Precast wall panels and their manufacturing method

Abstract

To provide a precast wall panel and a method for manufacturing the same, which eliminates the need to apply a primer undercoat or resin paint to the front surface of the panel body after molding, and allows for the formation of a transfer protection layer on the front surface of the panel body during molding. [Solution] A transfer protection layer is pre-formed on the flat formwork surface with the formwork positioned horizontally, by laminating a resin salt-blocking layer and an adhesive strengthening layer. When concrete is poured into this formwork to form the panel body, the adhesive function of the transfer protection layer and the adhesive function of the concrete are used in combination to transfer and cover the adhesive strengthening layer to the front surface of the panel body.

Description

Technical Field

[0001] The present invention relates to a precast wall material excellent in salt shielding property and a manufacturing method thereof.

Background Art

[0002] There is widely known a reinforced earth wall including a panel-shaped wall material, a strip-shaped retaining material called a skin chute connected to the back surface of the wall material, and an embankment layer constructed on the back side of the wall material, and supporting the wall material by burying each retaining material in the embankment layer (Patent Document 1).

[0003] For the retaining wall of the reinforced earth wall, a precast wall material having a panel shape is used (Patent Document 2). Since this type of wall material is manufactured by protruding a part of the connecting fitting of the retaining material on the back side, the wall material is manufactured using a box-shaped mold with an open upper surface. Specifically, while arranging reinforcing bars in the mold, after arranging the connecting fitting of the retaining material in the mold space, concrete is poured to form the panel body. After curing until the strength of the concrete is developed, the panel body is lifted with the front side facing downward and demolded.

[0004] On the other hand, when constructing a reinforced retaining wall near the coast, there has been pointed out "salt damage", which is a phenomenon of corrosion of reinforcing bars caused by the intrusion of salts (chloride ions) through minute holes on the front surface of the wall material.

[0005] As means for enhancing the resistance of the wall material to salt damage, the following methods are known. (1) A method of forming a protective layer by applying a salt-shielding resin to the front surface of the panel body after molding is completed. (2) A method of ensuring salt shielding property by using an impregnating material (silane-based, silicate-based) for the front surface of the panel body after demolding. (3) A method of ensuring salt shielding property by adding fibers or admixtures to concrete to enhance the airtightness of the concrete.

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Special Publication No. 44-25174 [Patent Document 2] Patent No. 6002348 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] Conventional salt damage countermeasures, which involve forming a protective layer on the front of the panel itself, have the following problems: <1> When the panel body is lifted and removed from the mold, the front of the panel body faces downwards. When manually applying resin to a panel with a downward-facing front, workers must apply the resin while facing upwards, which requires a great deal of effort to form a protective layer. Furthermore, it is difficult to apply the resin to a uniform thickness, making it easy for variations in the thickness of the protective layer to occur. <2> To apply resin to the front surface of a downward-facing panel, workers must work directly beneath the panel, which is a heavy object suspended in the air, raising concerns about worker safety. <3> The manufacturing process for wall materials treated to prevent salt damage requires a significant amount of time, as it includes the time needed for demolding and curing of the panel body, plus the time required for resin application and drying.

[0008] The method of ensuring salt resistance using impregnation materials has the following problems. <1> Silane-based and silicate-based impregnating materials have poor crack-following capabilities, so they cannot completely prevent salt infiltration when used alone. <2> In particular, silane-based impregnating materials have low resistance to UV degradation, which leaves problems with their long-term durability.

[0009] Methods that improve the airtightness of concrete by adding fibers or admixtures present the following problems. <1> The cost of additives such as fibers and admixtures is high. <2> In conventional concrete manufacturing plants, cleaning is required each time the type of concrete is changed, resulting in a significant amount of time and effort being spent on concrete changes.

