Manufacturing method of precast residual formwork panel

Abstract

To provide a method for manufacturing a precast residual formwork panel, which suppresses the formation of capillary voids in a precast residual formwork concrete panel body and improves the water impermeability of the precast residual formwork concrete panel body.SOLUTION: There is provided a manufacturing method of a precast residual formwork panel for use in the manufacture of a water-impermeable precast residual formwork panel, which includes: a mixing step of mixing a concrete raw material containing cement, gravel as crushed stone aggregate of limestone and sand as crushed stone aggregate of limestone with kneading water heated to a temperature of 60°C to 85°C in advance to obtain a fluidized cement composition having an as-mixed temperature of 15°C to 45°C corresponding to an outside air temperature of 0°C to 40°C; and a heat insulation curing step of naturally lowering the temperature of the fluidized cement composition to the outside air temperature without externally re-heating the fluidized cement composition charged into a forming mold so as to suppress a bleeding phenomenon in which the fluidized cement composition is discharged to the outside of the forming mold by expansion of the kneading water.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a precast residual form panel for producing a water-impermeable precast residual form panel. [Background technology]

[0002] Precast remaining form panels are used to construct remaining formwork. Conventional precast panels have many capillary voids, so when a remaining formwork is constructed using these precast panels, the mixing water for hydration reaction contained in the poured fresh concrete flows out or evaporates through the capillary voids. As a result, the concrete shrinks rapidly, cracks occur, and a tearing force is generated in the precast remaining formwork panel, making the precast remaining formwork panel more likely to crack. In addition, when cracks or capillary voids occur on the back surface of the precast remaining formwork panel, sewage such as rainwater may enter the inside of the main body of the precast remaining formwork panel through the cracks or capillary voids, which may lead to deterioration of the main body of the precast remaining formwork panel. Furthermore, there has been a case where the sewage that has entered the main body of the precast remaining formwork panel leaks out onto the surface of the precast remaining formwork panel, contaminating the surface of the precast remaining formwork panel.

[0003] As a result of cracks occurring in the precast panels, the remaining formwork formed by these precast panels suffers from frost damage, salt damage, efflorescence, etc. In order to prevent such cracks, frost damage, salt damage, efflorescence, etc., the inventors have proposed a manufacturing method for a precast remaining formwork panel for sealing voids formed in the precast panels, such as capillary voids (for example, Patent Documents 1 to 3).

[0004] The manufacturing method of the precast remaining form panel described in Patent Document 1 includes a step of pouring a cement composition, which is mortar mixed with a fatty acid compound or concrete mixed with a fatty acid compound, into a molding form, a compaction step of compacting the cement composition poured into the molding form, and a curing step of hardening the cement composition. In this manufacturing method of the precast remaining form panel, in the compaction step and the curing step, excess water containing mixing water, fatty acid compound, and calcium hydroxide eluted from the cement is pushed up to the back side of the panel body, so that it is stored over the entire back side of the panel body, covering the back side of the panel body with excess water, and the excess water is present so as to fill the capillary voids formed inside the panel body. Then, in the curing process, calcium hydroxide that dissolves when the cement in the cement composition hardens reacts with the fatty acids in the fatty acid compound to form fatty acid calcium that is insoluble in water and water-repellent, forming a waterproof layer containing fatty acid calcium over the entire back surface of the panel body, and this waterproof layer seals capillary voids, etc.

[0005] Moreover, the manufacturing method of a precast remaining form panel described in Patent Document 2 includes a covering step of covering the entire back surface of the panel body with a covering material, and a curing step of hardening the cement composition, in which a mixture of a cement composition constituting mortar or concrete and mixing water is poured into a molding form, and excess water containing calcium hydroxide dissolved from the cement composition in the mixing water is pushed up to the back surface of the panel body, so that the excess water fills capillary voids and the like formed inside the panel body and the entire back surface of the panel body is covered with excess water containing calcium hydroxide. This manufacturing method of a precast remaining form panel includes a covering step of covering the entire back surface of the panel body with a covering material, and a curing step of hardening the cement composition. In this manufacturing method of a precast remaining form panel, by covering the entire back surface of the panel body with a covering material, it is possible to prevent a chemical reaction between carbon dioxide in the outside air and calcium hydroxide and the formation of a permeable calcium carbonate fine powder layer on the back surface of the panel body. During the curing process, the calcium hydroxide dissolved in the mixing water reacts chemically with the silica in the cement composition, forming a waterproof layer containing water-insoluble calcium silicate hydrate over the entire back surface of the panel body, and this waterproof layer seals capillary voids, etc.

