another face perpendicular or at an angle to the face in contact with the grout, to which the vibratory motor is mounted or connected. The length of the vibratory plate at an angle 95° (in the machine travel direction T) on the side in contact with the slurry is typically from about 2 inches to 24 inches. The preferred length of the plate on the side in contact with the slurry ranges from about 2 inches to 12 inches. The most preferred length of the plate on the side in contact with the slurry ranges from about 2 inches to 6 inches. The width of the 95° angle vibratory plate (in the direction transverse to the direction of travel of the machine T) may vary from about 1 foot to 8 feet. The preferred width of the metal plate ranges from about 2 feet to 6 feet, or from about 2 feet to 5 feet, or from about 3 feet to 4 feet. The thickness of the 95° angle vibratory plate on the side in contact with the grout is typically about 1 / 16 inch to 1 / 4 inch. The 95° angle vibratory plate may have a gradual taper from the side away from the grout contact to the edge in contact with the grout. The preferred thickness of the plate on the side in contact with the grout is about 1 / 8 inch with a gradual taper from 1 / 4 inch thick on the side away from the grout contact to 1 / 16 inch at the edge in contact with the grout. The 95° angle vibratory plate is positioned so that the functional edge of the plate remains in contact with the grout, at a depth of 0.05 inches or more into the grout. The 95 angle vibrating plate is vibrated by a vibrating motor 105 having a weight attached near the metal plate so that the vibrations of the motor and the vibrations of the plate remain in phase. The preferred distance of the rotating weight from the metal plate varies from about 0.50 to 8 inches, about 1 to 7 inches, or about 2 to 6 inches. The rotational speed of the eccentric weights is typically from about 100 rpm to about 4000 rpm. The vibratory motor is mounted so that the eccentric weight, which is attached to the rotating shaft, rotates in a plane parallel to the face of the metal plate in contact with the cementitious grout. The vibrating motor 105 is typically electrically driven, but may also be a pneumatic or gas-powered mechanical device. Vibrations are typically produced by the rapid circular motion of the rotating shaft, to which an eccentric weight is attached. The eccentricity of the weight governs the amplitude of the vibrations, while the rotations per minute govern the frequency of the vibrations, and the magnitude of the weight governs the power required by the motor and the intensity of the vibration. The vibrator mounted on the top surface of the rear wall of the angle plate assembly imparts vibration in the plane parallel to the forming surface of the fiber-reinforced cementitious panel. It has been found that vibration imparted in the plane perpendicular to the forming surface of the fiber-reinforced cementitious panel produces less than optimal results. Additionally, the frequency, amplitude, and vibration mode of the angle plate assembly are controlled by a vibration controller. This vibration controller can be operated either electrically or pneumatically. When an electric vibrator is used, the extent and mode of vibration of the rigid plate assembly are effectively controlled by varying the RPM of the eccentric rotating weight within the vibrator assembly. The type and amount of vibration applied is tailored based on the rheological properties of the fiber-reinforced grout and the thickness of the grout layer used to form the panel. Quite unexpectedly, it has been discovered that a more uniform panel surface profile across the width of the panel is obtained when the outer edge of the bottom wall of the angled rigid plate assembly is positioned lower than the top surface of the panel being formed. Accordingly, the outer edge of the bottom wall of the angled rigid plate assembly is positioned from about 0.01 inches to 0.25 inches lower than the top surface of the panel being formed. For example, if the desired panel thickness is 0.75 inches, the outer edge of the bottom wall of the angled rigid plate assembly is positioned from about 0.55 inches to 0.74 inches from the bottom cast surface of the panel, in other words, from about 0.55 inches to 0.74 inches from the movable pattern over which the cast surface of the panel rides.Preferably, the outer edge of the bottom wall of the rigid angle plate assembly is positioned from about 0.02 inches to 0.15 inches below the top surface of the panel being formed. More preferably, the outer edge of the bottom wall of the rigid angle plate assembly is positioned from about 0.03 inches to 0.10 inches lower than the top surface of the panel being formed. It is an unexpected discovery that setting the rigid plate assembly below the target panel thickness does not have the effect of reducing the actual thickness of the panel being formed. H. Apply additional layers To construct a fiber-reinforced concrete (FRC) panel (structural cementitious panel) of the desired thickness, additional layers are typically added. To that end, a second grout feeder 78, which is substantially identical to feeder 44, is provided in operative relationship with movable carrier 14 and is arranged to deposit an additional layer 80 of grout 46 over the existing layer 77. Next, an additional chopper 82, substantially identical to choppers 36 and 66, is provided in operative relationship with frame 12 for depositing a third layer of fibers 68 that are provided from a rack (not shown) that is constructed and arranged relative to frame 12 in a manner similar to rack 31. Fibers 68 are deposited onto slurry layer 80 and embedded through the use of a second embedding device 86. Similar in construction and arrangement to embedding device 70, second embedding device 86 is mounted slightly higher relative to movable carrier frame 14 so that first layer 77 is not disturbed. In this manner, second layer 80 of slurry and embedded fibers is created. Referring to Figures 1A and 6, with each successive layer of settable grout and fibers, an additional grout feed station 78 followed by a fiber chopper 82 and an embedding device 86 is provided on the production line 10. Preferably, four total layers 77, 80, 88, 90 are provided to form the SCP panel 92. For clarity, additional mixers may be used to feed the additional grout feed stations 78, but are not required. They are not shown in Figures. An important feature of the present invention is that the panel 92 has multiple layers 77, 80, 88, 90 which, upon setting, form an integral fiber-reinforced mass. As long as the presence and placement of the fibers in each layer are controlled and maintained within certain desired parameters as described and disclosed herein, it will be virtually impossible to delaminate the panel 92 produced by the present process. I. Shaping, smoothing and cutting After the four layers of settable grout have been deposited, they are embedded in the fibers as described above. If desired, another thickness control device 93 having an angled plate 95 can be provided as a smoothing device downstream of the last embedding device 86. After the panel layers 92 have been smoothed by the thickness control device 93, they will begin to set. Once the layers are configured, the respective panels 92 are separated from each other by a cutting device 98, which is typically a saw or a waterjet cutter. Other cutting devices, including movable knives, are considered suitable for this operation, as long as they can create suitably sharp edges in the present panel composition. The cutting device 98 is arranged relative to the production line 10 and the frame 12, so that panels, not shown, are produced having a desired length. Since the speed of the carrier 14 is relatively slow, the cutting device can be mounted to cut perpendicular to the direction of travel of the carrier 14.At faster production speeds, such cutting devices are known to be mounted on the production line 10 at an angle to the direction of travel of the web. After cutting, the separated panels are stacked for further handling, packaging, storage, and / or shipping, as is well known in the art. Production line 10 includes sufficient fiber chopping stations 36, 66, 82, slurry feed stations 44, 78, and embedding devices 70, 86 to produce at least four layers 77, 80, 88, and 90 (Figure 6). Additional layers may be created by repeating stations as described above in connection with production line 10. After creating the FRC panels 92, a bottom 102 or lower face of the panel may be smoother than the top or upper face 96, even after being engaged by the forming device 94. In some cases, depending on the application of the panel 92, it may be preferable to have one smooth face and one relatively rough face. However, in other applications, it may be desirable to have a panel in which both faces 96, 102 are smooth. The smooth texture is generated by the contact of the grout with the smooth carrier 14 or the carrier web 26. Another feature of the present invention is that the resulting FRC panel 92 is constructed so that the fibers 30, 68 are evenly distributed throughout the panel. It has been found that this allows for the production of relatively stronger panels with relatively less and more efficient use of fibers. The volume fraction of fibers relative to the volume of slurry in each layer preferably constitutes a range of about 1% to 5% by volume, preferably 1.5% to 3% by volume, of the slurry layers 77, 80, 88, 90. If desired, the outer layers 77, 90 may have a higher volume fraction than either or both of the inner layers 80, 88. In the invention by using multiple discrete layers of fiber, a desired fiber volume fraction in the panel, Vf, e.g., a percentage fiber volume content in each grout layer of 1-5%. A preferred thickness of the individual grout layers is <0.35 inches. A more preferred thickness of the individual grout layers is ≥0.30 inches. A most preferred thickness of the individual grout layers is ≥0.25 inches. A preferred fiber strand diameter is ≤30 tex. A most preferred fiber strand diameter is ≤70 tex. Suitable layer thicknesses range from about 0.05 inch to 0.35 inch (0.13 to 0.9 cm). For example, to manufacture a structural panel of nominal thickness 3 / 4 inch (1.9 cm), four layers are preferred with an especially preferred grout layer thickness of less than about 0.25 inch (0.64 cm) in the preferred structural panel produced by the present process. ηζααηη / ζζηζ / Ε / γίΛΐ If desired there may be a further thickness control device 93 having an angled plate 95 after each embedding roller 48 and / or headbox 78. III. Second version of a production line The incorporation of a volume fraction of loose fibers distributed throughout the grout 46 is an important factor in achieving the desired panel strength. Therefore, it is desirable to improve the efficiency of fiber incorporation. It is believed that the system depicted in Figures 1A-6 in some cases requires excessive numbers of grout layers to obtain an FRC panel with a sufficient fiber volume fraction. Accordingly, an alternative FRC panel production line or system is illustrated in Figure 7 and generally designated 130 for producing high performance fiber reinforced FRC panels incorporating a relatively high volume of fibers per layer of grout. In many cases, higher levels of fibers per panel are achieved through the use of this system. Whereas the system of Figures 1A-6 describes the depositing of a single discrete layer of fibers into each subsequent discrete layer of grout that is deposited after the initial layer, production line 130 includes a method of building up multiple discrete layers of reinforcing fibers into each discrete layer of grout to achieve a desired panel thickness. Most preferably, the system described embeds at least two discrete layers of reinforcing fibers, in a single operation, into a single discrete layer of grout.Discrete reinforcing fibers are embedded in the discrete grout layer by using a suitable fiber embedding device. More specifically, as seen in Figure 7, to implement the present multi-layer system 130 of fibers 30, 68 for each grout layer 46, additional chopping stations 142 are provided between the embedding device 136 and subsequent grout feed boxes 78, so that, for each grout layer 46, the fibers 30, 68 are deposited before and after the deposition of the grout. It has been found that this improvement allows for the introduction of significantly more fibers into the grout and consequently increases the strength of the resulting SCP panel. Preferably, while only three layers are shown, four total layers of grout and fiber combined to form the SCP panel 92 are provided. IV. Third version of a production line that deposits fiber-laden grout from a headbox to make an FRC panel from a single layer of grout. The thickness control device of the invention may also be applied to a process for making fiber-reinforced cementitious (FRC) panels in which, instead of adding fibers to the slurry in the moving carrier web, the fibers are mixed with the slurry upstream of the moving carrier web to form a fiber-laden cementitious slurry. This fiber-laden cementitious slurry is then fed to a headbox, and then deposited by the headbox onto the moving carrier web. A. Panel production Figure 8 shows diagrammatically a production line generally designated 310 for producing cementitious panels, for example, for producing fiber reinforced concrete (FRC) panels. The production line 310 includes a support frame or forming table 312 having a plurality of legs 313 or other supports. Included in the support frame 312 is a movable carrier 314, such as an endless rubber-like conveyor belt with a smooth, water-impermeable surface; however, porous surfaces, such as a web, are contemplated. As is well known in the art, the support frame 312 may be made of at least one table-like segment, which may include legs designated 313 or other support structure. The support frame 312 also includes a main drive roller 316 at a distal end 318 of the frame, and an idler roller 320 at a proximal end 322 of the frame.Also, at least one belt tracking and / or tensioning device 324 is typically provided to maintain a desired tension and positioning of the carrier 314 on the ηζααηη / ζζηζ / Ε / γίΛA rollers. 316, 320. In this version, the cementitious panels are produced continuously as the mobile carrier advances in a direction T from the proximal end 322 to the distal end 318. In this embodiment, a web 326 of kraft paper, release liner, polymer film, plastic carrier, or nonwoven fiber mat may be provided to support a slurry prior to setting and placed over the carrier belt 314 to protect and / or keep it clean. However, it is also contemplated that instead of the continuous web 326, individual sheets (not shown) of a relatively rigid material, e.g., polymeric plastic sheets, may be placed on the carrier 314. These carrier films or sheets may be eliminated from the panels being produced at the end of the line, or they may be incorporated as a permanent feature into the panel as part of the overall composite design.When these films or sheets are incorporated as a permanent feature into the panel, they can provide enhanced attributes to the panel, including improved aesthetics, improved tensile and flexural strengths, improved impact and blast resistance, improved environmental durability such as water and water vapor transmission resistance, freeze-thaw resistance, salt fouling resistance, and chemical resistance. ηζααηη / ζζηζ / Ε / γίΛΐ Production line 310 employs a thickness control device 93 having an angled plate 95, details of which are described above. Figure 8 shows a forming table 312, a carrier belt 314, and a carrier web 326 and an optional lower support plate 46A. The production line 310 provides a rigid, flat support bed under each angled rigid plate 95 that is conformable and configured sufficiently to support the fiber-laden slurry and preferably resist the downward force exerted by the angled rigid plate 95 with a deflection of less than 0.03 inches, preferably less than 0.01 inches, preferably less than 0.003 inches. The rigid, flat support bed is provided to counteract the downward force of the fiber-laden slurry covered with the liner passing under the rigid horizontal upper forming plate 446 and may, for example, be any of the following: the forming table 312 if sufficiently rigid, the forming table 312 is further supported by the rigid lower forming plate 46A, which is provided under the carrier belt 314, rigid panels used on the carrier belt 314 under or instead of the carrier web 326, the endless belt 314 could be supported by sufficient ηζααηη / ζζηζ / Ε / γίΛA rollers to be rigid, or there could be a break in the forming table 312 and the rigid lower forming plate 46A is placed at the break directly under the portion of the endless belt under the upper forming plate 446. As mentioned