Inorganic binder-based construction materials with improved fire resistance behavior - Patents.com

Abstract

The present invention relates to an inorganic binder-based construction material comprising thermally pretreated silicate glass fibers, optionally colloidal silica, and further additives, and having increased fire resistance such that it has delayed shrinkage when exposed to high temperatures relative to an inorganic binder-based construction material having conventional glass fibers and optionally colloidal silica but otherwise the same composition. The claimed inorganic binder-based construction material provides improved resistance to spalling, thus ensuring that corresponding structures maintain their integrity over time when exposed to fire. The present invention also relates to a method for producing the inorganic binder-based construction material and the use of thermally pretreated silicate glass fibers and optional colloidal silica to delay the shrinkage of the inorganic binder-based construction material when exposed to high temperatures.

Description

[Technical field]

[0001] The present invention relates to a fire-resistant inorganic binder-based construction material and a method for producing such a construction material.In particular, the present invention relates to an inorganic binder-based construction board having increased fire resistance.

[0002] Prior Art Inorganic binder-based construction materials, such as those made from clay, cement, and plaster, are extremely common throughout the world and are known for their fire ratings. Of these, gypsum is an important building commodity, as evidenced by the hundreds of millions of square feet of gypsum core wallboard manufactured and sold annually for use in the building industry. Gypsum wallboard, also commonly known as drywall, gypsum board, gypsum sheathing, and plasterboard, as well as other inorganic binder-based construction materials, such as fiber cement boards, must have certain basic characteristics to meet accepted industry standards. Some of these criteria relate to fire resistance, i.e., the maximum temperature the material can withstand while maintaining its structural integrity and without cracking or crumbling (losing its integrity), or the time it takes to burn through, crumble, or otherwise destroy the integrity of the material at certain elevated temperatures. These characteristics are important in reducing the spread of fire and harm to individuals. Fire resistance should be distinguished from flame retardancy, which is the ability of a material to withstand high temperatures for a specified period of time without igniting and burning.

[0003] Hardened gypsum (CaSO 4 ×2H 2 Due to the water of crystallization contained in the gypsum (CaSO), gypsum building materials have advantageous properties in the event of a fire, since water can evaporate from the gypsum and bind a large amount of the energy of the fire. Since this is an endothermic process, the evaporation of the bound water cools the gypsum building material. As the evaporation of water increases, calcium sulfate hemihydrate (CaSO 4 ×1 / 2H 2 O) is formed in a further step, which is then converted to calcium anhydrite (CaSO4 ). However, the disadvantage of liberating water from the gypsum is that calcium sulfate hemihydrate or anhydrite occupies a smaller volume than the calcium sulfate dihydrate precursor. In addition, heating the material results in further loss of volume, causing the building material to shrink. Since gypsum boards are typically applied to a metal stud framework, the shrinking boards can be expelled from their attachments. Individual pieces of the drywall construction can fall off the drywall construction, posing a risk of injury to individuals in the room. Additionally, cracks and gaps allow fire to spread behind the drywall construction and into adjacent rooms. Fiber cement boards face similar problems.

[0004] In the prior art, several attempts are described that aim to retard or prevent the shrinkage of inorganic binder systems, especially gypsum building materials, under the influence of strong heat (e.g. fire) for longer periods of time. For this purpose, for example, refractory materials such as clay or thermally expansive materials such as vermiculite are incorporated into the building materials, which, due to their expansion behavior when exposed to heat, can at least partially compensate for the volumetric shrinkage of gypsum.

[0005] Conventional glass fibers are often incorporated to strengthen inorganic binder-based boards and make them more resilient to bursting in the event of a fire. Glass fibers facilitate the distribution of strain resulting from the shrinkage of building materials during high temperatures, thus retarding both the shrinkage and the fracture of the corresponding inorganic binder-based products.

[0006] Conventional glass fibers cannot usually withstand high temperatures exceeding 900° C., which may occur during a fire. For example, most conventional glass fibers soften or melt at around 700° C. to 1000° C., and as a result, conventional glass fibers can no longer provide their reinforcing effect to inorganic binder-based boards at these high temperatures.

[0007] There is also a need for inorganic binder-based construction materials that have increased fire resistance in general, and in particular that at least significantly delay the time it takes for a fire to break through to the rear of a drywall construction.

[0008] The present application provides a solution to these needs. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing the expansion and contraction profiles of Samples 1, 2, 3, 4, and 5 in the examples. [Diagram 2] FIG. 2 is a diagram showing the expansion and contraction profiles of Samples 1, 2, 3, and 6 in the examples. [Diagram 3] FIG. 3 is a diagram showing the expansion and contraction profiles of Samples 1, 6, and 7 in the examples. [Figure 4] FIG. 4 is a diagram showing the results of a deflection / deformation test at high temperatures for Samples 1, 8, 9, 10, 11, 12, and 13 in the examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] A first aspect of the present invention is an inorganic binder-based construction material comprising at least an inorganic binder, silicate glass fibers, and optionally further additives. The silicate glass fibers are thermally pretreated fibers.

