Manufacturing method for precast remaining frame mold panel

Abstract

To provide a manufacturing method for a precast remaining frame mold panel which can manufacture a lightweight precast remaining frame mold panel, improve the impermeability of a precast concrete panel body, and prevent crack caused by aging.SOLUTION: A manufacturing method for a precast remaining frame mold panel is the manufacturing method for an impermeable precast remaining frame mold panel that uses volcanic lapilli and volcanic ash as lightweight aggregate, and includes a mixing step of mixing a concrete raw material containing cement, volcanic lapilli as coarse aggregate, and volcanic ash as fine aggregate with mixing water to obtain a fluidized cement composition, and an insulation curing step of allowing the temperature of the fluidized cement composition poured into a forming frame mold to naturally drop to ambient temperature without externally reheating the fluidized cement composition, thereby preventing the bleeding phenomenon of the fluidized cement composition being discharged outside the forming frame mold.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a precast remaining form panel that can suppress cracks caused by alkali-aggregate reaction. [Background technology]

[0002] Precast retained formwork panels are made of concrete. Cracks occurring during the construction of precast retained formwork panels and cracks occurring due to concrete deterioration after the construction of walls (remaining formwork) made with precast retained formwork panels have been a problem. Alkali-aggregate reaction (AAR) is a known concrete deterioration phenomenon. In AAR, the alkaline aqueous solution contained in concrete reacts with aggregates such as gravel and sand, causing expansion and cracking. One type of AAR is the alkali-silica reaction. In this reaction, silica minerals in the aggregate react with alkaline components in the concrete to produce silica gel. This silica gel absorbs water, causing expansion within the concrete. The pressure of this expansion causes internal cracks. Cracks include tortoiseshell-shaped cracks that appear on the surface due to concrete expansion, as well as cracks that appear perpendicular to or parallel to the rebar or horizontally.

[0003] If cracks occur in the precast remaining form panels, the remaining formwork made up of the precast remaining form panels may suffer from frost damage, salt damage, efflorescence, etc. In order to prevent such cracks, frost damage, salt damage, efflorescence, etc., the inventor has proposed a method for manufacturing a precast remaining form panel to close voids formed in the precast remaining form panels, such as capillary voids (for example, Patent Document 1).

[0004] The method for manufacturing a precast remaining form panel described in Patent Document 1 includes the steps of: pouring a fluidized cement composition obtained by mixing concrete raw materials containing cement, gravel, and sand with 5 to 40% by weight of limestone fine powder relative to the cement in the concrete raw materials and mixing water; or pouring a fluidized cement composition obtained by mixing mortar raw materials containing cement and sand with 5 to 40% by weight of limestone fine powder relative to the cement in the mortar raw materials and mixing water into a forming form; molding the fluidized cement composition poured into the forming form; and curing the fluidized cement composition. In this method for manufacturing a precast remaining form panel, during the molding and curing steps, excess water containing calcium hydroxide eluted from the cement is pushed up toward the back side of the panel body and pooled throughout the back surface of the panel body, covering the back surface of the panel body and filling capillary voids and the like formed within the panel body. When the cement in the fluidized cement composition hardens, a waterproof layer is formed over the entire back surface of the panel body, preventing the carbon dioxide in the outside air from chemically reacting with calcium hydroxide and forming a permeable fine powder layer of calcium carbonate over the entire back surface of the panel body, while at the same time naturally blocking capillary voids and the like with the waterproof layer. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 7314430 Summary of the Invention [Problem to be solved by the invention]

[0006] Conventional manufacturing methods have been effective in sealing capillary voids, but they have not been able to completely seal the capillary voids. This allows moisture to penetrate the interior of the precast remaining formwork panel through the formed capillary voids, which can react with silica minerals and cause alkali-silica reaction. Furthermore, the continuous moisture penetration accelerates the alkali-silica reaction, potentially leading to cracks after several years. Given this background, there has been a need for a manufacturing method for precast remaining formwork panels that can completely seal the capillary voids in precast concrete panels, preventing moisture penetration and thereby suppressing expansion cracks caused by alkali-silica reaction.