above, it is also contemplated that, instead of the continuous carrier web 326, individual sheets (not shown) of a relatively rigid material, e.g., sheets of polymeric plastic, may be placed on the carrier 314. These may also provide the rigid, flat support bed. In this embodiment, continuous reinforcement 344 such as a wick, a nonwoven fiber web, or a reinforcing mesh web such as fiberglass mesh may be provided to be embedded in the grout prior to setting and reinforcing the resulting cementitious panels. The continuous wicks, nonwoven fiber web, and / or reinforcing mesh 344 from roller 342 are fed through headbox 340 to lie over the grout in carrier 314. However, it is also contemplated that the continuous reinforcement 344 may be employed after headbox 340 or not at all. Continuous scrim or strands can be made from various reinforcing fiber materials, including glass fibers; polymeric materials such as polypropylene, polyethylene, polyvinyl alcohol, etc.; carbon; graphite; aramid, ceramic; steel; cellulosic or natural fibers such as jute or sisal; or a combination of these. A roving is an assembly of continuous reinforcing monofilaments. The scrim is a web of continuous fibers running in the machine direction and the cross direction. The reinforcement may also be provided as a nonwoven web made of discrete reinforcing fibers. The lower continuous reinforcement, if desired, is fed behind the headbox 340 and rests directly on top of the conveyor / forming belt. The lower continuous reinforcement passes under the headbox, and the grout in the headbox 340 is poured directly onto its top as the continuous reinforcement moves forward.For example, continuous reinforcement may be provided by a web or roller (not shown) upstream of the headbox in addition to that provided by web 326 to position continuous reinforcement above web 326. It is also contemplated that the cementitious panels produced by the present line 10 may be formed directly on the carrier 314. In the latter situation, at least one belt washing unit 328 is provided. The carrier 314 is moved along the support frame 312 by a combination of motors, pulleys, belts or chains driving the main drive roller 316 as is known in the art. It is contemplated that the speed of the carrier 314 may be varied to suit the product being made. The present production line 310 includes a continuous grout mixer 302. The grout mixer may be a single-shaft or twin-shaft mixer. The dry powder feeder 304 feeds the dry components of the cementitious composition, except for the reinforcing fibers, to the grout mixer 302. The liquid pump 306 feeds an aqueous medium, such as water, with liquid or water-soluble additives to the grout mixer 302. The grout mixer 302 mixes the dry components and the aqueous medium to form a cementitious slurry 331. The cementitious slurry 331 feeds a first grout accumulator and a positive displacement pump 330 which pumps the slurry to a fiber-slurry mixer 332. A fiber feeder 334 feeds fibers 335 to the fiber-slurry mixer 332. Thus, in the fiber-slurry mixer 332, the fibers and slurry are mixed to form a fiber-slurry mixture 336.The fiber grout mixture 336 feeds a second grout accumulator and a positive displacement pump 338 which pumps the fiber-grout mixture 336 to a headbox 340. The headbox 340 deposits the fiber-slurry mixture 346 onto the release paper web 326 (if present) or, if present, the continuous reinforcement 344 provided by the rovings and / or mesh roller 342, which travels on the movable carrier 314. To assist in leveling the fiber-slurry mixture 346, a vibratory forming plate 350 may be provided under or slightly downstream of where the headbox 340 deposits the fiber-slurry mixture 346. The headbox 340 will deposit a fiber grout mixture as a layer onto a moving surface of a cementitious panel production line uniformly as a 0.125 to 2 inch thick, preferably 0.25 to 1 inch thick, typically 0.40 to 0.75 inch thick layer onto the moving surface of the panel production line to produce a fiber-reinforced cementitious panel. The fiber-grout mixture has a viscosity of less than 45,000 centipoise, preferably less than 30,000 centipoise, more preferably less than 15,000 centipoise, and most preferably less than 10,000 centipoise when measured by the use of a Brookfield Viscometer, Model DV-II+ Pro with an HA4 Spindle accessory operating at a speed of 20 RPM. Typically, the resulting fiber-slurry mixtures have a viscosity of at least 1500 centipoise. The resulting fiber-grout mixture further has a slump according to a slump test using a 4 inch high, 2 inch diameter tube, which is 4 to 11 inches. The fiber-grout mixture is not suitable for extrusion manufacturing processes which typically rely on grout mixture compositions having extremely high viscosity. The slump test used in the present disclosure uses a hollow cylinder about 5.08 cm (2 inches) in diameter and about 10.16 cm (4 inches) long which is held vertically with one open end resting on a smooth plastic surface. The cylinder is filled to the top with the cementitious mixture and the top surface is then tapped to remove excess grout mixture.The cylinder is then gently lifted vertically to allow the slurry to flow out the bottom and spread over the plastic surface to form a circular medallion. The medallion diameter is then measured and recorded as the material slump. As used herein, compositions with good flow behavior produce a higher slump value. The headbox 340 is arranged transversely to the direction of travel T of the carrier web 314. The fiber-slurry mixture 346 is deposited in a cavity of the headbox 340 and discharged onto the moving carrier web 326 (or the conveyor belt 314) through a discharge opening on the moving carrier web 326. The fiber-reinforced cement slurry may be pumped through a hose system and a hose oscillator to the headbox 340 or may be dropped into the headbox 340 directly from the fiber-grout mixer 332. The oscillator system would in either case be used to agitate the slurry. The thickness of the product formed by use of the headbox 340 is controlled by the flow rate of slurry in the headbox 340, the amount of slurry lift head in the headbox 340, and the headbox discharge opening spacing for a given line speed. Preferably, the line speed is 1 to 100 feet per minute, more preferably 5 to 50 feet per minute. Other speeds above 100 feet per minute are also contemplated, as would be understood by one skilled in the art.The size (volume) of the slurry chamber of the headbox 340 is adjusted based on the line speed and the thickness of the product being produced. Preferably, the slurry is deposited into the headbox at a rate of approximately 0.10–25 cubic feet per minute. The headbox discharge opening space 340 is a transverse opening through which the fiber-slurry mixture is discharged from the headbox 40 to the moving carrier frame 326. The fiber-slurry mixture from the headbox is deposited on the moving carrier frame 326 at a stage close to the desired thickness and finish of the final panel 355. Downstream of the headbox, a thickness control device 93 is provided for controlling the thickness of the deposited fiber-laden slurry 346. It has the same parts and operation as described above for the headbox thickness control device 93 for the multi-layer processes and apparatus of Figure 1A. In addition to the vibration provided by the angle plate 95 of the headbox thickness control device 93, additional vibration may be added to improve forming, and different forms of continuous reinforcements such as mesh and roving may be added to improve the flexural strength of the product being formed. For example, a vibration unit 350 may be located beneath the headbox 340 under the conveyor belt 314. The vibration unit 350 typically vibrates at a rate of 500 to 3000 cycles per minute, preferably 1000 to 2000 cycles per minute. The vibration unit 350 is typically a single mass system of a table, springs, and two motors that direct forces directly onto the depositing mat of fiber cement slurry and cancel them out in other directions. This 350 unit sits under the 340 inlet box and extends approximately 3 to 6 inches beyond the inlet box. The grout 346 sets as it travels along the movable carrier 326. At the distal end 318 of the support frame 312, a cutter 354 cuts the set grout into ηζααηη / ζζηζ / Ε / γίΛA FRC panels 355. The FRC panels (boards) 355 are then placed on an unloading and curing rack (not shown) and allowed to cure. Although not shown in Figure 8, production line 310 employs edge forming and leakage prevention devices. These are edge tapes or edge rails (used individually or in combination). The fiber-grout mixtures 336 discharged from the fiber-grout mixer 332 are suitable for making a fiber-reinforced cement (FRC) building panel or board 355. The fiber-slurry mixture discharging from the fiber-slurry mixer has a slump of 4 to 11 inches, preferably 6 to 10 inches, as measured according to a slump test using a 4-inch tall, 2-inch diameter pipe and a viscosity of less than 45,000 centipoise, preferably less than 30,000 centipoise, more preferably less than 15,000 centipoise, and most preferably less than 10,000 centipoise when measured using a Brookfield Viscometer, Model DV-II+ Pro with an HA4 Spindle accessory operating at a speed of 20 RPM. Typically, the resulting fiber-slurry mixtures have a viscosity of at least 1500 centipoise. The resulting fiber-grout mixture also has a slump according to the ηζααηη / ζζηζ / Ε / γίΛΐ slump test using a 4-inch high, 2-inch diameter pipe, which is 4 to 11 inches.The resulting fiber grout mixture is not suitable for extrusion manufacturing processes which typically rely on grout mix compositions having extremely high viscosity. The resulting fiber-grout mixture is a uniform fiber grout mixture having a consistency that will allow the fiber-grout mixture to be discharged from the horizontal fiber grout mixer and is suitable to be deposited as a continuous layer onto a moving surface of a panel production line uniformly as a 0.25 to 2.00 inch thick, preferably 0.25 to 1 inch thick, more preferably 0.5 to 0.75 inch thick layer on the moving surface of the panel production line to produce a fiber reinforced cement board. Preferred fiber-grout mixtures with favorable rheological properties that are processed through this headbox can be beneficially used as a workable slurry having a consistency that facilitates further processing and formation of panel products on a continuous forming line operating at high line speeds. Preferred fiber-grout mixtures for use with the single-layer process headbox are distinguished from the cementitious mixtures used in the extrusion / extrusion / E / GA extrusion processes. Such cementitious mixtures used in the extrusion processes have a slump of 2 to 3 inches as measured by a slump test using a 4-inch high, 2-inch diameter pipe and have a viscosity greater than 50,000 centipoise, more typically greater than 100,000 centipoise, and most typically greater than 200,000 centipoise. The extrusion mixtures also do not include plasticizers and superplasticizers, which are present in the fiber-grout mixtures of the present invention. As mentioned above, plasticizers are commonly manufactured from lignosulfonates, a byproduct of the paper industry.Superplasticizers have generally been manufactured from sulfonated naphthalene condensate or sulfonated melamine formaldehyde, or based on polycarboxylic ethers. B. Grout mixer for single-coat process Any of a variety of continuous or batch mixers may be employed as the slurry mixer 302. For example, the mortar mixers described in ICRI Guideline No. 320.5R-2014, Technical Guidelines, Pictorial Atlas of Concrete Repair Equipment, International Concrete Repair Institute, May 2014, which are incorporated by reference, may be used in this invention to prepare cementitious slurry 303. These include horizontal shaft mixers, tumbling mortar mixers, stationary rotary drum mixers, pan type mixers, rotary tub rotary paddle mixers, planetary paddle mixers, horizontal shaft mixer-pump combinations, and vertical shaft mixer-pump combinations. Horizontal shaft mixer-pump combinations and vertical shaft mixer-pump combinations are continuous mixers. Continuous grout mixers can also be used to prepare grout continuously. Commercially available continuous mixers are manufactured by PFT GmbH and Co. KG, based in Iphofen, Germany. These continuous mixers are capable of mixing as well as continuously pumping the grout to the point of application. These mixers have a mixing chamber where all of the dry solid materials are mixed together with the liquid additives, including water, through the use of a high-speed rotating cage agitator. In normal operation, the mixed cementitious grout continuously exits the mixing chamber and is pumped forward by a progressing cavity pump (rotor-stator type pump) to the point of application. Preferred PFT mixers for this invention include the PFT G4 mixing pump, the PFT G5 mixing pump, and the PFT MONOJET 2.13, the PFT T2E mixer pump, the PFT MSI ηζααηη / ζζηζ / Ε / γίΛΐ and MS2 mixer pump. In addition, the continuous grout mixers described in U.S. Patent No. 7,513,963 B2 to George et al., which is incorporated by reference, may also be used in the present invention. For example, the continuous grout mixer 302 may be a single-shaft or twin-shaft horizontal mixer. The term horizontal, when used with mixers, generally means horizontal. Therefore, a mixer that is oriented within plus or minus 20 degrees of horizontal would still be considered a horizontal mixer. C. Continuous horizontal fiber-slurry mixer for single-layer process The continuous fiber-slurry mixer of the present invention is preferably a horizontal continuous mixer. An example of this is described in published U.S. patent application No. 2018 / 0036912 to Dubey et al., which is incorporated herein by reference. The cementitious grout and fibers are mixed in the mixing chamber of the horizontal fiber-grout mixer for an average mixing residence time of about 5 to about 240 seconds, preferably 10 to 180 seconds, more preferably 10 to 120 seconds, most preferably 10 to 60 seconds while rotating blades apply a shearing force, wherein the central rotating shaft rotates at 30 to 450 RPM, most preferably 40 to 300 RPM, most preferably 50 to 250 RPM during mixing, to the fiber-grout mixture. Each horizontal shaft is externally connected to a drive mechanism and a drive motor, for example, powered by electricity, fuel gas, gasoline, or another hydrocarbon, to achieve shaft rotation when the mixer is in operation. Typically, an electric motor and drive mechanism will drive the central shaft(s) in the mixing chamber. D. Inlet ports for the continuous mixer The size, location, and orientation of the raw material inlet ports (inlet ducts) of the fiber-grout mixer are configured to facilitate the introduction of raw material into the fiber-grout mixer and also to minimize the potential for blockage of the grout mixture ports in the mixer. The cementitious grout from the grout mixer is preferably conveyed by use of a grout hose to the fiber-grout mixer and is introduced into the fiber-grout mixer through an inlet port that is prepared to accept the grout hose. Fibers can be introduced into the continuous fiber-slurry mixer gravimetrically or volumetrically by using a variety of metering equipment, such as screw feeders or vibratory feeders. Fibers can be transported from a fiber feeder to the fiber-slurry mixer by a variety of conveying devices. For example, fibers can be transferred by the use of screws (augers), air conveying, or simple gravity deposition. Discrete or chopped fibers can be made from different reinforcing fiber materials, including glass fiber; polymeric materials such as polypropylene, polyethylene, polyvinyl alcohol, etc.; carbon; graphite; aramid; ceramics; steel; cellulosic or natural fibers such as jute or sisal; or a combination of these. The fiber length is approximately 2 inches or less and most preferably less than 1.5 inches or less. E. Forming and Cutting for Single Layer Process After provision of the fiber-embedded settable slurry layer as described above, frame 312 may have forming devices provided to shape an upper surface of the setting fiber-slurry mixture 346 traveling on belt 314. If desired, an additional thickness control device 93 (not shown) may be provided downstream of the thickness control device 93 shown in Figure 8. After the one or more thickness control devices 93, the grout layer has begun to set and the respective ηζααηη / ζζηζ / Ε / γίΛΐ 100 panels 355 are separated from one another by a cutting device 354, which is typically a water jet cutter or a flying saw. The cutting device 354 is arranged relative to the line 310 and the frame 312 so that the panels produced are of the desired length. When the speed of the carrier web 14 is relatively slow, the cutting device 354 may be mounted to cut perpendicular to the direction of travel of the web 314. At faster production speeds, such cutting devices are known to be mounted on the production line 310 at an angle to the direction of travel of the web. After cutting, the separated panels 355 are stacked for further handling, packaging, storage, and / or shipping, as is well known in the art. Another feature of the present invention is that the resulting cementitious panel, e.g., fiber reinforced concrete (FRC) panel, 55 is constructed such that the fibers 335 are evenly distributed throughout the panel. It has been found that this allows for the production of relatively stronger panels with relatively less and more efficient use of fibers. The volume fraction of fibers relative to the volume of grout in each layer preferably ranges from 1% to 5% by volume, preferably from 1.5% to 3% by volume, of the ηζααηη / ζζηζ / Ε / γίΛA fiber-grout mixture 46. 