[0010] The present invention has been made in view of the above points, and aims to provide a precast wall material and a method for manufacturing the same that can solve the problems described above. [Means for solving the problem]

[0011] The present invention provides a wall material for a reinforced earth wall, comprising a precast panel body having a front, back, and circumferential surface, and a displacement protection layer covering the front surface of the panel body, wherein the displacement protection layer is a laminated structure of an adhesive strengthening layer adhering to and covering the front surface of the panel body, and a resin salt-blocking layer laminated to and adhering to the adhesive strengthening layer, and when concrete is poured into a formwork that has the displacement protection layer covered in advance of the formwork surface to form the panel body, one side of the adhesive strengthening layer is penetrated and fixed to the surface layer of the front surface of the panel body. In another embodiment of the present invention, the salt-blocking layer of the transition protection layer is a resin coating having salt-blocking properties. The present invention relates to a method for manufacturing a wall material for a reinforced earth wall, which simultaneously forms a precast panel body having a front, back, and circumferential surface and a displacement protection layer covering the front surface of the panel body using a formwork, comprising: a formwork assembly step of forming a formwork space by positioning the formwork surface of the formwork that forms the front surface of the panel body horizontally; and a laminated structure consisting of a resin salt-blocking layer formed on the upper surface of the horizontal formwork surface positioned horizontally on the formwork, and an adhesive strengthening layer formed by adhering to the upper surface of the salt-blocking layer. The process includes the steps of attaching a transfer protection layer to the horizontal formwork surface, arranging reinforcing bars within the formwork, pouring concrete into the formwork so as to form the panel body and adhere the transfer protection layer to cover the front surface of the panel body, and demolding the panel body after the concrete has hardened, wherein the transfer protection layer is transferred from the formwork side to the panel body side by utilizing the adhesive force between the front surface of the panel body and the transfer protection layer when the panel body is demolded. In another embodiment of the present invention, a release agent is applied to the horizontal formwork surface of the formwork to form a release layer, and the transfer protection layer is attached to the upper surface of the release layer. In another embodiment of the present invention, in the step of attaching the transition protection layer to the horizontal formwork surface, a resin-based salt-blocking coating is poured onto the horizontal formwork surface to form the salt-blocking layer. In another embodiment of the present invention, in the step of pouring concrete, the concrete is poured when the adhesive strengthening layer of the transfer protection layer exposed on the horizontal formwork surface is in a softened state. [Effects of the Invention]

[0012] The present invention provides at least one of the following effects. <1> This method eliminates the need for cumbersome processes such as applying a salt-resistant resin to the front surface of the molded panel body, impregnating the front surface of the panel body with silane-based or silicate-based impregnating materials after demolding, or adding fibers or admixtures to the concrete before pouring. As a result, wall materials with a highly salt-resistant, high-quality transition protection layer covering the front surface of the panel body can be manufactured simply and economically. <2> By pouring concrete into formwork that has a displacement protection layer attached to its surface beforehand, the panel body molding process and the process of attaching the displacement protection layer to the front surface of the panel body can be carried out efficiently in a short period of time. Therefore, it eliminates the need for workers to apply resin to panels suspended in the air, a dangerous task that was previously required, thus ensuring worker safety. <3> A salt-blocking layer can be formed with uniform thickness and high quality on the horizontal formwork surface of a formwork with a well-maintained working environment. Therefore, the salt barrier layer can fully exhibit its intended salt barrier performance. <4> Since the salt-blocking layer formed on the horizontal formwork surface is transferred and attached to the front surface of the panel body during molding, there is no need to apply a primer or resin paint to the front surface of the panel body after molding. <5>By using both the adhesion of the strengthening layer and the adhesion of the concrete, the transfer protection layer can be firmly attached to the front surface of the panel body as compared with the case where a resin paint is applied later to the cured panel body. Therefore, by applying the wall material to the reinforced earth retaining wall, it is possible to effectively suppress peeling due to external factors, and the durability of the transfer protection layer is greatly improved. <6>The transfer protection layer covering the front surface of the panel body, without using a silane-based or silicate-based impregnating material, not only exhibits high salt barrier properties (salt resistance), but also has high resistance to ultraviolet degradation, so it can maintain high durability against ultraviolet rays over a long period of time.

