Soil-wood hybrid board, method for manufacturing soil-wood hybrid board, and soil-wood hybrid wall

Abstract

A soil-wood hybrid board (100) has: a lower surface (11) extending in a first plane (17); and an upper surface (12) that extending in a second plane (18)parallel to the first plane (17). The soil-wood hybrid board (100) comprises: a wood part (2) that forms the lower surface (11); and a soil part (3) that forms a part of the upper surface, is disposed on the wood part (2) so as to be in contact with the wood part (2), and includes a soil component. The soil part (3) has a first top surface (31) included in the upper surface (12). The wood part (2) comprises: a base part (21) that extends along the lower surface (11); a first protruding part (25) that protrudes from the base part (21) toward the upper surface (12), extends along at least a part of the outer edges (19) of the wood part (2), and has a second top surface (251) included in the upper surface (12); and second protruding parts (26A, 26B) that protrude from the base part (21) toward the upper surface (18), are spaced from the first protruding part (25) in a first direction (D1) in which the first protruding part (25) extends and in a second direction (D2) orthogonal to a protruding direction in which the first protruding part (25) protrudes, and have a third top surface (261) included in the upper surface (18).

Description

Civil-engineering hybrid board, method for manufacturing civil-engineering hybrid board, and civil-engineering hybrid wall

[0001] This disclosure relates to a civil-engineering hybrid board, a method for manufacturing a civil-engineering hybrid board, and a civil-engineering hybrid wall. This application claims priority to Japanese Application No. 2024-023717, filed February 20, 2024, and incorporates the entire disclosure of said Japanese application by reference.

[0002] A method for manufacturing an earthen wall by applying a soil composition containing soil components and water to the main surfaces of vertical boards is known (see, for example, Patent Document 1 below). The vertical boards described in Patent Document 1 extend along a vertical plane. The soil composition is applied so as to embed multiple horizontal members (laths) that contact the main surfaces of the vertical boards. The multiple horizontal members are arranged at intervals from one another in the vertical direction. Each of the multiple horizontal members extends in the horizontal direction. In the method described in Patent Document 1, the soil composition is applied to the vertical boards by a plasterer. This results in the manufacture (construction) of an earthen wall with a flat front surface. The earthen wall described in Patent Document 1 can be called an earthen-wood hybrid wall because it contains soil components and wood. A earthen-wood hybrid wall exhibits the physical properties of both earth and wood.

[0003] JP 2009-121105 A

[0004] There is a demand for a manufacturing method (construction) for civil-engineering hybrid walls that can be easily constructed even by amateurs who are not plasterers (craftsmen). For example, a method has been proposed in which multiple civil-engineering hybrid boards with upper and lower surfaces are stacked in the thickness direction. In the manufacturing of the proposed civil-engineering hybrid board, the lower surface is formed only from wood boards, and the upper surface is formed only from soil components (soil). In other words, the proposed plan uses a civil-engineering hybrid board that has a wooden board as the lower layer and an upper soil layer stacked on top of the lower layer. The wooden board of one civil-engineering hybrid board is stacked on top of the soil portion of another civil-engineering hybrid board.

[0005] In the above-mentioned trial plan, the mechanical strength of the soil portion is low, so the civil-engineering hybrid wall does not stand up on its own and is prone to collapse.

[0006] The present disclosure provides a civil-engineering hybrid board and a manufacturing method thereof that can easily manufacture a civil-engineering hybrid wall while being able to stand on its own, and a civil-engineering hybrid wall that is a civil-engineering hybrid yet able to stand on its own.

[0007] The presently disclosed civil-engineering hybrid board has a lower surface extending along a first plane and an upper surface extending along a second plane parallel to the first plane. The civil-engineering hybrid board includes a wood portion forming the lower surface, and a soil portion forming a part of the upper surface, the soil portion being disposed on the wood portion so as to contact the wood portion, the soil portion including a soil component. The soil portion has a first top surface included in the upper surface. The wood portion includes a base portion extending along the lower surface, a first protruding portion protruding from the base portion toward the upper surface, the first protruding portion extending along at least a part of the outer edge of the wood portion and having a second top surface included in the upper surface, and a second protruding portion protruding from the base portion toward the upper surface, the second protruding portion being spaced apart from the first protruding portion in a first direction in which the first protruding portion extends and a second direction perpendicular to the protruding direction in which the first protruding portion protrudes, the second protruding portion having a third top surface included in the upper surface.

[0008] The civil-engineering hybrid board and its manufacturing method of the present disclosure enable the easy manufacture of a mud wall, while also enabling the manufacture of a self-supporting mud wall. The civil-engineering hybrid wall of the present disclosure is self-supporting despite being a civil-engineering hybrid.

[0009] FIG. 1 is a perspective view of a civil-engineering hybrid board of the present disclosure. FIG. 2 is a cross-sectional view of the civil-engineering hybrid board shown in FIG. 1. FIG. 3 is a cross-sectional view of the civil-engineering hybrid board shown in FIG. 1. FIG. 4 is a perspective view showing step (1) in the manufacturing method of a civil-engineering hybrid board. FIG. 5 is a cross-sectional view taken along line XX in FIG. 4. FIG. 6 shows an embodiment in which a board is cut into two pieces in step (1) and used. FIG. 7 is a perspective view showing step (2) in the manufacturing method of a civil-engineering hybrid board. FIG. 8 is a front view of a civil-engineering hybrid wall of the present disclosure. FIG. 9 is an enlarged cross-sectional view of a portion of the civil-engineering hybrid wall shown in FIG. 8. FIG. 10 is an enlarged cross-sectional view of a portion of the civil-engineering hybrid wall shown in FIG. 9. FIG. 11 is a plan view of a modified civil-engineering hybrid board.

[0010] [Summary of the embodiment] The civil-engineering hybrid board of the present disclosure has a lower surface extending along a first plane and an upper surface extending along a second plane parallel to the first plane. The civil-engineering hybrid board includes a wood portion forming the lower surface, and a soil portion forming a part of the upper surface, the soil portion being disposed on the wood portion so as to contact the wood portion, the soil portion including a soil component. The soil portion has a first top surface included in the upper surface. The wood portion includes a base portion extending along the lower surface, a first protruding portion protruding from the base portion toward the upper surface, the first protruding portion extending along at least a part of the outer edge of the wood portion and having a second top surface included in the upper surface, and a second protruding portion protruding from the base portion toward the upper surface, the second protruding portion being spaced apart from the first protruding portion in a first direction in which the first protruding portion extends and a second direction perpendicular to the protruding direction in which the first protruding portion protrudes, the second protruding portion having a third top surface included in the upper surface.

