Paving material and construction method for paving material

Abstract

The present invention provides a paving material capable of suitably suppressing warpage.　A paving material 1 includes a body portion 10 having a paired front surface F1 and rear surface F2. The body portion 10 is provided with at least one rear-side recess 12 extending in the length direction and open on the lower side in the thickness direction. The rear-side recess 12 has at least one engagement recess 13 having an inner peripheral surface 12b formed so as to sandwich, in the thickness direction T, at least one end of the ends of an internal space 12a in the width direction W.

Description

Pavement materials and application methods for pavement materials

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to paving materials and methods for applying paving materials.

[0002] Conventionally, the surface of the ground or the like has been covered with paving material. For example, Patent Document 1 discloses a mat to be laid on the ground or the like. The mat includes a base, a rigid plate laminated on the base, and a cushion layer laminated on the rigid plate. The rigid plate is provided with elongated ribs. The ribs are made of a hard material. This makes it possible to prevent the mat from warping in the longitudinal direction of the ribs.

[0003] JP 2009-275374 A

[0004] However, depending on the material of the ribs, the ribs may expand or contract due to heat, water absorption, etc. In this case, there is a risk that the rug may warp.

[0005] An object of the present disclosure is to provide a paving material and a method for constructing the paving material that can effectively suppress warping.

[0006] The paving material of the present disclosure comprises a main body portion having a mating front and back surface, and the direction perpendicular to the back surface is defined as the thickness direction, the direction in the thickness direction when looking at the front surface from the back surface is defined as the upper thickness direction, the direction in the thickness direction when looking at the back surface from the front surface is defined as the lower thickness direction, one direction perpendicular to the thickness direction is defined as the length direction, and the direction perpendicular to the thickness direction and the length direction is defined as the width direction.The main body portion is provided with at least one back recess extending in the length direction and opening to the lower side in the thickness direction, and the back recess has at least one engaging recess having an inner surface formed to sandwich at least one of the widthwise ends of the internal space in the thickness direction.

[0007] The method for applying the paving material of the present disclosure comprises the steps of placing a base on the ground, placing a first adhesive on the base, placing a second adhesive on the back surface of the paving material of the present disclosure, and joining the first adhesive and the second adhesive.

[0008] Fig. 1 is a perspective view of a paving material of a first embodiment. Fig. 2 is a front view of a paving material of a first embodiment. Fig. 3 is a process diagram showing a method for applying a paving material. Fig. 4 is a schematic diagram for explaining a method for applying a paving material. Fig. 5 is a front view of a paving material of a second embodiment. Fig. 6 is a front view of a paving material of a third embodiment. Fig. 7 is a front view of a paving material of a fourth embodiment. Fig. 8 is a front view of a paving material of a fifth embodiment.

[0009] First Embodiment A first embodiment of the present disclosure will now be described with reference to the drawings. As shown in Figures 1 and 2, a paving material 1 includes a main body 10 having a pair of front and back surfaces F1 and F2. The paving material 1 is used with the back surface F2 facing the ground G, for example, with an adhesive such as mortar in contact with the back surface F2. The front surface F1 and the back surface F2 each have a rectangular planar shape, more specifically, a square planar shape.

[0010] In this specification, the direction perpendicular to the back surface F2 is referred to as the "thickness direction T." Of the directions in the thickness direction T, the direction when looking from the back surface F2 to the front surface F1 is referred to as the "upper thickness direction T1," and the direction in the thickness direction T when looking from the front surface F1 to the back surface F2 is referred to as the "lower thickness direction T2." Of the directions perpendicular to the thickness direction T, one direction is referred to as the "length direction L." The direction perpendicular to the thickness direction T and the length direction L is referred to as the "width direction W." Of the directions in the width direction W, one direction is referred to as the "one width direction side W1," and the other direction is referred to as the "other width direction side W2."

[0011] The main body 10 is formed as a plate overall, for example, a square plate when viewed in the thickness direction T. Each side of the front surface F1 and each side of the back surface F2 extend parallel to either the length direction L or the width direction W. When the paving material 1 is in use, the thickness direction T coincides with the direction perpendicular to the ground G. The paving material 1 is formed, for example, as a single piece. The material of the paving material 1 will be described later.

[0012] The thickness direction T dimension of the paving material 1 is, for example, 20 mm. The thickness direction T dimension of the paving material 1 is preferably within the range of 5 mm to 60 mm. The length direction L dimension of the paving material 1 is, for example, 190 mm. The length direction L dimension of the paving material 1 is preferably within the range of 100 mm to 2000 mm. The width direction W dimension of the paving material 1 is, for example, 190 mm. The width direction W dimension of the paving material 1 is preferably within the range of 100 mm to 800 mm.

[0013] As shown in Fig. 2, the main body 10 is provided with at least one back-side recess 12 that extends in the length direction L and opens to the lower side T2 in the thickness direction. The back-side recess 12 is recessed from the back surface F2. The back-side recess 12 has a groove shape that extends in the length direction L. The back-side recess 12 penetrates the main body 10 in the length direction L.

[0014] The main body 10 is provided with a plurality of rear recesses 12 spaced apart in the width direction W; specifically, five rear recesses 12 are provided. The rear recesses 12 are arranged, for example, at equal intervals. The central rear recess 12 among the rear recesses 12 is arranged in the center of the main body 10 in the width direction W. The rear recesses 12 at both ends in the width direction W among the rear recesses 12 are each spaced apart from the end of the main body 10 on the other width direction side W2.

[0015] The internal space 12a of each rear recess 12 has an isosceles trapezoidal shape in which the width W dimension increases toward the upper side T1 in the thickness direction when viewed in the length direction L. Each rear recess 12 is a dovetail groove. The open end of each rear recess 12 is chamfered.

[0016] The back side recess 12 has an inner surface 12b formed to sandwich at least one of the ends (more specifically, both ends) of the internal space 12a of the back side recess 12 in the width direction W in the thickness direction T.