[0011] The inorganic binder according to the present invention includes all particulate building materials that can be physically or preferably chemically hardened when the inorganic binder in dry / powder form is mixed with a fluid, for example with water. Chemical hardening includes chemical reactions (e.g. hydration), while physical hardening can be, for example, drying. The inorganic binder can be a calcium sulfate containing binder, for example gypsum, and its partially dehydrated forms, i.e. α- or β-hemihydrate (e.g. stucco) or anhydrite. The inorganic binder can also be or include lime, clay or cement binders (e.g. Portland cement, Portland cement blends, other kiln cements, calcium aluminate or calcium sulfoaluminate, magnesia cement, magnesium oxychloride cement, belite cement), as well as combinations thereof. The inorganic binder can be a hydraulic binder (e.g., cement, pozzolan, hydraulic lime, calcium sulfate hemihydrate or anhydrite, calcium silicate, clinker, fly ash) or a non-hydraulic binder (e.g., clay, non-hydraulic lime, water glass). Hydraulic binders harden by hydration, whereas non-hydraulic binders require exposure to, for example, carbon dioxide, for hardening. Construction materials based on inorganic binders can further comprise various additives known to those skilled in the art, such as fillers, accelerators, retarders, rheology modifiers, hydrophobizing agents, fireproofing materials, etc. Apart from hardening, the process for the preparation of inorganic binder-based construction materials can further comprise a drying step.

[0012] In the case of calcium sulfate as an inorganic binder, the dehydrated forms (α- and β-hemihydrate and anhydrite) are hydrated in the presence of water. In this hardening process, calcium sulfate dihydrate (i.e., gypsum) is formed. The calcium sulfate dihydrate crystals are interlocked and therefore provide strength, but the excess water must be further evaporated for the complete hardening of the material.

[0013] The term "mineral binder-based construction material" includes workable / formable mixtures containing inorganic binders as well as hardened / set mixtures containing inorganic binders. Hardened / set mixtures include shaped bodies such as building boards (e.g., plasterboard or cement board), bricks, laid base coats (e.g., laid plaster), laid mortar, laid filler, laid joint compound or laid screed. Workable / formable mixtures include bodies that have not yet been shaped (i.e., powder mixtures), such as base coats (e.g., plaster), mortar, filler, joint compound or screed, the shaping of which takes place only by the optional addition of water and application to a surface.

[0014] The inorganic binder may comprise at least 50% by weight of calcium sulfate binder, based on the total weight of the inorganic binder. The calcium sulfate material may be a calcium sulfate dihydrate (CaSO 4 ×2H 2 O, also known as gypsum), hemihydrate (CaSO 4 ×1 / 2H 2 O, also called stucco) or anhydrite (CaSO 4 ), naturally occurring calcium sulfate material can be mined in any of the above forms. In the manufacture of building boards, the greatest amount of calcium sulfate binder is added as the hemihydrate, which hardens during the manufacturing process to form the dihydrate in the finished building board. Dry powder compounds such as gypsum, fillers or joint compounds are sold with calcium sulfate binder present in the anhydrite or hemihydrate form. After being mixed with water, the calcium sulfate binder eventually hardens to form the dihydrate.

[0015] The term "silicate glass fiber" in the present invention refers to a glass fiber mainly made of silica (SiO 2 ), i.e. is meant to denote fibers that primarily comprise >80% by weight silica, based on the total weight of the fiber, the silica being preferably amorphous.

[0016] The term "thermally pretreated" in the present invention is meant to indicate that the silicate glass fibers have undergone a temperature pretreatment, i.e., a thermal pretreatment, before mixing them with an inorganic binder and water and before forming them into boards or other construction materials. Thermally pretreated silicate glass fibers are typically produced and used for thermal insulation, for example in high temperature gaskets or insulation mats, mainly for the metal and glass industries.

[0017] Preferably, the thermal pretreatment of the pretreated silicate glass fiber comprises heating the silicate glass fiber for at least 30 minutes to a temperature between 700° C. and 1000° C., preferably between 850° C. and 1000° C. More preferably, the thermal pretreatment of the silicate glass fiber is maintained for 45 minutes to 420 minutes, and most preferably, the thermal pretreatment of the silicate fiber is maintained for 200 minutes to 400 minutes.

[0018] In a preferred embodiment of the present invention, the thermally pretreated silicate glass fibers are at least 91 wt. %, more preferably at least 95 wt. %, and even more preferably at least 98 wt. % silica (SiO 2 ) and alumina (Al 2 O 3 In a particularly preferred embodiment, the thermally pretreated silicate glass fiber contains at least 90% by weight, in particular 90 to 99% by weight, preferably 93 to 98% by weight, of silica (SiO 2 ) and 1 to 10% by weight, preferably 2 to 7% by weight of alumina (Al 2 O 3 ), where the specific weight percentage is based on the total weight of the fibers.

[0019] Alternatively, or in addition, the thermally pretreated silicate glass fibers of the present invention can have a melting point of at least 1300°C, more preferably at least 1500°C, and even more preferably at least 1700°C.

[0020] Alternatively or additionally, the thermally pretreated silicate glass fiber in the present invention can have a softening point of at least 1200°C, more preferably at least 1300°C, even more preferably at least 1500°C, and most preferably at least 1600°C. A relatively high softening point ensures the structural integrity of the fiber and, consequently, the stability of the building material up to this temperature. The softening point is the temperature at which there is a significant change in physical properties. The glass material changes from hard to soft but is not yet molten.