[0007] Furthermore, in recent years, there has been a demand for lightweight precast remaining formwork panels, as crack formation has been suppressed and the transportation of precast remaining formwork panels is a manual task. Specifically, there is a desire to reduce the weight from the current 21 kg to around 16 kg.

[0008] Therefore, an object of the present invention is to provide a method for manufacturing a precast remaining form panel that can produce a lightweight precast remaining form panel and can suppress cracking over time due to alkali-aggregate reaction. [Means for solving the problem]

[0009] The method for manufacturing a precast remaining form panel according to the present invention is a method for manufacturing a non-permeable precast remaining form panel using volcanic lapilli and volcanic ash as aggregate, and includes a mixing step of mixing concrete raw materials containing cement, the volcanic lapilli as coarse aggregate, and the volcanic ash as fine aggregate with mixing water for hydration reaction that has been heated to a temperature of 60°C to 85°C in advance, to obtain a fluidized cement composition with a mixing temperature of 15°C to 45°C, which corresponds to an ambient temperature of 0°C to 40°C; and a mixing step of mixing a panel body with the back surface facing upward and the fluidized cement composition is poured into a forming form designed to be kept horizontal and stable; excess water containing calcium hydroxide eluted from the cement in the mixing water is pushed up toward the back surface of the panel body, thereby being stored over the entire back surface of the panel body, covering the back surface of the panel body with the excess water; and the excess water is allowed to intervene so as to fill capillary voids formed inside the panel body, and vibration is applied to the fluidized cement composition poured into the forming form, thereby molding the fluidized cement composition poured into the forming form. After the step of molding the fluidized cement composition, the temperature of the fluidized cement composition in the molding form is naturally lowered to the ambient temperature over a period of 3 hours or more without externally reheating the fluidized cement composition charged into the molding form, thereby preventing the bleeding phenomenon in which the mixing water for hydration reaction containing calcium hydroxide eluted from the fluidized cement composition expands in volume and is discharged to the outside of the molding form, thereby preventing the occurrence of capillary voids in the fluidized cement composition and maintaining the fluidized cement composition in a state where the strength for demolding is ensured. and a demolding process of removing the molding form after the thermal curing process, wherein when the fluidized cement composition hardens in the thermal curing process, an alkaline component contained in the fluidized cement composition reacts chemically with silica contained in the volcanic lapilli and volcanic ash to produce alkaline silica gel, thereby forming a waterproof layer over the entire back surface of the panel body, and preventing carbon dioxide in the outside air from chemically reacting with the calcium hydroxide to form a water-permeable fine powder layer of calcium carbonate over the entire back surface of the panel body,The capillary voids are almost completely blocked by the waterproof layer, dramatically improving the impermeability of the panel body and preventing expansion cracks caused by alkali-silica reaction of the coarse aggregate of the volcanic lapilli and the fine aggregate of the volcanic ash over time.

[0010] The method for manufacturing a precast remaining formwork panel according to the present invention is characterized in that, in the step of molding the fluidized cement composition, a stainless steel connecting fitting is embedded in the back surface of the panel body. [Effects of the Invention]

[0011] The method for manufacturing precast remnant formwork panels according to this embodiment uses concrete raw materials containing cement, volcanic lapilli as coarse aggregate, and volcanic ash as fine aggregate. Because volcanic lapilli and volcanic ash are lightweight aggregates, the manufactured precast remnant formwork panels are lighter than conventional panels.

[0012] The method for manufacturing a precast remaining form panel of the present invention involves mixing concrete raw materials containing cement, volcanic lapilli coarse aggregate, and volcanic ash fine aggregate with mixing water for hydration reaction that has been heated to a temperature of 60 to 85°C, to obtain a fluidized cement composition with a mixing temperature of 15 to 45°C, which corresponds to an ambient temperature of 0 to 40°C. The fluidized cement composition is then poured into a forming formwork and allowed to naturally cool to ambient temperature over a period of three hours or more without external reheating. This prevents the volume of the mixing water for hydration reaction, which contains calcium hydroxide eluted from the fluidized cement composition, from expanding and being discharged outside the forming formwork, thereby preventing the formation of capillary voids in the fluidized cement composition. Since moisture does not penetrate into the panel body, alkali-silica reaction between the volcanic lapilli coarse aggregate and the volcanic ash fine aggregate does not occur, thereby preventing expansion cracks caused by the alkali-silica reaction. Therefore, the precast remaining formwork panels are prevented from cracking due to expansion over time.