Brief Description of the Drawings

[0013] [Figure 1] It is an explanatory view of the wall material according to the present invention with a part broken, (a) is a perspective view of the wall material seen from the front side, and (b) is a perspective view of the wall material seen from the back side [Figure 2] Cross-sectional view of the formwork and the wall material produced using the formwork [Figure 3] It is an explanatory view of the manufacturing method of the wall material, (a) is a partial cross-sectional view of the formwork in which a release layer and a salt barrier layer are laminated on a horizontal formwork surface, and (b) is a partially enlarged cross-sectional view of the laminated part of the release layer and the salt barrier layer and the formwork [Figure 4] It is an explanatory view of the manufacturing method of the wall material, which is a partially enlarged cross-sectional view of the transfer protection layer formed by laminating a release layer and a salt barrier layer and the formwork [Figure 5] It is an explanatory view of the manufacturing method of the wall material, which is a partially enlarged cross-sectional view of the panel body, the transfer protection layer, and the formwork immediately after placing the concrete for the panel body on the upper surface of the transfer protection layer [Figure 6] It is an explanatory view of the manufacturing method of the wall material, which is a partially enlarged cross-sectional view of the panel body and the formwork at the time of demolding the panel body

Embodiments for Carrying Out the Invention

[0014] <1>Outline of the precast wall material It will be described with reference to FIGS. 1 and 2. The precast wall material according to the present invention (hereinafter referred to as "wall material 10") is a precast wall material applicable to reinforced earth walls. The wall material 10 comprises a panel body 20 having a front surface 21, a back surface 22, and a peripheral surface 23, and a multi-layered transfer protection layer 30 attached to and covering the front surface 21 of the panel body 20.

[0015] The transfer protection layer 30 is not formed by applying resin to the completed panel body 20 afterwards. Instead, when the panel body 20 is molded using the mold 50, the transfer protection layer 30 is transferred from the mold 50 side to the panel body 20 side, thereby adhering to and covering the front surface 21 of the panel body 20.

[0016] <2> Panel body The panel body 20 is a thin concrete pressure-receiving plate for supporting the earth pressure of the embankment. The panel body 20 shown in Figure 1 has multiple reinforcing bars and multiple L-shaped or I-shaped connecting fittings 25 embedded inside. The connecting fitting 25 is a connecting element for connecting bracing materials 40 such as skin plates, and a part of it protrudes laterally from the back surface 22 of the panel body 20. The planar shape of the panel body 20 is not limited to the roughly cross shape shown in the illustration, but may be rectangular, polygonal, arched, or the like. There are no particular restrictions on the planar shape of the panel body 20.

[0017] In this invention, since the front surface 21 of the panel body 20 is covered with a salt-resistant displacement protection layer 30, there is no need to use expensive special concrete for the concrete of the panel body 20, and inexpensive general concrete can be used.

[0018] <3> Metastasis protective layer As shown in Figures 4-6, the transfer protection layer 30 is a barrier layer that is attached to and covers the front surface 21 of the panel body 20, preventing air and water from passing into the concrete structure. It consists of an adhesive strengthening layer 31 bonded to the front surface 21 of the panel body 20 and a salt-blocking layer 32 bonded to and laminated to the adhesive strengthening layer 31.

[0019] <3.1>Adhesion reinforcement layer The adhesive strengthening layer 31 is located between the front surface 21 of the panel body 20 and the transfer protection layer 30, and penetrates into the structure of the semi-cured front surface 21 of the panel body 20 and the uncured and softened transfer protection layer 30, respectively, thereby exhibiting high adhesive function to both the panel body 20 and the transfer protection layer 30. Adhesion-enhancing layer The resin adhesive constituting the adhesion-enhancing layer 31 includes one of the following: epoxy resin, urethane resin, or acrylic resin. In practical terms, it is desirable to use a mixture of an amine curing agent and a wet-surface-compatible epoxy resin adhesive, which has high adhesion to semi-cured concrete.