[0011] In the civil-engineering hybrid board of the present disclosure, the mechanical strength of the wood portion is higher than that of the soil portion. By bringing the underside of another civil-engineering hybrid board into contact with the second top surface of the first protrusion and the third top surface of the second protrusion in the civil-engineering hybrid board of the present disclosure, a self-supporting civil-engineering hybrid wall can be easily manufactured.

[0012] In the above-described civil-engineering hybrid board, the first top surface, the second top surface, and the third top surface may be flush with each other. The first top surface, the second top surface, and the third top surface of the civil-engineering hybrid board of the present disclosure can be reliably brought into contact with the underside of another civil-engineering hybrid board. This allows for the production of a civil-engineering hybrid wall with reduced gaps.

[0013] In the above-described civil-engineering hybrid board, the second protrusion may protrude from a central portion of the base in the first direction. Compared to an embodiment in which the second protrusion protrudes from an end portion of the base in the first direction, the civil-engineering hybrid board of the present disclosure can improve the stability of its self-standing.

[0014] In the civil-engineering hybrid board, the second protrusions may be arranged in a plurality at intervals in the first direction. According to the civil-engineering hybrid board of the present disclosure, the length of the civil-engineering hybrid board in the first direction can be increased while the second protrusions improve the stability of the board.

[0015] In the civil-engineering hybrid board, the outer edge may have a first edge and a second edge spaced apart from the first edge in the second direction. The civil-engineering hybrid board may have a first side along the first edge, connecting the upper and lower surfaces, and a second side along the second edge, connecting the upper and lower surfaces. The base portion may have a first base side along the first edge, the first base side being included in the first side, and a second base side along the second edge, the second base side being included in the second side. In the civil-engineering hybrid board of the present disclosure, the first side includes the first base side, and the second side includes the second base side, thereby simplifying the configuration of the civil-engineering hybrid board.

[0016] In the above-described civil-engineering hybrid board, the first protruding portion may have a first protruding side surface along the first edge, and the first protruding side surface may be further included in the first side surface. The first base side surface and the first protruding side surface may be flush with each other. In the civil-engineering hybrid board of the present disclosure, the first base side surface and the first protruding side surface can be easily brought into contact with the vertical wall extending in the up-down direction. This allows for stable production of civil-engineering hybrid walls.

[0017] In the above-described civil-engineering hybrid board, the first side surface may consist only of a first base side surface and a first protruding side surface. The civil-engineering hybrid board of the present disclosure has a simple structure. The first side surface can be easily joined to the vertical wall.

[0018] In the civil-engineering hybrid board, the wood part may include a base part, a first board part disposed on the base part, the first board part having a length shorter than that of the base part in the second direction, and a second board part disposed on the first board part, the second board part having a length shorter than that of the first board part in the second direction. The first protruding part may include a first end part of the first board part and a second board part. The first protruding side surface may be formed from the first board part and the second board part. In the civil-engineering hybrid board disclosed herein, the first protruding part can be formed by stacking the second board part on the first end part of the first board part, so the posture of the first protruding part is stable. Furthermore, the first protruding side surface can be easily and reliably joined to the vertical board.

[0019] In the above-mentioned civil-engineering hybrid board, the second plate portion may be formed separately from the first plate portion. This civil-engineering hybrid board has a simple structure and can be easily manufactured.

[0020] In the above-described civil-engineering hybrid, the length of the base portion minus the length of the first plate portion in the second direction may be the same as the length of the second plate portion in the second direction. A plate having the same length in the second direction as the base portion may be cut into two pieces in the second direction, and one of the two cut pieces may be stacked on the base portion to serve as the first plate portion, and the other may be stacked on the first plate portion to serve as the second plate portion. Therefore, compared to an embodiment in which the first plate portion and the second plate portion are prepared separately, a civil-engineering hybrid plate can be produced that is environmentally friendly and inexpensive.

[0021] In the above-described civil-engineering hybrid board, the wood portion may further include a third board portion disposed on the first board portion, the third board portion disposed at a distance from the second board portion in the second direction. The second protruding portion may include a second end portion disposed at a distance from the first end portion in the second direction, and the third board portion. In the civil-engineering hybrid board of the present disclosure, the second protruding portion can be formed by stacking the third board portion on the first board portion, so the posture of the second protruding portion is stable. Therefore, the posture of another civil-engineering hybrid in contact with the second top surface and the third top surface can be stabilized.

[0022] In the above-described civil-engineering hybrid board, the second end may have a second side surface. The third board portion may have a third side surface. The second side surface and the third side surface may be flush. The civil-engineering hybrid board of the present disclosure has a simple configuration. The civil-engineering hybrid wall can be easily brought into contact with the flush second side surface and third side surface, thereby reducing the gap between the soil portion and the wood portion.

[0023] In the above-mentioned civil-engineering hybrid board, the third plate portion may be formed separately from the first plate portion. This civil-engineering hybrid board has a simple structure and can be easily manufactured.

[0024] In the above-described civil-engineering hybrid board, the length of the third plate portion in the second direction may be the same as the length of the second plate portion in the second direction. In the present disclosure, the second plate portion and the third plate portion having the same length in the second direction can be easily prepared. Therefore, a low-cost civil-engineering hybrid board can be obtained.

[0025] In the above-described civil-engineering hybrid board, the soil portion may have a soil side surface along the second edge, and may further include a soil side surface included in the second side surface. The second side surface may consist only of a second base side surface and a soil side surface. The civil-engineering hybrid board of the present disclosure has a simple structure.

[0026] In the above-mentioned civil-engineering hybrid board, the second base side surface and the soil side surface may be flush with each other. Flush second base side surface and the soil side surface have an excellent aesthetic appearance.

[0027] In the above-mentioned civil-engineering hybrid board, the soil side may be the main part of the second side. In the present disclosure, a civil-engineering hybrid wall can be manufactured that fully utilizes the physical properties of the soil part.

[0028] The method for manufacturing a civil-engineering hybrid board includes the steps of: (1) placing a wooden portion inside a formwork, the wooden portion including a base portion extending along a first plane; a first protruding portion protruding from the base portion, the first protruding portion extending along at least a portion of the outer edge of the wooden portion and having a second top surface; and a second protruding portion protruding from the base portion, the second protruding portion being spaced apart from the first protruding portion in a first direction in which the first protruding portion extends and a second direction perpendicular to the protruding direction in which the first protruding portion extends, the second protruding portion having a third top surface; and (2) placing a soil composition containing soil components and water on the base portion inside the formwork, and drying the soil composition to form a soil portion containing the soil components, the soil portion including the first top surface, from the soil composition. The civil-engineering hybrid board has a lower surface extending along the first plane, the lower surface formed from the base portion, and an upper surface extending along a second plane parallel to the first plane. In step (2), the soil portion is formed so that the first top surface, the second top surface, and the third top surface are included in the upper surface. The manufacturing method of the present disclosure makes it possible to easily manufacture a self-supporting civil-engineering hybrid wall.