[0006] Furthermore, the manufacturing method of the precast remaining form panel described in Patent Document 3 includes a step of pouring a fluidized cement composition obtained by mixing concrete raw materials including cement, gravel, and sand, 5% to 40% by weight of limestone fine powder relative to the cement in the concrete raw materials, and mixing water, or a fluidized cement composition obtained by mixing mortar raw materials including cement and sand, 5% to 40% by weight of limestone fine powder relative to the cement in the mortar raw materials, and mixing water, into a molding form, a molding step of molding the fluidized cement composition poured into the molding form, and a curing step of hardening the fluidized cement composition. In this manufacturing method of the precast remaining form panel, in the molding step and the curing step, excess water containing calcium hydroxide dissolved from the cement is pushed up to the back side in the mixing water, so that it is stored in the entire back area of ​​the panel body, covering the back side of the panel body with the excess water, and the excess water is present so as to fill capillary voids formed inside 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, which prevents 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, and at the same time, capillary voids, etc. are naturally blocked by the waterproof layer. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 6487107 [Patent Document 2] Patent No. 6537754 [Patent Document 3] Patent No. 7314430 Summary of the Invention [Problem to be solved by the invention]

[0008] Although the precast remaining formwork precast panels manufactured by the manufacturing methods described in Patent Documents 1 to 3 were more effective at blocking capillary voids than conventional ones, it was difficult to completely prevent capillary voids. Therefore, the influence of capillary voids increases depending on the thickness of the precast remaining formwork panel, and further improvement was desired.

[0009] Specifically, in a thick precast concrete panel for remaining formwork, even if some capillary voids are formed, they are not likely to be significantly affected by cracks caused by capillary voids, but in a thin precast concrete panel for remaining formwork, for example 25mm to 50mm thick, the surface of the panel for remaining formwork may be contaminated by cracks caused by capillary voids. Also, the formation of cracks may reduce the strength of the main body of the precast concrete panel for remaining formwork.

[0010] Given this background, there has been a demand for a manufacturing method for precast remaining formwork panels that can completely seal capillary voids and the like in precast remaining formwork concrete panels and that can be applied to precast remaining formwork concrete panels, more so than the manufacturing methods proposed to date.

[0011] Therefore, an object of the present invention is to provide a manufacturing method for a precast remaining formwork panel that suppresses the formation of capillary voids in the precast remaining formwork concrete panel body and improves the water impermeability of the precast remaining formwork concrete panel body. [Means for solving the problem]

[0012] The method for producing a precast remaining form panel according to the present invention is a method for producing a non-permeable precast remaining form panel, and includes a mixing step of mixing concrete raw materials including cement, gravel which is a crushed limestone aggregate, and sand which is a crushed limestone aggregate, with mixing water for hydration reaction which 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 corresponding to an outside air temperature of 0°C to 40°C, a pouring step of pouring the fluidized cement composition into a forming form designed so that the back surface of the panel body is maintained facing upward and horizontal after the mixing step, a molding step of molding the fluidized cement composition poured into the forming form, and a molding step of allowing the temperature of the fluidized cement composition in the forming form to drop naturally to the outside air temperature over a period of 3 hours or more without reheating the fluidized cement composition poured into the forming form from the outside, so that the mixing water for hydration reaction containing calcium hydroxide dissolved from the fluidized cement composition is heated to a temperature of 60°C to 85°C in advance, and .... The method includes a heat retention and curing step in which the fluidized cement composition is cured until a demolding strength is ensured while suppressing the occurrence of capillary voids in the fluidized cement composition by suppressing the bleeding phenomenon in which the fluidized cement composition expands and is discharged outside the molding formwork, and a demolding step in which the molding formwork is removed after the heat retention and curing step. In the heat retention and curing step, excess water containing calcium hydroxide dissolved from the cement is pushed up to the rear side of the mixing water and is stored over the entire rear side of the panel body, covering the rear side of the panel body with the excess water and intervening so as to fill capillary voids formed inside the panel body, so that when the fluidized cement composition hardens, a waterproof layer is formed over the entire rear side of the panel body, preventing the formation of a permeable calcium carbonate fine powder layer over the entire rear side of the panel body due to a chemical reaction between carbon dioxide in the outside air and calcium hydroxide. At the same time, the capillary voids are almost completely blocked by the waterproof layer, dramatically improving the water impermeability of the panel body.