[0017] More specifically, when viewed in cross section in the longitudinal direction L, the inner surface 12b of the back recess 12 has a straight portion (referred to as the "bottom portion 12ba") extending parallel to the width direction W, a straight portion (referred to as the "first oblique portion 12bb") extending from the end of the bottom portion 12ba on one width side W1 toward the lower thickness side T2 and the other width side W2, and a straight portion (referred to as the "second oblique portion 12bc") extending from the end of the bottom portion 12ba on the other width side W2 toward the lower thickness side T2 and the one width side W1 (see Figure 2). The inner peripheral surface 12b is formed such that the bottom portion 12ba and the first oblique portion 12bb sandwich the end of the internal space 12a on one widthwise side W1 in the thickness direction T, and the bottom portion 12ba and the second oblique portion 12bc sandwich the end of the internal space 12a on the other widthwise side W2. The end of the internal space 12a on the one widthwise side W1 is, for example, the region of the internal space 12a closest to the one widthwise side W1. The end of the internal space 12a on the other widthwise side W2 is, for example, the region of the internal space 12a closest to the other widthwise side W2.

[0018] In addition, in a cross-sectional view in the length direction L, a virtual straight line extending parallel to the thickness direction T and passing through the center of the opening of the back-side recess 12 in the width direction W is defined as a "reference line SL." In a region of the inner circumferential surface 12b of the back-side recess 12 on one width direction side W1 of the reference line SL, the distance between the inner circumferential surface 12b and the reference line SL at the upper thickness direction side T1 of two different positions in the thickness direction T is greater than the distance between the inner circumferential surface 12b and the reference line SL at the lower thickness direction side T2 of two different positions in the thickness direction T. In a region of the inner circumferential surface 12b of the back-side recess 12 on the other width direction side W2 of the reference line SL, the distance between the inner circumferential surface 12b and the reference line SL at the upper thickness direction side T1 of two different positions in the thickness direction T is greater than the distance between the inner circumferential surface 12b and the reference line SL at the lower thickness direction side T2 of two different positions in the thickness direction T.

[0019] More specifically, a region of the inner circumferential surface 12b of the back-side recess 12 on one widthwise side W1 of the reference line SL includes an inclined surface that slopes away from the reference line SL (i.e., toward the one widthwise side W1) as it moves from the lower thickness direction side T2 toward the upper thickness direction side T1. A region of the inner circumferential surface 12b of the back-side recess 12 on the other widthwise side W2 of the reference line SL includes an inclined surface that slopes away from the reference line SL (i.e., toward the other widthwise side W2) as it moves from the lower thickness direction side T2 toward the upper thickness direction side T1.

[0020] The internal space 12a of the rear recess 12 is convex in a direction away from the reference line SL at a position spaced from the opening of the rear recess 12 to the upper side T1 in the thickness direction.

[0021] The back side recess 12 has two different thickness direction T positions within the internal space 12a, and the dimension of the width direction W of the internal space 12a at the upper thickness direction T1 position is larger than the dimension of the width direction W of the internal space 12a at the lower thickness direction T2 position.

[0022] The rear recesses 12 correspond to the engagement recess, the first engagement recess, and the second engagement recess, respectively. Hereinafter, the rear recesses 12 corresponding to the engagement recesses may be referred to as "engagement recesses 13." The internal space of the engagement recess 13 may be referred to as "internal space 13a." The inner peripheral surface of the engagement recess 13 may be referred to as "inner peripheral surface 13b."

[0023] In this case, the multiple rear recesses 12 have at least one engagement recess 13 .

[0024] The main body 10 is provided with a plurality of (specifically, five) engagement recesses 13 spaced apart in the width direction W.

[0025] Each of the plurality of (specifically, five) engaging recesses 13 is a dovetail groove.

[0026] Of the multiple (specifically, five) rear recesses 12 , the rear recesses 12 at both ends in the width direction W each serve as an engagement recess 13 .

[0027] One engagement recess 13 is arranged on the opposite side of the center of the width direction W of the main body 10 from the other engagement recesses 13. For example, the engagement recess 13 furthest on one width direction side W1 of each engagement recess 13 is arranged on the opposite side of the center of the width direction W of the main body 10 from the engagement recess 13 furthest on the other width direction side W2 of each engagement recess 13, and more specifically, they are arranged symmetrically with each other across the center of the width direction W of the main body 10.

[0028] The multiple (specifically, five) back side recesses 12 have at least one (specifically, five) first engagement recesses 13 and at least one (specifically, five) second engagement recesses 13.

[0029] The thickness direction T dimension of the internal space 12a of each backside recess 12 is, for example, 5 mm. The thickness direction T dimension of the internal space 12a of each backside recess 12 is preferably within a range of 1 / 20 to 1 / 2 of the thickness direction T dimension of the main body 10. The width direction W dimension of the opening end of the internal space 12a of each backside recess 12 is, for example, 15.5 mm. The width direction W dimension of the opening end of the internal space 12a of each backside recess 12 is preferably within a range of 1 / 30 to 1 / 2 of the width direction W dimension of the main body 10. The distance between the opening ends of adjacent backside recesses 12 is, for example, 17.5 mm. The distance between the opening ends of adjacent backside recesses 12 is preferably within a range of 1 / 30 to 1 / 2 of the width direction W dimension of the main body 10.

[0030] When the paving material 1 is in use, a second adhesive 54 is disposed on the back surface F2 of the main body 10. The second adhesive 54 extends into the internal space 12a of the back recess 12 (engagement recess 13). When the second adhesive 54 is hardened, the engagement recess 13 and the second adhesive 54 engage with each other. This creates an anchor effect on the back surface F2 of the paving material 1, preventing the paving material 1 from separating from the second adhesive 54.

[0031] The main body 10 is also provided with at least one front-side recess 15 that opens to the upper side T1 in the thickness direction. The front-side recess 15 is recessed from the surface F1. The front-side recess 15 is groove-shaped and extends in the length direction L. The front-side recess 15 penetrates the main body 10 in the length direction L. The size of the recess in the front-side recess 15 is smaller than the size of the recess in the back-side recess 12. A plurality of front-side recesses 15 are provided side by side in the width direction W.

[0032] By providing a plurality of front side recesses 15 on the main body 10, the direction of reflection of light hitting the main body 10 can be changed, thereby giving the paving material 1 a unique luster.

[0033] There are no particular limitations on the shape of the internal space 15a of the front-side recess 15 as viewed in the length direction L, the size of the recess in the front-side recess 15, or the number of front-side recesses 15. By appropriately changing the shape of the internal space 15a of the front-side recess 15 as viewed in the length direction L, the size of the recess in the front-side recess 15, the number of front-side recesses 15, etc., it is possible to vary the aesthetic appearance of the paving material 1.