101 It is contemplated that similar numbered elements shown in the figures of the present description are the same, unless otherwise indicated. PRODUCTION LINE AND METHOD WITH THICKNESS CONTROL DEVICE EMPLOYING A FIXED HORIZONTAL FORMING PLATE V. Fourth version of a production line that deposits discrete layers of fiber and grout to make a multi-layer FRC panel Figure 9 is a schematic elevational view of a fourth version of an FRC panel production line 410 of the present invention which is the production line of Figure 1A with an angle plate smoothing device 93 having the angle plate 95 but modified to apply a coating 444 and employ a fixed horizontal forming plate 446. The height of the fixed horizontal forming plate 446 above the movable carrier frame is adjustable, for example, by means of jack screws or, for example, by means of a linear actuator with servo control. In the FRC panel production line 410, the first layer 77 is brought into contact with the thickness control device 93 of the present invention to control the thickness of the first layer of formed, but not yet set, fiber-reinforced cementitious panel comprising fiber-laden cementitious slurry comprising cementitious material and chopped fibers 102 is embedded in the movable carrier frame 26. The thickness control device 93 comprises the angled rigid plate 95 and the U-shaped mounting bracket 97 for mounting the angled rigid plate 95 on the support frame or the forming table 12 for the movable carrier frame 26. Then, downstream of the thickness control device 93, a coating sheet 444 is applied by a roller 442 onto the surface 77 of the moving fiber-laden slurry. The coating-covered slurry layer then passes the stationary horizontal forming plate 446 which is held in place by supports 448. Therefore, the invention provides an FRC panel production line and a method for producing FRC panels that reduces thickness variation during the forming of fiber-reinforced cementitious panels, with the use of a liner, such as a glass mat that is placed across the width of the forming surface and a rigid horizontal top forming plate. With the new invention, a liner, such as a glass mat, is applied to one or both surfaces of the structural panel during the forming process. Then, the rigid horizontal top forming plate 446 that is oriented horizontally is used to form the glass / cement slurry of the structural panel to the desired thickness. The position of the entire forming plate 446 is fixed to provide a gap 103 fixed between the lower surface of the forming plate and the movable carrier frame below. It is therefore not a floating plate. Because of its horizontal orientation, the entire lower surface of the rigid horizontal upper forming plate 446, not just the downstream end as in the rigid angled plate 95 described above, comes into contact with the surface of the panel being formed as it passes beneath the forming plate. This process produces panels with less variation in thickness, thus allowing panels to be formed with a reduced average thickness of, say, 0.80 , without having local thin spots below 0.72 .Most preferably, the fixed horizontal forming plate 446, when used in conjunction with the top liner 444, allows for the formation of a panel having the desired thickness such that there is no need for finishing operations, such as surface sanding, to bring the panel thickness to the target panel thickness. Therefore, it is possible to use less raw material while making the same finished product. Additional savings will come from reduced scrap handling costs, as well as from items such as reduced equipment wear and increased manufacturing speed. As mentioned, one or more liner(s) may be used in this invention. In addition, the one or more liner(s) may be temporary, so that the 104 coating(s) may be removed before or during the finishing operation, or the coating(s) may remain on the finished product. The fixed horizontal forming plate 446 is positioned at a height such that the bottom surface of the fixed horizontal forming plate 446 contacts the top liner 444. Typically, in operation, the fixed horizontal forming plate 446 is positioned to locate the bottom surface of the fixed horizontal forming plate 446 at a height of 0.001 to 0.05 inches, e.g., 0.01 to 0.03 inches, less than or greater than the target thickness of the FRC panel. For example, for a 0.75 inch FRC panel, the height of the fixed horizontal forming plate 446 may be set to 0.73 inches or 0.77 inches. Most preferably, the fixed horizontal forming plate 446 is positioned to locate the bottom surface of the fixed horizontal forming plate 446 at a height that is equal to the target thickness of the panel. For example, if the desired panel thickness is 0.75 inches, the fixed horizontal forming plate height is set to 0.75 inches. As seen in Figure 9 the invention can provide a production line for FRC panels and a method for producing FRC panels which reduces thickness variation during the formation of fiber reinforced cementitious panels, with the use of the angle plate 95 described ηζααηη / ζζηζ / Ε / γίΛΐ 105 above and with the use of liner 444, such as a glass mat that is positioned across the width of the forming surface, and the fixed horizontal forming plate 446. Such a FRC panel production line and method would contact the fiber laden slurry with the 95 angled plate described above, then apply liner 444, such as a glass mat to the top surface of the structural panel during the forming process, and then pass the fiber laden slurry covered with the liner under the rigid horizontal upper forming plate 446. In order to achieve the target panel thickness during the panel forming process by using the fixed horizontal forming plate 446 and the liner 444, a grout head is continuously maintained just behind the fixed horizontal forming plate 446. This grout head is located over and above the continuous and substantially flat band of FRC slurry approaching the fixed horizontal forming plate 446. The presence of this excess grout behind the fixed horizontal forming plate 446 ensures that the FRC slurry exiting the fixed horizontal forming plate 446 has the correct volume and thickness. In the absence of a grout head behind the fixed horizontal forming plate 446, any reduction and / or fluctuation in grout volume that occurs behind 106 the fixed horizontal forming plate 446 could result in the formation of a panel having a thickness less than the target panel thickness. A continuous grout head is maintained behind the fixed horizontal forming plate 446 by adjusting the volume output of one or more grout pumps feeding grout to the forming line. Optionally, a separate grout pump feeding grout directly and immediately behind the fixed horizontal forming plate 446 may be provided. The volume of the grout head immediately behind the fixed horizontal forming plate 446 is sufficient to counteract any normal variations in grout pump feed rates typically observed with industrial pumps feeding cementitious grouts.The actual volume of the grout head required behind the fixed horizontal forming plate 446 is dependent upon several factors including the speed of the production line, the distance between the grout feeding apparatus 44 on the production line and the fixed horizontal forming plate 446, and the ability of the process to control grout leakage and overflow behind and around the fixed horizontal forming plate 446. Preferably, the size and volume of the grout head is uniform across the width of the panel behind the fixed horizontal forming plate 446. The length of the grout head extending in the ηζααηη / ζζηζ / Ε / γίΛA direction. 107 of the machine behind the fixed horizontal forming plate 446 is preferably 1 inch to 30 inches, more preferably 2 inches to 24 inches, and most preferably 3 inches to 18 inches. A smaller slurry head length, such as 4 inches to 12 inches, is preferred because it minimizes static zones in the slurry head where reinforcement and setting of the slurry can occur prematurely, causing problems with uniform formation of the fiber-laden slurry as it passes under the fixed horizontal forming plate 446. To facilitate continuous maintenance of the grout head behind the fixed horizontal forming plate 446, the distance between the last grout feeding apparatus 44 and the fixed horizontal forming plate 446 should be minimized. The distance between the last grout feeding apparatus 44 on the production line and the fixed horizontal forming plate 446 is preferably less than 100 feet, more preferably less than 50 feet, and most preferably less than 25 feet, e.g., less than 10 feet. However, when the horizontal forming plate 446 is employed in the production lines and methods of the present invention, the use of the angled plate 95 described above is optional. Likewise, when the plate at an angle of 95 described ηζααηη / ζζηζ / Ε / γίΛΐ 108 is previously employed in the production lines and methods of the present invention, the use of the horizontal forming plate 446 is optional. The production line and method may also optionally apply a coating, such as a glass mat, to the bottom surface of the structural panel upstream of the grout inlet box during the forming process. In a preferred embodiment of this invention, a side wiper 500 also referred to as a slurry containment device is installed on each side of the forming plate 446. The wipers 500 may be attached to the forming plate mounting frame 377 or other structural parts of the production line, as would be appreciated by one of skill in the art. The purpose of the side wipers 500 is to retain slurry at the edges of the panel being formed, thereby preventing excess slurry from flowing past the edges of the panel being formed where it might seep between the upper forming plate 446 and the top surface of the glass mat, creating an undesired appearance and / or thickness variation in the panel being formed.The wipers 500 also function to stop the grout from leaking around the sides of the forming plate 446, thereby preventing the buildup of hardened grout that could otherwise hinder continued operations. A vibrator 502 may be used. 109 join each of the wipers 500. The vibration keeps the grout from setting in the wiper 500 itself and also prevents premature setting and / or solidification of the grout behind the forming plate 446. In another preferred embodiment of this invention, another vibrator 504 or a plurality of vibrating means are mounted under the bed of the forming line just before and / or below the upper forming plate 446. A purpose of this (these) vibrator(s) 502, 504 is to keep the grout head active behind the forming plate which prevents the grout from setting while behind the forming plate. The invention therefore provides a production line for fiber-reinforced cementitious panels comprising: a movable carrier web, a support frame for supporting the movable carrier web, wherein the panel is transported on the movable carrier web having a direction of travel relative to the support frame, and means for applying a coating, such as a glass mat, onto a fiber-laden cementitious slurry on the movable carrier web, the means for applying the coating being positioned across the width of a forming surface of the movable carrier web, 110 a horizontal thickness control device for controlling the thickness of a formed, but not yet set, fiber-reinforced cementitious panel comprising a fiber-laden cementitious slurry comprising cementitious material and chopped fibers embedded on the movable carrier web, wherein the horizontal thickness control device comprises a rigid horizontal upper forming plate (e.g., horizontal forming plate 446), wherein the rigid horizontal upper forming plate has a planar bottom surface, an upstream end and a downstream end, and a forming plate mounting frame for mounting the rigid horizontal upper forming plate in a horizontal orientation on the support frame for the movable carrier web, wherein the rigid horizontal upper forming plate is mounted to the forming plate mounting frame,and a rigid, flat support bed beneath the rigid horizontal upper forming plate, which is sufficiently conformable and configured to support the fiber-laden cementitious slurry and preferably resist the downward force exerted by the rigid horizontal upper forming plate with a deflection of less than 0.03 inches, preferably less than 0.01 inches, preferably less than 0.003 inches, 111 inches, the forming plate mounting frame for fixedly maintaining, but adjustable, the height of the rigid horizontal upper forming plate above the movable carrier frame and maintaining the rigid horizontal upper forming plate parallel relative to the movable carrier frame, to fixedly locate the flat bottom surface at a height of 0.1 to 2 inches, preferably 0.2 to 1.1 inches, more preferably 0.5 to 1.1 inch, on the moving carrier web, wherein the upstream end of the planar lower surface extends through the moving web transversely, relative to the direction of travel of the moving web, wherein the downstream end of the planar lower surface extends through the moving web transversely, relative to the direction of travel of the moving web, and wherein the entire planar lower surface is adapted and configured to come into contact with the coating in the fiber-laden slurry when carried on the moving carrier web. Therefore, the invention also provides a process for making a fiber-reinforced cementitious panel comprising: ηζααηη / ζζηζ / Ε / γίΛΐ 112 conveying a fiber-laden slurry for a panel on a moving carrier web, the moving carrier web being supported by a support frame, wherein the panel is transported on the moving carrier web having a travel direction relative to the support frame, applying a coating, such as a glass mat, onto a fiber-laden cementitious slurry on the moving carrier web, across a width of a forming surface of the moving carrier web to cover the forming surface, passing the forming surface covered by the coating under a horizontal thickness controlling device to control a thickness of a formed, but not yet set, fiber-reinforced cementitious panel comprising a fiber-laden cementitious slurry comprising cementitious material and chopped fibers embedded in the moving carrier web,wherein the horizontal thickness control device comprises a rigid horizontal upper forming plate (e.g., horizontal forming plate 446), wherein the rigid horizontal upper forming plate has a flat bottom surface, an upstream end and a downstream end, and a forming plate mounting frame for mounting ηζααηη / ζζηζ / Ε / γίΛA, 113 the rigid horizontal upper forming plate in a horizontal orientation on the support frame for the mobile carrier frame, wherein the rigid horizontal upper forming plate is mounted to the forming plate mounting frame, and a rigid, flat support bed under the rigid horizontal upper forming plate, which is adapted and configured sufficiently to support the fiber-laden cementitious slurry and preferably resist the downward force exerted by the rigid horizontal upper forming plate with a deflection of less than 0.03 inches, preferably less than 0.01 inches, preferably less than 0.003 inches, controlling the thickness of the formed, but not yet set, fiber-reinforced cementitious panel, when the formed, but not yet set, fiber-reinforced cementitious panel, covered with the coating, comprising a fiber-filled cementitious slurry, comes into contact with a lower surface of the rigid horizontal upper forming plate; the mounting frame to maintain a fixed, but adjustable, height of the angled plate above the movable carrier frame and to maintain the rigid horizontal upper forming plate parallel relative to the movable carrier frame, to fixedly locate the flat lower surface at a height of 0.1 to 2 inches above the carrier frame 114 movable, wherein the upstream end of the planar lower surface extends through the movable web transversely, relative to the direction of travel of the movable web, wherein the downstream end of the planar lower surface extends through the movable web transversely, relative to the direction of travel of the movable web, and wherein the entire planar lower surface contacts the coating in the fiber-laden slurry when carried on the movable carrier web. Figure 9 shows a forming table 12, an endless belt 14, and a carrier web 26 and optional lower support plates 46A, 46B. The production line 410 provides a rigid, flat support bed under the rigid horizontal upper forming plate 446 that is conformable and configured sufficiently to support the fiber-laden slurry and preferably resist the downward force exerted by the rigid horizontal upper forming plate 446 with a deflection of less than 0.03 inch, preferably less than 0.01 inch, preferably less than 0.003 inch. The rigid, flat support bed is provided to counteract the downward force of the ηζααηη / ζζηζ / Ε / γίΛΐ laden grout 115 fiber covered with the cladding that passes under the rigid horizontal upper forming plate 446 and, for example, may be any of the following: the forming table 12 if sufficiently rigid, the forming table 12 is further supported by the rigid lower forming plate 46A, which is provided under the carrier belt 14, rigid panels used on the carrier belt 14 under or instead of the carrier web 26, the endless belt 14 could be supported by sufficient rollers to be rigid, or there could be a break in the forming table 12 and the rigid lower forming plate 46A is placed at the break directly under the portion of the endless belt under the upper forming plate 446. Figure 9A shows a first enlarged perspective view of a portion of the FRC panel production line 410 of Figure 9 for applying the facing 444 and employing a fixed horizontal top forming plate 446. For clarity, the mounting frame is not shown. Figure 9B shows a second, enlarged perspective view of a portion of the FRC panel production line shown in Figure 9 for applying the coating and employing a stationary forming plate. For clarity, the mounting frame is not shown. 