[0021] Alternatively or in addition, the thermally pretreated silicate glass fibers in the present invention can be shrink-resistant at high temperatures. By high temperatures, it is meant exposure to at least 700°C and at most 1000°C, preferably at least 900°C for at least 30 minutes. Specifically, the thermally pretreated silicate glass fibers can shrink less than 7%, preferably less than 5%, more preferably 3% or less, and most preferably 2% or less when exposed to a temperature of 1000°C for at least 30 minutes. By shrinkage of fibers, it is meant that when the thermally pretreated silicate glass fibers are exposed to an elevated temperature of at least 700°C, at most 1000°C, preferably at least 900°C, for at least 30 minutes, the thermally pretreated silicate glass fibers retain at least 93.1%, preferably at least 95.1%, more preferably at least 97%, and most preferably at least 98% or their original length. Minimal shrinkage is advantageous in that the described fibers do not release or break away from the binder matrix and therefore can continue to provide stability and / or cohesion to the building material when the inorganic binder-based construction material is exposed to high temperatures, such as those that may be experienced during a fire. The term cohesion is meant to indicate that no part of the building material will fall off. Cohesion is further meant to indicate that the fibers can hold the matrix material together tightly and keep it in an integrated state.

[0022] Alternatively or additionally, the thermally pretreated silicate glass fibers of the present invention may lose 2% to 6% by weight when exposed to a temperature of 500°C for 45 to 75 minutes. When exposed to a temperature of 500°C for 45 to 75 minutes, non-pretreated silicate glass fibers may typically lose 9% to 13% by weight, and non-treated glass fibers, i.e., conventional glass fibers, may lose 0% to 3% by weight. Since the weight loss of these fibers is nearly identical at 500°C, there is generally no further weight loss for non-pretreated silicate glass fibers and thermally pretreated silicate glass fibers when exposed to 1000°C for 45 to 75 minutes. However, there is generally a weight loss of 9% to 13% by weight for conventional glass fibers at 1000°C for 45 to 75 minutes. The weight loss in this case is based on the weight of the fiber at ambient temperature before the fiber is heated to 500°C for 45 to 75 minutes.

[0023] Alternatively, or in addition, the thermally pretreated silicate glass fibers of the present invention can maintain their structural integrity and flexibility after exposure to 1000° C. for 45 to 75 minutes. Non-pretreated silicate glass fibers can maintain their structural integrity after the same exposure, but can be brittle. At 1000° C. for 45 to 75 minutes, conventional glass fibers lose their structural integrity and form a molten mass.

[0024] Preferably, the thermally pretreated silicate glass fibers have low lung bio-persistence, meaning that the fibers are not considered a potential health hazard, especially upon respiratory exposure.

[0025] The term "conventional glass fiber" refers to amorphous silica (SiO 2 ), preferably 50 to 70% by weight of amorphous SiO based on the total weight of the fiber. 2Amorphous materials have no or very low (<3%) crystallinity or long-range order. More preferably, conventional glass fibers contain 50-65 wt. % amorphous SiO, all based on the total weight of the fiber. 2 Conventional glass fibers contain Al 2 O 3 , B 2 O 3 , CaO, MgO and / or other metal oxides. Conventional fibers generally have a melting point below 1000°C and / or a softening point below 900°C, preferably around 700°C.

[0026] The inorganic binder-based construction material may further comprise colloidal silica.

[0027] In the present invention, the term "colloidal silica", also known as silica sol, is intended to denote a suspension of fine, amorphous, non-porous, typically spherical silica particles in a liquid phase, the colloidal silica particles typically having an average particle size in the range of about 1 to 50 nm.

[0028] The use of thermally pretreated silicate glass fibers, optionally in combination with colloidal silica, improves the fire resistance of inorganic binder-based construction materials compared to inorganic binder-based construction materials of otherwise identical composition that do not contain thermally pretreated silicate glass fibers. Preferred are embodiments of the building materials of the present invention that include both thermally pretreated silicate glass fibers and colloidal silica, as the combination of thermally pretreated silicate glass fibers and colloidal silica provides the best properties in terms of fire resistance.

[0029] Fire resistance means that a system or component, such as a building structure or building material, exhibits the ability to withstand fire or extremely high temperatures. Extremely high temperatures are temperatures above 600°C, preferably above 900°C, for at least 60 minutes, preferably at least 120 minutes. Resisting fire or extremely high temperatures means that a material, such as a construction material, can withstand without maintaining its structural integrity and cracking or crumbling (losing its integrity). Resisting fire or extremely high temperatures further means that a material, such as a construction material, exhibits no structural failure or flame transfer to the side away from the fire. The building material of the present invention is fire resistant and / or can withstand a temperature of at least 945°C for at least 120 minutes when tested by exposure to temperatures according to the temperature profile of DIN EN 1363-1:2012-10 for the first 60 minutes and constant exposure to 945°C for the next 60 minutes. Within the scope of the present invention, the length of time until the construction material of the present invention begins to shrink under defined temperature conditions and the time until the construction material of the present invention reaches a certain shrinkage rate under these temperature conditions is extended, thus providing a more fire resistant construction material and / or a more fire resistant structure. The respective measurements for determining this delay in the present invention were carried out according to and with the apparatus described in WO 2017 / 000972 A1.

[0030] The apparatus of WO 2017 / 000972(A1) allows to simultaneously and / or continuously measure the change in length of one sample and the change in weight of another sample during heating. Since only the change in length is relevant to the present invention, only this part of the apparatus will be described. A table-shaped sample holder is arranged in the oven chamber. Two cylindrical support members on columns are arranged on the table-shaped holder. The sample rests on these cylindrical support members and is further supported by a counter-bearing on the other side. The two support members are shaped to provide a minimum contact area between such support members and the sample. The cylindrical support members being arranged horizontally provide such a minimum contact area between the support members and the sample. It is preferable to have a minimum contact area in order to reduce friction between the sample and its support, i.e. the support members, during expansion or contraction. This avoids measurement errors and allows smooth recording without sudden jumps in the data that are method-related and not process-related. The sample is fixed on this counter-bearing, thereby limiting the change in length to the other side. The change in length can be measured by a length measuring device on the opposite side of the counter-bearing. The length measuring device comprises a detector rod and a rod position sensor for detecting and recording the change in position of the detector rod along the longitudinal axis. The detector rod is made of a heat-resistant material, for example a ceramic material, and has a detector tip at one end, which is in contact with the first sample on the opposite side of the counter-bearing. The detector rod extends from the position sensor outside the chamber into the heating chamber. The detector rod is under pressure by a spring and is pressed against the side of the sample by the spring force. This allows continuous measurements while the oven is heated according to a standard temperature-time curve.