[0034] The thickness direction T dimension of the internal space 15a of each front-side recess 15 is, for example, 1 mm. The thickness direction T dimension of the internal space 15a of each front-side recess 15 is preferably within a range of 1 / 300 to 1 / 4 of the thickness direction T dimension of the main body 10. The width direction W dimension of the opening end of the internal space 15a of each front-side recess 15 is, for example, 1.5 mm. The width direction W dimension of the opening end of the internal space 15a of each front-side recess 15 is preferably within a range of 1 / 1600 to 1 / 35 of the width direction W dimension of the main body 10.

[0035] The four sides that make up the periphery of the front surface F1 of the main body 10 are chamfered, more specifically, all four sides that make up the periphery of the front surface F1 are chamfered. The four sides that make up the periphery of the back surface F2 of the main body 10 are chamfered, more specifically, of the four sides that make up the periphery of the back surface F2, two sides extending in the length direction L are chamfered. This makes it possible to reduce stress concentration on the angular portions of the main body 10, thereby improving the impact resistance of the paving material 1.

[0036] Next, the material of the paving material 1 will be described. The paving material 1 contains, for example, a low-melting-point resin, and non-low-melting-point resin particles and cellulose-based material particles dispersed in the low-melting-point resin. Note that a molded body of a composition containing a resin substrate containing a low-melting-point resin, non-low-melting-point resin particles dispersed in the resin substrate, and cellulose-based material particles dispersed in the resin substrate is sometimes referred to as a "resin composition molded body." The paving material 1 is a resin composition molded body.

[0037] The low-melting-point resin is, for example, a resin whose melting point is in the range of 80°C or higher and lower than 190°C. The low-melting-point resin is, for example, a thermoplastic resin. Examples of low-melting-point resins include polystyrene (PS), acrylonitrile-butadiene-styrene resin (ABS), polyethylene (PE), polymethyl methacrylate (PMMA), polycarbonate (PC), polypropylene (PP), polyamide 12 (PA12), and polyacetal (POM).

[0038] The content of the low-melting-point resin, as a content relative to the total amount of the resin composition molded article, is in the range of 12% by mass to 78% by mass, or may be in the range of 12% by mass to 48% by mass, or 14% by mass to 43% by mass, or 17% by mass to 43% by mass.

[0039] The low-melting-point resin may contain at least polyethylene (PE) and polypropylene (PP). The mass ratio of PE to PP (PE / PP) may be, for example, 5.0 or less, or 3.0 or less.

[0040] The non-low melting point resin particles include, for example, at least one of a high melting point resin having a melting point of 190°C or higher and a thermosetting resin. The melting point of the high melting point resin is, for example, 340°C or lower. Examples of high melting point resins include polyethylene terephthalate (PET), polyamide 6 (PA6), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), and polyether ether ketone (PEEK). The thermosetting resin is a resin after curing. Examples of thermosetting resins include polyimide (PI), polyurethane (PU), and phenolic resin (PF). The average major axis of the non-low melting point resin particles is, for example, less than 3 mm.

[0041] The low-melting-point resin and non-low-melting-point resin particles may be derived from waste, which allows for effective use of resources. The low-melting-point resin and non-low-melting-point resin particles may be separated and recovered from waste plastic collected in accordance with the Containers and Packaging Recycling Law, for example.

[0042] Plastic waste can include municipal solid waste, industrial waste, and marine plastic waste. Municipal waste is waste other than industrial waste and marine plastic waste, including household waste discarded from ordinary households. Plastic waste may contain substances other than synthetic resins. The substances other than synthetic resins may be inorganic or organic. Examples of inorganic substances include magnetic substances, non-magnetic metals, glass, pebbles, metals, shells, sand, desiccants such as silica gel, and iron-based oxygen absorbers. Examples of magnetic substances include iron, stainless steel, ferrite, cobalt, and nickel. Examples of non-magnetic metals include aluminum, copper, zinc, and brass. Examples of organic substances include oils and fats, food residues, and surfactants.

[0043] Examples of plastic waste derived from municipal waste include plastics used as product containers and packaging materials. Waste plastic residue is the residue remaining after separating and recovering a portion of the resin contained in waste plastic derived from municipal waste, such as the residue remaining after separating and recovering a portion of the low-melting-point resin. The low-melting-point resin to be separated and recovered may include, for example, at least one of PP, PE, and PS, or may include both PP and PE. Waste plastic residue may be the residue remaining after separating and recovering 5% by mass or more of the low-melting-point resin contained in the waste plastic, or 5% by mass to 95% by mass or less, or 5% by mass to 50% by mass or less, or 5% by mass to 15% by mass or less. The sum of PP and PE may account for 20% by mass or more of the separated and recovered low-melting-point resin, or may be in the range of 50% by mass to 100% by mass or less, or 70% by mass to 100% by mass or less.

[0044] Plastic waste derived from industrial waste is plastic waste generated as a result of business activities. Examples of plastic waste derived from industrial waste include substandard products and surplus production. Plastic waste derived from marine plastic waste is plastic waste that has accumulated in the ocean due to direct disposal of plastic in the ocean or plastic discarded on land that has washed up in rivers and lakes. Plastic waste derived from marine plastic waste includes, for example, plastic discarded in the ocean (plastic pieces, PET bottles, fishing gear), and microplastics that are plastic products that have deteriorated due to the effects of waves and ultraviolet rays and are now 5 mm or smaller in size.

[0045] When the plastic waste is waste plastic residue, the content of low-melting-point resin in the synthetic resin contained in the waste plastic residue may be, for example, 95% by mass or less, or may be, for example, in the range of 25% by mass to 95% by mass or less, or in the range of 35% by mass to 90% by mass or less. The total content of PE, PP, and PS in the synthetic resin contained in the waste plastic residue may be 80% by mass or less, or may be 70% by mass or less. The total content of PE, PP, and PS may be in any of the ranges of 5% by mass to 80% by mass, 25% by mass to 80% by mass, 25% by mass to 75% by mass, or 30% by mass to 70% by mass.