[0013] Furthermore, in this method for manufacturing a precast remaining form panel using raw concrete materials, during the thermal curing step, excess water containing calcium hydroxide eluted from the cement is pushed up toward the rear surface of the mixing water, thereby pooling over the entire rear surface of the panel body, covering the rear surface of the panel body and filling voids such as capillary voids formed within the panel body. As the fluidized cement composition hardens, the alkaline component contained in the fluidized cement composition reacts chemically with the silica contained in the volcanic lapilli and volcanic ash to produce alkaline silica gel, forming a waterproof layer over the entire rear surface of the panel body and preventing the formation of a permeable calcium carbonate fine powder layer over the entire rear surface of the panel body. Furthermore, the waterproof layer almost completely blocks voids such as capillary voids, dramatically improving the impermeability of the panel body.

[0014] In the method for manufacturing a precast remaining form panel according to the present invention, the stainless steel connecting fittings can be embedded in a predetermined position in the fluidized cement composition so that they protrude from the back surface of the panel body during the insertion process. Even in this case, the gap formed between the embedded portion of the connecting fittings and the panel body is almost completely sealed by the waterproof layer, dramatically improving the impermeability of the panel body. [Brief explanation of the drawings]

[0015] [Figure 1] 1A and 1B are diagrams illustrating a precast remaining formwork panel according to an embodiment of the present invention, in which (a) is a cross-sectional view and (b) is a rear view. [Figure 2] 1 is an enlarged view of a connection portion of a precast remaining formwork panel according to an embodiment of the present invention. [Figure 3] 1A, 1B, and 1C are diagrams illustrating the manufacturing process of a precast remaining form panel according to an embodiment of the present invention, showing each step. [Figure 4] 1A and 1B are diagrams showing a remaining formwork constructed by a remaining formwork construction method according to an embodiment of the present invention, in which (a) is a cross-sectional view and (b) is a front view. DETAILED DESCRIPTION OF THE INVENTION

[0016] The manufacturing method of a precast remaining form panel according to the present invention will be described with reference to Figures 1 to 4, taking a manufacturing method of a precast remaining form panel as an example. In the drawings, the horizontal direction of the precast remaining form panel is referred to as width direction X, the vertical direction as height direction Y, and the thickness direction as front-to-rear direction Z.

[0017] In the manufacturing method of a precast remnant form panel according to this embodiment, a water-impermeable precast remnant form panel 1 shown in Fig. 1 is manufactured. As shown in Fig. 1(a), this precast remnant form panel 1 comprises a precast remnant form panel body 2 (hereinafter also referred to as panel body 2), a plurality of connectable metal fittings 3 provided at predetermined positions on the back surface 2a of the panel body 2, and a waterproof layer 4 formed on the back surface 2a etc. of the panel body 2. This precast remnant form panel 1 is a water-impermeable precast remnant form panel that uses volcanic lapilli and volcanic ash as lightweight aggregate.

[0018] [Panel body 2] As shown in FIGS. 1(a) and 1(b), the panel body 2 is rectangular, and a panel body 2 having a height of 300 mm and a width of 900 mm is used, for example. Two connecting fittings 3 are provided on the back surface 2a of the panel body 2 in the width direction X and the height direction Y. These connecting fittings 3 are provided so as to protrude from the back surface 2a of the panel body 2. A plurality of reinforcing bars 5 are provided inside the panel body 2 in the width direction X and the height direction Y to ensure the strength of the panel body 2. The size (height and width) of the panel body 2 can be changed as appropriate.