[0013] The method for producing a precast remaining form panel according to the present invention is a method for producing a non-permeable precast remaining form panel, and includes a mixing step of mixing mortar raw materials containing cement and sand, which is a crushed limestone aggregate, with mixing water for hydration reaction, which 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 corresponding to an outside air temperature of 0°C to 40°C, a pouring step of pouring the fluidized cement composition into a molding form designed so that the back surface of the panel body is maintained facing upward and horizontal after the mixing step, a molding step of molding the fluidized cement composition poured into the molding form, and a molding step of allowing the temperature of the fluidized cement composition in the molding form to drop naturally to the outside air temperature over a period of 3 hours or more without reheating the fluidized cement composition poured into the molding form after the molding step, so that the mixing water for hydration reaction, which contains calcium hydroxide dissolved from the fluidized cement composition, expands in volume and forms a fluidized cement composition. and a demolding step of removing the molding form after the warming and curing step, in which excess water containing calcium hydroxide dissolved from the cement in the mixing water is pushed up toward the rear surface side and is stored over the entire rear surface side of the panel body, covering the rear surface of the panel body with the excess water and intervening so as to fill the capillary voids formed inside the panel body, so that when the fluidized cement composition hardens, a waterproof layer is formed over the entire rear surface side of the panel body, preventing the formation of a permeable fine powder layer of calcium carbonate over the entire rear surface side of the panel body due to a chemical reaction between carbon dioxide in the outside air and calcium hydroxide, and at the same time, the capillary voids are almost completely blocked by the waterproof layer, dramatically improving the water impermeability of the panel body.

[0014] The manufacturing method of a precast remaining formwork panel of the present invention is characterized in that, in the pouring process, a stainless steel connected fitting is embedded at a predetermined position in the fluidized cement composition so that it protrudes from the back surface of the panel body. Effect of the Invention

[0015] The method for producing a precast remaining form panel according to the present invention involves mixing concrete raw materials containing cement, gravel which is a crushed limestone aggregate, and sand which is a crushed limestone aggregate, with mixing water for hydration reaction which has been heated in advance to a temperature of 60°C to 85°C, to obtain a fluidized cement composition with a mixing temperature of 15°C to 45°C which corresponds to an outside air temperature of 0°C to 40°C, and allowing the temperature of the fluidized cement composition in the forming form to drop naturally to the outside air temperature over a period of 3 hours or more without reheating the fluidized cement composition from the outside. This prevents the bleeding phenomenon in which the mixing water for hydration reaction containing calcium hydroxide dissolved from the fluidized cement composition expands in volume and is discharged outside the forming form, thereby preventing the generation of capillary voids in the fluidized cement composition.

[0016] In addition, in the manufacturing method of the precast remaining form panel using the raw concrete material, in the heat retention curing step, excess water containing calcium hydroxide dissolved from the cement is pushed up to the back side in the mixing water and is stored on the entire back side of the panel body, covering the back side of the panel body with the excess water and filling voids such as capillary voids formed inside the panel body, so that when the fluidized cement composition hardens, a waterproof layer is formed on the entire back side of the panel body, preventing the formation of a permeable calcium carbonate fine powder layer on the entire back side of the panel body. The waterproof layer almost completely blocks voids such as capillary voids, dramatically improving the water impermeability of the panel body.

[0017] The manufacturing method of the present invention for producing a precast remaining form panel involves mixing mortar raw materials containing cement and sand, which is a crushed limestone aggregate, with mixing water for hydration reaction that has been heated in advance to a temperature of 60°C to 85°C, to obtain a fluidized cement composition with a mixing temperature of 15°C to 45°C, which corresponds to an outside air temperature of 0°C to 40°C, and allowing the temperature of the fluidized cement composition in the forming form to naturally drop to the outside air temperature over a period of 3 hours or more without reheating the fluidized cement composition from the outside. This prevents 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 outside the forming form, and thereby prevents the generation of capillary voids in the fluidized cement composition.