[0046] The form of the plastic waste is not particularly limited, and may be, for example, bale-like or block-like. When the production units (lots) of resin composition molded products are divided according to the type of plastic waste, the plastic waste used in each production unit may be generated at different locations or times. For example, the plastic waste used in each production unit may have a standard deviation of 2% by mass or more in the content of low-melting-point resin, and may be in the range of 2% by mass or more and 23% by mass or less.

[0047] The particle size of the cellulose-based material particles is not particularly limited, but among particles with a major axis of 1.0 mm or more, the content of particles with a major axis of 2.5 mm or more may be 30% by number or less. Furthermore, the content of particles with a major axis of less than 1.5 mm may be 40% by number or more and 60% by number or less. The content of these particles can be determined by observing a cross section of a resin composition molded product using an optical microscope and measuring the particle diameter of the cellulose-based material particles.

[0048] The content of cellulose-based material particles having a major axis of 4.0 mm or more may be 2.0 particles / 100 mm or less, or 1.0 particles / 100 mm or less, as the average content contained in a 10 mm x 10 mm region of the cross section of the resin composition molded product. The average content of cellulose-based material particles can be determined, for example, by dividing the cross section of the resin composition molded product into 10 mm x 10 mm regions and measuring the particle sizes of the cellulose-based material particles present in 1,000 divided regions using an optical microscope.

[0049] The cellulosic material particles include at least wood particles. The cellulosic material particles may include pulp particles as particles other than wood particles. The content of wood particles relative to the cellulosic material particles may be 52% by mass or more, or 82% by mass or more.

[0050] The wood particles are, for example, crushed waste wood. In this case, resources can be effectively utilized. Examples of waste wood that can be used include construction waste, thinned wood, and sawdust. The average major axis of the wood particles is, for example, less than 3 mm.

[0051] The content of the cellulose-based material particles, as a content relative to the total amount of the resin composition molded body, is in the range of 12% by mass to 48% by mass, and may be in the range of 22% by mass to 38% by mass.

[0052] The ratio of the content of the cellulose-based material particles to the content of the low-melting-point resin contained in the resin substrate (content of cellulose-based material particles / content of low-melting-point resin) may be 4.0 or less.

[0053] The content of the cellulosic material particles may vary depending on the size of the cellulosic material particles. For example, in the case of cellulosic material particles that have passed through a sieve with 1 mm openings, the content may be in the range of 12% by mass to 48% by mass.

[0054] The ratio of the content of cellulose-based material particles passing through a sieve with 1 mm mesh size to the content of low-melting-point resin may be within the range of 0.2 to 4.0.

[0055] In the case of cellulose-based material particles that have passed through a sieve with 2 mm openings, the content may be in the range of 12% by mass or more and 38% by mass or less.

[0056] The ratio of the content of cellulose-based material particles passing through a sieve with 2 mm openings to the content of low-melting-point resin may be in the range of 0.05 or more and 2.5 or less.

[0057] In the case of cellulose-based material particles that have passed through a sieve with 3 mm openings, the content may be in the range of 12% by mass or more and 38% by mass or less.

[0058] The ratio of the content of cellulose-based material particles passing through a sieve with 3 mm openings to the content of low-melting-point resin may be in the range of 0.05 to 1.5.

[0059] The particle size of the non-low melting point resin particles is not particularly limited, but among particles with a major axis of 1.0 mm or more, the content of particles with a major axis of 2.5 mm or more may be 30% by number or less, and the content of particles with a major axis of less than 1.5 mm may be 40% by number or more.

[0060] The content of non-low melting point resin particles having a major axis of 4.0 mm or more may be 2.0 particles / 100 mm or less, or 1.0 particles / 100 mm or less, as the average content contained in a 10 mm x 10 mm cross-sectional area of ​​the resin composition molded body.

[0061] The content of the non-low melting point resin particles is in the range of 12% by mass to 78% by mass inclusive, or may be in the range of 17% by mass to 73% by mass inclusive, or in the range of 32% by mass to 58% by mass inclusive, relative to the total amount of the resin composition molded article.

[0062] The content of non-low melting point resin particles and low melting point resin may be, for example, 0.3 or more and less than 10, in terms of the ratio of the content of non-low melting point resin particles to the content of low melting point resin (content of non-low melting point resin particles / content of low melting point resin).

[0063] The paving material 1 may further contain additives such as pigments, compatibilizers for improving the affinity between the low-melting resin particles, non-low-melting resin particles, and wood particles, fillers, lubricants, weathering agents, heat stabilizers, foaming agents, and antistatic agents.

[0064] The content of the additive is, for example, in the range of 4% by mass to 11% by mass relative to the total amount of the resin composition molded article.

[0065] The resin composition molded product may contain inevitable impurities. Inevitable impurities are impurities that are inevitably mixed in raw materials or during the production process. Examples of inevitable impurities include aluminum derived from aluminum-deposited plastics contained in waste plastics used as raw materials for low-melting-point resins and non-low-melting-point resin particles. The aluminum content relative to the total amount of the resin composition molded product may be, for example, less than 2 mass%.

[0066] When the plastic waste is waste plastic residue, the content of non-low melting point resin in the synthetic resin contained in the waste plastic residue may be, for example, 5% by mass or more, may be in the range of 5% by mass or more and 75% by mass or less, or may be in the range of 10% by mass or more and 65% by mass or less.

[0067] Next, a method for manufacturing the paving material 1 will be described.

[0068] The method for manufacturing the paving material 1 includes a resin raw material preparation step, a wood particle preparation step, a mixing step, and an extrusion step.

[0069] First, a resin raw material preparation process is carried out. In the resin raw material preparation process, for example, low-melting point resin and non-low-melting point resin particles are recovered from a plastic raw material. The plastic raw material is, for example, plastic waste. The resin raw material preparation process includes, for example, a crushing process, a magnetic material removal process, a non-magnetic metal removal process, a water washing process, a volume reduction process, and a pulverization process.