116 Figure 9C shows a U-shaped mounting frame 337 of the rigid upper forming plate 446 in a horizontal orientation on the support frame 12 for the movable carrier frame 26 and a liner 444 of the FRC panel production line 410 of Figure 9. The U-shaped mounting frame 377 having a crossbar 451 and legs 453 and brackets 448 are provided with servo-controlled actuators 449 extending downwardly from the crossbar 451. The servo-controlled actuators 449 are provided to adjust and control the height H of the rigid horizontal upper forming plate 446 in the horizontal orientation on the movable carrier frame 26 such that the horizontal forming plate 446 contacts the liner 444 at top face 96. The upstream edge 446A (Figure 9D) of the horizontal forming plate 446 is preferably beveled, where it first contacts the liner 444, to avoid damaging the liner 444 that might otherwise occur. VI. Fifth version of a production line that deposits fiber-laden grout from a headbox to make an FRC panel from a single layer of grout Figure 10A is a schematic elevation view of a fifth version of a FRC panel production line 510 with an angle plate 95 of the present invention being 117 is modified to apply a coating 444 and employ a stationary forming plate 446 and optionally a lower support plate 46B. This is production line 310 of Figure 8 that is modified to apply coating 444 from a roller 442 and employ stationary forming plate 446 supported by supports 448. It may also optionally employ lower support plates 46A, 46B. Similar numbered elements in Figure 10A and other figures herein are the same elements and operate in the same manner unless otherwise indicated. If desired, an additional fixed forming plate 446 (not shown) may be provided and applied to the liner 444 upstream or downstream of the fixed forming plate 446 shown in FIG. 10A. Wrapping a fiber-reinforced concrete (FRC) panel in layers of nonwoven fiber The invention also encompasses making a board that is wrapped in a nonwoven fiber mat, typically a nonwoven polymer fiber mat such as a polypropylene mat or a substantially inorganic nonwoven fiber mat such as a fiberglass mat, in the panel production line. The inorganic nonwoven fiber mat may optionally be coated with a variety of coating materials that impart handling characteristics to the continuous web and improve the physical and mechanical durability. 118 chemistry. The nonwoven fiber mat is preferably applied to both main faces of the panel, but can optionally be applied to only one of the main faces of the panel. Figure 10A shows cementitious panel production line 610 for use with the present fiber-grout mixing device. It is production line 510 of Figure 10A that is modified to apply a nonwoven fiber mat 444A below the fiber-grout mixture and apply a nonwoven fiber mat 444 above the fiber-grout mixture 346 to wrap the produced board 355. (However, this modification could also be used to modify any version of the present invention, e.g., versions of the invention for making multi-layer FRC panels.) Reference numerals similar to those in Figure 10A or other figures in the present disclosure are employed in Figure 10B to represent similar elements operating in a similar manner. Both the angle plate 95 and the horizontal forming plate 446 described above are shown being used in the cementitious panel production line 610. Optionally, bottom support plates 46A, 46B may also be employed. In this and other production lines and methods of the present invention using the horizontal forming plate 446, use of the angle plate 95 described above is 119 optional. Likewise, when the angle plate 95 described above is used in the production lines and methods of the present invention, the use of the horizontal forming plate 446 is optional. Figure 10B shows a first continuous nonwoven fiber mat (preferably fiberglass or multi-layer polyolefin) 444A from a feed roll 442A passing under a roll 442B on the surface of the moving belt 314. Then, the fiber-reinforced cementitious grout mixture 346 produced by the fiber-grout mixer is deposited onto the first nonwoven fiber mat 444A by use of the forming headbox 340. The nonwoven fiber mat 444A on the moving surface of the panel production line 610 extends from the right and left sides of the setting fiber-grout mixture 346 to the board 355. The mat 444A may optionally be larger than the width of the panel that is subsequently formed, with the edges 444B and 444C being folded to a vertical position before passing under the feed roll 442A. inlet box 340. Then, the surface of the depositing fiber-laden slurry 346 is smoothed by passing the depositing fiber-laden slurry 346 under the plate at an angle 95 to contact the surface of the depositing fiber-laden slurry 346 with the downstream end of the plate at ηζααηη / ζζηζ / Ε / γίΛA 120 angle 95 as described above. In the event that the mat 444A is larger than the panel that is subsequently formed, an optional folding unit 230 may optionally further fold the vertical edges 444B, 444C (see Figure 10C) of the mat 444A to not only wrap around the right and left sides of the setting fiber-slurry mixture 346 for the board 355, but also to optionally fold the vertical portions again to provide an overlap area with the mat 444. Thus, the mat 444A may be wrapped around the setting fiber-slurry mixture 346 of the board 355 to wrap around the right and left edges 444B, 444C (Figure 10C) of the mat 444A and optionally provide an overlap area with the mat 444, when the board 355 is not completely formed. forged. The invention then feeds the top mat (web) 444 of nonwoven fiber material from the feed roll 442, then under an optional application roll 442C onto the top surface of the fiber-grout mixture. Optionally, glue may be applied to the top mat (web) 444 and / or to the folded edges of the mat 444A where they overlap. The fiber-grout mixture 346 covered by the nonwoven fiber mat 444 then passes under the horizontal forming plate 446 to smooth the surface of the panel 355. ηζααηη / ζζηζ / Ε / γίΛΐ 121 Therefore, the method may comprise: applying a first web 444A of nonwoven fibers to the moving surface of a panel production line, the first web 444A being sufficiently impermeable to prevent seepage of the fiber-slurry mixture into the panel production line; the first web 444A being larger than the cement board 355 being made; forming a continuous trough by folding outer portions of the first web 444A upright; continuously depositing the fiber-slurry mixture 346 from the headbox 340 onto the first frame 444A and distributing the fiber-slurry mixture 346 laterally to fill the trough to a substantially uniform depth; passing the fiber-grout mixture 346 under the 95° angle plate so that it comes into contact with the downstream end of the 95° angle plate to smooth the surface of the fiber-grout mixture 346; then, at folding station 230, fold the edges of the bottom facing 444A to provide an overlap area with the top facing 444; and apply the second web 444 of nonwoven fibers to an upper surface of the fiber-slurry setting mixture 346 on the panel production line 610; then contacting the second web 444 of nonwoven fibers on the upper surface of the ηζααηη / ζζηζ / Ε / γίΛΐ fiber mixture 122 setting grout 346 with the fixed forming plate 446; and then cutting the setting panel 355 with the cutting device 354 to form the FRC panels 355. The folding unit 230 may optionally be located downstream of the fixed upper forming plate 446. In this case, the vertical edges 444B and 444C may not pass under the upper forming plate 446 but adjacent its edges. The folding unit 230 will then further fold the vertical edges 444B and 444C so that the overlap is formed with these portions of the mat 444A that is located above the mat 444. The folding unit 230 may be any suitable folding unit. For example, US 5,221,386 to EnsmingerEnsminger et al., which is incorporated herein by reference, describes an apparatus for wrapping bare surfaces of cement-set panels with a woven network of reinforcing fibers underlying the top, bottom, and longitudinal edge surfaces (in other words, embedded).The Ensminger et al. apparatus may be adapted to the folding unit 230 by replacing its cement and woven netting with a setting fiber-slurry mixture 346 for the board 355 and the nonwoven fiber mats 444, 444A (which do not embed). The Ensminger et al. apparatus includes a pair of edging rails which slidably rest on a conveyor belt and define the path of the cement board being made on the conveyor belt and a ηζααηη / ζζηζ / Ε / γίΛA. 124 In this production line 210, an optional web 326 of release paper, polymer film, or a plastic carrier, for supporting a grout prior to setting, may be provided and placed over the carrier 314 to protect and / or keep it clean. However, it is also contemplated that, in place of the continuous web 326, individual sheets (not shown) of a relatively rigid material, e.g., polymeric plastic sheets, may be placed on the carrier 314. These carrier films or sheets may be eliminated from the panels being produced at the end of the line, or they may be incorporated as a permanent feature of the panel as part of the overall composite design.When these films or sheets are incorporated as a permanent feature into the panel, they can provide enhanced attributes to the panel, including improved aesthetics, improved tensile and flexural strengths, improved impact and blast resistance, improved environmental durability such as water and water vapor transmission resistance, freeze-thaw resistance, salt fouling resistance, and chemical resistance. The nonwoven fiber mat 444, 444A may optionally be used in conjunction with a web 326 (for example, the web 326 could be a release paper that prevents any slurry permeating through the nonwoven fiber mat 444A from reaching the forming belt). When 125 the web 326 is employed as a permanent feature of the panel and the relatively impermeable nonwoven fiber mat 444, 444A is employed, the web 326 may be affixed to the nonwoven fiber mat 444, 444A with adhesive (e.g., the web 326 may be provided with pressure sensitive adhesive). However, the web 326 or individual sheets of relatively rigid material (not shown) are optional and are preferably not employed in this production line 610 of Figure 10B (former 42) when the relatively impermeable mats 444A, 444 are employed. Or preferably, the continuous web 326 is the relatively impermeable nonwoven fiber mat and in that case, the relatively impermeable nonwoven fiber mat 444A is not employed. Figure 10C is a schematic perspective view of an FRC panel 355 of Figure 10B being wrapped in the nonwoven fiber mat made according to production line 610. The coated nonwoven fiber mat includes a setting fiber-slurry blend core 346, a front mat 444, and a back mat 444A having right and left edges wrapped around the right and left sides of the panel 355 toward the front of the panel. The mats 444 and 444A are preferably of the same material, but may optionally be made of different materials depending on the product application requirements. In some embodiments, the nonwoven fiber mat may be used in a variety of ways. 126 only on one of the main faces of the panel. On production line 610, vertical portions of the first facing (mat) 444A are folded before applying the top web to make a panel such as that of Figure 10C. In an alternative (not shown), the folding unit 230 moves from upstream of the forming plate 446 to be downstream of the horizontal forming plate 446. The fiber-slurry mixture 346 covered by the nonwoven fiber facing mat 444 passes under the horizontal forming plate 446 to smooth the surface of the panel upstream of the folding unit 230. The folding unit 230 then folds the edges of the lower facing 444A over the edges of an upper facing 444 to wrap the FRC panel 355. In particular, the right and left edges 444B, 444C are wrapped and optionally glued where they overlap the upper facing 444. The setting fiber-slurry mixture that is wrapped for the board 355 is then processed as described above for the production line 310 of Figure 8. Materials and structures for non-woven fiber mats that do not fully embed These nonwoven fiber mats of the invention are designed not to be completely embedded in the fiber-slurry mixture, such as, for example, the steles 444, 444A of ηζααηη / ζζηζ / Ε / γίΛΐ 127 Figure 10B , comprise any suitable type of polymer fiber, glass fiber, or combination thereof. Preferably, the majority of the fibers in the nonwoven fiber mat are glass fibers or polymeric fibers. Non-limiting examples of suitable fibers include glass fibers, polyamide fibers, polyaramid fibers, polypropylene fibers, polyester fibers (e.g., polyethylene terephthalate (PET)), polyvinyl alcohol (PVOH), polyvinyl acetate (PVAc), cellulosic fibers (e.g., cotton, rayon, etc.), and combinations thereof, preferably glass fibers. Furthermore, the fibers in the mat may be hydrophobic or hydrophilic, coated or uncoated. These nonwoven fiber mats are not permeable to the fiber-grout mixture or, at most, are slightly permeable to the fiber-grout mixture. In particular, the nonwoven fiber mats provide sufficient impermeability to prevent the fiber-grout mixture of the invention from leaking through even when the fiber-grout mixture of the invention is vibrated and / or passed under forming plates on the production line. The fiber-grout mixture of the invention may undergo shear thinning when vibrated or spread on the panel production line. This makes it important to select the appropriate nonwoven sheet to prevent leaks. If the mats are glass fiber mats, they will not 128 woven, there are coated nonwoven fiberglass mats so that they do not completely embed into the fiber-reinforced cementitious grout material. This aspect of the invention with non-embedding mats does not use a woven glass mat because the woven glass mat is not tight enough to prevent the grout from seeping through. The invention contemplates the use of top and / or bottom nets and meshes, e.g., woven glass mats, when embedding is desired. Alternatively, non-woven fiber mats are preferably made of polyolefin (preferably polypropylene and / or polyethylene). The nonwoven fiber mats may each be a single layer. For example, preferred coated fiberglass mats are a single layer. However, polymer mats are preferably made of more than one layer. For example, Figure 10D shows a side cross-sectional view of a polymer fiber mat having a laminated composite structure of a spunbond layer of fibers and a relatively impermeable meltblown layer of fibers. More preferably, mat 444 is a polyolefin mat having two spunbond layers 446A, 446C of fibers and a meltblown layer 446B of fibers sandwiched between the spunbond layers. The ηζααηη / ζζηζ / Ε / γίΛΐ layer 129 melt-blown provides sufficient impermeability to not let the fiber-slurry mixture of the invention leak through even when the fiber-slurry mixture of the invention is vibrated and / or goes under the forming plates on the production line. The fibers used in the nonwoven glass mat should be at least 0.25 inches long or more, more preferably at least one-half