[0019] [Connected metal fitting 3] The connected metal fitting 3 has a hook portion 6 and embedded portions 7 connected to both ends of the hook portion 6 (Fig. 1(a)). The connected metal fitting 3 is attached to the panel main body 2 with the embedded portions 7 embedded inside the panel main body 2 and the hook portions 6 protruding from the back surface 2a of the panel main body 2. The connected metal fitting 3 can be made of metal, and it is preferable to use a material with excellent corrosion resistance, such as stainless steel (SUS304).

[0020] [Waterproof layer 4] The waterproof layer 4 is formed by a chemical reaction between the alkaline component contained in the fluidized cement composition C and the silica contained in the volcanic lapilli and volcanic ash to produce alkaline silica gel, which is insoluble in water. layer As shown in Figure 2, this waterproof layer 4 is formed over the entire back surface 2a of the panel body 2, as well as in the capillary gap 9A and the gap 9B formed between the embedded portion 7 of the connected metal fitting 3 and the panel body 2.

[0021] Next, a method for manufacturing a precast remaining form panel will be described.

[0022] The method for manufacturing a precast remaining form panel according to this embodiment is a method for manufacturing a water-impermeable precast remaining form panel 1. This method for manufacturing a precast remaining form panel includes the following steps: a mixing step of mixing concrete raw materials containing cement, volcanic lapilli as coarse aggregate, and volcanic ash as fine aggregate with mixing water for hydration reaction that has been heated to a predetermined temperature in advance to obtain a fluidized cement composition C having a predetermined mixing temperature corresponding to an ambient temperature of 0°C to 40°C; a charging step of charging fluidized cement composition C into a forming form 22 after the mixing step; a molding step of molding the fluidized cement composition C charged into the forming form 22; a heat-retaining and curing step of allowing the temperature of the charged fluidized cement composition C to drop naturally to the ambient temperature over a predetermined period of time or more without externally reheating the charged fluidized cement composition C, thereby hardening the fluidized cement composition C; and a demolding step of removing the forming form 22 after the heat-retaining and curing step. In the method for producing a recast remaining form panel according to the present invention, no heating is performed in the mixing step except for heating the mixing water for the hydration reaction to increase its temperature.

[0023] [Mixing process] In the mixing step, concrete raw materials including cement, volcanic lapilli as coarse aggregate, and volcanic ash as fine aggregate are mixed with mixing water for the hydration reaction that has been heated to a temperature of 60 to 85°C in advance, to obtain a fluidized cement composition with a mixing temperature of 15 to 45°C, corresponding to an ambient temperature of 0 to 40°C. Note that the mixing temperature is preferably 15°C higher than 0°C when the ambient temperature is 0°C in winter, and preferably 5°C higher than 40°C when the ambient temperature is 40°C in summer.

[0024] [Feeding process] In the pouring step, as shown in FIG. 3, a molding form 22 is used to form the panel body 2. The molding form 22 is designed so that the back surface 2a of the panel body 2 faces upward and is maintained horizontally. The upper side of the molding form 22 corresponds to the back surface 2a of the panel body 2. Specifically, as shown in FIG. 3(a), a mixture with fluidized cement composition C is poured into the molding form 22 placed on a platform 21 equipped with a vibration device 20, and the vibration device 20 applies vibration to the fluidized cement composition C. As a result, excess water containing calcium hydroxide eluted from the fluidized cement composition C is pushed up to the back surface 2a of the panel body 2. This excess water then fills capillary voids 9A formed inside the panel body 2 and voids 9B formed between the embedded portions 7 of the connected metal fittings 3 and the panel body 2, and the entire back surface of the panel body 2 is covered with excess water containing calcium hydroxide.

[0025] [Burial process] After the pouring step, as shown in Figures 3(b) and (c), the connected metal fittings 3 attached to the reinforcing bars 5 are embedded in the fluidized cement composition C poured into the forming formwork 22. Specifically, the connecting portion of the hook portion 6 and the embedded portion 7 and the embedded portion 7 are pushed to a predetermined position in the fluidized cement composition C, and the connected metal fittings 3 are embedded so that the hook portion 6 protrudes from the back surface 2a of the panel main body 2. Note that if the connected metal fittings 3 are not formed integrally with the panel main body 2, the embedding step is not performed.