[0070] The shredding process is a process in which plastic waste is shredded using a shredder to obtain plastic fragments. The magnetic substance removal process is a process in which magnetic substances contained in plastic fragments are removed and recovered using a magnetic separator. The non-magnetic metal removal process is a process in which non-magnetic metals contained in plastic fragments are removed and recovered using a non-magnetic metal separator. The water washing process is a process in which plastic fragments are crushed into coarse plastic particles using a wet crushing and washer equipped with a crushing function, while deposits adhering to the coarse plastic particles are washed and removed. The deposits include organic matter such as oils and fats, food residue, and surfactants, and inorganic matter such as glass, pebbles, metals, shells, sand, desiccants, and oxygen absorbers. The volume reduction process is a process in which moisture adhering to the coarse plastic particles is removed and the volume of the coarse plastic particles is reduced using a compression volume reduction machine. The crushing process is a process in which the coarse plastic particles are crushed using a crusher to obtain resin composition particles.

[0071] Next, a wood particle preparation step is carried out. In the wood particle preparation step, wood particles are collected from wood, for example, waste wood. The wood particle preparation step includes, for example, a crushing step, a magnetic substance removal step, and a pulverization step.

[0072] The crushing step is a step of crushing wood using a crusher to obtain wood chips. The magnetic substance removal step is a step of removing and recovering magnetic substances contained in the wood chips using a magnetic separator. The pulverization step is a step of crushing the wood chips using a pulverizer to obtain wood particles. The wood chips may be crushed simultaneously with the crushing of the plastic coarse particles using the same device as that used to crush the plastic coarse particles.

[0073] The plastic raw materials and wood used in the resin raw material preparation step and wood particle preparation step are not limited to waste materials, but may also be valuable resources. In the resin raw material preparation step and wood particle preparation step, ready-made resin powder or wood powder may be prepared as low-melting point resin and non-low-melting point resin particles or wood particles.

[0074] Next, a mixing step is carried out. The mixing step is a step of mixing low-melting point resin and non-low-melting point resin particles with wood particles. In the mixing step, the resin particles / resin composition particles and wood particles are put into a mixer. The mixer is, for example, a heater mixer. The resin particles / resin composition particles and wood particles are kneaded while being heated by the mixer. This allows for a mixture in which each raw material is uniformly dispersed (hereinafter sometimes referred to as a "raw material mixture").

[0075] The total content of the low-melting point resin and non-low-melting point resin in the raw material mixture is, for example, within the range of 50 to 90% by mass. The content of wood particles is, for example, within the range of 5 to 40% by mass. The content of additives is, for example, within the range of 5 to 40% by mass. Furthermore, the ratio of the content of the low-melting point resin to the content of the non-low-melting point resin in the resin composition powder mixture is, for example, within the range of 1 / 3 to 5 by mass.

[0076] Next, the extrusion process is carried out. The extrusion process is a process in which the raw material mixture is extruded using an extrusion molding machine. The raw material mixture is extruded from the nozzle of the extrusion molding machine while being molded into the desired shape. The opening shape of the nozzle is the same as the shape of the paving material 1 when viewed in the length direction L. Therefore, the molded body that comes out of the nozzle has the back side recess 12, front side recess 15, etc. formed in the desired shape. Each side of the main body 10 and the open end of each back side recess 12 are, for example, rounded. The molded body formed in the extrusion process is cut in a direction perpendicular to the direction in which the molded body is extruded. This allows a molded body of the desired dimensions to be obtained.

[0077] The back-side recess 12 and the front-side recess 15 are each provided to penetrate the main body 10 in the length direction L. With this configuration, the back-side recess 12 and the front-side recess 15 can be easily formed in the main body 10 by extrusion molding.

[0078] The shape of each part of the main body 10 may be formed by grinding the molded body after the extrusion process.

[0079] The molding temperature of the extruder varies depending on factors such as the type and content of the low-melting-point resin contained in the raw material mixture, but is preferably, for example, 80°C or higher. This allows the low-melting-point resin particles to melt. A molded product can be obtained in which non-low-melting-point resin particles and wood particles are dispersed in the low-melting-point resin. Because wood particles decompose and gasify at temperatures above 190°C, which can cause bubbles to form in the molded product of the raw material mixture, the molding temperature of the extruder is preferably below 190°C.

[0080] The method for producing the paving material 1 (resin composition molded article) of this embodiment may also include an analysis step.

[0081] The analysis step is carried out before the mixing step. The analysis step is a step of analyzing the composition of the resin composition powder. The composition of the resin composition powder can be determined by the ratio of the content of the low-melting point resin to the content of the non-low-melting point resin in the resin composition powder.

[0082] The content of low-melting point resin and the content of non-low-melting point resin in the resin composition powder can be analyzed by, for example, separating the low-melting point resin and the non-low-melting point resin by utilizing the difference in specific gravity between them, and measuring the content of each separated resin.

[0083] More specifically, for example, a resin composition powder is immersed in a heavy liquid as a sample powder. Next, the amount of floating matter rising to the surface of the heavy liquid and the amount of sediment that sinks are measured. The floating matter is scooped out of the heavy liquid. The sediment is recovered by filtering the heavy liquid after all of the floating matter has been scooped out. The recovered floating matter and sediment are washed with water, dried, and the amounts of floating matter and sediment are measured. The amount of floating matter is then taken as the content of the low-melting-point resin, and the amount of sediment is taken as the content of the non-low-melting-point resin. This allows the contents of the low-melting-point resin and non-low-melting-point resin to be measured quickly and accurately.

[0084] The specific gravity of the heavy liquid can be, for example, 1.08 to 1.13. This allows for more accurate measurement of the content of low-melting-point resin and non-low-melting-point resin. The heavy liquid may be, for example, an organic solvent such as ethylene glycol, or an aqueous solution of an inorganic salt such as a sodium chloride solution. To prevent the sample powder from floating up due to its buoyancy, the particle size of the sample powder may be 3 mm or less. Furthermore, if air bubbles are attached to the sample powder, resin powder that would otherwise settle in the heavy liquid may float up. By stirring under appropriate conditions or adding a surfactant or the like to the heavy liquid, air bubble attachment can be suppressed, improving analytical accuracy.

[0085] When the analysis step is performed, the mixing ratio of the resin composition powder to the melting point resin-containing powder and / or the non-low melting point resin-containing powder may be adjusted in the mixing step based on the ratio of the low melting point resin content to the non-low melting point resin content of the resin composition powder obtained in the analysis step.