[0020] <3.2> Salt barrier layer The salt-blocking layer 32 is a resin barrier layer that is not breathable or permeable to water, and has a salt-blocking function that protects the front surface 21 and the reinforcing bars inside the panel body 20 from external forces and salt damage. In this invention, "salt-blocking function (salt-resistant function)" refers not only to the function of preventing the intrusion of chloride ions into the concrete structure, but also to the function of preventing the intrusion of moisture and carbon dioxide. As the resin coating that constitutes the salt-blocking layer 32, one of the following can be used: epoxy resin coating, polyurethane resin coating, acrylic silicone resin coating, or polymer cement-based corrosion inhibitor. In practical terms, it is desirable to use a mixture of an amine curing agent and an epoxy resin-based paint, which is suitable for wet surfaces and has high adhesion to semi-cured concrete.

[0021] <3.3> Layer thickness of the adhesive strengthening layer and the salt barrier layer The thickness of the adhesive strengthening layer 31 and the salt-blocking layer 32 can be selected as appropriate. In practical terms, the thickness of the adhesive strengthening layer 31 is thinner than the thickness of the salt-blocking layer 32. In other words, the adhesive strengthening layer 31 and the salt-blocking layer 32 have the same composition, and the total film thickness of both layers 31 and 32 is ensured to be approximately 2 mm.

[0022] <4> Reasons for providing a displacement protection layer on the formwork side For example, if we consider a configuration in which a slurry-like salt-blocking coating is applied to the panel body 20, when the concrete is in an unhardened state, the salt-blocking coating cannot be applied because the concrete does not have a fixed shape. Furthermore, if a salt-blocking coating is applied directly to cover the front surface 21 of the panel body 20 with a salt-blocking layer, it is necessary to wait for the panel body 20 to harden and then apply a primer to the front surface 21 of the panel body 20, which requires a lot of time for manufacturing.

[0023] Therefore, in this invention, instead of applying resin to the completed panel body 20 afterwards, a transfer protection layer 30 is provided on the mold 50 side. If a transfer protection layer 30 is provided in advance on the formwork 50 side, when the panel body 20 is formed using the formwork 50, the transfer protection layer 30 provided on the formwork 50 side can be transferred to the panel body 20 side. In other words, the reason why the present invention provides the displacement protection layer 30 on the formwork 50 side is to ensure high-quality formation of the displacement protection layer 30 and to firmly adhere the displacement protection layer 30 to the panel body 20.

[0024] [Manufacturing method for wall panels] A method for manufacturing the wall material 10 using formwork 50 will be described.

[0025] <1> Formwork assembly As shown in Figure 2, a horizontally positioned steel formwork 50 is used. Check the horizontality of the horizontal formwork surface 51. A separate end frame member 52 is assembled to the periphery of the upper surface of the horizontal formwork surface 51, following the contour shape of the panel body 20.

[0026] The space enclosed by the horizontal formwork surface 51 and the end frame material 52 becomes the formwork space. The horizontal formwork surface 51 is a formwork surface for forming the front surface 21 of the panel body 20, and the end frame member 52 is a formwork member for forming the circumferential surface 23 of the panel body 20, with its inner surface functioning as a formwork surface. The end frame material 52 has a height greater than or equal to the structural thickness of the panel body 20. The end frame members 52 can be dismantled relative to the horizontal formwork surface 51.

[0027] <2> Pre-application of a transfer protection layer to the formwork Referring to Figures 3 and 4, the process of first attaching the transfer protection layer 30 to the horizontal formwork surface 51 of the formwork 50 will be explained.