[0018] Furthermore, in the manufacturing method of the precast remaining form panel using this mortar raw material, the excess water containing calcium hydroxide dissolved from the cement is pushed up to the rear side in the mixing water during the heat retention curing process, and is stored on the entire rear side of the panel body, covering the rear side of the panel body with the excess water, and the excess water is present so as to fill voids such as capillary voids formed inside the panel body, and when the fluidized cement composition hardens, a waterproof layer is formed on the entire rear side of the panel body, which prevents the carbon dioxide in the outside air from reacting with calcium hydroxide and forming a permeable calcium carbonate fine powder layer on the entire rear side of the panel body. The waterproof layer almost completely blocks voids such as capillary voids, dramatically improving the water impermeability of the panel body.

[0019] 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 in the inserting step. Even in this case, the gap formed between the embedded part of the connecting fittings and the panel body is almost completely filled with the waterproof layer, dramatically improving the water impermeability of the panel body.

[0020] In this way, the manufacturing method of the precast remaining form panel of the present invention can improve water impermeability by almost completely sealing voids such as capillary voids, and can particularly suppress the formation of cracks in thin precast remaining form panels, thereby preventing a decrease in strength. [Brief description of the drawings]

[0021] [Figure 1] 1A and 1B are diagrams illustrating a precast remaining form panel according to an embodiment of the present invention, in which (a) is a cross-sectional view and (b) is a rear view. [Diagram 2] FIG. 2 is an enlarged view of a connected portion of a precast remaining formwork panel according to an embodiment of the present invention. [Diagram 3] 1 is a diagram for explaining a manufacturing process of a precast remaining form panel according to an embodiment of the present invention. FIG. [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) shows a cross-sectional view and (b) shows a front view. [Diagram 5] 1 is a rear view of a remaining formwork constructed by a remaining formwork construction method according to an embodiment of the present invention. FIG. [Figure 6] 1 is an image showing the results of a water permeability test (immediately after the start of the test) of a precast remaining formwork panel according to an embodiment of the present invention. [Figure 7] 13 is an image showing the results of a water permeability test of a precast remaining formwork panel according to an embodiment of the present invention (situation 3.5 hours after the start of the test). [Figure 8] 13 is an image showing the results of a water permeability test (six hours after the start of the test) of a precast remaining formwork panel according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] The manufacturing method of the precast remaining form panel according to the present embodiment will be described with reference to Fig. 1 to Fig. 5. In the drawings, the horizontal direction of the precast remaining form panel is indicated as width direction X, the vertical direction is indicated as height direction Y, and the thickness direction is indicated as front-rear direction Z.

[0023] In the manufacturing method of a precast remaining form panel according to this embodiment, a non-water-permeable precast remaining form panel 1 shown in Fig. 1 is manufactured. As shown in Fig. 1(a), this precast remaining form panel 1 comprises a precast remaining form panel body 2 (hereinafter also referred to as the panel body 2), a plurality of connected 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 of the panel body 2, etc. [Panel body 2] 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 connected metal fittings 3 are provided in the width direction X and the height direction Y on the back surface 2a of the panel body 2. The connected metal 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. [Connected metal fitting 3] The connected metal fitting 3 comprises a hook portion 6 and an embedded portion 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 portion 7 embedded inside the panel main body 2 and the hook portion 6 protruding from the back surface 2a of the panel main body 2. The connected metal fitting 3 can be made of metal, and is preferably made of a material with excellent corrosion resistance, such as stainless steel (SUS304). [Waterproof layer 4] The waterproof layer 4 is composed of a layer containing calcium hydrate, which is insoluble in water. As shown in Fig. 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. It is considered that the calcium hydrate contained in this waterproof layer 4 is produced by a chemical reaction between the limestone crushed aggregate in the fluidized cement composition C constituting the panel body 2 and a component that dissolves when the cement in the fluidized cement composition C hardens.

[0024] Next, a method for manufacturing a precast remaining form panel will be described.

[0025] The manufacturing method of the precast remaining form panel according to the present embodiment is a method for manufacturing a non-permeable precast remaining form panel 1. The manufacturing method of the precast remaining form panel includes a mixing step of mixing concrete raw materials including cement, gravel which is a crushed limestone aggregate, and sand which is a crushed limestone aggregate, with mixing water for hydration reaction which has been heated to a predetermined temperature in advance, to obtain a fluidized cement composition C having a predetermined mixing temperature corresponding to an outside air temperature of 0°C to 40°C, a charging step of charging the fluidized cement composition C into a molding form 22 after the mixing step, a molding step of molding the fluidized cement composition C charged into the molding form 22, a heat retention curing step of naturally lowering the temperature of the charged fluidized cement composition C to the outside air temperature over a predetermined time or more without reheating the charged fluidized cement composition C from the outside, and hardening the fluidized cement composition C, and a demolding step of removing the molding form 22 after the heat retention curing step. In the method for producing a recast remaining form panel according to the present invention, no heating is carried out in the mixing step except for heating the mixing water for the hydration reaction to increase its temperature.