[0086] The analysis process determines the ratio of low-melting-point resin to non-low-melting-point resin in the resin composition powder, and the mixing process adjusts the content of the low-melting-point resin to the non-low-melting-point resin to an appropriate component ratio, thereby maintaining a stable viscosity of the molten raw material mixture. This improves moldability during extrusion. This allows plastic waste to be used in shapes that are difficult to mold, further expanding the scope of effective use of plastic waste.

[0087] In this way, the paving material 1 can be obtained.

[0088] Next, a method for applying the paving material 1 will be described with reference to FIGS.

[0089] 3 and 4, the construction method for the paving material 1 is a so-called improved pressure-bonding method. The construction method for the paving material 1 includes the steps of: step S1 of placing a first base 51 on the ground G; step S2 of placing a second base 52 on the first base 51; step S3 of placing a first adhesive 53 on the second base 52; step S4 of placing a second adhesive 54 on the back surface F2 of the paving material 1; step S5 of joining the first adhesive 53 and the second adhesive 54; and step S6 of filling the joints. Step S5 of joining the first adhesive 53 and the second adhesive 54 is sometimes simply referred to as the "joining step S5."

[0090] First, step S1 is performed to place the first base 51 on the ground G. The first base 51 is, for example, concrete. The concrete is placed on the ground G to form a concrete layer. Next, surface treatment of the first base 51 is performed. Dirt and the like on the top surface of the first base 51 is removed using a wire brush, a scraper, or the like. A water absorption adjuster is applied to the top surface of the first base 51 to adjust the water absorption of the first base 51. Note that, as a preliminary step to the step of placing the first base 51 on the ground G, gravel removal, ground compaction, and the like may be performed, for example.

[0091] Next, step S2 is performed to place the second base 52 on the first base 51. The second base 52 is, for example, basa mortar or mortar. The basa mortar or the like is placed on the first base 51 to form a layer of basa mortar or the like. Next, the base is cured for, for example, about two weeks. Next, dirt and the like on the top surface of the second base 52 is removed using a sander, scraper, wire brush, high-pressure washer, or the like. Next, a water absorption adjuster is applied to the top surface of the second base 52 to adjust the water absorption of the second base 52.

[0092] In addition, the process S1 of placing the first base 51 on the ground G and the process S2 of placing the second base 52 on the first base 51 correspond to the process of placing a base on the ground G.

[0093] Next, step S3 is performed to place the first adhesive 53 on the second base 52. The first adhesive 53 is, for example, mortar. A paste-like mortar is prepared as the first adhesive 53. The paste-like first adhesive 53 is applied to the upper surface of the second base 52. At this time, the first adhesive 53 is rubbed toward the second base 52 to bring the first adhesive 53 and the second base 52 into close contact with each other. Next, the first adhesive 53 is applied over the first adhesive 53 on the second base 52. The thickness of the first adhesive 53 applied over the second base 52 is, for example, in the range of 3 mm to 4 mm for the two layers combined.

[0094] Next, step S4 is performed to place a second adhesive 54 on the back surface F2 of the paving material 1. The second adhesive 54 is, for example, mortar. A paste-like mortar is prepared as the second adhesive 54. The paste-like second adhesive 54 is applied to the back surface F2 of the paving material 1. The second adhesive 54 is filled into the internal space 12a of each back-side recess 12. The second adhesive 54 is placed from the back surface F2 into the internal space 12a of each back-side recess 12. Note that the second adhesive 54 does not have to fill the entire internal space 12a of the back-side recess 12, and may only fill a portion of the internal space 12a of the back-side recess 12 on the open end side.

[0095] Next, the bonding process S5 is performed. The paving material 1 with the second adhesive 54 applied to its back surface F2 is placed on the first adhesive 53 applied to the second base 52. This bonds the first adhesive 53 and the second adhesive 54. At this time, the first adhesive 53 and the second adhesive 54 are bonded in a paste state. Multiple paving materials 1 are arranged in a desired pattern on the first adhesive 53 applied to the second base 52. Adjacent paving materials 1 may be spaced apart or abutting. The multiple paving materials 1 may be arranged with the length directions L of each paving material 1 parallel to each other or with the length directions L of each paving material 1 intersecting each other. Once the first adhesive 53 and the second adhesive 54 harden, the paving material 1 and the second base 52 are bonded together by the first adhesive 53 and the second adhesive 54. The first adhesive 53 and the second adhesive 54 correspond to adhesives.

[0096] Next, the joint filling step S6 is carried out. A joint material is filled between adjacent paving materials 1. The joint material is, for example, joint sand. If excess first adhesive 53 or second adhesive 54 is present between adjacent paving materials 1, the excess first adhesive 53 or second adhesive 54 is removed with a joint trowel or the like prior to the joint filling step S6.

[0097] This completes the construction of the paving material 1.

[0098] The paving material 1 of this embodiment has the following effects.

[0099] In this embodiment, the paving material 1 includes a main body 10 having a pair of front and back surfaces F1 and F2. The main body 10 includes at least one rear recess 12 extending in the length direction L and opening to a lower side T2 in the thickness direction. The rear recess 12 includes at least one engaging recess 13 having an inner peripheral surface 12b formed to sandwich, in the thickness direction T, at least one of the ends of the internal space 12a in the width direction W.

[0100] This configuration allows adhesive to penetrate into the engagement recess 13 during use. In this case, an anchoring effect can be generated on the back surface F2 of the paving material 1, preventing the paving material 1 from separating from the ground G. The back recess 12 extends in the length direction L. This prevents the paving material 1 from separating from the ground G at multiple locations in the length direction L of the paving material 1. This prevents warping of the paving material 1 in the length direction L, even if the paving material 1 attempts to expand due to water absorption, etc. Therefore, it is possible to provide a paving material 1 that can effectively prevent warping.

[0101] Furthermore, when the dimension T of the paving material 1 in the thickness direction becomes small, the paving material 1 is more likely to warp, but this configuration can suppress the warping of the paving material 1. Therefore, the paving material 1 can be made thinner.

[0102] In this embodiment, the engagement recess 13 is located at two different positions in the thickness direction T, and the width W dimension of the internal space 13a at the upper thickness direction position T1 is larger than the width W dimension of the internal space 13a at the lower thickness direction position T2.

[0103] With this configuration, the anchor effect generated on the back surface F2 of the paving material 1 can be made stronger, so that warping of the paving material 1 can be more effectively suppressed.