[0028] <2.1> Application of release layer As shown in the transfer protection layer, a known release agent (e.g., a silicone demolding release agent) is thinly applied to the entire surface of the release layer 33 exposed on the inside of the mold 50 to form the release layer 33. The means of applying the release agent 33 may be appropriately selected and adopted from known methods such as roller application, brush application, trowel application, or spatula application. The release layer 33 functions to facilitate the removal of the transfer protection layer 30 from the horizontal formwork surface 51 during demolding.

[0029] <2.2> Formation of the salt barrier layer A slurry-like salt-blocking paint is poured onto the upper surface of the release layer 33 to form a salt-blocking layer 32 of a predetermined thickness.

[0030] Since the formation of the salt barrier layer 32 can be performed by workers in a stable downward position, the physical burden on workers is significantly reduced compared to when the coating work is performed in an upward position. Furthermore, since the formation of the salt-blocking layer 32 can be carried out by pouring in salt-blocking paint, it becomes easier to control the thickness of the salt-blocking layer 32 compared to when a worker applies the paint in an upward position, resulting in less variation in the thickness of the salt-blocking layer 32 and enabling a uniform thickness finish.

[0031] <2.3> Formation of the adhesive strengthening layer Next, after leaving the salt-blocking layer 32 for about two hours, an adhesive is applied to the upper surface of the salt-blocking layer 32 to form an adhesive strengthening layer 31. The adhesive can be applied using known methods such as roller application, brush application, trowel application, or spatula application, selected as appropriate. A transfer protection layer 30 is formed by laminating an adhesion strengthening layer 31 onto the upper surface of the salt barrier layer 32. By applying adhesive to the salt-blocking layer 32 when it is semi-cured or immediately after it has hardened, a portion of one side of the adhesive-reinforcing layer 31 penetrates into the structure of the salt-blocking layer 32, causing the adhesive-reinforcing layer 31 and the salt-blocking layer 32 to become one.

[0032] <2.4> Laminated Structure As explained above, a laminated structure is formed on the upper surface of the horizontal formwork surface 51, with the release layer 33, salt barrier layer 32, and adhesive strengthening layer 31 stacked in order from bottom to top, and the adhesive strengthening layer 31 is exposed on the uppermost surface of the horizontal formwork surface 51.

[0033] <3> Assembly of reinforcing bars, installation of connecting hardware The prescribed reinforcing bars (main bars, auxiliary bars) are assembled within the formwork 50, and multiple connecting fittings 25 are installed in the designated positions. The method of installing the reinforcing bars and connecting fittings 25 is the same as before. The components to be installed within the formwork 50 are not limited to reinforcing bars and connecting fittings 25; other necessary accessories (such as embedded nuts for suspension) may also be included as needed.

[0034] <4> Concrete pouring Referring to Figure 5, the process of pouring concrete into the formwork 50 to shape the panel body 20, while simultaneously adhering and covering the front surface 21 of the panel body 20 with a transfer protection layer 30, will be described.

[0035] <4.1> Molding of the panel body A bonding reinforcement layer 31 is formed, and within 5 to 10 minutes, slurry-like concrete is poured into the formwork 50 to shape the panel body 20. The important point here is that the concrete is poured when the adhesion strengthening layer 31 of the transfer protection layer 30 is still softened (partially dry).

[0036] After applying the adhesive strengthening layer 31, it is preferable to pour the concrete at a temperature of 15°C or higher. The viscosity of the adhesive strengthening layer 31 at this time is adjusted to 20,000 to 500,000 mPa·s. Furthermore, although this is not the case at temperatures of around 5°C, the specified adhesive strength can be obtained by pouring concrete 60 to 120 minutes after applying the adhesive strengthening layer 31 (viscosity of approximately 190,000 to 960,000 mPa·s).

[0037] Concrete can be poured in one go, or it can be poured in multiple stages. An internal vibrator is used to create a dense structure in the concrete. The top surface of the panel body 20, which corresponds to the back surface 22 of the panel body 20, is smoothed using a trowel or similar tool.