[0026] The limestone used is preferably of amorphous calcite origin (crystal grain size 100 μm or less), and in order to promote reactivity, the purity of the limestone is preferably 95% or more.

[0027] For the cement composition C, mortar raw materials including cement and sand, which is a crushed limestone aggregate, can also be used. [Mixing process] In the mixing process, concrete raw materials including cement, gravel which is a crushed limestone aggregate, and sand which is a crushed limestone aggregate are mixed with mixing water for the hydration reaction which has been heated in advance to a temperature of 60°C to 85°C to obtain a fluidized cement composition with a mixing temperature of 15°C to 45°C, which corresponds to an outside air temperature of 0°C to 40°C.

[0028] When the outside air temperature is 0°C in winter, the mixing temperature is preferably 15°C higher than 0°C, and when the outside air temperature is 40°C in summer, the mixing temperature is preferably 5°C higher than 40°C. [Feeding process] In the casting process, as shown in Fig. 3, the panel body 2 is formed using a molding form 22. 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 becomes the back surface 2a side of the panel body 2.

[0029] Specifically, as shown in FIG. 3(a), a mixture with fluidized cement composition C is poured into a molding formwork 22 placed on a stand 21 equipped with a vibration device 20, and the fluidized cement composition C is vibrated by the vibration device 20.

[0030] As a result, excess water containing calcium hydroxide eluted from the fluidized cement composition C is pushed up toward the back surface 2a of the panel body 2. This excess water then fills capillary gaps 9A formed inside the panel body 2 and gaps 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. [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 into the fluidized cement composition C to a predetermined position, and the hook portion 6 of the connected metal fittings 3 are embedded so as to protrude 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. [Thermal curing process] In the heat-retaining curing step, the fluidized cement composition C is hardened until the demolding strength is ensured. Specifically, the fluidized cement composition C, which has been poured into the molding form 22 and is at a temperature higher than the outside air temperature, is allowed to naturally drop in temperature to the outside air temperature over a period of 3 hours or more without reheating from the outside. When the temperature is naturally lowered to the outside air temperature, the mixing water for the hydration reaction, which contains calcium hydroxide dissolved from the fluidized cement composition C, expands in volume and is discharged to the outside of the molding form 22, thereby preventing the bleeding phenomenon. By preventing bleeding, the occurrence of capillary voids 9a and voids 9b in the fluidized cement composition C is prevented.

[0031] In the heat retention curing process, excess water containing calcium hydroxide dissolved from the cement is pushed up toward the rear surface 2a of the mixing water, and is stored in the entire 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 inside the panel body 2. When the fluidized cement composition C hardens, a waterproof layer 4 is formed over the entire rear surface 2a of the panel body 2. This prevents a permeable calcium carbonate fine powder layer from being formed 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. [Demolding process] In the demolding process, the molding frame 22 is removed after a heat-retaining curing process is performed for a predetermined time.

[0032] Next, a construction method using the precast remaining form panel 1 manufactured by the above-mentioned manufacturing method will be described. The cement-based consolidation material used in the remaining form construction method can be anything that contains moisture and hardens over time, such as concrete, mortar, and aerated mortar. In this embodiment, an example will be described in which concrete 12 is used as the cement-based consolidation material.

[0033] 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 in the entire back surface 2a of the panel body 2, in the capillary gaps 9A, and in the gaps 9B. When constructing the remaining form 10, as shown in Fig. 4(a), the precast remaining form panel 1 is fixed to the front surface of the wooden form 13 by connecting the precast remaining form panel 1 to the wooden form (concrete panel) 13 using steel connecting fittings (separators) 11 connected to the connected fittings 3.

[0034] By applying sealant 14 to the joints 8 between adjacent precast remaining form panels 1, the top, bottom, left and right ends of the waterproof layer 4 are joined together by the sealant 14, as shown in Fig. 5. By joining the ends of the waterproof layer 4 together, the entire back surface 2a of the precast remaining form panel 1 is completely covered by the waterproof layer 4 and the sealant 14. For example, a silicone sealant or waterproof tape can be used as the sealant 14.