[0031] When the inorganic binder-based construction material is a cement building material, shrinkage is not a primary concern, but non-uniform stresses are generated within the cement article when exposed to fire. This can lead to fractionation and spalling of the cement material. The thermally pretreated silicate glass fibers prevent shedding, i.e., larger pieces of the construction material from falling off the article. The cohesion of the article increases with fiber content. In the case of cement wallboard or cement siding, this is crucial to reduce injuries in a house fire. The shedding and cohesion discussed are also relevant to other inorganic binder-based construction materials.

[0032] If the inorganic binder-based construction material contains calcium sulfate binder, CaSO 4 ×2H 2 Evaporation of water from O results in the formation of phases with lower water content and smaller volume, specifically calcium sulfate hemihydrate or anhydrite. This volume change can be detected, for example, by measuring the length of the test specimen body before and after a defined temperature treatment. After the temperature treatment, the length of the specimen body is shorter. However, it must be noted that absolute values ​​are of little importance in this context, since the shrinkage rate of calcium sulfate building materials / building products also depends on the origin of the calcium sulfate binder. It is well known that calcium sulfates can contain different impurities depending on their origin, and these impurities can affect the properties of the building material. Therefore, only calcium sulfates of the same origin can be directly compared. It is believed that the thermally pretreated silicate fibers advantageously shrink less than similar fibers with similar softening and / or melting points when exposed to high temperatures, such as those that can be experienced during a fire. It is further believed that due to their improved ability to maintain their size (i.e. shrink less), these fibers are not released or separated from the binder matrix even under shrinkage stress, and can continue to provide stability and / or cohesion of the building material.

[0033] However, when exposed to high temperatures, the compact specimens generally expand to some extent before they begin to shrink. This expansion is due to the presence of gypsum (CaSO 4 ×2H 2 O), which is believed to be associated with the release of water of crystallization, thereby generating water vapor. The expansion phase begins with the heating of the sample body and ends when the sample body begins to shrink, i.e., decrease in size or length.

[0034] The difference between the length of the specimen before the application of the temperature and the length of the specimen after the application of the specified temperature for 120 minutes is expressed as a percentage of the original length (=length before the application of the temperature). A positive percentage value for the change in length indicates expansion (expansion rate), i.e. an increase in length, and a negative percentage value indicates contraction (contraction rate), i.e. a decrease in length. The lower the contraction rate (i.e. the less negative the value), the less the construction material will shrink as a result of the temperature treatment. The length of the specimen is the direction in space in which the specimen has the greatest extent. Without being bound by theory, it is believed that the construction material or its specimen may also shrink in other dimensions (i.e. other directions), such as, for example, width or height.

[0035] Both the duration of the time interval from the start of the high temperature treatment to the start of the shrinkage phase (i.e. the phase or period at the start of the high temperature treatment during which the length of the sample specimen decreases), which often coincides with the duration of the expansion phase (i.e. the phase or period at the start of the high temperature treatment during which the length of the sample specimen increases), and the shrinkage percentage depend on the sample size and the sample shape. If the sample specimens are taken from plates produced on a production line, the orientation of the sample with respect to the production direction is also relevant. Therefore, samples of approximately the same shape, size, weight, and, if applicable, the same sample orientation should be compared with each other.

[0036] An important advantage lies in the fact that this construction material, when exposed to a temperature of at least 80° C., exhibits a temporarily delayed shrinkage phase, i.e., a stage or period during which the length of the specimen decreases, relative to an inorganic binder-based construction material having an otherwise identical composition, containing conventional glass fibers instead of thermally pretreated silicate glass fibers, and optionally colloidal silica. In particular, in the case of calcium sulfate construction materials, it is important to understand that calcium sulfate construction materials lose water when exposed to a temperature of at least 80° C. This is due to the fact that the H incorporated in the crystalline calcium sulfate structure is lost. 2 This means that the O molecules are gradually removed. The dihydrate changes to hemihydrate and finally to anhydrite. Calcium sulfate molecules with lower water content also occupy less space. This means that calcium sulfate building materials can shrink.

[0037] In a preferred embodiment, the onset of the shrinkage phase of the construction material of the invention is delayed: the time interval from the start of the high-temperature treatment until a test specimen of the construction material of the invention starts to shrink (=delayed shrinkage) is longer than the time interval until a corresponding test specimen of essentially the same composition, but with conventional glass fibers (instead of thermally pretreated silicate glass fibers) and optionally colloidal silica, starts to shrink when exposed to temperatures according to the standard temperature-time curve described in DIN EN 1363-1:2012-10 and maintained at 945°C for 60 to 120 minutes. Preferably, the time interval in which the specimen reaches 99% of its initial length is at least 1.35 times, more preferably at least 1.5 times, even more preferably at least 1.6 times, the time interval in which a specimen of otherwise identical composition, with conventional glass fibers (instead of thermally pretreated glass fibers) and optionally colloidal silica, reaches 99% of its initial length when exposed to temperatures according to the standard temperature-time curve described in DIN EN 1363-1:2012-10 and the temperature is maintained at 945° C. for 60 to 120 minutes. For example, if a conventional specimen starts to shrink in 10 minutes, a specimen according to the invention having a shrinkage delay of at least 1.5 times starts to shrink only after 15 minutes or less when exposed to the mentioned temperatures.