[0029] In the method for manufacturing the civil-engineering hybrid board, the proportion of the soil component in the soil composition may be 60 mass% or more and 95 mass% or less. According to the manufacturing method of the present disclosure, construction of the civil-engineering hybrid wall is easy.

[0030] In the method for manufacturing the civil-engineering hybrid board, the soil composition may contain soil components, sand (excluding the soil components), a hardening material, water, and an organic material (excluding the soil components). The mixing ratio of sand to 100 parts by mass of the soil components may be 100 parts by mass or more and 200 parts by mass or less, the mixing ratio of the hardening material to 100 parts by mass of the soil components may be 10 parts by mass or more and 20 parts by mass or less, the mixing ratio of water to 100 parts by mass of the soil components may be 10 parts by mass or more and 50 parts by mass or less, and the mixing ratio of the organic material to 100 parts by mass of the soil components may be 1 part by mass or more and 10 parts by mass or less. The manufacturing method disclosed herein can improve the mechanical strength of the soil part.

[0031] In the method for manufacturing the civil-engineering hybrid wall, step (1) may use a wooden part including a first board portion disposed on a base portion, the first board portion having a length shorter than that of the base portion in the second direction, and a second board portion disposed on the first board portion, the second board portion having a length shorter than that of the first board portion in the second direction. In step (1), a board having the same length in the second direction as that of the base portion may be cut into two pieces in the second direction, and one of the two cut boards may be stacked on the base portion to serve as the first board portion, and the other may be stacked on the first board portion to serve as the second board portion. This manufacturing method reduces the environmental impact and enables the manufacture of civil-engineering hybrid walls at low cost.

[0032] The civil-engineering hybrid wall of the present disclosure comprises a first civil-engineering hybrid plate extending along a horizontal plane and a second civil-engineering hybrid plate disposed on the first civil-engineering hybrid plate. Each of the first civil-engineering hybrid plate and the second civil-engineering hybrid plate is the civil-engineering hybrid plate described above. The base portion of the second civil-engineering hybrid plate contacts at least a portion of the first top surface, at least a portion of the second top surface, and at least a portion of the third top surface of the first civil-engineering hybrid plate. Even when the first civil-engineering hybrid plate contacts the second civil-engineering hybrid plate, the first civil-engineering hybrid plate can ensure the first civil-engineering hybrid plate's ability to stand on its own. This allows for easy production of a self-supporting civil-engineering hybrid wall.

[0033] The civil-engineering hybrid wall of the present disclosure comprises a first civil-engineering hybrid plate extending along a horizontal plane, a second civil-engineering hybrid plate placed on the first civil-engineering hybrid plate, and vertical wooden plates extending along a vertical plane. Each of the first civil-engineering hybrid plate and the second civil-engineering hybrid plate is the civil-engineering hybrid plate described above. The base portion of the second civil-engineering hybrid plate contacts at least a portion of the first top surface, at least a portion of the second top surface, and at least a portion of the third top surface of the first civil-engineering hybrid plate. The first side surfaces of the first civil-engineering hybrid plate and the second civil-engineering hybrid plate are joined to the vertical plates using connecting members. The first civil-engineering hybrid plate can ensure its self-supporting ability even when it comes into contact with the second civil-engineering hybrid plate. Furthermore, because the first side surfaces of the first civil-engineering hybrid plate and the second civil-engineering hybrid plate are joined to the vertical plates using connecting members, the self-supporting ability of each of the first civil-engineering hybrid plate and the second civil-engineering hybrid plate can be improved. This makes it easier to manufacture a more self-supporting civil-engineering hybrid wall.

[0034] [Specific Example of the Embodiment] A specific example of a civil-engineering hybrid board according to the present disclosure will be described with reference to Figures 1 to 3. In the following drawings, the same or corresponding parts are designated by the same reference numerals, and their description will not be repeated. Figure 1 is a perspective view of a civil-engineering hybrid board according to the present disclosure. Figure 2 is a cross-sectional view of the civil-engineering hybrid board shown in Figure 1. Figure 2 is a cross-sectional view taken along line XX in Figure 1. Figure 3 is a cross-sectional view of the civil-engineering hybrid board shown in Figure 1. Figure 3 is a cross-sectional view taken along line YY in Figure 1.

[0035] [Shape of the civil-engineering hybrid board 1] The civil-engineering hybrid board 1 has a rectangular flat plate shape. The civil-engineering hybrid board 1 has a thickness. The civil-engineering hybrid board 1 has a lower surface 11, an upper surface 12, a first side surface 13, a second side surface 14, and both side surfaces 15 and 16.

[0036] The lower surface 11 extends along the first plane 17. The lower surface 11 is flat. The upper surface 12 extends along the second plane 18. The second plane 18 is disposed at a distance from the first plane 17 in the thickness direction D3 (vertical direction D4). The upper surface 12 is flat. The first side surface 13 connects the lower surface 11 and the upper surface 12. The first side surface 13 is flat. The second side surface 14 extends along the second direction D2 (described later). The second side surface 14 connects the lower surface 11 and the upper surface 12. The second side surface 14 is flat. The second side surface 14 is parallel to the first side surface 13.

[0037] The civil-engineering hybrid board 1 has an outer edge 19 when viewed in the thickness direction D3. The thickness direction D3 is the thickness direction of the civil-engineering hybrid board 1. The outer edges 19 of the lower surface 11 and the upper surface 12 are common to the outer edge 19 of the civil-engineering hybrid board 1. The outer edge 19 has a first side 191, a second side 192, and two sides 193 and 194. The first side 191 is along the first direction D1. The second side 192 is disposed at a distance from the first side 191 in the second direction D2. The second direction D2 is a direction perpendicular to the thickness direction D3 (vertical direction D4) of the civil-engineering hybrid board 1 and the first direction D1. The vertical direction D4 corresponds to the thickness direction D3. The vertical direction D4 is the up-down direction in the vertical direction. The second side 192 is parallel to the first side 191. Each of the two sides 193 and 194 connects the first side 191 and the second side 192. The first side surface 13 is aligned along the first side 191. The second side surface 14 is aligned along the second side 192. The second side surface 14 is parallel to the first side surface 13. Each of the two side surfaces 15 and 16 is aligned along the respective sides 193 and 194.

[0038] [Configuration of Civil-Engineering Hybrid Board 1] The civil-engineering hybrid board 1 includes a wood portion 2 and a soil portion 3. In the present disclosure, the civil-engineering hybrid board 1 is composed of only the wood portion 2 and the soil portion 3.