[0026] [Thermal curing process] In the heat-retention curing step, fluidized cement composition C is hardened until the demolding strength is ensured. Specifically, fluidized cement composition C is poured into forming mold 22 and is at a temperature higher than the ambient temperature. The temperature of fluidized cement composition C is then naturally lowered to the ambient temperature over a period of 3 hours or more without external reheating. During the natural lowering to the ambient temperature, the mixing water for the hydration reaction, which contains calcium hydroxide eluted from fluidized cement composition C, expands in volume and is discharged to the outside of forming mold 22. This prevents the bleeding phenomenon. By preventing bleeding, the generation of capillary voids 9A and voids 9B in fluidized cement composition C is prevented.

[0027] During the heat-retention curing process, excess water containing calcium hydroxide eluted from the cement is pushed up toward the rear surface 2a of the panel body 2 and pools throughout the rear surface 2a of the panel body 2. The excess water covers the rear surface 2a of the panel body 2 and fills the capillary voids 9A and voids 9B formed within the panel body 2. When the fluidized cement composition C hardens, the alkaline component contained in the fluidized cement composition C reacts chemically with the silica contained in the volcanic lapilli and volcanic ash to produce alkaline silica gel, forming a waterproof layer 4 over the entire rear surface 2a of the panel body 2. This prevents a permeable calcium carbonate fine powder layer from forming over the entire rear surface 2a of the panel body 2. Furthermore, the waterproof layer 4 almost completely blocks the capillary voids and voids 9B.

[0028] [Demolding process] In the demolding step, the molding frame 22 is removed after a predetermined time of heat-retaining and curing step.

[0029] Next, a construction method using the precast remaining form panel 1 manufactured by the above-mentioned manufacturing method will be described. The cementitious solidifying material used in the remaining formwork construction method can be any material that contains moisture and hardens over time, such as concrete, mortar, and aerated mortar. In this embodiment, an example will be described in which ready-mixed concrete 12 is used as the cementitious solidifying material.

[0030] In the construction method according to this embodiment, as shown in Fig. 4(b), precast remaining form panels 1 are stacked to construct a remaining form 10. In this precast remaining form panel 1, a waterproof layer 4 is formed over the entire back surface 2a of the panel body 2, in the capillary voids 9A, and in the voids 9B. When constructing the remaining form 10, as shown in Fig. 4(a), the precast remaining form panel 1 is fixed to the front of the wooden form 13 by connecting the precast remaining form panel 1 to the wooden form (plywood) 13 using steel connecting fittings (separators) 11 connected to the connecting fittings 3.

[0031] Next, a cement-based solidifying material pouring step is performed. Specifically, fresh concrete 12 is poured between the remaining precast formwork panel 1 and the wooden formwork 13 (FIG. 4(a)). The fresh concrete 12 is poured so as to come into contact with the waterproof layer 4 formed on the back surface 2a of the panel body 2.

[0032] After pouring the fresh concrete 12, the fresh concrete 12 is hardened (cement-based binder hardening process). At this time, the waterproof layer 4 is formed in the capillary voids 9A and voids 9B, so that moisture in the fresh concrete 12 is prevented from penetrating into the interior of the panel body 2 through the capillary voids 9A and voids 9B. This prevents moisture from being released and evaporated from the fresh concrete 12, and prevents cracks in the fresh concrete 12 due to drying shrinkage.

[0033] Next, the effects of the method for manufacturing a precast remaining form panel according to this embodiment will be described.

[0034] The manufacturing method for precast remnant formwork panels according to this embodiment uses concrete raw materials containing cement, volcanic lapilli as coarse aggregate, and volcanic ash as fine aggregate. Because volcanic lapilli and volcanic ash are lightweight aggregates, the manufactured precast remnant formwork panels are lighter than conventional panels. Specifically, precast remnant formwork panels manufactured using this manufacturing method for precast remnant formwork panels according to this embodiment weigh 30 to 40 percent less than those made using conventional gravel or sand.