[0038] In order to obtain comparable results, sample bodies of the inorganic binder-based construction material according to the invention were subjected to a temperature treatment according to the standard temperature-time curve according to DIN EN 1363-1:2012-10 for the first 60 minutes of heating. On that basis, the oven heating curve should fulfill the following formula: T=345 log 10 (8t+1)+20 During the ceremony T is the average furnace temperature in degrees Celsius and t is the elapsed time in minutes. For the first 60 minutes the samples are heated to approximately 945°C. After this initial period the temperature application according to the tests carried out deviated from DIN EN 1363-1:2012-10. For the subsequent test runs, i.e. from 60 min to 120 min, a constant temperature application of 945°C was used.

[0039] A test specimen made from an inorganic binder having a composition according to the invention, when exposed for the first 60 minutes to a temperature according to the temperature profile of DIN EN 1363-1:2012-10, exhibits a smaller shrinkage after at least 60 minutes than a test specimen containing conventional glass fibers and optionally colloidal silica, but of otherwise identical composition. In particular, the shrinkage of a test specimen according to this embodiment is at least 10% lower (i.e. less negative), preferably at least 20% lower, more preferably at least 40% lower, after at least 60 minutes than a test specimen made from an inorganic binder having conventional glass fibers (instead of thermally pretreated glass fibers) but of otherwise identical composition. Alternatively or additionally, as described above, the shrinkage of the test specimens according to the present embodiment may be at least 10% lower (i.e. less negative), preferably at least 20% lower, more preferably at least 40% lower after at least 120 minutes, when the test specimens are subjected to a standard temperature-time curve according to DIN EN 1363-1:2012-10 for the first 60 minutes and then to a constant 945° C. for the next 60 minutes. As described above, the type, weight, size and orientation with respect to the manufacturing direction of the inorganic binder-based construction materials should be comparable, if applicable.

[0040] In a preferred embodiment of the present invention, the construction material of the present invention comprises 0.01-5 wt.%, preferably 0.05-2 wt.%, more preferably 0.1-1.5 wt.% of thermally pretreated silicate glass fibers, based on the total weight of the inorganic binder used in the production of the building material. In this regard, it has been found that if the amount of thermally pretreated silicate glass fibers is less than 0.01 wt.%, the stabilizing effect of the fibers on the composition for retarding and / or reducing shrinkage may not be sufficient, while with an amount of thermally pretreated silicate glass fibers exceeding 5 wt.%, the retardation and / or reduction of shrinkage is not further improved. The optimal amount of thermally pretreated silicate glass fibers to provide the desired retardation and / or reduction of shrinkage silicate glass fibers is 0.1-1.5 wt.%.

[0041] In a preferred embodiment in which the inorganic binder-based construction material is a calcium sulfate construction material, the term "stucco" refers to calcium sulfate hemihydrate (CaSO 4 ×1 / 2H 2 O), which is conventionally used to prepare slurries for calcium sulfate building boards. Stucco is also the base for calcium sulfate undercoats or plasters. However, it is not excluded that the stucco may contain minor amounts of calcium sulfate anhydrite, for example in an amount of less than 20% by weight (based on the total weight of the stucco), preferably less than 10% by weight. The term "gypsum" refers to calcium sulfate dihydrate (CaSO 4 ×2H 2 As noted above, the construction material of the present invention preferably includes both a workable / moldable mixture that includes stucco and possibly unbound water as well as hardened inorganic binders depending on the mixture, and preferably calcium sulfate is present primarily as calcium sulfate dihydrate.

[0042] If the calcium sulfate building material is still workable, calcium sulfate hemihydrate or stucco is usually present in an amount of at least 50% by weight, based on the dry material used in the calcium sulfate building material. Preferably, the amount of calcium sulfate is in the range of 60-99% by weight, even more preferably in the range of 70-98% by weight, even more preferably in the range of 75-95% by weight. The method of calcination is not critical, with alpha or beta calcined stucco being suitable.

[0043] Regarding the length of the thermally pretreated silicate glass fibers, the construction material of the present invention is not subject to any relevant restriction, except that the fibers should be long enough to provide the desired stabilization, but not so long that they interfere / hinder the mixing process in which the construction material is prepared. Particularly suitable lengths include lengths in the range of 1 to 20 mm, in particular 2 to 15 mm, more particularly 4 to 13 mm, and most particularly 4 to 8 mm.

[0044] In addition, the diameter of the thermally pretreated silicate glass fibers should, on the one hand, be such that the fibers are sufficiently elastic and do not break easily, but on the other hand, they should not be too thick so as not to be too bulky, in order to avoid having to incorporate a large amount of fibers into the composition to provide sufficient stabilization. In the implementation of the present invention, fibers having an average particle size in the range of 1 to 20 μm, preferably 2 to 10 μm, can be advantageously used.

[0045] For the colloidal silica incorporated in the construction material of the invention, preferred amounts of 0.01 to 10% by weight, based on the total weight of the inorganic binder, may be mentioned, with amounts of 0.1 to 5% by weight of colloidal silica being particularly preferred, and amounts ranging from 0.3 to 2.0% by weight being even more preferred. In this regard, it should be noted that although colloidal silica is most frequently used as a colloidal dispersion in water, the above weight percentages are given for colloidal silica on a dry basis.