or three-quarters of an inch long, and most preferably at least about one inch long, but mixtures of fibers of different lengths and / or fiber diameters may be used as known. It is preferred that these fibers be coated with a silane-containing sizing composition as is well known in the industry. A preferred continuous glass fiber for the fibrous web is at least one member selected from the group consisting of E, C, and T type sodium borosilicate glasses and mixtures thereof.As is known in the glass art, C glass typically has a soda lime borosilicate composition which provides it with improved chemical stability in corrosive environments, and T glass typically has a magnesium aluminosilicate composition and especially high tensile strength in filament form. The present mat is preferably composed of E glass, which is also known as electrical glass and typically has a composition of ηζααηη / ζζηζ / Ε / γίΛΐ. 130 calcium aluminoborosilicate and a maximum alkali content of 2.0%. E-glass fiber is commonly used to reinforce various articles. The chopped fibers of the principal portion may have variable lengths, but are most commonly of substantially similar length. E-glass fiber has sufficiently high strength and other mechanical properties to produce acceptable mats and is relatively low cost and widely available. Most preferred is E-glass, which has an average fiber diameter of about 11+ / -1.5 pm and a length ranging from about 6 to 12 mm. Nonwoven fiber mats generally comprise fibers that are bonded together by a binder, solvent treatment, or heat. The binder can be any binder typically used in the matting industry. Suitable binders include, but are not limited to, urea formaldehyde, melamine formaldehyde, melamine formaldehyde with stearate, polyester, acrylics, polyvinyl acetate, urea formaldehyde or melamine formaldehyde that is modified or blended with polyvinyl acetate or acrylic, styrene-acrylic polymers, and combinations thereof. Typical polymeric fibers are any of nylon, polyester, polyethylene, or polypropylene. Any suitable amount of binder can be used. However, meltblown nonwoven fiber mats do not require a binder. ηζααηη / ζζηζ / Ε / γίΛΐ 131 Typically, the fibrous mat may have any suitable weight effective to prevent bleed-through during manufacturing. Typically, for glass mat the basis weight will be about 18 lb / 1000 ft2 or more (e.g., about 18-30 lb / 1000 ft2), equivalent to about 88 g / m2 or more (e.g., about 88147 g / m2). In one embodiment, the fibrous mat, especially a fiberglass mat, has a basis weight of about 20 lb / 1000 ft2 or more (e.g., about 20-26 lb / 1000 ft2, or about 2326 lb / 1000 ft2), equivalent to about 98 g / m2 or more (e.g., about 98-127 g / m2 or more). Typically, for the polymer mat, the basis weight will be about 8 lbs / 1000 ft2 or more (e.g., about 8-30 lbs / 1000 ft2), equivalent to about 39 g / m2 or more (e.g., about 39-147 g / m2), preferably a basis weight of about 15 lbs / 1000 ft2 or more (e.g., about 15-20 lbs / 1000 ft2), equivalent to about 73 g / m2 or more (e.g., about 73-98 g / m2 or more). Each of the mats is preferably made of a single layer of nonwoven glass fiber. Alternatively, each is preferably made of a nonwoven polymer mat (preferably polyolefin) having a multilayer laminated structure. Figure 44 is a schematic view of the ηζααηη / ζζηζ / Ε / γίΛΐ 132 a nonwoven polymer front mat 44 having a preferred multi-layer structure of three layers 46A, 46B, 46C. This polymer mat 44 has two spunbond layers 46A, 46C of fibers and a meltblown layer 46B of fibers that are sandwiched between the spunbond layers 46A, 46C. The meltblown layer provides sufficient impermeability to not let the inventive fiber-slurry mixture seep through even when the inventive fiber-slurry mixture is vibrated and / or goes under forming plates on the production line. Nonwoven fiber mats applied to panel surfaces provide a smooth surface to the finished product and also assist with the stacking of fiber-reinforced concrete panels during manufacturing. Instead of having to stack the panels on a separate rack during curing, if the panels are sufficiently set, the wrapped panels can be placed directly on top of each other while they cure. Casting the edges of fiber-reinforced concrete panels to a nonwoven fiber mat will facilitate edging and cleaning. A panel that is cast with the back, sides, and front made of the sufficiently impermeable mat will have the benefit of a better surface, easier cleaning, and simplified stacking of the board (during manufacturing). This process 133 will also produce an FRC panel that requires little or no surface finishing. The use of nonwoven glass mats has the advantage of better bonding than nonwoven polymer mats. The use of nonwoven polymer mats has the advantage of better alkali resistance than nonwoven glass mats. EXAMPLES Example 1 - Plant test data and pilot plant test data Production run 1 using a Type 1 electric vibration motor with controller at various vibration and gap configurations between the metal plate and the forming surface. Mounting angle of vibrating plate to forming surface = 20 degrees (approximately). A Type 1 vibrator refers to a DC boosted and regulated motor to generate the desired vibration characteristics. The Type 1 vibrator assembly includes a lithium iron phosphate battery pack (36V, 10 amp-hour capacity), a control box, a throttle assembly to regulate vibration intensity, and a DC motor with a gearbox and rotating eccentric weight(s). TABLE 1 shows the experimental conditions. The vibrating plate and motor were installed on the production line by using the mounting frame as shown in Figure 1. 134 described above. The gap between the forming surface and the vibratory plate was set up and measured using gauge blocks, and the vibration settings were adjusted with the accelerator assembly according to the test conditions. The vibratory plate was engaged after stable production conditions were obtained, under the desired experimental configurations. Sample panels produced with the vibratory plate of the invention were marked and collected for curing. Similarly, samples under other experimental conditions as in Table 1 were also marked and collected for curing. Regular vibratory plates remained engaged or were disengaged depending on the experimental conditions, and the sample panels were collected accordingly.After curing, the formed sample panels were cut into four pieces A, B, C, and D as seen schematically in Figure 11A, piece A was formed before piece D, and the thickness was measured at 1 inch intervals across all edges of the pieces. Figure 11A shows the dimensions in inches. Figure 11A is a cutting diagram of the sample panels for the experimental conditions. Thickness measurements were made along the edges of these pieces and integrated to estimate the standard deviation in the machine and cross-machine directions. The data measurements. Thickness measurements obtained along the forming direction (along the panel length at the longer edge) were used to estimate the standard deviation of thickness in the machine direction. Thickness measurements obtained along the direction perpendicular to the forming direction (along the panel width at the shorter edge) were used to estimate the standard deviation of thickness in the cross-machine direction. Similarly, the difference between the maximum and minimum panel thicknesses in each direction was estimated. ηζααηη / ζζηζ / Ε / γίΛΐ TABLE 1: Experimental Conditions with the Type 1 Electric Vibration Motor Conditions Regular Plate Gap in Inches Regular Plate Current Invention Vibration Setting Intensity Gap in Inches VS1 #1 0.75 YY Low 0.75 VS1 #2 0.75 NY Low 0.75 VS1 #3 0.75 NY Low 0.75 VS1 #4 0.75 NY Low 0.724 VS1 #5 0.75 NY Low 0.701 VS1 #6 0.75 YY Low 0.701 VS1 #7 0.75 YY Low 0.701 VS2#1 0.75 NY Medium 0.75 Control #1 0.75 YN - 0.75 Control #2 0.75 YN — 0.75 Figure 11B shows the standard deviation in inches and the difference in maximum and minimum thickness in inches of panels formed at different 136 experimental conditions of Table 1 on the samples measured in the cross-machine direction with and without the angle plate thickness control device of the present invention. Control #1 and Control #2 are experimental conditions without the angle plate thickness control device of the present invention. Figure 12 shows a cross-sectional thickness profile in inches of a cementitious panel formed from Figure 11A in the cross-machine direction without using the angle plate thickness control device of the present invention. Figure 13 shows a cross-sectional thickness profile in inches of a cementitious panel formed from Figure 11A in the cross-machine direction by use of the angle plate thickness control device of the present invention. Example 2 - Data from plant trials and pilot plant trial testing the angled plate thickness control device Production test 2 using a type 2 electric vibration motor with a controller in various vibration configurations and spacing between the metal plate and the forming surface. The mounting angle of the vibrating plate at an angle to the forming surface (ηζααηη / ζζηζ / Ε / γίΛΐ) 137 of the fiber-laden slurry was 20 degrees (approximately). A Type 2 vibrator refers to an AC powered and regulated motor to generate the desired vibration characteristics. The Type 2 vibrator assembly included an AC powered (110-120 V, 1.3 amp) electrical control box with rotary knob / dial to regulate vibration intensity and a motor with a gearbox and rotating eccentric weight(s). TABLE 2 shows the experimental conditions. The vibratory plate and motor were installed on the production line using the mounting frame as described above. The gap between the forming surface and the vibratory plate was set up and measured using the gauge blocks, and the vibration settings were adjusted with the rotary knob / dial on the electrical control box according to the test conditions. The vibratory plate was engaged after stable production conditions were obtained, at the desired experimental settings. The sample panels produced with the vibratory plate of the invention were marked and collected for curing. Similarly, samples under other experimental conditions as in Table 2 were also marked and collected for curing. The vibratory plates 138 regular panels remained engaged or became disengaged depending on the experimental conditions and sample panels were collected accordingly. After curing, the formed sample panels were cut into eight pieces A1, A2, B1, B2, C1, C2, D1, and D2 as in Figure 11C, formed before piece A1 and A2 before pieces D1 and D2 and the thickness was measured at 1 in. interval across all edges of the pieces. Figure 11C is a cutting diagram of the sample panels for the experimental conditions. Thickness measurements were made along the edges of these pieces and integrated to estimate the standard deviation in the machine and cross-machine directions. Thickness data measurements obtained along the forming direction (along the length of the panel at the longest edge) were used to estimate the standard deviation of the thickness in the machine direction.Thickness data measurements obtained along the direction perpendicular to the forming direction (along the panel width at the shortest edge) were used to estimate the standard deviation of thickness in the cross-machine direction. Similarly, the difference between the maximum and minimum panel thicknesses in each direction was estimated. 139 TABLE 2: Experimental conditions with the type 2 electric vibration motor Regular Plate Current Invention Configuration Space, In Use, Space, In Use, Vibration, Panel # Conditions inches S / N inches S / N % 1 Control (SP5) -1 0.85 S - N - 2 Control (SP5) -1 0.85 S - N - 3 Without SP5 - N - N - 4 MS (50%, 0.7) + SP5 0.85 S 0.70 S 50 5 MS (50%, 0.7) 0.85 N 0.70 S 50 6 MS (50%, 0.7) 0.85 N 0.70 S 50 7 MS (50%, 0.68) 0.85 N 0.68 S 50 8 MS (50%, 0.68) 0.85 N 0.68 S 50 9 MS (70%, 0.68) 0.85 N 0.68 S 70 10 MS (50%, 0.68) 0.85 N 0.68 S 50 11 MS (50%, 0.68) + SP5 0.85 S 0.68 S 50 12 Control (SP5) -2 0.85 S - N - 13 Control (SP5) -2 0.85 S - N - Figure 14 shows the standard deviation in inches and the difference in the maximum and minimum thickness of panels formed under different experimental conditions of Table 2 on samples measured in the cross-machine direction with and without the angle plate thickness control device of the present invention. Control #1 and Control #2 are experimental conditions without the angle plate thickness control device of the present invention. Figure 15 shows the standard deviation and difference in the maximum and minimum thickness of panels formed under different experimental conditions of Table 2 on samples measured in the cross-machine direction with and without the angle plate thickness control device of the present invention. 140 minimum in inches of the panels formed under different experimental conditions in TABLE 2 on samples measured in the machine direction with and without the angle plate thickness control device of the present invention. Control #1 and Control #2 are experimental conditions without the angle plate thickness control device of the present invention. Figure 14 has information on panel thickness measurements across the cross machine direction (XMD), while Figure 15 has information on panel thickness measurements along the machine direction (MD). The purpose is to demonstrate the reduction in variation in both the XMD and MD. The units in Figures 11A-17 are inches. The panel tested was 4 ft by 8 ft. Therefore, the cross-machine direction measurements were 48 inches across, and the down-machine direction measurements were 96 inches across. Figure 16 (Panel #12 Cross Machine Direction) shows a cross-sectional thickness profile in inches of cementitious panels formed without the use of the angle plate thickness control device of the present invention. Figure 17 (Panel #7 Machine Cross Direction) shows a cross-section thickness profile ηζααηη / ζζηζ / Ε / γίΛΐ 141 inches of cementitious panels formed by using the angle plate thickness control device of the present invention. TABLES 3A and 3B provide a comparison of the forming thickness variation in inches for cementitious panels formed with and without the use of the angle plate thickness control device of the present invention. Table 3A ηζααηη / ζζηζ / Ε / γίΛΐ Production Trial 1 Control 1 Control 2 Without the current invention Without the current invention XMD MD Overall XMD MD Overall MaximumMinimum 0.156 0.087 0.156 0.162 0.142 0.195 Standard Deviation 0.031 0.018 0.030 0.032 0.024 0.035 Mean 0.872 0.898 0.881 0.861 0.902 0.875 Production Trial 2 Control 1 (average) Control 2 (average) Without the current invention Without the current invention XMD MD Overall XMD MD Overall MaximumMinimum 0.110 0.103 0.116 0.158 0.164 0.168 Standard Deviation 0.023 0.024 0.024 0.032 0.049 0.042 Medium 0.885 0.897 0.891 0.879 0.884 0.882 142 ηζααηη / ζζηζ / Ε / γίΛΐ Table 3B Production Test 1 Production Test 2 With Type 1 Motor With Type 2 Motor Low Vibration, 0.70 in. Gap 50% Configuration, 0.70 in. Gap (Average) XMD MD Overall XMD MD Overall MaximumMinimum 0.090 0.093 0.110 0.094 0.103 0.108 Standard Deviation 0.018 0.017 0.018 0.019 0.029 0.025 Mean 0.851 0.860 0.854 0.869 0.875 0.873 Example 3: Data when a coating is applied and the thickness control device comprising the fixed horizontal forming plate is used Table 4 below shows the thickness data in inches when a coating is applied and a horizontal forming plate is used at a fixed height above the moving carrier frame of the single-ply FRC panel production line. The data were based on pilot-scale production using a pilot line. The board composition was consistent with that described above for the single-layer process. The boards were made by using a gypsum-cement binder composition. The cementitious binder comprises a mixture composed of alpha calcium sulfate hemihydrate, portland cement, silica fume, and hydrated lime added in the following proportions: 62:25:12:1, respectively. 