[0038] <4.2> Integration of the panel body and the transfer protection layer By pouring slurry-like concrete into the formwork 50, the concrete comes into contact with the softened adhesion-reinforcing layer 31. Since both the concrete and the adhesive strengthening layer 31 are in an unhardened state, the adhesive strengthening layer 31 and the concrete structure penetrate each other and become one. In this invention, by using a common mold 50, the molding process of the panel body 20 and the coating process of the transfer protection layer 30 onto the panel body 20 are performed simultaneously. In other words, a wall material 10 is formed by covering the front surface 21 of the panel body 20 with a transfer protection layer 30 using a formwork 50.

[0039] <5> Health care After the concrete is poured, it is allowed to cure for a specified period of time. To prevent drying, sheet curing using a damp sheet or steam curing may be performed. During the curing period of the wall material 10, the hardening phenomenon of the transition protection layer 30 also progresses in parallel.

[0040] <6> demolding The explanation will be given with reference to Figures 2 and 6. After the prescribed curing period has elapsed, the end frame members 52 are dismantled, and the panel body 20 is lifted and demolded while maintaining its horizontal position. In this invention, when demolding the wall material 10 from the formwork 50, the transfer protection layer 30 is transferred from the formwork 50 side toward the panel body 20, as detailed below.

[0041] <6.1> Adhesion between formwork and transfer protection layer Before demolding, a transfer protection layer 30 is located between the horizontal formwork surface 51 and the front surface 21 of the panel body 20. Because the salt-blocking layer 32 is in between the horizontal formwork surface 51 and the transfer protection layer 30, no significant adhesive force is generated.

[0042] <6.2> Adhesion between the transfer protection layer and the panel body Before demolding, the transfer protection layer 30 and the front surface 21 of the panel body 20 are integrally joined via the adhesive strengthening layer 31. The bonding force between the displacement protection layer 30 and the front surface 21 of the panel body 20 is superior to the bonding force between the horizontal formwork surface 51 and the displacement protection layer 30.

[0043] <6.3> Transition of the Transitional Protective Layer Therefore, when a demolding force is applied to the wall material 10, the displacement protection layer 30 attached to the horizontal formwork surface 51 of the formwork 50 separates from the horizontal formwork surface 51, and the separated displacement protection layer 30 detaches from the formwork 50 together with the panel body 20. In other words, when the wall material 10 is demolded, the transfer of the transfer protection layer 30 from the formwork 50 side to the panel body 20 side is completed. Even if a peeling force is applied during demolding, the high adhesive strength prevents the transfer protection layer 30 from peeling off the front surface 21 of the panel body 20.

[0044] Thus, in this invention, by simply forming the displacement protection layer 30 in advance on the horizontal formwork surface 51 of the formwork 50, the front surface 21 of the panel body 20 can be covered with the displacement protection layer 30 without adding any special steps for covering the displacement protection layer 30. Therefore, the process of applying a salt-resistant resin to the front surface 21 of the panel body 20 after curing and completing the panel body 20, as in the conventional method, becomes completely unnecessary. Furthermore, in order to cover the front surface 21 of the panel body 20 with the transfer protection layer 30, workers are freed from the dangerous task of having to get under the panel body 20 suspended in the air to apply the resin, thereby ensuring worker safety.

[0045] <7> Characteristics of the transfer protection layer The main characteristics of the transfer protection layer 30 covering the front surface 21 of the panel body 20 will be described.

[0046] <7.1> Adhesion between the transfer protection layer and the panel body By pouring concrete while the adhesive strengthening layer 31 is still soft and unhardened, the adhesive strengthening layer 31 and the concrete structure penetrate each other, and the joint surface becomes completely and firmly integrated. As a result, the adhesion strength between the front surface 21 of the panel body 20 and the transfer protection layer 30 is significantly higher compared to a proportional wall material in which a resin is applied to the hardened panel body 20 afterward to form a transfer protection layer 30.