[0046] In the research underlying the present invention, it was found that when forming inorganic binder-based slurries, especially calcium sulfate slurries, smaller amounts of added colloidal silica (e.g., 0.4 wt%) do not affect the properties of the mixture, but when added in an amount of, for example, 2 wt%, it has a liquefying effect, and the addition of larger amounts of colloidal silica (e.g., about 4 wt%) even has a thickening effect. In addition, at >4 wt%, colloidal silica had an accelerating effect on the setting of the inorganic binder-based slurry. The acceleration was particularly pronounced when approximately 10-15 wt% colloidal silica was added. Advantageously, the thermally pretreated silicate glass fibers do not affect the inorganic binder-based slurry properties, such as flowability and / or its setting behavior. The thermally pretreated silicate glass fibers also do not appear to affect any foam in the slurry, and in particular, they do not appear to destroy the foam.

[0047] Further additives can be incorporated into the construction material of the present invention to adjust or optimize one or more of its workability and final properties. For example, conventional glass fibers can be added to further reinforce the building material, foaming agents can be added to control the density of the hardened composition, dispersants can be added to help disperse the dry material in the aqueous slurry, organic binders can be added for bonding, for example, to bond the liner to the core, and accelerators and retarders can be added to control the time required for the composition to harden. In addition, it is possible to incorporate agents that resist water decomposition of the hardened construction material, and other fire-resistant additives, such as clay, colloidal alumina, feldspar-free muscovite, unexpanded vermiculite, and water-insoluble calcium sulfate anhydrite whisker fibers. Suitable additives are well known and available to those skilled in the art.

[0048] Preferably, the inorganic binder-based construction material is devoid of vermiculite.

[0049] According to a particularly preferred embodiment of the invention, the construction material of the invention can be a board, a brick, a base coat, a mortar, a filler, a joint compound and / or a screed.

[0050] A building board according to the present invention refers to a flat sheet used in construction to assemble walls, floors or ceilings. Examples of these building boards or panels include, but are not limited to, wallboard, drywall, plasterboard, fiberboard, cement board, screed board. A building board has two main surfaces, the top and bottom of the building board. Many construction boards can have liners, which can cover the main surface / major surface, and often at least two edges. The core of a construction board according to an embodiment of the present invention can include one or more layers. The construction board can have a core with at least one inorganic binder-based layer, which comprises thermally pretreated silicate glass fiber and optionally colloidal silica. If the core comprises only one layer, this layer comprises thermally pretreated silicate glass fiber and optionally colloidal silica. If the core comprises two or more layers, at least one layer comprises thermally pretreated silicate glass fiber and optionally colloidal silica. The fire resistance of inorganic binder-based construction boards can be effectively increased if thermally pretreated silicate glass fibers are incorporated into at least one layer of the core.

[0051] A preferred embodiment of the inorganic binder-based construction board is a calcium sulfate building board, in particular a gypsum plasterboard or gypsum fiberboard. Alternatively or additionally, the construction material can be a calcium sulfate plaster, a primer, a joint compound or a mortar. The plaster or primer can be a dry or ready-to-use mixture of inorganic binder and additives, which is spread on the wall and / or ceiling to form a smooth and hard surface when dry. It is generally used for protective and / or decorative purposes. Water can be added to the dry mixture before application.

[0052] According to a particularly preferred embodiment of the invention, the construction material can be a screed. The screed can be a dry mixture of an inorganic binder, preferably a calcium sulfate building material. This material can contain further additives and can be mixed with water before application.

[0053] The fire resistance of gypsum building plaster or screed can be effectively increased when thermally pretreated silicate glass fibers and optionally colloidal silica are incorporated into the dry or ready-to-use mix.

[0054] A further aspect of the present invention is a method for the production of an inorganic binder-based construction material, comprising the steps of: (i) mixing an inorganic binder with water and thermally pretreated silicate glass fibers to form a mixture; (ii) forming a construction material from the mixture; (iii) curing the construction material; and Includes.

[0055] The mixture of (i) may optionally include colloidal silica.

[0056] The construction material prepared according to the above method can be a board, a brick, a base coat, a mortar, a filler, a joint compound and / or a screed.

[0057] Yet another aspect of the present invention is the use of thermally pretreated silicate glass fibers and optionally colloidal silica to improve the fire resistance of inorganic binder-based construction materials compared to inorganic binder-based construction materials having conventional glass fibers and optionally colloidal silica but otherwise the same composition. Preferably, this can prevent the construction material from falling off and / or improve its adhesion when exposed to high temperatures, preferably during a fire.

[0058] A further embodiment of the present invention is the use of thermally pretreated silicate glass fibers and optionally colloidal silica in an inorganic binder-based construction material to retard and / or reduce shrinkage of test specimens when exposed to high temperatures, preferably during fire, compared to an inorganic binder-based construction material having conventional glass fibers and optionally colloidal silica, but otherwise the same composition.

[0059] Any preferred or particularly preferred embodiment described above in relation to one aspect is also applicable to all other aspects of the invention, unless the combination is clearly inconsistent with that aspect, and therefore all such combinations are considered to be encompassed by and described in the present invention, even if not explicitly indicated.