[0104] In this embodiment, the engagement recess 13 is a dovetail groove.

[0105] With this configuration, the anchor effect generated on the back surface F2 of the paving material 1 can be made stronger, so that warping of the paving material 1 can be more effectively suppressed.

[0106] Furthermore, since the engaging recesses 13 have an isosceles trapezoidal shape in which the width W dimension increases toward the upper side T1 in the thickness direction when viewed in the length direction L, it is possible to prevent the position of the paving material 1 from shifting in the width direction W in either direction of the width direction W. This makes it possible to effectively prevent the position of the paving material 1 from shifting.

[0107] In this embodiment, the main body 10 is provided with a plurality of engagement recesses 13 spaced apart in the width direction W.

[0108] This configuration can prevent the paving material 1 from separating from the ground G at multiple locations in the width direction W of the paving material 1. This effectively prevents the paving material 1 from warping in the width direction W.

[0109] In this embodiment, of the plurality of rear recesses 12 , at least the rear recesses 12 at both ends in the width direction W are each formed as an engagement recess 13 .

[0110] This configuration makes it easier to increase the distance between the engaging recesses 13 in the width direction W. This makes it possible to more effectively suppress warping of the paving material 1 in the width direction W.

[0111] In this embodiment, one engagement recess 13 is provided on the opposite side of the center of the width direction W of the main body 10 from the other engagement recess 13 .

[0112] This configuration can prevent the paving material 1 from separating from the ground G in the regions on each end side of the width direction W of the paving material 1. This makes it possible to more effectively prevent the paving material 1 from warping in the width direction W.

[0113] In this embodiment, the multiple back side recesses 12 have at least one first engagement recess having an inner surface 12b formed to sandwich the end of the internal space 12a on one width side W1 in the thickness direction T, and at least one second engagement recess having an inner surface 12b formed to sandwich the end of the internal space 12a on the other width side W2 in the thickness direction T.

[0114] With this configuration, the first engaging recess prevents the position of the paving material 1 from shifting to the other widthwise side W2, and the second engaging recess prevents the position of the paving material 1 from shifting to the one widthwise side W1. This effectively prevents the position of the paving material 1 from shifting.

[0115] In this embodiment, the paving material 1 includes wood particles.

[0116] This configuration makes it possible to obtain a paving material 1 that has a texture similar to that of wood, thereby improving the design of the paving material 1.

[0117] Furthermore, wood particles have a high affinity for water. Therefore, if wood particles are included in the paving material 1, there is a risk that the paving material 1 will be prone to absorbing water and expanding. However, according to this embodiment, the back recess 12 can suppress the absorbing water expansion of the paving material 1 and the warping of the paving material 1 that results from the absorbing water expansion of the paving material 1. This allows the design of the paving material 1 to be improved while suppressing warping of the paving material 1.

[0118] In this embodiment, the paving material 1 includes a low-melting resin, non-low-melting resin particles, and wood particles dispersed in the low-melting resin. The low-melting resin has a melting point in the range of 80° C. or higher and lower than 190° C. The non-low-melting resin particles include at least one of a high-melting resin and a thermosetting resin having a melting point of 190° C. or higher.

[0119] With this configuration, the wood particles are dispersed in the low-melting resin. This prevents the wood particles from coming into contact with water, thereby suppressing water absorption by the wood particles. Non-low-melting resin particles are dispersed in the low-melting resin. This prevents the water absorption of the paving material 1 from increasing, while enhancing the impact resistance of the paving material 1.

[0120] When dispersing wood particles and non-low-melting resin particles in a low-melting resin, the mixture of wood particles, non-low-melting resin particles, and low-melting resin is heated to melt the low-melting resin. However, the wood particles may gasify at high temperatures. This can cause bubbles to form in the molded product, which can detract from the aesthetic appearance of the molded product.

[0121] However, with this configuration, the melting point of the low-melting-point resin is in the range of 80°C or higher and lower than 190°C. Therefore, the low-melting-point resin can be melted at a temperature in the range of 80°C or higher and lower than 190°C. By setting the temperature of the raw material mixture in the range of 80°C or higher and lower than 190°C, gasification of the wood particles can be suppressed. Therefore, the wood particles and non-low-melting-point resin particles can be dispersed in the low-melting-point resin while suppressing the generation of bubbles in the molded product of the raw material mixture.

[0122] Furthermore, with this configuration, the weight of the paving material 1 can be reduced, which improves workability when installing the paving material 1, etc.

[0123] According to this embodiment, the paving material 1 is used with the back surface F2 facing the ground, with the adhesive in contact with the back surface F2.

[0124] According to this configuration, the inside of the rear recess 12 can be filled with adhesive, so that a stronger anchor effect can be generated.

[0125] According to this embodiment, the construction method of the paving material 1 includes a step S1 of placing a first base 51 on the ground G, a step S2 of placing a second base 52 on the first base 51, a step S3 of placing a first adhesive 53 on the second base 52, a step S4 of placing a second adhesive 54 on the back surface F2 of the paving material 1, and a step S5 of joining the first adhesive 53 and the second adhesive 54.

[0126] According to this construction method, the paving material 1 and the second base 52 can be bonded together using the first adhesive 53 and the second adhesive 54. In step S4, in which the second adhesive 54 is placed on the back surface F2 of the paving material 1, the second adhesive 54 can be efficiently inserted into the internal space 12a of the back-side recess 12. This allows for a more efficient anchoring effect between the paving material 1 and the second base 52. This effectively prevents the paving material 1 from warping.

[0127] Second Embodiment Next, a paving material 1 according to a second embodiment of the present disclosure will be described with reference to Fig. 5. The following description will focus on differences from the first embodiment, and the same components as those in the first embodiment will be denoted by the same reference numerals and description thereof will be omitted.

[0128] 5 , in the second embodiment, the main body 10 is provided with five rear recesses 12 aligned in the width direction W. Each of the five rear recesses 12 has two engagement recesses 13.

[0129] It is preferable that two or more engagement recesses 13 are provided in the main body 10 at intervals in the width direction W. In this case, warping of the paving material 1 in the width direction W can be more effectively suppressed.