[0039] [Wood Part 2] The wood part 2 forms the entire lower surface 11. The wood part 2 forms part of the upper surface 12, the entire first side surface 13, part of the second side surface 14, and parts of both side surfaces 15 and 16. The wood part 2 includes the outer edge 19 described above. The wood part 2 is made of a wood material. The wood part 2 may be configured with a non-combustible material supported on the wood material. The wood part 2 may also be made of a main body made of a wood material and a surface layer (coating layer) made of a non-combustible material disposed on the surface of the main body. The wood part 2 includes a base part 21, a first plate part 22, a second plate part 23, and multiple third plate parts 24A and 24B.

[0040] [Base portion 21] The base portion 21 extends along the lower surface 11. Specifically, the base portion 21 is a flat plate. The base portion 21 has a rectangular shape. The base portion 21 includes end portions 2101 and 2102 and a central portion 2103. The end portions 2101 and 2102 are located at both ends of the base portion 21 in the first direction D1. The end portions 2101 and 2102 are arranged at an interval from each other in the first direction D1. The central portion 2103 is a portion between the end portions 2101 and 2102. The central portion 2103 includes the center (midpoint) of the base portion 21 in the first direction D1.

[0041] The base portion 21 has a base lower surface 211, a base upper surface 212, a first base side surface 213, a second base side surface 214, and two base side surfaces 215, 216. The base lower surface 211 forms the lower surface 11. In other words, the base lower surface 211 consists only of the lower surface 11. The base upper surface 212 is disposed above the base lower surface 211 with a gap therebetween. The first base side surface 213 is aligned with the first edge 191. The first base side surface 213 connects the base lower surface 211 and the base upper surface 212. The first base side surface 213 is included in the first side surface 13. The second base side surface 214 is aligned with the second edge 192. The second base side surface 214 is disposed with a gap therebetween and the first base side surface 213. The second base side surface 214 is included in the second side surface 14. The base side surfaces 215 and 216 are aligned along the sides 193 and 194, respectively.

[0042] [First Plate 22] The first plate 22 is disposed on the base 21. Specifically, the first plate 22 contacts the base upper surface 212. In this embodiment, the first plate 22 is a plate. The first plate 22 has a rectangular shape. The first plate 22 is disposed at the center and one end of the base upper surface 212 in the second direction D2. The first plate 22 includes a first end 2201 and a second end 2202. The first end 2201 is located at one end of the first plate 22 in the second direction D2. The first end 2201 is aligned with the first edge 191. The second end 2202 is disposed at a distance from the first end 2201 in the second direction D2. The second end 2202 is located at the other end of the first plate 22 in the second direction D2. The second end 2202 is located between the first base side surface 213 and the second base side surface 214 (at the middle portion) when viewed in the thickness direction D3.

[0043] The first plate portion 22 includes a first plate top surface 221, a first plate side surface 222, a second plate side surface 223, and two plate side surfaces 224, 225. The first plate top surface 221 is disposed above the base top surface 212 with a gap therebetween. The first plate top surface 221 is parallel to the base top surface 212. The first plate side surface 222 is aligned with the first edge 191 and is flush with the first base side surface 213. The first plate side surface 222 is included in the first side surface 13. The first plate side surface 222 is an end surface of the first end portion 2201. The second plate side surface 223 is disposed with a gap therebetween and the second plate side surface 223 is an end surface of the second end portion 2202. The two plate side surfaces 224, 225 are aligned with the two edges 193, 194, respectively.

[0044] The first plate portion 22 has a length L2 in the second direction D2 that is shorter than the length L1 of the base portion 21. The length L2 of the first plate portion 22 is the distance from the first plate side surface 222 to the second plate side surface 223. The length L1 of the base portion 21 is the distance from the first base side surface 213 to the second base side surface 214.

[0045] [Second plate portion 23] The second plate portion 23 is disposed on the first plate portion 22. The second plate portion 23 contacts the first plate upper surface 221. More specifically, the second plate portion 23 is disposed on the first plate upper surface 221 of the first end portion 2201. In this embodiment, the second plate portion 23 is a plate. The second plate portion 23 is formed separately from the first plate portion 22. The second plate portion 23 has a rectangular shape. The second plate portion 23 has a second plate upper surface 231, a third plate side surface 232, a fourth plate side surface 233, and both plate side surfaces 234, 235.

[0046] The second plate top surface 231 is disposed above the first plate top surface 221 with a gap therebetween. The second plate top surface 231 is parallel to the first plate top surface 221. The third plate side surface 232 is along the first edge 191. The third plate side surface 232 is flush with the first plate side surface 222. The first base side surface 213, the first plate side surface 222, and the third plate side surface 232 form the first side surface 13. In other words, the first side surface 13 consists only of the first base side surface 213, the first plate side surface 222, and the third plate side surface 232.

[0047] The fourth plate side surface 233 is disposed at a distance from the third plate side surface 232. When viewed in the thickness direction D3, the fourth plate side surface 233 is located between the first plate side surface 222 and the second plate side surface 223. The plate side surfaces 234, 235 are aligned along the edges 193, 194, respectively.

[0048] The second plate portion 23 has a length L3 in the second direction D2 that is shorter than the length L2 of the first plate portion 22. The length L3 of the second plate portion 23 in the second direction D2 is the length from the third plate side surface 232 to the fourth plate side surface 233. In the present disclosure, the length L3 of the second plate in the second direction D2 is the same as the length (L1-L2) obtained by subtracting the length L2 of the first plate portion 22 from the length L1 of the base portion 21 in the second direction D2.

[0049] [Third Plate Portions 24A, 24B] The plurality of third plate portions 24A, 24B are arranged on the first plate portion 22. Each of the plurality of third plate portions 24A, 24B contacts the first plate upper surface 221. Each of the plurality of third plate portions 24A, 24B is arranged on the first plate upper surface 221 of the second end portion 2202. The plurality of third plate portions 24A, 24B overlap the central portion 2103 when viewed in the thickness direction D3. The plurality of third plate portions 24A, 24B are arranged at intervals from each other in the first direction D1. In this embodiment, each of the plurality of third plate portions 24A, 24B is a plate. Each of the plurality of third plate portions 24A, 24B is formed separately from the first plate portion 22. Each of the plurality of third plate portions 24A, 24B has a third plate upper surface 241, a fifth plate side surface 242, a sixth plate side surface 243, and both plate side surfaces 244, 245.

[0050] The third plate top surface 241 is disposed above the first plate top surface 221 with a gap therebetween. The third plate top surface 241 is parallel to the first plate top surface 221. The fifth plate side surface 242 is flush with the second plate side surface 223. The fifth plate side surface 242 is located between the second base side surface 214 and the fourth plate side surface 233 when viewed in the thickness direction D3. The sixth plate side surface 243 is disposed with a gap therebetween in the second direction D2. The sixth plate side surface 243 is located between the fifth plate side surface 242 and the fourth plate side surface 233. The sixth plate side surface 243 faces the fourth plate side surface 233. The plate side surface 225 of the third plate portion 24A faces the plate side surface 224 of the third plate portion 24B.