[0060] The present invention will now be illustrated by means of examples which should not be construed as limiting the scope of the invention in any way. EXAMPLES

[0061] Example 1: Relative shrinkage behavior of gypsum prisms For the following tests, prisms (specimens) with dimensions 10 cm x 4 cm x 2 cm were prepared from the compositions shown in Table 1 below (all weight percentages are based on the total weight of the stucco as a reference). The prisms were prepared by thoroughly premixing the stucco, accelerator and thermally pretreated silicate or conventional glass fibre by shaking in a bag. The liquid additives (including colloidal silica used as a 40% aqueous solution) were mixed with water which was mixed with the dry mix, and the dry components were introduced into the aqueous mixture and stirred until a homogenous calcium sulfate slurry was formed. They were then poured into respective prism moulds from which the prisms were removed after 30 minutes. The prisms were then dried at 40°C to a constant weight of about 1250 kg / m 3 The density was set to .

[0062] A suitable commercially available thermally pretreated silicate glass fiber is 95±1 wt. % SiO 2 and 3.5±0.5 wt% Al 2 O 3 and optionally minor amounts (i.e., less than 1 wt.%) of Na 2 It is sold by Fingerhuth Heat Protection as isoTex® 1200.GS6.T based on other ingredients such as .O.

[0063] [Table 1] 1 = reference sample, 2 = Johns Manville Fiberglass M 3001 / 2, 3 = isoTex (registered trademark) 1200.GS6.T (Fingerhuth Heat protection), 4 = 40% aqueous colloidal solution

[0064] The shrinkage behavior of the prisms thus prepared was investigated by heating them and maintaining the temperature at 945°C for 60 to 120 minutes according to the standard temperature-time curve described in DIN EN 1363-1:2012-10. The respective expansion and contraction profiles are shown in the accompanying figures 1 to 3.

[0065] As is evident from FIG. 1, the samples without thermally pretreated silicate or conventional glass fibers (sample 1) and the samples containing only conventional glass fibers (samples 2 and 3) all have final shrinkage values ​​of about -8 to -10%. On the other hand, the samples with thermally pretreated silicate glass fibers (samples 4 and 5) have final shrinkage values ​​of about -4 to -7%. In all samples, an initial expansion phase up to about 20 min can be observed, which is probably due to the evaporation of water of crystallization. The samples without thermally pretreated silicate glass fibers start to shrink after this initial expansion phase. This shrinkage is delayed in the samples with thermally pretreated silicate glass fibers.

[0066] Figure 2 shows the effect of colloidal silica on the shrinkage behavior. Colloidal silica has a positive impact on the shrinkage behavior since it prevents the rapid decline in length loss. With the addition of colloidal silica, the final shrinkage value was only about -5.2% (sample 6).

[0067] The combined effect of adding thermally pretreated silicate glass fiber and colloidal silica is shown in Figure 3. For Sample 7, which contained 1.7% colloidal silica and 0.5% thermally pretreated silicate glass fiber, the final shrinkage value was significantly better than the nearly identical sample (Sample 6) in which the thermally pretreated silicate glass fiber was replaced with conventional glass fiber.

[0068] Example 2: Relative stability at high temperatures To determine the stability at high temperatures, porous prisms were used because non-porous prisms break very easily, however, they do not show any expansion phase.

[0069] Test prisms (16 cm x 4 cm x 2 cm) were prepared by a method similar to that described in Example 1. The mixture of dry ingredients was introduced into the liquid additive / water mixture, followed by the addition of foam, which had been previously prepared separately. The foam was then mixed into the calcium sulfate slurry for 20 seconds, and the resulting mixture was poured into the prism mould. After approximately 10-15 minutes, the prisms were removed from the mould and dried at 40°C to a constant weight of approximately 850 kg / m 3 The composition of the test prism thus prepared is shown in Table 2 below.

[0070] [Table 2] 1 = reference sample, 2 = Johns Manville Fiberglass M 3001 / 2, 3 = isoTex (registered trademark) 1200.GS6.T (Fingerhuth Heat protection), 4 = 40% aqueous colloidal solution

[0071] The test prism was subjected to a deflection / deformation test at high temperature as described below. Two horizontal ceramic tubes were placed parallel to each other on a ceramic support in an oven chamber. The test prism was placed on two parallel horizontal ceramic tubes placed 11 cm apart from each other. A 200 g weight was placed in the center of the prism to simulate the dead load of a building board. The 200 g weight was transferred onto the prism by pressing a ceramic rod onto a ceramic plate (1 cm x 1 cm) placed on the upper surface of the prism. The oven chamber was heated according to the standard temperature-time curve described in DIN EN 1363-1:2012-10, and the temperature was maintained at 945 °C for 60 to 120 min. This time-temperature curve predetermines the temperature course during the classification test of the fire resistance of the structural elements. The deflection of the test prism was measured at 15 s intervals via the ceramic rod. The results of these measurements are shown in Figure 4.

[0072] As is evident from this figure, the gypsum prisms without the addition of any type of fiber were not stable and broke after about 6 minutes (Sample 1). Adding conventional glass fiber to the prisms delayed failure by about 38 minutes (Sample 8), with failure occurring after about 44 minutes. By adding colloidal silica to the conventional glass fiber samples (Samples 10 and 12), failure could be further delayed, with failure occurring after about 66 minutes (Sample 10) and 76 minutes (Sample 11). Specifically, the sample with 0.3% conventional glass fiber (Sample 8) began to sag after only 20 minutes, the sample with 0.5% conventional glass fiber and 1% colloidal silica (Sample 10) began to sag after 45 minutes, and the sample with 0.5% glass fiber and 1.7% colloidal silica (Sample 12) began to sag after 50 minutes.