143 expanded perlite as a lightweight filler. The perlite particles were chemically coated with a silicon-based hydrophobic chemical coating to reduce water absorption by the particles. The weight ratio of perlite to cementitious binder was 0.09. Water and chemical processing aids were added in sufficient quantities to obtain an aqueous slurry of the workable consistency required for the process. Alkali-resistant glass fibers were used as structural reinforcement in the panel. The pilot-scale production line comprises equipment for mixing a slurry of cement, water, and fiberglass, as well as equipment for delivering the mix to a forming area on a conveyor belt, as shown in Figure 10A. A strip of board is then formed on the conveyor. A liner and top forming plate were used to control the thickness of the formed board, as described herein. In this example, an experimental horizontal forming plate was constructed from reinforced plywood, and height adjustment was achieved with jack screws. The experimental mounting frame was constructed from extruded aluminum. Although the experimental horizontal forming plate assembly was not industrially robust, the formed board thickness results show a surprising improvement over the previous ones. 144 normal production results. ηζααηη / ζζηζ / Ε / γίΛΐ Table 4 Inventive Examples Comparative Example Panel #1 Panel #2 Panel #3 Panel #4 Average Panel #C-1 Panel #0-2 Panel #C-3 Panel #C-4 Maximum Thickness (inches) 0.585 0.584 0.564 0.554 0.563 0.995 0.932 0.944 0.933 Minimum Thickness (inches) 0.522 0.509 0.500 0.469 0.500 0.792 0.758 0.788 0.771 Range (MaximumMinimum) (inches) 0.063 0.039 0.064 0.085 0.063 0.203 0.174 0.156 0.162 Standard Deviation (inches) 0.015 0.008 0.009 0.014 0.012 0.300 0.028 0.301 0.032 Example 4 - Data from plant tests testing the thickness control device comprising the fixed horizontal forming plate The data were generated from a trial in a large-scale manufacturing plant. In the following TABLE 5, samples denoted by R are control samples, made on an FRC panel production line using a normal method without thickness control device comprising the fixed horizontal forming plate. Samples beginning with T are test samples, made on a production line with the thickness control device. 145 thickness comprising the fixed horizontal forming plate of the invention. Each R or T sample is a 4' x 8' panel. The board composition was consistent with that described above for the single-ply process. The boards were made using a gypsum-cement binder composition. The cementitious binder comprises a mixture composed of alpha calcium sulfate hemihydrate, Portland cement, silica fume, and hydrated lime added in the following proportions: 62:25:12:1, respectively. Expanded perlite was used as a lightweight filler. The perlite particles were chemically coated with a silicone-based hydrophobic chemical coating to reduce water absorption by the particles. The weight ratio of perlite to cementitious binder was 0.09. Water and chemical processing aids were added in sufficient quantities to obtain an aqueous slurry of the workable consistency required for the process. Alkali-resistant glass fibers were used as structural reinforcement in the panel. The experimental forming board system described in Example 3 was removed from the pilot scale line and installed on a production line, similar to Figure 8. Again, the formed board thickness results showed a striking improvement compared to normal production results. 146 Table 5 #R3 #R4 #2R1 T1 T2 T4 Standard Deviation (inches) 0.022 0.016 0.028 0.012 0.012 0.010 Range (inches) 0.101 0.092 0.131 0.057 0.061 0.050 The standard deviation and range are approximately 500 data points per 4 ft x 8 ft panel. The sampling pattern was developed by marking sample lines on a 2 ft x 2 ft grid, and individual thickness measurements were located every inch along the grid lines. The data are also shown graphically by Figures 18-29 which show the cross-section profiles measured in the cross-machine direction and the off-machine direction in a multi-layer FRC panel production process. In these figures, the top and bottom solid unmarked straight lines for the data points are + / - 0.03 inch off the actual average thickness of each FRC panel. The data lines in Figures 18-29 are the individual thickness measurements, each inch in the machine direction (8 ft) and in the cross-machine direction (4 ft). Therefore, in Figures 18-29 the Y-axis is the thickness in inches. In the figures for the cross-section profiles measured in the cross-machine direction, the X-axis is each of the 48 inches across the four-foot cross-machine direction of the FRC panel. In the figures for 147 cross-section profiles are measured in the machine direction, the X-axis is each of the 96 inches across the eight foot machine direction of the FRC panel. Figure 18 (#R3 Cross-machine direction) shows a cross-sectional profile of a cementitious panel being formed for an example #R3 of the present disclosure which is measured in the cross-machine direction of a control sample, made on an FRC panel production line with a normal method without thickness control device comprising the fixed horizontal forming plate. Figure 19 (#R3 Machine Direction) shows a cross-sectional profile of a cementitious panel being formed for an example #R3 of the present disclosure being measured in the machine direction of a control sample, made on an FRC panel production line with a normal method without thickness control device comprising the fixed horizontal forming plate. Figure 20 (#R4 Cross-machine direction) shows a cross-sectional profile of a cementitious panel being formed for an example #R4 of the present disclosure which is measured in the cross-machine direction of a control sample, made on an FRC panel production line with a normal method without thickness control device comprising the fixed horizontal forming plate. 148 Figure 21 (#R4 Machine Direction) shows a cross-sectional profile of a cementitious panel being formed for an example #R4 of the present disclosure being measured in the machine direction of a control sample, made on an FRC panel production line with a normal method without thickness control device comprising the fixed horizontal forming plate. Figure 22 (#2R1 Cross-machine direction) shows a cross-sectional profile of a cementitious panel being formed for an example #2R1 of the present disclosure which is measured in the cross-machine direction of a control sample, made on an FRC panel production line with a normal method without thickness control device comprising the fixed horizontal forming plate. Figure 23 (#2R1 Machine Direction) shows a cross-sectional profile of a cementitious panel being formed for an example #2R1 of the present disclosure being measured in the machine direction of a control sample, made on an FRC panel production line with a normal method without thickness control device comprising the fixed horizontal forming plate. Figure 24 (#T1 Cross Machine Direction) shows a cross-sectional profile of a cementitious panel that is formed for an example #T1 of the present disclosure that is measured in the cross machine direction of 149 test samples made on a production line with the thickness control device comprising the fixed horizontal forming plate of the invention. Figure 25 (#T1 Machine Direction) shows a cross-sectional profile of a cementitious panel being formed for an example #T1 of the present disclosure being measured in the machine direction of test specimens made on a production line with the thickness control device comprising the fixed horizontal forming plate of the invention. Figure 26 (#T2 Cross-machine direction) shows a cross-sectional profile of a cementitious panel being formed for an example #T2 of the present disclosure which is measured in the cross-machine direction of test specimens made on a production line with the thickness control device comprising the fixed horizontal forming plate of the invention. Figure 27 (#T2 Machine Direction) shows a cross-sectional profile of a cementitious panel being formed for an example #T2 of the present disclosure being measured in the machine direction of test specimens made on a production line with the thickness control device comprising the fixed horizontal forming plate of the invention. 150 Figure 28 (#T4 Cross-machine direction) shows a cross-sectional profile of a cementitious panel being formed for an example #T4 of the present disclosure which is measured in the cross-machine direction of test specimens made on a production line with the thickness control device comprising the fixed horizontal forming plate of the invention. Figure 29 (#T4 Machine Direction) shows a cross-sectional profile of a cementitious panel being formed for an example #T4 of the present disclosure being measured in the machine direction of test specimens made on a production line with the thickness control device comprising the fixed horizontal forming plate of the invention. The data from this example demonstrated the effectiveness of the fixed horizontal forming plate of this invention in reducing thickness variation. The data from this example demonstrated that the concept produced FRC panels with a dramatic reduction in thickness variation for FRC panels formed with multiple layers of cement slurry and fiberglass, in addition to panels formed with only a single layer of premixed cement slurry and fiberglass. This reduction allows the average thickness of the formed panels to be reduced while avoiding gap points. 151 individual thinners that would result in the panel being rejected for not meeting specifications. Example 5: Achieving the target panel thickness on the panel forming line by employing a coating fabric and a thickness control device comprising the fixed horizontal forming plate A production trial using a fixed forming plate was conducted using a multi-layer process in a large-scale manufacturing facility. A glass mat facing was used in conjunction with the fixed forming plate. The multi-layer panel was made by using four distinct grout layers and seven discrete fiber layers. The target panel thickness was 0.77 inches with a tolerance of + / - 0.03 inches. The fixed forming plate was the same as that described in Example 4. The forming plate was adjusted so that the gap between the bottom surface of the forming plate and the forming surface was approximately 0.77 inches. The boards were made using a gypsum-cement binder composition. The cementitious binder comprises a mixture composed of alpha calcium sulfate hemihydrate, Portland cement, silica fume, and hydrated lime added in the following proportions: 62:25:12:1, respectively. Expanded perlite was used as a lightweight filler. The perlite particles were coated with ηζααηη / ζζηζ / Ε / γίΛA 152 was chemically coated with a silicone-based hydrophobic chemical coating to reduce water absorption by the particles. The weight ratio of perlite to cementitious binder was 0.09. Water and chemical processing aids were added in sufficient quantities to obtain an aqueous slurry of the workable consistency required for the process. Alkali-resistant glass fibers were used as structural reinforcement in the panel. Five panels of size 48 inches x 96 inches were selected for thickness measurement. Thickness measurements were made in the machine direction (i.e., along the 96 inch dimension) as well as in the cross-machine direction (i.e., across the 48 inch dimension). The thickness measurements were made at a 4 inch interval, i.e., 24 measurements were made in the machine direction and 12 measurements were made in the cross-machine direction. TABLE 6 shows the average measured thickness as well as the measured standard deviation. It can be seen that the average measured thickness of five panels was 0.783 inches in the machine direction as well as 0.783 inches in the cross-machine direction. It can also be seen that the measured panel thickness fell within the target thickness description of 0.77 + / - 0.03 inches. ηζααηη / ζζηζ / Ε / γίΛΐ ηζααηη / ζζηζ / Ε / γίΛΐ Table 6 Properties Panel Thickness Being Measured Cross Machine Direction Machine Direction (inches) (inches) Average Thickness 0.783 0.783 Average Std. Dev. 0.011 0.006 Example 6: Improving the weather and outdoor durability of panels using a glass mat coating It has been unexpectedly discovered that the application of a facing fabric material over the panel surface helps to significantly improve the durability of the panels when exposed to weathering in outdoor environments. The panels of Example 4 comprising the glass mat facing were exposed to weathering at an outdoor weathering farm, which is located in Illinois, USA, as shown in Figure 30. The panels (of a sample size of 24 in x 24 in) were exposed for around nine months, where they witnessed a winter season, a spring season, and a summer season. At the end of the summer season, observations were made to evaluate the physical characteristics and durability of the panel. Figure 31A shows a photograph of an unfaced FRC panel after nine months of weathering exposure. 154 exterior. Figure 31B shows a photograph of an FRC panel with glass mat facing on the top surface only after nine months of outdoor exposure. The glass matted panels were found to be in very good condition with the fiberglass mat firmly adhered to the base panel. The back surface and cut edges were in very good condition with no observable signs of material erosion or damage. This unexpected physical behavior is comparatively superior to FRC panels without glass mat where panel surface erosion (light pitting and surface wear) can be observed with prolonged outdoor weathering exposure. CLAUSES OF THE INVENTION The following clauses describe aspects of the invention. Clause 1. A fiber-reinforced cementitious panel production line comprising: a movable carrier frame, a support frame for supporting the movable carrier frame, wherein the panel is transported on the movable carrier frame having a travel direction relative to the support frame, and a thickness control device for controlling the thickness of a formed fiber-reinforced cementitious panel, but 155 which is not yet set, comprising a fiber-laden cementitious slurry comprising cementitious material and chopped fibers embedded in the movable carrier web, wherein the thickness control device comprises a rigid angled plate and a mounting frame for mounting the rigid angled plate on the support frame for the movable carrier web, and a rigid, planar support bed under the rigid angled plate, which is adapted and configured sufficiently to support the fiber-laden slurry and preferably resist the downward force exerted by the rigid angled plate with a deflection of less than 0.03 inches, preferably less than 0.01 inches, preferably less than 0.003 inches, the angled rigid plate having an upstream transverse rear wall, a downstream transverse bottom wall extending downstream from a lower end of the upstream transverse rear wall, open side walls and an open top, wherein the bottom surface of the bottom wall has a flat horizontal profile, the upstream transverse rear wall meets the downstream bottom wall to form a bent transition section that is aligned transversely to the direction of travel of the movable carrier frame, and the upstream transverse rear wall meets the ηζααηη / ζζηζ / Ε / γίΛA. 156 downstream transverse bottom wall to form an angle (Θ) in a range of 60 to 120 degrees, preferably 70° to 110°, and most preferably 80° to 100°, the upstream transverse rear wall directing from the upwardly bent transition section away from the movable carrier frame, the downstream transverse bottom wall directing from the downwardly bent transition section towards the movable carrier frame, the angled rigid plate transverse to the upstream rear wall being mounted on the mounting bracket to be transverse to the direction of travel of the movable carrier frame, a vibrator being attached to the angled rigid plate transverse to the upstream rear wall, the mounting bracket for fixedly but adjustable maintaining the height of the angled plate above the movable carrier frame and maintaining in a fixed but adjustable manner,the angle of the mounting member a (alpha) of the angled plate relative to the movable carrier frame of 5o to 30°, typically the angle is in the range of 10° to 25°, to fixedly locate a downstream end of the transverse bottom wall at a height of 0.1 to 2 inches, preferably 0.2 to 1.1 inches, above the movable carrier frame, wherein the downstream end of the bottom wall, 157 transverse is transverse to the direction of travel of the slurry and the movable carrier web, wherein the downstream end of the transverse bottom wall extends transversely across the movable carrier web, and wherein the downstream end of the transverse bottom wall is capable of contacting the fiber-laden slurry when carried over the movable carrier web. Clause 2. The apparatus of Clause 1, wherein the thickness controlling device comprises the angled rigid plate and wherein the mounting frame comprises a U-shaped mounting bracket for mounting the angled rigid plate on the support frame for the movable carrier frame, the mounting bracket having opposite vertical members, a tiltable cross mounting member having opposite ends that are mounted on the respective vertical members at a fixed but adjustable angle relative to the movable carrier frame and a fixed but adjustable height above the movable carrier frame, the mounting frame further having a connector plate having an upper end portion that is attached to the cross mounting member and a lower end portion that is attached to a rear wall of the angled rigid plate, the vibrator (vibration motor) is also mounted on the rear wall of the angled rigid plate. 