[0035] The precast remaining formwork panel 1 according to this embodiment is made by mixing concrete raw materials containing volcanic lapilli as coarse aggregate and volcanic ash as fine aggregate with preheated mixing water for hydration reaction to obtain a fluidized cement composition with a mixing temperature of 15 to 45°C, which corresponds to an ambient temperature of 0 to 40°C, and then allowing the temperature to rise naturally to the ambient temperature without heating. This causes the alkaline components contained in the fluidized cement composition C to chemically react with the silica contained in the volcanic lapilli and volcanic ash to produce alkaline silica gel, forming a waterproof layer 4 over the entire back surface 2a of the panel body 2, and filling the capillary voids 9A and the voids 9B (not shown in the drawing) formed between the embedded portions 7 of the connected metal fittings 3 and the panel body 2 with water-insoluble silica gel. Preventive It is almost completely sealed by the water layer 4. In this way, the formation of the waterproof layer 4 prevents the formation of a water-permeable fine powder layer of calcium carbonate over the entire back surface 2a of the panel body 2, and almost completely seals the capillary voids 9A and the voids 9B formed between the embedded portions 7 of the connected metal fittings 3 and the panel body 2. This prevents moisture from penetrating into the interior of the panel body 2, prevents alkali-silica reaction between the coarse aggregate of the volcanic lapilli and the fine aggregate of the volcanic ash, and inhibits expansion cracks caused by the alkali-silica reaction, thereby preventing expansion cracks that occur over time.

[0036] Furthermore, the formation of the waterproof layer 4 prevents the formation of a water-permeable fine powder layer of calcium carbonate over the entire back surface 2a of the panel body 2, and by almost completely blocking the capillary gap 9A and the gap 9B formed between the embedded portion 7 of the connected metal fitting 3 and the panel body 2, it is possible to dramatically improve the water impermeability of the panel body 2. Because the water impermeability of the panel body 2 is dramatically improved, this is particularly suitable for panel bodies 2 that are thin.

[0037] In the manufacturing method for precast remaining formwork panels according to this embodiment, concrete raw materials containing volcanic lapilli as coarse aggregate and volcanic ash as fine aggregate are used, and therefore the hydration reaction is significantly faster than when using, for example, silica fine powder, and the waterproof layer 4 can be formed in a short time on the back surface 2a of the panel main body 2 and in the capillary voids 9A and voids 9B. Furthermore, because the hydration reaction does not slow down even at low temperatures (for example, 5 degrees), the manufacturing method according to this embodiment is particularly useful when manufacturing the panel main body 2 at low temperatures.

[0038] Furthermore, the manufacturing method of the precast remaining form panel according to this embodiment contributes to energy conservation because, in the thermal curing step, the temperature of the fluidized cement composition C is naturally lowered to the ambient temperature over a period of 3 hours or more without externally reheating the fluidized cement composition C. The construction method using the precast remaining form panel 1 according to this embodiment maintains the appearance of the remaining form 10 after construction and allows the remaining form 10 to be maintained stably for a long period of time without reducing durability.

[0039] Furthermore, in the precast remaining form panel 1 used in this embodiment, the waterproof layer 4 is formed, and the capillary voids 9A and voids 9B in the panel body 2 are almost completely blocked. This prevents the poured fresh concrete 12 from rapidly releasing moisture and evaporating from the capillary voids 9A during the cementitious hardening process. As a result, the fresh concrete 12 gradually hardens and becomes less likely to crack, preventing cracks from occurring in the panel body 2 after the remaining formwork 10 is constructed. This effect of reducing the likelihood of cracks occurring due to the gradual hardening of the fresh concrete 12 is effective when constructing the remaining formwork 10 in the summer or when building the remaining formwork 10 in a sunny location.

[0040] As explained above, by using the construction method according to this embodiment, deterioration of the precast remaining formwork panel 1 due to salt damage or frost damage can be prevented, cracks can be prevented from occurring in the precast remaining formwork, and the surface of the remaining formwork can be prevented from becoming contaminated.