[0073] The gypsum prisms with thermally pretreated silicate glass fibers (Samples 9, 11, and 13) appeared to exhibit greater flexibility and were able to withstand strain for longer. The sample without colloidal silica (Sample 9) failed similarly, albeit with some delay, after about 82 minutes, compared to the sample containing conventional glass fibers and colloidal silica (Sample 12). Both samples containing both thermally pretreated silicate glass fibers and colloidal silica (Samples 11 and 13) did not fail during the 120 minute test run. Samples 11 (1.0% colloidal silica) and 13 (1.7% colloidal silica) reached maximum deflections of 28 mm and 18 mm, respectively. Thus, the deflections of the samples with thermally pretreated silicate glass fibers (Samples 9, 11, and 13) are significantly different from the deflections of the conventional glass fiber samples (Samples 8, 10, and 12). The sample with 0.3% thermally pretreated silicate glass fiber (Sample 9) begins to deflect after 35 minutes, the sample with 0.5% thermally pretreated silicate glass fiber and 1% colloidal silica (Sample 11) begins to deflect after 60 minutes, and the sample with 0.5% thermally pretreated silicate glass fiber and 1.7% colloidal silica (Sample 13) begins to deflect after 70 minutes. Furthermore, the time for the thermally pretreated silicate glass fiber samples to deform and bend is significantly longer than the conventional glass fiber samples.

Claims

1. 1. An inorganic binder-based construction material comprising an inorganic binder, silicate glass fibers and optionally further additives, characterized in that the silicate glass fibers are thermally pretreated silicate glass fibers and the inorganic binder-based construction material comprises 0.01 to 5 wt. % of the thermally pretreated silicate glass fibers, based on the total weight of the inorganic binder.

2. 2. The inorganic binder-based construction material according to claim 1, characterized in that the thermal pretreatment of the pretreated silicate glass fibers comprises heating the silicate glass fibers to a temperature of 700°C to 1000°C for at least 30 minutes.

3. 3. A construction material based on inorganic binders according to claim 1 or 2, characterized in that the construction material further comprises colloidal silica.

4. 4. Construction material based on inorganic binders according to claim 1, characterized in that a test specimen of said construction material based on inorganic binders, when exposed to a temperature according to the standard temperature-time curve according to DIN EN 1363-1:2012-10, said temperature being maintained at 945°C for 60 to 120 minutes, has a temporarily delayed shrinkage phase, whereby the time interval during which said test specimen reaches 99% of its initial length is at least 1.35 times the time interval during which a test specimen having an otherwise identical composition, comprising non-thermally pretreated glass fibres and optionally colloidal silica, reaches 99% of its initial length.

5. 5. Construction material based on inorganic binders according to claim 1, characterized in that test specimens of said construction material based on inorganic binders, when exposed for the first 60 minutes to temperatures according to the temperature profile of DIN EN 1363-1:2012-10, show a smaller shrinkage after at least 60 minutes than a test specimen of otherwise identical composition comprising glass fibres and optionally colloidal silica that have not been thermally pretreated.

6. 6. The construction material based on inorganic binder according to claim 1, characterized in that it contains 0.05 to 2 wt.-%, based on the total weight of the inorganic binder, of thermally pretreated silicate glass fibers.

7. The inorganic binder-based construction material is 90 to 99% by weight of SiO based on the total weight of the fibers. ２ and 1 to 10 wt. % Al ２ O ３ 7. A construction material based on inorganic binders according to claim 1, characterized in that it comprises thermally pretreated silicate glass fibres comprising:

8. 8. A construction material based on inorganic binders according to claim 1, characterized in that it comprises thermally pretreated silicate glass fibres having a length of 1 to 20 mm.

9. 9. A construction material based on an inorganic binder according to claim 1, characterized in that it comprises thermally pretreated silicate glass fibres having an average fibre diameter of 1 to 20 μm.

10. 10. The construction material based on inorganic binder according to claim 1, characterized in that it contains 0.01 to 10 wt.-% colloidal silica, based on the total weight of the inorganic binder.

11. 11. A construction material based on inorganic binder according to any one of claims 1 to 10, characterized in that the construction material is a board, a brick, a primer, a mortar, a filler, a joint compound or a screed.

12. 12. The inorganic binder-based construction material according to claim 11, characterized in that the board has a core with at least one inorganic binder-based layer, the inorganic binder-based layer comprising thermally pretreated silicate glass fibers and optionally colloidal silica.

13. The inorganic binder-based construction material according to any one of claims 1 to 12, wherein the inorganic binder comprises calcium sulfate, lime, clay and / or cement.

14. 1. A method for the production of an inorganic binder-based construction material, comprising: (i) mixing an inorganic binder with water, thermally pretreated silicate glass fibers, and optionally other additives to form a mixture; (ii) forming a construction material from the mixture; (iii) allowing the construction material to harden; and the inorganic binder-based construction material comprises 0.01 to 5 wt. % of thermally pretreated silicate glass fibers, based on the total weight of the inorganic binder.

15. Use of thermally pretreated silicate glass fibers and optionally colloidal silica in an inorganic binder-based construction material to improve the fire resistance of the inorganic binder-based construction material compared to an inorganic binder-based construction material having non-thermally pretreated glass fibers and optionally colloidal silica but otherwise the same composition, said use comprising 0.01 to 5 weight percent of thermally pretreated silicate glass fibers, based on the total weight of the inorganic binder.

16. 1. Use of thermally pretreated silicate glass fibers and optional colloidal silica in an inorganic binder-based construction material to retard and / or reduce shrinkage of a test specimen when exposed to high temperatures, compared to an inorganic binder-based construction material having the same composition but with glass fibers and optionally colloidal silica that have not been thermally pretreated, said use comprising 0.01 to 5% by weight of thermally pretreated silicate glass fibers, based on the total weight of the inorganic binder.

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