158 Clause 3. the apparatus of Clause 2, wherein the U-shaped mounting frame has upright members which are fixedly attached to a stationary frame cross member, the U-shaped mounting frame further having a tiltable cross-mounting member which is movably attached to the upright members, the tiltable cross-mounting member having opposite ends, each being rotatably mounted on a respective metal plate with holes for angle adjustment. Clause 4. The apparatus of Clause 3, wherein each of the opposite ends of the cross-mounting member is paired with a hole that is selected from the tiltable cross-mounting member for angle adjustment to fixedly set the angle a (alpha) of the angled rigid plate relative to the movable carrier frame. Clause 5. The apparatus of Clause 4, wherein to assist in adjusting the angle, the tilting cross-mount member is provided with a handle for raising and lowering the vibrating plate. Clause 6. The apparatus of any one of Clauses 1 to 5, wherein the length of the rigid angled plate in the direction of travel of the machine T on the side in contact with the slurry is typically from about 2 inches to 24 inches and the width of the vibratory angled plate in the transverse direction of the direction of 159 T machine travel may vary from about 1 foot to 8 feet, where the preferred width of the metal plate varies from about 2 feet to 6 feet, or from about 2 feet to 5 feet, or from about 3 feet to 4 feet. Clause 7. The apparatus of any one of Clauses 1 through 6, wherein the thickness of the 95 angled vibratory plate on the grout contact side is typically about 1 / 16 inch to 1 / 4 inch, wherein the preferred plate thickness on the grout contact side is about 1 / 8 inch with a gradual taper from 1 / 4 inch thick on the side that is conformable and configured to taper away from grout contact to 1 / 16 inch at the grout contact edge. Clause 8. The apparatus of any one of Clauses 1 to 7, wherein the depth of embedding the angled plate and the vibration means in the fiber-laden slurry is to apply force to the surface of the panel sufficient to control the thickness of the surface. Clause 9. The apparatus of any one of Clauses 1 to 8, further comprising means for depositing chopped fibers onto the slurry which is carried on the carrier frame movable relative to the support frame, ηζααηη / ζζηζ / Ε / γίΛΐ 160 means for embedding the fibers in the slurry on the movable carrier frame to form the fiber-reinforced concrete panel being formed but not yet set, by passing the slurry with the deposited fibers through an embedding device for use in the fiber-reinforced concrete panel production line into contact with a first plurality of axially spaced discs which are axially fixed to a first elongated shaft which is integrally formed and rotatably secured to the support frame and into contact with a second plurality of axially spaced discs which are axially fixed to a second elongated shaft which is integrally formed and rotatably secured to the support frame; the first axis is arranged relative to the second axis to be horizontally aligned and the discs to interlock with each other, and wherein, when viewed from the side, the peripheries of the first and second plurality of discs overlap each other. Clause 10. The apparatus of any one of Clauses 1 to 8, further comprising a mixer for mixing the cementitious slurry and reinforcing fibers to form the fiber-laden slurry and feeding the fiber-laden slurry to a headbox, a headbox for depositing a layer of fiber-laden slurry onto the movable carrier web, 161 wherein the fiber-slurry mixture being deposited from the headbox has a slump of 4 to 11 inches as measured by a slump test using a 4 inch high, 2 inch diameter pipe, the resulting fiber-slurry mixtures also have a viscosity of less than 45,000 centipoise when measured by using a Brookfield Viscometer, Model DV11+ Pro with an HA4 Spindle attachment operating at a speed of 20 RPM. Clause 11. A continuous process for controlling the thickness of a formed, but not yet set, fiber-reinforced cementitious panel comprising a fiber-laden cementitious slurry comprising cementitious material and embedded chopped fibers, in the fiber-reinforced cementitious panel production line according to claim 1, comprising the steps of: conveying the panel on a movable carrier frame having a direction of travel relative to a support frame for supporting the movable carrier frame, Contacting the formed, but not yet set, fiber-reinforced cementitious panel comprising grout and embedded chopped fibers with a downstream end of a thickness control device, wherein the thickness control device comprises a rigid angled plate and 162 a mounting frame for mounting the rigid angled plate onto the support frame for the movable carrier frame, and a rigid, flat support bed under the rigid angled plate, which is adapted and configured sufficiently to support the fiber-laden slurry and preferably resist the downward force exerted by the rigid angled plate with a deflection of less than 0.03 inches, preferably less than 0.01 inches, preferably less than 0.003 inches, the rigid angled plate having an upstream transverse rear wall, a downstream transverse bottom wall extending downstream from a lower end of the upstream transverse rear wall, open side walls, and an open top, wherein the bottom surface of the bottom wall has a flat horizontal profile,the upstream transverse rear wall meets the downstream bottom wall to form a folded transition section that is aligned transversely to the direction of travel of the movable carrier frame, and the upstream transverse rear wall meets the downstream transverse bottom wall to form an angle in a range of 60 to 120 degrees, preferably 70° to 110°, and most preferably 80° to 100°, the upstream transverse rear wall is directed from the folded transition section upwardly away from the ηζααηη / ζζηζ / Ε / γίΛA carrier frame, 163 movable, the downstream transverse bottom wall is directed from the downwardly bent transition section toward the movable carrier frame, wherein the angled plate transverse to the upstream rear wall is mounted to the mounting bracket to be transverse to the direction of travel of the movable carrier frame, a vibrator being attached to the angled plate transverse to the upstream rear wall, the mounting bracket fixedly but adjustable maintains the height of the angled plate above the movable carrier frame and fixedly but adjustable maintains the angle of the angled plate relative to the movable carrier frame at less than 30°, typically the angle is 5° to 30°, preferably in the range of 10° to 25°, to fixedly locate the downstream end of the bottom wall at a height of 0.1 to 2 inches, preferably 0.2 to 1.1 inch, above the moving carrier web, where the downstream end of the bottom wall comes into contact with the fiber-laden slurry carried in the moving carrier web to control the thickness of the fiber-laden slurry. Clause 12. The process of Clause 11, wherein the angled plate is arranged over the entire width of the panel being formed. Clause 13. The process of any of the Clauses ηζααηη / ζζηζ / Ε / γίΛΐ 164 11-12, wherein the angled vibratory plate is positioned so that the functional edge of the plate remains in contact with the grout, at a depth of 0.05 inches or more in the grout. Clause 14. The process of any of Clauses 11-13, wherein the angled vibrating plate is vibrated by a vibrating motor 105 having a weight attached at a distance from the metal plate, wherein the distance of the rotating weight intervals from the metal plate is about 0.50 to 8 inches, about 1 to 7 inches, or about 2 to 6 inches, so that the vibrations of the motor and the plate remain in phase. Clause 15. The process of any of Clauses 11-14, wherein the rotational speed of the eccentric weights is typically from about 100 rpm to about 4000 rpm, the vibratory motor is mounted for use such that the eccentric weight which is attached to the rotating shaft rotates in the plane parallel to the face of the metal plate which touches the cementitious slurry. Clause 16. The process of any of Clauses 11-15, further comprising chopped fibers being deposited on the slurry being carried on the movable carrier web relative to the support frame, ηζααηη / ζζηζ / Ε / γίΛΐ embedding the fibers in the slurry on the web 165 movable carrier at a fiber embedding station for forming the fiber reinforced concrete panel being formed but not yet set by passing the slurry with the deposited fibers through an embedding device for use in the fiber reinforced concrete panel production line to contact a first plurality of axially spaced discs axially fixed to a first integrally formed elongated shaft rotatably secured to the support frame and contacting a second plurality of axially spaced discs axially fixed to a second integrally formed elongated shaft rotatably secured to the support frame; the first axis is arranged relative to the second axis to be horizontally aligned and the discs to interlock with each other, and wherein, when viewed from the side, the peripheries of the first and second plurality of discs overlap each other. Clause 17. The process of Clause 16, where the panel discharged from the fiber embedding station passes to the thickness control device. Clause 18. The process of Clause 16, wherein in addition the panel passes through at least two fiber embedding stations and the panel discharged from the most downstream fiber embedding station is fed to the thickness control device. ηζααηη / ζζηζ / Ε / γίΛΐ 6 Clause 19. The process of any of Clauses ll-15, further comprising mixing the cementitious slurry and reinforcing fibers to form the fiber-laden slurry and feeding the fiber-laden slurry into a headbox, depositing a layer of fiber-laden slurry from the headbox onto the moving carrier frame, wherein the fiber-slurry mixture being deposited from the headbox has a slump of 4 to 11 inches as measured according to a slump test by use of a 4-inch tall, 2-inch diameter pipe, the resulting fiber-slurry mixtures also having a viscosity of less than 45,000 centipoise when measured by use of a Brookfield Viscometer, Model DV11+ Pro with an HA4 Spindle attachment operating at a speed of 20 RPM. Clause 20. The process of Clause 19, wherein the fiber-slurry mixture being deposited from the headbox has a slump of 4 to 11 inches, as measured according to a slump test using a 4-inch high, 2-inch diameter pipe. The resulting fiber-slurry mixtures also have a viscosity of less than 45,000 centipoise, preferably less than 30,000 centipoise, more preferably less than 15,000 centipoise, and most preferably less than 10 centipoise. 167 000 centipoise when measured using a Brookfield Viscometer, Model DV-II+ Pro with an HA4 Spindle accessory operating at a speed of 20 RPM, typically the resulting fiber-slurry mixtures have a viscosity of at least 1500 centipoise. Clause 21. The process of Clause 20, wherein the cementitious slurry and fibers are discharged from the headbox and uniformly deposited as a continuous layer of 0.125 to 2 inches in thickness on a moving surface of a panel production line to produce a fiber reinforced cementitious panel, wherein an outer edge of the bottom wall of the angle plate assembly is located approximately 0.01 inches to 0.25 inches lower than the upper surface of the panel being formed. Clause 22. The process of any of Clauses 11-21, wherein the dry cementitious powder comprises a reactive powder portion and an optional lightweight filler portion, wherein the reactive portion comprises, on a dry basis, 35 to 75% by weight of alpha calcium sulfate hemihydrate, 20 to 55% by weight of hydraulic cement, 0.2 to 3.5% by weight of lime, and 5 to 25% by weight of an active pozzolan. Clause 23. The process of any of Clauses 11-22, wherein the slurry has a weight ratio of water to cement of about 0.20 to about 0.7:1. Clause 24. The process of any of the Clauses ηζααηη / ζζηζ / Ε / γίΛΐ 168 11-23, wherein the dry cementitious powder comprises 20 to 50% by weight of the lightweight filler particles on a dry basis, wherein the lightweight filler particles are selected from the group consisting of ceramic microspheres, glass microspheres, fly ash cenospheres and perlite. Clause 25. The process of any of Clauses 11-24, wherein the mobile carrier frame moves at a speed of 1 to 100 feet per minute. Clause 26. A production line for fiber-reinforced cementitious panels comprising: a movable carrier web, a support frame for supporting the movable carrier web, wherein the panel is transported on the movable carrier web having a travel direction relative to the support frame, and means for applying a coating, such as a glass mat, over a fiber-laden cementitious slurry on the movable carrier web, the means for applying the coating being positioned across the width of a forming surface of the movable carrier web, a horizontal thickness control device for controlling the thickness of a formed, but not yet set, fiber-reinforced cementitious panel comprising a fiber-laden cementitious slurry comprising cementitious material and chopped fibers embedded on the movable carrier web, 169 wherein the horizontal thickness control device comprises a rigid horizontal upper forming plate (e.g., horizontal forming plate 446), wherein the rigid horizontal upper forming plate has a planar bottom surface, an upstream end and a downstream end, and a forming plate mounting frame for mounting the rigid horizontal upper forming plate in a horizontal orientation on the support frame for the movable carrier frame, wherein the rigid horizontal upper forming plate is mounted to the forming plate mounting frame, and a rigid, planar support bed under the rigid horizontal upper forming plate, which is adapted and configured sufficiently to support the fiber-laden cementitious slurry and preferably resist the downward force exerted by the rigid horizontal upper forming plate with a deflection of less than 0.03 inches, preferably less than 0.01 inches, preferably less than 0.003 inches, the forming plate mounting frame for maintaining in a fixed but adjustable manner the height of the rigid horizontal upper forming plate on the movable carrier frame and maintaining the horizontal upper forming plate ηζααηη / ζζηζ / Ε / γίΛΐ. 170 rigid parallel relative to the movable carrier web, to fixedly locate the planar lower surface at a height of 0.1 to 2 inches, preferably 0.2 to 1.1 inches, above the movable carrier web, wherein the upstream end of the planar lower surface extends through the movable web transversely, relative to the direction of travel of the movable web, wherein the downstream end of the planar lower surface extends through the movable web transversely, relative to the direction of travel of the movable web, and wherein the entire planar lower surface is capable of contacting the coating in the fiber-laden slurry when carried on the movable carrier web. Clause 27. The apparatus of Clause 26, which further comprises: means for depositing chopped fibers onto the slurry which is carried on the movable carrier frame relative to the support frame, means for embedding the fibers in the slurry on the movable carrier frame to form the fiber-reinforced concrete panel which is formed, but not yet set, by passing the slurry with the deposited fibers through an embedding device for use in the ηζααηη / ζζηζ / Ε / γίΛΐ line 171 production of fiber reinforced concrete panels to come into contact with a first plurality of axially spaced discs that are axially fixed to a first elongated shaft that is integrally formed and rotatably secured to the support frame and come into contact with a second plurality of axially spaced discs that are axially fixed to a second elongated shaft that is integrally formed and rotatably secured to the support frame; The first axis is arranged relative to the second axis to be horizontally aligned and the discs to interlock with each other, and wherein, when viewed from the side, the peripheries of the first and second plurality of discs overlap each other. Clause 28. The apparatus of Clause 26, further comprising a mixer for mixing the cementitious slurry and reinforcing fibers to form the fiber-laden slurry and feeding the fiber-laden slurry to a headbox, a headbox for depositing a layer of fiber-laden slurry onto the moving carrier frame, wherein the fiber-slurry mixture being deposited from the headbox has a slump of 4 to 11 inches, which is measured according to a slump test by using a 4-inch high and 2-inch diameter pipe, the resulting fiber-slurry mixtures also 172 have a viscosity of less than 45,000 centipoise when measured using a Brookfield Viscometer, Model DV11+ Pro with an HA4 Spindle accessory operating at a speed of 20 RPM. Clause 29. The apparatus of any of Clauses 26-28, wherein an upstream end of the horizontal forming plate is chamfered. Clause 30. A process for making a fiber-reinforced cementitious panel comprising: conveying a fiber-laden slurry for a panel on a moving carrier web, the moving carrier web being supported by a support frame, wherein the panel is transported on the moving carrier web having a travel direction relative to the support frame, applying a