[0051] The third plate portions 24A, 24B each have a length L4 in the second direction D2 that is shorter than the length of the first plate portion 22. The length L4 of the third plate portion 24 is the distance from the fifth plate side surface 242 to the sixth plate side surface 243. In the present disclosure, the length L4 of the third plate portion 24 in the second direction D2 is the same as the length L3 of the second plate portion 23 in the second direction D2.

[0052] [Soil section 3] The soil section 3 is placed on the wooden section 2 so as to contact the wooden section 2. The soil section 3 forms part of the upper surface 12, part of the second side surface 14, and parts of both side surfaces 15 and 16. The soil section 3 does not form the lower surface 11 or the first side surface 13. The soil section 3 contains soil components. The soil section 3 contacts areas of the base upper surface 212 where the first plate section 22, the second plate section 23, and the third plate sections 24A and 24B are not located, as well as the second plate side surface 223, the fourth plate side surface 233, the fifth plate side surface 242, the sixth plate side surface 243, and both plate side surfaces 244 and 245.

[0053] The soil portion 3 has a first top surface 31, a soil side surface 32, a second soil side surface 33, and both soil sides 34, 35. The first top surface 31 is the upper surface of the soil portion 3. The first top surface 31 is included in the upper surface 12 of the soil-engineering hybrid board 1. The first top surface 31 extends along the second plane 18. The first top surface 31 has a frame-like shape when viewed in the thickness direction D3. The first top surface 31 is flat.

[0054] The soil side surface 32 is along the second edge 192. The soil side surface 32 is further included in the second side surface 14. In other words, the second side surface 14 includes the second base side surface 214 and the soil side surface 32. In the present disclosure, the second side surface 14 consists only of the second base side surface 214 and the soil side surface 32. The soil side surface 32 is flat. The second base side surface 214 and the soil side surface 32 are flush with each other. In the present disclosure, the soil side surface 32 is the main portion of the second side surface 14. Specifically, the percentage of the area of ​​the soil side surface 32 in the area of ​​the second side surface 14 is 75% or more, preferably 90% or more. The upper limit of the percentage is not limited and may be, for example, 99%. If the percentage of the area of ​​the soil side surface 32 is equal to or greater than the above-mentioned lower limit, a soil-engineering hybrid wall 100 can be manufactured that fully demonstrates the physical properties of the soil portion 3.

[0055] The second soil side surface 33 faces the fourth plate side surface 233. The soil side surface 34 is flush with the plate side surface 224. The soil side surface is included in the side surface 15. The soil side surface 35 is flush with the soil side surface 225. The soil side surface 35 is included in the side surface 16.

[0056] [Details of Wooden Part 2] The wooden part 2 includes a first protruding part 25 and second protruding parts 26A and 26B.

[0057] [First protrusion 25] The first protrusion 25 includes a first end 2201 of the first plate portion 22 and the second plate portion 23. In the present disclosure, the first protrusion 25 consists only of the first end 2201 of the first plate portion 22 and the second plate portion 23. The first protrusion 25 extends along a first side 191, which is an example of a portion of the outer edge 19 of the wood portion 2. The first protrusion 25 protrudes from the base portion 21 toward the upper surface 12. The first protrusion 25 extends from the base upper surface 212 to the upper surface 12. The protrusion direction of the first protrusion 25 corresponds to the thickness direction D3 (up-down direction D4) of the civil-engineering hybrid board 1. The first protrusion 25 has a second top surface 251 and a first protruding side surface 252.

[0058] The second top surface 251 consists only of the second plate upper surface 231. In other words, the second top surface 251 is the second plate upper surface 231. The second top surface 251 is flat. The second top surface 251 is parallel to the base upper surface 212. The second top surface 251 is included in the upper surface 12. The first top surface 31 and the second top surface 251 are flush with each other.

[0059] The first protruding side surface 252 includes a first plate side surface 222 and a third plate side surface 232. In the present disclosure, the first protruding side surface 252 consists only of the first plate side surface 222 and the third plate side surface 232. The first protruding side surface 252 is along the first edge 191. The first protruding side surface 252 is further included in the first side surface 13. In other words, the first side surface 13 has a first base side surface 213 and a first protruding side surface 252. In the present disclosure, the first side surface 13 consists only of the first base side surface 213 and the first protruding side surface 252. The first base side surface 213 and the first protruding side surface 252 are flush with each other.

[0060] [Second protrusions 26A, 26B] The second protrusions 26A, 26B include a second end 2202 of the first plate portion 22 and third plate portions 24A, 24B. Specifically, the second protrusion 26A includes the third plate portion 24A and a portion of the second end 2202 that overlaps with the third plate portion 24A. The second protrusion 26B includes the third plate portion 24B and a portion of the second end 2202 that overlaps with the third plate portion 24B. Each of the second protrusions 26A, 26B protrudes from the base portion 21 toward the upper surface 12. Each of the second protrusions 26A, 26B extends from the base upper surface 212 to the upper surface 12. Each of the multiple second protrusions 26A, 26B is arranged at an interval from the first protrusion 25 in the second direction D2. Each of the second protrusions 26A, 26B overlaps with the first protrusion 25 when viewed in the second direction D2. Each of the second protrusions 26A, 26B protrudes from the central portion 2103 of the base portion 21 in the first direction D1. The second protrusions 26A, 26B are arranged at intervals from each other in the first direction D1. Each of the second protrusions 26A, 26B has a third top surface 261 and a second protruding side surface 262.

[0061] The third top surface 261 consists only of the third plate upper surface 241. In other words, the third top surface 261 is the third plate upper surface 241. The third top surface 261 is flat. The third top surface 261 is parallel to the base upper surface 212. The third top surface 261 is included in the upper surface 12. The first top surface 31, the second top surface 251, and the third top surface 261 are flush with each other. The first top surface 31, the second top surface 251, and the third top surface 261 are continuous along the second plane 18. In the present disclosure, the upper surface 12 consists only of the first top surface 31, the second top surface 251, and the third top surface 261.

[0062] The second protruding side surface 262 includes the second plate side surface 223 and the fifth plate side surface 242. The second protruding side surface 262 is composed only of the second plate side surface 223 and the fifth plate side surface 242. The second protruding side surface 262 is located between the first protruding side surface 252 and the second side surface 14 when viewed in the thickness direction D3.