[0041] Although the present embodiment has been described above, it is possible to select and / or change the configurations given in the above embodiment to other configurations as appropriate without departing from the spirit of the present invention.

[0042] In this embodiment, in the manufacturing method for precast remaining formwork panels, the aggregate used in the concrete raw materials can be only volcanic lapilli and volcanic ash. In this embodiment, an example has been described in which the connected metal fittings 3 are embedded so as to protrude from the back surface 2a of the panel main body 2 and formed integrally, but it is also possible to attach the connected metal fittings after the panel main body is formed. For example, screw holes are formed in each of the four corners of the back surface of the panel main body, and the connected metal fittings are fixed into these screw holes. [Explanation of symbols]

[0043] 1 Precast remaining formwork panels (panels) 2 Precast remaining formwork panel body (panel body) 2a Back (back side) 3 Connected metal fittings 4 waterproof layer 5. Reinforced concrete 6 Hook part 7 Buried section 9A Capillary void 9B gap (gap formed between the embedded portion 7 and the panel body 2) 10 Remaining formwork 11 Connecting fittings (separators) 12 Ready-mixed concrete (cement-based solidifying material) 13 Wooden formwork (plywood) 20 Vibration device 21 units 22 Forming mold C. Fluidized cement composition X Width direction Y Height direction Z front and back direction

Claims

1. A method for manufacturing a precast remaining form panel, which manufactures a non-permeable precast remaining form panel using volcanic lapilli and volcanic ash as aggregate, a mixing step of mixing concrete raw materials including cement, the volcanic lapilli as a coarse aggregate, and the volcanic ash as a fine aggregate with mixing water for a hydration reaction that has been heated to a temperature of 60°C to 85°C in advance, to obtain a fluidized cement composition having a mixing temperature of 15°C to 45°C, which corresponds to an ambient temperature of 0°C to 40°C; After the mixing step, the fluidized cement composition is poured into a molding form designed so that the back surface of the panel body faces upward and is maintained horizontally, and excess water containing calcium hydroxide eluted from the cement in the mixing water is pushed up toward the back surface of the panel body, thereby being accumulated over the entire back surface of the panel body, covering the back surface of the panel body with the excess water, and the excess water is allowed to intervene so as to fill capillary voids formed inside the panel body. This is done by vibrating the fluidized cement composition poured into the molding form, thereby molding the fluidized cement composition poured into the molding form. and a heat-retention curing step of, after the step of molding the fluidized cement composition, allowing the temperature of the fluidized cement composition in the molding form to drop naturally to an ambient temperature over a period of 3 hours or more without externally reheating the fluidized cement composition charged into the molding form, thereby preventing the occurrence of capillary voids in the fluidized cement composition and hardening the fluidized cement composition until a demolding strength is ensured, by preventing the volume expansion of the mixing water for hydration reaction containing calcium hydroxide eluted from the fluidized cement composition and causing it to be discharged outside the molding form, thereby preventing the occurrence of capillary voids in the fluidized cement composition. A demolding process of removing the molding form after the heat retention and curing process, When the fluidized cement composition hardens in the thermal insulation curing process, the alkaline component contained in the fluidized cement composition reacts chemically with the silica contained in the volcanic lapilli and volcanic ash to produce alkaline silica gel, thereby forming a waterproof layer over the entire back surface of the panel body. This prevents the carbon dioxide in the outside air from chemically reacting with the calcium hydroxide to form a water-permeable fine powder layer of calcium carbonate over the entire back surface of the panel body, and at the same time, the capillary voids are almost completely blocked by the waterproof layer, dramatically improving the impermeability of the panel body and suppressing expansion cracks that occur over time due to alkali-silica reaction of the coarse aggregate of the volcanic lapilli and the fine aggregate of the volcanic ash. A method for manufacturing a precast remaining form panel.

2. In the step of molding the fluidized cement composition, a stainless steel connecting fitting is embedded in the back surface of the panel body.

2. The method for manufacturing a precast remaining form panel according to claim 1.

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