[0035] Next, a cement-based solidifying material casting process is performed. Specifically, concrete 12 is cast between the remaining precast formwork panel 1 and the wooden formwork 13 (FIG. 4(a)). The concrete 12 is cast so as to come into contact with the waterproof layer 4 formed on the back surface 2a of the panel body 2.

[0036] After the concrete 12 is poured, the concrete 12 is hardened (cement-based binder hardening step). At this time, since the waterproof layer 4 is formed in the capillary voids 9A and the voids 9B, the moisture in the concrete 12 is prevented from penetrating into the inside of the panel body 2 through the capillary voids 9A and the voids 9B. This prevents the moisture in the concrete 12 from being released and evaporated, and prevents cracks in the concrete 12 due to drying shrinkage. [Water permeability test] A concrete specimen (concrete specimen 1) manufactured by the manufacturing method of the precast remaining form panel according to this embodiment was prepared by mixing concrete raw materials including gravel, which is a crushed limestone aggregate, sand, which is a crushed limestone aggregate, and mixing water at 63.3°C in an environment with an outside air temperature of 36°C to obtain a fluidized cement composition at 40.1°C. The fluidized cement composition was poured into a formwork and allowed to cool naturally to the outside air temperature over a period of 3 hours or more without being reheated from the outside, thereby producing specimen 1.

[0037] On the other hand, the concrete specimen (concrete specimen 2) manufactured by the conventional manufacturing method was manufactured by mixing concrete raw materials including gravel and sand, which are crushed limestone aggregates, with mixing water (tap water) at 31.4°C in an environment of an outside air temperature of 36°C to obtain a fluidized cement composition at 34.8°C, which is lower than the outside air temperature of 36°C. The fluidized cement composition was poured into a formwork and heated and heated during the thermal curing process (heated by the outside air). Therefore, bleeding occurred during the manufacturing process of concrete specimen 2.

[0038] The permeability test of specimen 1, specimen 2 and marble was carried out as follows. 1.0 ml of water was dripped onto each specimen, and observations were carried out for 6 hours from immediately after dripping, and photographs were taken with a digital camera.

[0039] The results of the permeability tests are shown in Figures 6 to 8.

[0040] In concrete specimen 2, the water droplets spread immediately after the drops were added (Figure 6) and the water began to seep through, and after 3.5 hours, almost all of the water had seeped through (Figure 7).

[0041] On the other hand, in concrete specimen 1, no water permeation was observed immediately after the dripping, and even after 3.5 hours, water was clearly still remaining (Fig. 7). After 6 hours, the dripped water had disappeared (Fig. 8).

[0042] Furthermore, in the case of the impermeable marble, the water that was added by drops evaporated after six hours (Fig. 8). From this, it can be said that the water also evaporated and disappeared in the concrete specimen 1 due to the effect of evaporation.

[0043] It was found that concrete specimen 1 had clearly improved impermeability compared to concrete specimen 2. The capillary void reduction rate of concrete specimen 1 was 100% (6 hours / 6 hours x 100), while the capillary void reduction rate of concrete specimen 2 was 58.3% (3.5 hours / 6 hours x 100). This shows that concrete specimen 1 has roughly the same level of impermeability as marble, and that its impermeability has been dramatically improved.

[0044] From the above, it was found that in the concrete specimen 1 manufactured by the manufacturing method according to this embodiment, the waterproof layer is formed densely, which significantly reduces the permeability and dramatically improves the impermeability compared to the concrete specimen 2 manufactured by the conventional manufacturing method.

[0045] Next, the effects of the method for manufacturing a precast remaining form panel according to this embodiment will be described.

[0046] In precast concrete panels made using conventional manufacturing methods, a waterproof layer was formed naturally, providing a certain level of effectiveness. However, in thinner precast concrete panels made using conventional methods, there was a demand for further suppression of capillary voids and for even higher levels of water impermeability.