[0063] [Size of the civil-engineering hybrid board 1] The thickness of the civil-engineering hybrid board 1 is 3 cm or more and 8 cm or less. The length of the civil-engineering hybrid board 1 in the first direction D1 is 30 cm or more and 180 cm or less. The length L1 of the civil-engineering hybrid board 1 in the second direction D2 is 5 cm or more, or even 8 cm or more, and 20 cm or less, or even 18 cm or less. The length L3 of the first protrusion 25 in the protrusion direction is 2 cm or more and 7 cm or less. The length of the first protrusion 25 in the second direction D2 is 2 cm or more and 5 cm or less. The length L4 of each of the second protrusions 26A, 26B in the second direction D2 is 2 cm or more and 5 cm or less. The length of each of the second protrusions 26A, 26B in the first direction is 5 cm or more and 180 cm or less. The distance between the second protrusions 26A, 26B in the first direction is more than 0 cm and 50 cm or less. The distance between the first protrusion 25 and the second protrusion 26A in the second direction D2 is greater than 0 cm and is not greater than 10 cm. The length L2 of the first plate portion 22 in the second direction D2 is not less than 3 cm, or even not less than 6 cm and not greater than 18 cm.

[0064] Specific examples of the manufacturing method of the civil-engineering hybrid board 1 of the present disclosure will be described with reference to Figures 4 to 7. Figure 4 is a perspective view showing step (1) in the manufacturing method of the civil-engineering hybrid board. Figure 5 is a cross-sectional view taken along line XX in Figure 4. Figure 6 shows an embodiment in which the board is cut into two pieces in step (1) and then used. Figure 7 is a perspective view showing step (2) in the manufacturing method of the civil-engineering hybrid board.

[0065] The manufacturing method of the civil-engineering hybrid board 1 includes steps (1) and (2). In this manufacturing method, steps (1) and (2) are carried out in this order.

[0066] [Step (1)] As shown in Figures 4 and 5, in step (1), the wooden part 2 is placed inside a formwork 4. The formwork 4 has a U-shape when viewed in the thickness direction D3. The formwork 4 includes a first formwork plate 41, a second formwork plate 42, and a third formwork plate 43. The second formwork plate 42 faces the first formwork plate 41. The second formwork plate 42 is positioned with a gap between it and the first formwork plate 41. The second formwork plate 42 is parallel to the first formwork plate 41. The third formwork plate 43 connects one end of the first formwork plate 41 and one end of the second formwork plate 42.

[0067] The wooden part 2 includes a base part 21, a first protruding part 25, and a plurality of second protruding parts 26A, 26B. The base part 21 extends along a first plane 17. The first protruding part 25 protrudes from the base part 21. The first protruding part 25 extends along a first side 191, which is an example of a portion of the outer edge 19 of the wooden part 2. The first protruding part 25 has a second top surface 251. Each of the plurality of second protruding parts 26A, 26B protrudes from the base part 21. Each of the plurality of second protruding parts 26A, 26B is disposed at an interval from the first protruding part 25 in the second direction D2. Each of the plurality of second protruding parts 26A, 26B has a third top surface 261.

[0068] In step (1), the wooden part 2 is placed between the first mold plate 41 and the second mold plate 42. The second base side surface 214 of the base part 21 and both base side surfaces 215, 216 (see FIG. 3 ) are brought into contact with the inner surface of the formwork 4. Specifically, the second base side surface 214 is brought into contact with the third mold plate 43. The both base side surfaces 215, 216 are brought into contact with the first mold plate 41 and the second mold plate 42, respectively.

[0069] As shown in Figure 6, step (1) uses a wooden piece 2 including a first board portion 22, a second board portion 23, and third board portions 24A and 24B. In step (1), a board 20 having a length L0 equal to the length L1 of the first board portion 22 is cut into two pieces in the second direction D2, as shown by the thick chain line. One piece 201 of the two cut boards 201 and 202 is stacked on the base portion 21 to serve as the first board portion 22. The other piece 202 is stacked on a first end portion 2201 of the first board portion 22 to serve as the second board portion 23. Furthermore, another board 202 is cut into multiple pieces in the first direction D1, and these pieces are stacked on the second end portion 2202 of the third board portion 24 to serve as the third board portions 24A and 24B.

[0070] [Step (2)] As shown in Figure 7, in step (2), a soil composition containing soil components and water is placed inside the formwork 4 and on the base portion 21. In step (2), the soil portion 3 is formed from the soil composition. The soil portion 3 includes a first top surface 31. In step (2), the soil portion 3 is formed by drying the soil composition. In step (2), the soil portion 3 is formed so that the first top surface 31, the second top surface 251, and the third top surface 261 are included in the upper surface 12. Specifically, the soil composition is placed (applied) inside the formwork 4 so that the upper surface of the soil composition and the upper surface of the formwork 4 are flush with each other.

[0071] The soil composition contains soil components and water. Examples of the soil components include construction waste soil. The soil components are components excluding sand, which will be described later. The proportion of the soil components in the soil composition is 60% by mass or more, or even 70% by mass or more, and 95% by mass or less, or even 90% by mass or less. The proportion of water in the soil composition is the remainder of the proportions of the soil components described above.

[0072] In addition to soil components and water, the soil composition may further contain sand (excluding soil components), a hardening agent, and organic materials (excluding soil components). In other words, the soil composition may contain soil components, sand (excluding soil components), a hardening agent, water, and organic materials (excluding soil components). The sand is construction waste soil having a diameter of 2 mm or less and a diameter of 0.0625 mm or more. The sand is an inorganic particle of construction waste soil. An example of a hardening agent is magnesium oxide. An example of an organic material is rice straw, straw, and sawdust. The mixing ratio of sand per 100 parts by mass of soil components is 100 parts by mass or more and 200 parts by mass or less. The mixing ratio of hardening agent per 100 parts by mass of soil components is 10 parts by mass or more, 20 parts by mass or less, or even 15 parts by mass or less. The mixing ratio of water to 100 parts by mass of soil components is 10 parts by mass or more, further 15 parts by mass or more, and 50 parts by mass or less, further 30 parts by mass or less. The mixing ratio of organic material to 100 parts by mass of soil components is 1 part by mass or more and 10 parts by mass or less.

[0073] The drying time of the soil composition is 0.5 days or more and 10 days or less, preferably 1 day or more and 7 days or less. The drying temperature is room temperature (20°C to 30°C). During drying, it is sufficient if some or all of the water is removed from the soil composition.

[0074] As shown in Fig. 1, after the soil composition has dried, the formwork 4 is removed. Alternatively, the formwork 4 may be removed before or during the drying of the soil composition. In this way, a civil-engineering hybrid board 1 is produced. The formwork 4 is reused.

[0075] Specific examples of civil-engineering hybrid walls according to the present disclosure will be described with reference to Figures 8 to 10. Figure 8 is a front view of the civil-engineering hybrid wall according to the present disclosure. Figure 9 is an enlarged cross-sectional view of a portion of the civil-engineering hybrid wall shown in Figure 8. Figure 9 is a cross-sectional view taken along line XX in Figure 8. Figure 10 is an enlarged cross-sectional view of a portion of the civil-engineering hybrid wall shown in Figure 9. Figure 10 is a cross-sectional view taken along line YY in Figure 9.