[0047] Therefore, by applying the wall material 10 to the reinforced earth retaining wall, peeling due to external factors can be effectively suppressed, and the durability of the displacement protection layer 30 is improved.

[0048] <7.2> Salt-blocking effect by the transition protective layer The front surface 21 of the panel body 20 is covered with a resin-based transfer protection layer 30 that does not allow for air or water permeability. As a result, the wall material 10 can reliably block rainwater and salt (chloride ions) from entering through the front surface 21 of the panel body 20. Therefore, even when the wall material 10 is applied when constructing a reinforced earth retaining wall in a coastal area, the deterrent effect against salt damage can be maintained over a long period of time. Furthermore, because the displacement protection layer 30 has high salt-blocking performance, it becomes unnecessary to use expensive resin-coated reinforcing bars as reinforcing bars inside the panel body 20, making it possible to manufacture the wall material 10 at a low cost. [Explanation of Symbols]

[0049] 10. Wall materials (precast wall materials) 20... Panel body 21...Front of the main panel 22...Back of the main panel 23. The peripheral surface of the panel body 25... Connecting fittings 30. Transition protective layer 31...Adhesion reinforcement layer 32... Salt barrier layer 33...Release layer 40...Retaining material 50... formwork 51...Horizontal formwork surface 52... Gable frame material

Claims

1. A wall material for a reinforced earth wall comprising a precast panel body having a front, back and circumferential surface, and a displacement protection layer covering the front surface of the panel body, The aforementioned transfer protection layer consists of a laminated structure comprising an adhesive strengthening layer bonded to and covering the front surface of the panel body, and a resin salt-shielding layer bonded and laminated to the adhesive strengthening layer. When concrete is poured into a formwork that has been coated with the transfer protection layer prior to the formwork surface to form the panel body, the adhesive strengthening layer is characterized by penetrating and fixing one side of the adhesive strengthening layer to the surface layer of the front surface of the panel body. Precast wall panels.

2. The precast wall material according to claim 1, characterized in that the salt-blocking layer of the transition protection layer is a resin coating having salt-blocking properties.

3. A method for manufacturing wall material for reinforced earth walls, comprising using formwork to simultaneously form a precast panel body having a front, back, and circumferential surface, and a displacement protection layer covering the front surface of the panel body, A formwork assembly step for forming a formwork space by positioning the formwork surface of the formwork that forms the front surface of the panel body horizontally, A step of attaching a transfer protection layer, which consists of a laminated structure of a resin salt-blocking layer formed on the upper surface of the horizontal formwork surface positioned horizontally on the formwork, and an adhesion-enhancing layer formed by adhering it to the upper surface of the salt-blocking layer, to the horizontal formwork surface, The process of arranging reinforcing bars within the formwork, The process involves pouring concrete into the formwork so as to form the panel body and adhere the transfer protection layer to cover the front surface of the panel body, The process includes the step of demolding the panel body after the concrete has hardened, The method is characterized by transferring the transfer protection layer from the mold side to the panel body side by utilizing the adhesive force between the front surface of the panel body and the transfer protection layer when demolding the panel body. Manufacturing method for precast wall panels.

4. A method for manufacturing a precast wall material according to claim 3, characterized in that a release agent is applied to the horizontal formwork surface of the formwork to form a release layer, and the transfer protection layer is attached to the upper surface of the release layer.

5. A method for manufacturing a precast wall material according to claim 3 or 4, characterized in that, in the step of attaching the displacement protection layer to the horizontal formwork surface, a resin-based salt-blocking paint is poured onto the horizontal formwork surface to form a salt-blocking layer.

6. The method for manufacturing a precast wall material according to claim 3, characterized in that, in the step of pouring the concrete, the concrete is poured when the adhesive strengthening layer of the displacement protection layer exposed on the horizontal formwork surface is in a softened state.

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