[0047] The precast remaining form panel 1 according to this embodiment is prepared by mixing concrete raw materials including limestone crushed aggregate gravel and sand with mixing water for hydration reaction that has been heated in advance, obtaining a fluidized cement composition with a mixing temperature of 15 to 45°C corresponding to an outside air temperature of 0 to 40°C, and allowing the mixture to naturally rise and fall to the outside air temperature without heating, thereby forming a waterproof layer 4 over the entire back surface 2a of the panel body 2, and the capillary void 9A and the void 9B (not shown in the drawing) formed between the embedded part 7 of the connected metal fitting 3 and the panel body 2 are almost completely blocked by the waterproof layer 4 containing a water-insoluble calcium compound. In this way, the formation of the waterproof layer 4 can prevent the formation of a permeable calcium carbonate powder layer over the entire back surface 2a of the panel body 2, and the capillary void 9A and the void 9B formed between the embedded part 7 of the connected metal fitting 3 and the panel body 2 are almost completely blocked, thereby dramatically improving the impermeability of the panel body 2. The water impermeability of the panel body 2 is dramatically improved, and this is particularly suitable for a thin panel body 2.

[0048] In the manufacturing method of the precast remaining form panel according to this embodiment, concrete raw materials containing gravel, which is a crushed limestone aggregate, and sand, which is a crushed limestone aggregate, are used, so that the hydration reaction is significantly faster than when fine silica powder is used, for example, and the waterproof layer 4 can be formed in a short time on the back surface 2a of the panel main body 2 and on the capillary voids 9a and voids 9b. Since the hydration reaction is not slowed 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.

[0049] In addition, the waterproof layer 4 is formed on the panel body 2, and the impermeability of the panel body 2 is dramatically improved, so that rainwater that has infiltrated the hardened concrete 12 side and saltwater that has dissolved from the snow-melting agent are prevented from infiltrating into the inside of the panel body 2. Furthermore, the ends of the waterproof layers 4 of the adjacent panel bodies 2 are connected with the sealant 14, and the joints 8 and the concrete 12 side are blocked off, so that rainwater that has infiltrated the hardened concrete 12 side and saltwater that has dissolved from the snow-melting agent are prevented from leaking out of the gaps in the joints 8 to the surface (outside of the panel body 2) of the precast remaining formwork panel 1. Therefore, frost damage, salt damage, and efflorescence that occur to the panel body 2 can be prevented, and contamination, deterioration, damage, and deformation of the panel body 2, and corrosion of the reinforcing steel bars 5 that are the reinforcing materials of the panel body 2 can be avoided.

[0050] In addition, in the manufacturing method for precast remaining formwork panels according to this embodiment, the temperature of the fluidized cement composition C is naturally lowered to the outside air temperature over a period of 3 hours or more during the thermal curing process without reheating the fluidized cement composition C from the outside, thereby contributing to energy savings.

[0051] The construction method using the precast remaining formwork panel 1 according to this embodiment allows the appearance of the remaining formwork 10 to be maintained after construction, and the remaining formwork 10 to be maintained stably for a long period of time without reducing durability.

[0052] In addition, 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 of the panel body 2 are almost completely blocked, so that the water in the poured fresh concrete 12 is prevented from being rapidly released and evaporated from the capillary voids 9A during the cement-based hardening material hardening process. Therefore, the fresh concrete 12 gradually hardens and is less likely to crack, and cracks are prevented from occurring in the panel body 2 after the remaining formwork 10 is constructed. In this way, the effect of the fresh concrete 12 gradually hardening and thus making it less likely to crack is effective when constructing the remaining formwork 10 in the summer or when constructing the remaining formwork 10 in a sunny location.

[0053] As described 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 suppressed from occurring in the precast remaining formwork, and the surface of the remaining formwork can be prevented from being contaminated. Therefore, the construction method according to this embodiment is very useful and has high versatility.

[0054] Although the present embodiment has been described above, it is possible to select from the configurations given in the above embodiment, or to change to other configurations as appropriate, without departing from the spirit of the present invention.

[0055] In this embodiment, an example has been described in which concrete raw materials containing gravel, which is a crushed limestone aggregate, and sand, which is a crushed limestone aggregate, are used in the cement composition C, but mortar raw materials containing cement and sand, which is a crushed limestone aggregate, can also be used in the cement composition C. Even when using mortar raw materials, the same steps can be carried out as when using concrete raw materials, and the same action and effect can be enjoyed.

[0056] Furthermore, the thickness of the panel body 2 may be other than the example shown in this embodiment, and the manufacturing method of the precast remaining formwork panel of the present invention is particularly effective and useful for panel bodies 2 with thin thicknesses (25 mm to 50 mm).