[0076] The civil-engineering hybrid wall 100 comprises a first civil-engineering hybrid plate 101, a second civil-engineering hybrid plate 102, and a vertical plate 103.

[0077] The first civil-engineering hybrid plate 101 extends along a horizontal plane HP. The second civil-engineering hybrid plate 102 is disposed on top of the first civil-engineering hybrid plate 101. The first civil-engineering hybrid plate 101 and the second civil-engineering hybrid plate 102 are each the civil-engineering hybrid plate 1 described above. The first civil-engineering hybrid plate 101 and the second civil-engineering hybrid plate 102 are disposed such that the second direction D2 of the civil-engineering hybrid plate 1 corresponds to the front-to-rear direction D5 of the civil-engineering hybrid wall 100, and the first direction D1 of the civil-engineering hybrid plate 1 corresponds to the left-to-right direction D6 of the civil-engineering hybrid wall 100. Specifically, in the civil-engineering hybrid wall 100, the first civil-engineering hybrid plate 101 and the second civil-engineering hybrid plate 102 are disposed such that the second side surface 14 of the civil-engineering hybrid plate 1 faces forward F (front) and the first side surface 13 faces backward R (rear).

[0078] The base portion 21 (lower surface 11) of the second civil-engineering hybrid board 102 contacts a portion of the first top surface 31, a portion of the second top surface 251, and the third top surface 261 of the second protruding portion 26B of the first civil-engineering hybrid board 101. In the present disclosure, the base portion 21 of the second civil-engineering hybrid board 102 does not contact the third top surface 261 of the second protruding portion 26A. Note that the base portion 21 of the second civil-engineering hybrid board 102 may contact the entire first top surface 31 of the first civil-engineering hybrid board 101, the entire second top surface 251, or the third top surface 261 of the second protruding portion 26A.

[0079] The vertical board 103 is aligned along the vertical plane VP. In the present disclosure, the vertical board 103 extends along the vertical plane VP. The vertical board 103 is made of wood. The first side surface 13 of each of the first civil-engineering hybrid board 101 and the second civil-engineering hybrid board 102 is joined to the vertical board 103 using a joining member 105. The joining member 105 is a nail. The joining member 105 penetrates the first protrusion 25. The tip of the joining member 105 reaches the interior of the vertical board 103.

[0080] [Modification] A modification of the civil-engineering hybrid board 1 will be described with reference to Fig. 11. Fig. 11 is a plan view of the modified civil-engineering hybrid board.

[0081] The civil-engineering hybrid board 1 may include one second protrusion 26A. Although not shown, the civil-engineering hybrid board 1 may include three or more second protrusions 26A.

[0082] Although not shown, the first top surface 31, the second top surface 251, and the third top surface 261 do not have to be flush. For example, the first top surface 31 may be located near the lower side or near the upper side of the second top surface 251 and the third top surface 261. For example, due to shrinkage caused by drying of the soil composition as described above, the first top surface 31 of the soil portion 3 may be located lower than the second top surface 251 and the third top surface 261. For example, by placing an excess amount of soil composition in the formwork 4, the first top surface 31 of the soil portion 3 may be located higher than the second top surface 251 and the third top surface 261. Preferably, the first top surface 31, the second top surface 251, and the third top surface 261 are flush.

[0083] The first protrusion 25 may be formed from a single plate. The second plate 23 may be formed integrally with the first plate 22. In this modification, the first plate 22 and the second plate 23 may have an L-shape when viewed in the second direction D2.

[0084] The second protruding portion 26A may be formed from a single plate. Each of the plurality of third plate portions 24A, 24B may be formed integrally with the first plate portion 22.

[0085] The first protrusion 25 may extend along the first side 191 and the second side 192. The first protrusion 25 may extend along the first side 191, the second side 192, and the side 193. The first protrusion 25 may extend along the entire outer edge 19.

[0086] The vertical plate 103 may have a columnar shape extending along the vertical plane VP.

[0087] The above-described embodiments and modifications are merely examples, and the present invention is not limited to these details as long as the features of the invention are not impaired. Furthermore, although various embodiments and modifications have been described above, the present invention is not limited to these details. Other aspects that can be considered within the scope of the technical idea of ​​the present invention are also included within the scope of the present invention.

[0088] 1 Civil-engineering hybrid board, 11 Lower surface, 12 Upper surface, 13 First side, 14 Second side, 15, 16 Both sides, 17 First plane, 18 Second plane, 19 Outer edge, 191 First edge, 192 Second edge, 193, 194 Both sides, 2 Wood part, 20, 201, 202 Board, 21 Base part, 2101, 2102 Both ends, 2103 Central part, 211 Base lower surface, 212 Base upper surface, 213 First base side, 214 Second base side, 215, 216 Both base side, 219 Central part, 22 First board part, 2201 First end, 2202 Second end, 221 First board upper surface, 222 First board side, 223 Second board side, 224, 225 Both board side, 23 2nd plate portion, 231 2nd plate top surface, 232 3rd plate side surface, 233 4th plate side surface, 234, 235 Both plate side surfaces, 24, 24A, 24B 3rd plate portion, 241 3rd plate top surface, 242 5th plate side surface, 243 6th plate side surface, 244, 245 Both plate side surfaces, 25 1st protrusion, 251 2nd top surface, 252 First protruding side surface, 26A, 26B Second protruding part, 261 Third top surface, 262 Second protruding side surface, 3 Soil part, 31 First top surface, 32 Soil side, 33 Second soil side, 34, 35 Both soil sides, 4 Formwork, 41 First template, 42 Second template, 43 Third template, 100 Civil-wood hybrid wall, 101 1st civil-engineering hybrid board, 102 2nd civil-engineering hybrid board, 103 Vertical plate, 105 joint member, D1 first direction, D2 second direction, D3 thickness direction, D4 up-down direction, D5 front-back direction, D6 left-right direction, HP horizontal plane, VP vertical plane.

Claims

1. A civil-engineering hybrid board having a lower surface extending along a first plane and an upper surface extending along a second plane parallel to the first plane, comprising: a wood portion forming the lower surface; and a soil portion forming part of the upper surface, the soil portion being placed on the wood portion so as to be in contact with the wood portion, the soil portion including a soil component, wherein the soil portion has a first top surface included in the upper surface, and the wood portion comprising: a base portion extending along the lower surface; a first protruding portion protruding from the base portion toward the upper surface, the first protruding portion extending along at least a part of the outer edge of the wood portion, the first protruding portion having a second top surface included in the upper surface; and a second protruding portion protruding from the base portion toward the upper surface, the second protruding portion being spaced apart from the first protruding portion in a first direction in which the first protruding portion extends and a second direction perpendicular to the protruding direction in which the first protruding portion protrudes, the second protruding portion having a third top surface included in the upper surface.