coating, such as a glass mat, onto a fiber-laden cementitious slurry on the moving carrier web, across the width of a forming surface of the moving carrier web to cover the forming surface, passing the forming surface covered by the coating under a horizontal thickness controlling device to control the thickness of a formed, but not yet set, fiber-reinforced cementitious panel comprising a fiber-laden cementitious slurry comprising cementitious material and chopped fibers embedded in the ηζααηη / ζζηζ / Ε / γίΛΐ web 173 movable carrier, wherein the thickness control device comprises a rigid horizontal upper forming plate (e.g., horizontal forming plate 446), wherein the rigid horizontal upper forming plate has a planar bottom surface, an upstream end and a downstream end, and a forming plate mounting frame for mounting the rigid horizontal upper forming plate in a horizontal orientation on the support frame for the movable carrier frame, wherein the rigid horizontal upper forming plate is mounted to the forming plate mounting frame, and a rigid, planar support bed beneath the rigid horizontal upper forming plate, which is conformable and configured sufficiently to support the fiber-laden cementitious slurry and preferably resist downward force exerted by the rigid horizontal upper forming plate with a deflection of less than 0.03 inches, preferably less than 0.01 inches, preferably less than 0.003 inches, controlling the thickness of the formed, but not yet set, fiber-reinforced cementitious panel, when the formed, but not yet set, fiber-reinforced cementitious panel comes into contact with the covering, comprising a ηζααηη / ζζηζ / Ε / γίΛA. 174 fiber-filled cementitious grout, with a rigid horizontal upper forming plate bottom surface; the mounting frame for fixedly maintaining, but adjustable, the height of the rigid horizontal upper forming plate above the movable carrier web and keeping the plate parallel relative to the movable carrier web, to fixedly locate the planar lower surface at a height of 0.1 to 2 inches above the movable carrier web, wherein the upstream end of the planar lower surface extends through the movable web transversely, relative to the direction of travel of the movable web, wherein the downstream end of the planar lower surface extends through the movable web transversely, relative to the direction of travel of the movable web, and wherein the entire planar lower surface contacts the liner in the fiber-laden slurry when carried on the movable carrier web. Clause 31. The Clause 30 process: further comprising chopped fibers being deposited on the grout which is carried on the movable carrier frame relative to the support frame, embedding the fibers in the grout on the movable carrier frame to form the ηζααηη / ζζηζ / Ε / γίΛA reinforced concrete panel 175 fiber that is formed, but not yet set, by passing the slurry with the deposited fibers through an embedding device for use in the production line of fiber reinforced concrete panels to come into contact with a first plurality of axially separated discs that are axially fixed to a first elongated shaft that is integrally formed and rotatably secured to the support frame and come into contact with a second plurality of axially separated discs that are axially fixed to a second elongated shaft that is integrally formed and rotatably secured to the support frame; The first axis is arranged relative to the second axis to be horizontally aligned and the discs to interlock with each other, and wherein, when viewed from the side, the peripheries of the first and second plurality of discs overlap each other. Clause 32. The process of Clause 30, further comprising mixing the cementitious slurry and reinforcing fibers to form the fiber-laden slurry and feeding the fiber-laden slurry to a headbox, depositing a layer of fiber-laden slurry from the headbox onto the moving carrier frame, wherein the fiber-slurry mixture being deposited from the headbox has a slump of 4 to 11 inches, which is measured according to a slump test by ηζααηη / ζζηζ / Ε / γίΛA 176 Using a 4-inch tall, 2-inch diameter tube, the resulting fiber-slurry mixtures also have a viscosity of less than 45,000 centipoise when measured by using a Brookfield Viscometer, Model DV11+ Pro with an HA4 Spindle accessory operating at a speed of 20 RPM. Clause 33. The process of Clause 32, wherein the cementitious slurry and fibers are discharged from the headbox and uniformly deposited as a continuous layer of 0.125 to 2 inches in thickness on a moving surface of a panel production line to produce a fiber reinforced cementitious panel, wherein an outer edge of the bottom wall of the angle plate assembly is located approximately 0.01 inches to 0.25 inches lower than the top surface of the panel being formed. Clause 34. The process of any of Clauses 30 through 33, wherein the mobile carrier frame moves at a speed of 1 to 100 feet per minute. Clause 35. The process of any of Clauses 30 to 34, wherein the slurry has a weight ratio of water to cement of about 0.20 to about 0.7:1. Clause 36. The process of any one of Clauses 30 to 35, wherein the dry cementitious powder comprises a portion of reactive powder and an optional portion of lightweight filler, wherein the reactive portion comprises, on a dry basis, from 35 to ηζααηη / ζζηζ / Ε / γίΛΐ 177% by weight of alpha calcium sulfate hemihydrate, 20 to 55% by weight of hydraulic cement, 0.2 to 3.5% by weight of lime and 5 to 25% by weight of an active pozzolan. Clause 37. The process of any one of Clauses 30 to 36, wherein the dry cementitious powder comprises 20 to 50% by weight of the lightweight filler particles on a dry basis, wherein the lightweight filler particles are selected from the group consisting of ceramic microspheres, glass microspheres, fly ash cenospheres and perlite. Clause 38. The process of any one of Clauses 30 to 33, wherein the fixed horizontal forming plate is positioned to locate the bottom surface of the fixed horizontal forming plate at a height of 0.001 to 0.05 inches, preferably 0.01 to 0.03 inches, less than a target thickness of the FRC panel. While particular embodiments of the present production of fiber-reinforced cementitious structural panels have been shown and described, those skilled in the art will appreciate that changes and modifications can be made therein without departing from the invention in its broadest aspects and as set forth in the following claims. It is noted that in relation to this date, the best method known to the applicant to put the aforementioned invention into practice is the one that is clear from the present description of the invention.

Claims

1. A fiber-reinforced cementitious panel production line, characterized in that it comprises: a movable carrier web, a support frame for supporting the movable carrier web, wherein the panel is transported on the movable carrier web having a direction of displacement relative to the support frame, and a thickness control device for controlling the thickness of a formed, but not yet cured, fiber-reinforced cementitious panel comprising a fiber-loaded cementitious grout comprising cementitious material and chopped fibers embedded in the movable carrier web, wherein the thickness control device comprises an angled rigid plate and a mounting frame for mounting the angled rigid plate onto the support frame for the movable carrier web, and a flat, rigid support bed beneath the angled rigid plate, which is sufficiently adapted and configured to support the fiber-loaded grout and, preferably,resist the downward force exerted by the rigid angled plate 179 with a deviation of less than 0.03 inches, preferably less than 0.01 inches, preferably less than 0.003 inches, the rigid angled plate having an upstream transverse back wall, a downstream transverse bottom wall extending downstream from a lower end of the upstream transverse back wall, open side walls, and an open top, wherein the lower surface of the bottom wall has a flat horizontal profile, the upstream transverse back wall meets the downstream bottom wall to form a bent transition section that is aligned transversely to the direction of displacement of the moving carrier frame, and the upstream transverse back wall meets the downstream transverse bottom wall to form an angle (Θ) in a range of 60 to 120 degrees,The upstream transverse back wall is directed from the upward-bent transition section away from the moving carrier frame; the downstream transverse bottom wall is directed from the downward-bent transition section towards the moving carrier frame; the upstream transverse angled rigid plate of the back wall is mounted on the mounting bracket so that it is transverse to the direction of travel of the moving carrier frame; a vibrator is attached to the upstream transverse angled rigid plate of the back wall; the mounting bracket maintains a fixed, but adjustable, height of the angled plate above the moving carrier frame and maintains a fixed, but adjustable, angle of the mounting element (α) of the angled plate relative to the moving carrier frame from 5° to 30°; and a downstream end of the transverse bottom wall is fixedly located at a height of 0.1 to 2 inches.on the moving carrier weave, wherein the downstream end of the lower transverse wall is transverse to the direction of movement of the slurry and the moving carrier weave, wherein the downstream end of the lower transverse wall extends transversely through the moving weave, and wherein the downstream end of the lower transverse wall is capable of coming into contact with the fiber-laden slurry when it is conveyed on the moving carrier weave.

2. The apparatus according to claim 1, characterized in that the thickness control device comprises the angled rigid plate and wherein the mounting frame comprises a U-shaped mounting bracket for mounting the angled rigid plate onto the support frame 181 for the movable carrier frame, the mounting bracket having opposing vertical members, a tilting transverse mounting member having opposite ends that are mounted on the respective vertical members at a fixed but adjustable angle relative to the movable carrier frame and a fixed but adjustable height above the movable carrier frame, the mounting frame further having a connecting plate having an upper end portion that is attached to the transverse mounting member and a lower end portion that is attached to a rear wall of the angled rigid plate, the vibrator (vibration motor) also being mounted on the rear wall of the angled rigid plate.

3. The apparatus according to claim 2, characterized in that the U-shaped mounting frame has vertical members that are fixedly attached to a crossmember of the stationary frame, the U-shaped mounting frame further has a tilting cross-mounting member that is movably attached to the vertical members, the tilting cross-mounting member having opposite ends, each rotatably mounted on a respective metal plate with holes for angle adjustment.

4. The apparatus according to claim 3, characterized in that each of the opposite ends of the transverse mounting member is paired with an orifice selected from the tilting transverse mounting member ηζααηη / ζζηζ / E / γίΛΐ 182 for angle adjustment to fixedly configure the angle a (alpha) of the rigid plate at an angle relative to the movable carrier frame.

5. A fiber-reinforced cementitious panel characterized in that it is made by using the apparatus according to claim 1.

6. A fiber-reinforced cementitious panel production line, characterized in that it comprises: a movable carrier web, a support frame for supporting the movable carrier web, wherein the panel is transported on the movable carrier web having a direction of displacement relative to the support frame, and a means for applying a coating, such as a glass mat, onto a fiber-loaded cementitious grout on the movable carrier web, the means for applying the coating being placed across the width of a forming surface of the movable carrier web, a horizontal thickness control device for controlling the thickness of a formed, but not yet set, fiber-reinforced cementitious panel comprising a fiber-loaded cementitious grout comprising cementitious material and chopped fibers embedded on the movable carrier web,wherein the horizontal thickness control device comprises a rigid horizontal upper forming plate, wherein the rigid horizontal upper forming plate has a flat lower surface, an upstream end and a downstream end, and a forming plate mounting frame for mounting the rigid horizontal upper forming plate in a horizontal orientation on the support frame for the movable carrier frame, wherein the rigid horizontal upper forming plate is mounted on the forming plate mounting frame, and a rigid, flat support bed under the rigid horizontal upper forming plate, which is sufficiently adapted and configured to support the fiber-loaded cementitious grout and, preferably, resist the downward force exerted by the rigid horizontal upper forming plate with a deviation of less than 0.03 inches,The forming plate mounting frame maintains a fixed, yet adjustable, height of the rigid horizontal upper forming plate above the moving carrier web and keeps the rigid horizontal upper forming plate parallel to the moving carrier web, fixedly positioning the flat lower surface at a height of 0.1 to 2 inches, wherein the upstream end of the flat lower surface extends across the moving web transversely, relative to the direction of travel of the moving web, and wherein the downstream end of the flat lower surface extends across the moving web transversely, relative to the direction of travel of the moving web, and wherein the entire flat lower surface is capable of contacting the lining in the fiber-loaded slurry when carried on the moving carrier web.

7. A fiber-reinforced cementitious panel characterized in that it is made by using the production line according to claim 6.

8. A process for making a fiber-reinforced cementitious panel, characterized in that it comprises: transporting a fiber-loaded grout for a panel on a movable carrier web, the movable carrier web being supported by a support frame, wherein the panel is transported on the movable carrier web having a direction of displacement relative to the support frame, applying a coating over a fiber-loaded cementitious grout on the movable carrier web, across the width of a forming surface of the movable carrier web to cover the forming surface, passing the forming surface covered by the coating under a horizontal thickness control device for controlling the thickness of a formed, but not yet set, fiber-reinforced cementitious panel, comprising a fiber-loaded cementitious grout comprising cementitious material and chopped fibers embedded in the movable carrier web,wherein the thickness control device comprises a rigid horizontal top forming plate, wherein the rigid horizontal top forming plate has a flat bottom surface, an upstream end and a downstream end, and a forming plate mounting frame for mounting the rigid horizontal top forming plate in a horizontal orientation on the support frame for the movable carrier frame, wherein the rigid horizontal top forming plate is mounted on the forming plate mounting frame, and a rigid, flat support bed under the rigid horizontal top forming plate, which is sufficiently adapted and configured to support the fiber-loaded cementitious grout and, preferably, resist the downward force exerted by the rigid horizontal top forming plate with a deviation of less than 0.03 inches, controlling the thickness of the formed 186 fiber-reinforced cementitious panel,but not yet set, upon contact of the fiber-reinforced cementitious panel formed, but not yet set, covered with the coating, comprising a fiber-loaded cementitious grout, with a lower surface of the rigid horizontal upper forming plate; the mounting frame for maintaining in a fixed, but adjustable, manner the height of the rigid horizontal upper forming plate above the moving carrier frame and maintaining the plate parallel with respect to the moving carrier frame, for fixedly positioning the flat lower surface at a height of 0.1 to 2 inches above the moving carrier frame, wherein the upstream end of the flat lower surface extends across the moving frame transversely, with respect to the direction of displacement of the moving frame, wherein the downstream end of the flat lower surface extends across the moving frame transversely,with regard to the direction of movement of the moving frame.

9. The process according to claim 8, characterized in that the angled plate is disposed over the entire width of the formed panel, wherein the angled vibrating plate is positioned so that the functional edge of the plate remains in contact with the grout, at a depth of 0.05 inches or more in the grout. ηζααηη / ζζηζ / E / γίΛΐ 187 10. A fiber-reinforced cementitious panel characterized in that it is made using the process according to claim 8.

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