[0057] 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 are formed integrally with it, but it is also possible to have the connected metal fittings attached 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]

[0058] 1 Precast remaining formwork panels (panels) 2 Precast remaining formwork panel body (panel body) 2a Back (back side) 3 Connecting metal fittings 4 waterproof layer 5. Steel Bars 6 Hook part 7 Buried section 8 Joint 9A Capillary void 9B gap (gap formed between embedded portion 7 and panel body 2) 10 Remaining formwork 11 Connecting fittings (separators) 12 Concrete (cement-based solidifying material) 13 Wooden formwork (plywood) 14 Sealing materials 20 Vibration device 21 units 22 Forming mold C. Fluidized cement composition X Width direction Y Height direction Z front and rear direction

Claims

1. A method for manufacturing a precast remaining form panel, which manufactures a water-impermeable precast remaining form panel, comprising: A mixing process of mixing concrete raw materials including cement, gravel which is a crushed limestone aggregate, and sand which is a crushed limestone aggregate with mixing water for hydration reaction which 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 corresponding to an outside air temperature of 0°C to 40°C; After the mixing step, a step of pouring the fluidized cement composition into a molding form designed so that the rear surface of the panel body is maintained facing upward and horizontal; a molding step of molding the fluidized cement composition poured into the molding form; a heat retention curing step in which, after the molding step, the temperature of the fluidized cement composition in the molding formwork is naturally lowered to an outside air temperature over a period of 3 hours or more without externally reheating the fluidized cement composition charged in the molding formwork, thereby preventing a bleeding phenomenon in which mixing water for hydration reaction containing calcium hydroxide dissolved from the fluidized cement composition expands in volume and is discharged to the outside of the molding formwork, thereby preventing the generation of capillary voids in the fluidized cement composition, and hardening the fluidized cement composition until a demolding strength is ensured; A demolding process of removing the molding form after the heat retention and curing process, In the heat retention curing process, excess water containing calcium hydroxide dissolved from the cement is pushed up to the rear side of the mixing water, and is stored in the entire rear surface of the panel body. The rear surface of the panel body is covered with the excess water, and the excess water is present so as to fill capillary voids formed inside the panel body. When the fluidized cement composition hardens, a waterproof layer is formed over the entire back surface of the panel body, which prevents carbon dioxide in the outside air from chemically reacting with the calcium hydroxide to form a permeable fine powder layer of calcium carbonate over the entire back surface of the panel body. At the same time, the capillary voids are almost completely blocked by the waterproof layer, dramatically improving the impermeability of the panel body. A method for manufacturing a precast remaining form panel, comprising:

2. A method for manufacturing a precast remaining form panel, which manufactures a water-impermeable precast remaining form panel, comprising: A mixing process in which mortar raw materials including cement and sand, which is a crushed limestone aggregate, are mixed with mixing water for hydration reaction, which 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 outside air temperature of 0°C to 40°C; After the mixing step, a step of pouring the fluidized cement composition into a molding form designed so that the rear surface of the panel body is maintained facing upward and horizontal; a molding step of molding the fluidized cement composition poured into the molding form; a heat retention curing step in which, after the molding step, the temperature of the fluidized cement composition in the molding formwork is naturally lowered to an outside air temperature over a period of 3 hours or more without externally reheating the fluidized cement composition charged in the molding formwork, thereby preventing a bleeding phenomenon in which mixing water for hydration reaction containing calcium hydroxide dissolved from the fluidized cement composition expands in volume and is discharged to the outside of the molding formwork, thereby preventing the generation of capillary voids in the fluidized cement composition, and hardening the fluidized cement composition until a demolding strength is ensured; A demolding process of removing the molding form after the heat retention and curing process, In the heat retention curing process, excess water containing calcium hydroxide dissolved from the cement is pushed up to the rear side of the mixing water, and is stored in the entire rear surface of the panel body. The rear surface of the panel body is covered with the excess water, and the excess water is present so as to fill capillary voids formed inside the panel body. When the fluidized cement composition hardens, a waterproof layer is formed over the entire back surface of the panel body, which prevents carbon dioxide in the outside air from chemically reacting with the calcium hydroxide to form a permeable fine powder layer of calcium carbonate over the entire back surface of the panel body. At the same time, the capillary voids are almost completely blocked by the waterproof layer, dramatically improving the impermeability of the panel body. A method for manufacturing a precast remaining form panel, comprising:

3. In the pouring step, a stainless steel connecting fitting is embedded in a predetermined position of the fluidized cement composition so as to protrude from the rear surface of the panel body. A method for manufacturing a precast remaining form panel according to claim 1 or 2.

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