2. The civil-engineering hybrid board of claim 1, wherein said first top surface, said second top surface, and said third top surface are flush.

3. The civil-engineering hybrid board according to claim 1, wherein the second protrusion protrudes from a central portion of the base portion in the first direction.

4. The civil-engineering hybrid board according to claim 1, wherein a plurality of said second protrusions are arranged at intervals from each other in said first direction.

5. The civil-engineering hybrid board according to claim 1, wherein the outer edge has: a first side; and a second side arranged at a distance from the first side in the second direction; the civil-engineering hybrid board has: a first side surface along the first side, connecting the upper surface and the lower surface; and a second side surface along the second side, connecting the upper surface and the lower surface; and the base portion has: a first base side surface along the first side, the first base side surface being included in the first side surface; and a second base side surface along the second side, being included in the second side surface.

6. The civil-engineering hybrid board according to claim 5, wherein the first protruding portion has a first protruding side surface along the first edge, the first protruding side surface being further included in the first side surface, and the first base side surface and the first protruding side surface are flush with each other.

7. The civil-engineering hybrid board of claim 6, wherein said first side surface consists solely of said first base side surface and said first protruding side surface.

8. The civil-engineering hybrid board according to claim 7, wherein the wooden part comprises: the base part; a first board part arranged on the base part, the first board part having a length in the second direction shorter than that of the base part; and a second board part arranged on the first board part, the second board part having a length in the second direction shorter than that of the first board part; the first protruding part comprises a first end of the first board part and the second board part; and the first protruding side surface is formed by the first board part and the second board part.

9. The civil-engineering hybrid plate according to claim 8, wherein the second plate portion is formed separately from the first plate portion.

10. The civil-engineering hybrid board of claim 9, wherein the length of the base portion minus the length of the first plate portion in the second direction is the same as the length of the second plate portion in the second direction.

11. The civil-engineering hybrid board according to claim 10, wherein the wood portion further includes a third board portion disposed on top of the first board portion and spaced apart from the second board portion in the second direction, and the second protruding portion includes a second end portion of the first board portion spaced apart from the first end portion, and the third board portion.

12. The civil-engineering hybrid board according to claim 11, wherein the second end portion has a second side surface, the third board portion has a third side surface, and the second side surface and the third side surface are flush with each other.

13. The civil-engineering hybrid plate according to claim 11, wherein the third plate portion is formed separately from the first plate portion.

14. The civil-engineering hybrid board according to claim 13, wherein the length of the third plate portion in the second direction is the same as the length of the second plate portion in the second direction.

15. The civil-engineering hybrid board according to claim 5, wherein the soil portion has a soil side surface along the second edge and included in the second side surface, and the second side surface consists only of the second base side surface and the soil side surface.

16. The earth-engineering hybrid board of claim 15, wherein the second base side and the earth side are flush.

17. A soil-engineering hybrid board according to claim 15 or claim 16, wherein the soil side is the main portion of the second side.

18. A method for manufacturing a civil-engineering hybrid board, comprising: a step (1) of placing a wooden portion inside a formwork, the wooden portion including: a base portion extending along a first plane; a first protruding portion protruding from the base portion, the first protruding portion extending along at least a part of the outer edge of the wooden portion, the first protruding portion having a second top surface; and a second protruding portion protruding from the base portion, the second protruding portion being spaced apart from the first protruding portion in a first direction in which the first protruding portion extends and in a second direction perpendicular to the protruding direction in which the first protruding portion protrudes, the second protruding portion having a third top surface; and a step (2) of placing a soil composition containing soil components and water on the base portion inside the formwork, and drying the soil composition to form a soil portion containing the soil components, the soil portion having a first top surface, from the soil composition. The civil-engineering hybrid board has a lower surface extending along the first plane, the lower surface being formed from the base portion, and an upper surface extending along a second plane parallel to the first plane, and in step (2), the civil portion is formed so that the first top surface, the second top surface, and the third top surface are included in the upper surface.

19. A method for producing a civil-engineering hybrid board according to claim 18, wherein the proportion of the soil component in the soil composition is 60% by mass or more and 95% by mass or less.

20. A method for manufacturing a civil-engineering hybrid board as described in claim 18 or claim 19, wherein the soil composition contains the soil components, sand (excluding the soil components), hardening material, the water, and organic material (excluding the soil components), and the mixing ratio of the sand to 100 parts by mass of the soil components is 100 parts by mass or more and 200 parts by mass or less, the mixing ratio of the hardening material to 100 parts by mass of the soil components is 10 parts by mass or more and 20 parts by mass or less, the mixing ratio of the water to 100 parts by mass of the soil components is 10 parts by mass or more and 50 parts by mass or less, and the mixing ratio of the organic material to 100 parts by mass of the soil components is 1 part by mass or more and 10 parts by mass or less.

21. A method for manufacturing a civil-engineering hybrid board as described in claim 17 or 18, wherein in step (1), the wooden part includes a first board part placed on the base part, the first board part having a length in the second direction shorter than that of the base part, and a second board part placed on the first board part, the second board part having a length in the second direction shorter than that of the first board part, and in step (1), a board having the same length in the second direction as that of the base part is cut into two pieces in the second direction, and one of the two cut boards is stacked on the base part to be used as the first board part, and the other is stacked on the first board part to be used as the second board part.

22. A civil-engineering hybrid wall comprising: a first civil-engineering hybrid plate extending along a horizontal plane; and a second civil-engineering hybrid plate placed on the first civil-engineering hybrid plate, wherein each of the first civil-engineering hybrid plate and the second civil-engineering hybrid plate is a civil-engineering hybrid plate as defined in any one of claims 1 to 17, and wherein the base portion of the second civil-engineering hybrid plate contacts at least a portion of the first top surface, at least a portion of the second top surface, and at least a portion of the third top surface of the first civil-engineering hybrid plate.

23. A civil-engineering hybrid wall comprising: a first civil-engineering hybrid plate extending along a horizontal plane; a second civil-engineering hybrid plate placed on the first civil-engineering hybrid plate; and vertical wooden plates extending along a vertical plane, wherein each of the first civil-engineering hybrid plate and the second civil-engineering hybrid plate is the civil-engineering hybrid plate defined in claim 6; the base portion of the second civil-engineering hybrid plate contacts at least a portion of the first top surface, at least a portion of the second top surface, and at least a portion of the third top surface of the first civil-engineering hybrid plate; and a first side surface of each of the first civil-engineering hybrid plate and the second civil-engineering hybrid plate is joined to the vertical plates using a joining member.

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