[0130] The five back-side recesses 12 include three back-side recesses 12 that do not correspond to the engagement recesses 13. The engagement recesses 13 and the back-side recesses 12 that do not correspond to the engagement recesses are arranged alternately. Of the five back-side recesses 12, the back-side recess 12 closest to one widthwise side W1, the central back-side recess 12, and the back-side recess 12 closest to the other widthwise side W2 are back-side recesses 12 that do not correspond to the engagement recesses. In this way, the main body 10 may be provided with back-side recesses 12 that do not correspond to the engagement recesses.

[0131] It is preferable that one engaging recess 13 is disposed on the opposite side of the center of the width direction W of the main body 10 from the other engaging recess 13. In this case, warping of the paving material 1 in the width direction W can be more effectively suppressed.

[0132] The internal space 12a of the back-side recess 12 that does not correspond to the engagement recess 13 has, for example, an isosceles trapezoidal shape in which the width dimension W decreases toward the upper side T1 in the thickness direction when viewed in the length direction L. However, the shape of the internal space 12a of the back-side recess 12 that does not correspond to the engagement recess when viewed in the length direction L is not limited to this.

[0133] In adjacent back-side recesses 12, the region of the inner circumferential surface 12b of one back-side recess 12 facing the other back-side recess 12 and the region of the inner circumferential surface 12b of the other back-side recess 12 facing the one back-side recess 12 extend parallel to each other in a cross section perpendicular to the longitudinal direction L. This makes it easier to ensure a gap between adjacent back-side recesses 12, thereby improving the impact resistance of the paving material 1.

[0134] The main body 10 also has at least one side recess 16 that opens in the width direction W. The outer surfaces of the main body 10 that face each other in the width direction W are referred to as "side surfaces F3." The side recess 16 is recessed from the side surface F3. The side recess 16 has a groove shape extending in the length direction L. The side recess 16 penetrates the main body 10 in the length direction L. The internal space 16a of the side recess 16 has a triangular shape when viewed in the length direction L. The size of the recess in the side recess 16 is smaller than the size of the recess in the back recess 12. A plurality of side recesses 16 are provided side by side in the thickness direction T. The shape of the internal space 16a of the side recess 16 when viewed in the length direction L is not particularly limited.

[0135] If joint material or adhesive is placed between adjacent paving pieces 1, the joint material or adhesive can penetrate into the internal space 16a of the side recess 16. Therefore, when the paving piece 1 tries to warp in the width direction W, the end of the paving piece 1 in the width direction W gets caught by the joint material or adhesive. This prevents the paving piece 1 from warping.

[0136] Each of the paired side surfaces F3 is provided with at least one side surface recess 16, more specifically, with a plurality of side surface recesses 16. This makes it possible to more effectively suppress warping of the paving materials 1 when joint material or the like is disposed between adjacent paving materials 1.

[0137] The side recesses 16 are not essential components. By providing the main body 10 with the engagement recesses 13, warping of the paving material 1 can be sufficiently suppressed.

[0138] Third Embodiment Next, a paving material 1 according to a third embodiment of the present disclosure will be described with reference to Fig. 6. The following description will focus on differences from the first embodiment, and the same components as those in the first embodiment will be denoted by the same reference numerals and description thereof will be omitted.

[0139] 6, in the third embodiment, the main body 10 is provided with ten rear recesses 12, more specifically, the ten rear recesses 12 are provided at equal intervals in the width direction W. In this way, the number of rear recesses 12 is not particularly limited.

[0140] Of the back-side recesses 12 of the main body 10, the central back-side recess 12 (hereinafter referred to as the "back-side recess 17") is located at the center of the width direction W of the main body 10.

[0141] The raw material mixture tends to collect near the center of the width direction W of the main body 10 during molding. As a result, there is a risk that the center of the width direction W of the main body 10 will bulge in the thickness direction T. However, a backside recess 17 is provided in the center of the width direction W of the main body 10. Therefore, even if the raw material mixture collects near the center of the width direction W of the main body 10 during molding, the excess raw material mixture will rise toward the internal space 17a of the backside recess 17. This prevents the back surface F2 of the main body 10 from becoming convex toward the lower side T2 in the thickness direction. This prevents poor molding of the paving material 1.

[0142] The thickness direction T dimension of the internal space 17a of the rear recess 17 is smaller than the thickness direction T dimension of the internal space 12a of the rear recess 12 excluding the rear recess 17. This makes it possible to prevent a decrease in the impact resistance of the paving material 1.

[0143] The internal space 17a of the rear recess 17 has a semispherical shape that is convex toward the upper side T1 in the thickness direction when viewed in the length direction L.

[0144] The back-side recess 12 (referred to as "back-side recess 19A") located furthest to one widthwise side W1 of the main body 10 is recessed from the end on one widthwise side W1 and the lower thicknesswise side T2 of the main body 10 toward the other widthwise side W2 and the upper thicknesswise side. The back-side recess 19A has an inner circumferential surface 12b (referred to as "inner circumferential surface 19Bb") formed to sandwich the end on the other widthwise side W2 of its internal space 12a (referred to as "internal space 19Aa") in the thickness direction T. Therefore, the back-side recess 19A corresponds to the engagement recess and the second engagement recess.

[0145] The back-side recess 12 (referred to as the "back-side recess 19B") located furthest to the other widthwise side W2 of the main body 10 is recessed from the end on the other widthwise side W2 and the lower thicknesswise side T2 of the main body 10 toward the one widthwise side W1 and the upper thicknesswise side. The back-side recess 19B has an inner peripheral surface 12b (referred to as the "inner peripheral surface 19Bb") formed to sandwich the end on the one widthwise side W1 of its internal space 12a (referred to as the "internal space 19Ba") in the thickness direction T. Therefore, the back-side recess 19B corresponds to an engagement recess and a first engagement recess.

[0146] In this way, the rear recess 12 does not necessarily have to be spaced apart from each end of the main body 10 in the width direction W.

[0147] The four back side recesses 12 located between the back side recess 19A and the central back side recess 17 have internal spaces 12a that, when viewed in the length direction L, form parallelogram shapes with diagonal lengths that differ, and more specifically, form parallelogram shapes that incline toward the other width direction side W2 as they move toward the upper side T1 in the thickness direction.

[0148] The four back-side recesses 12 located between the back-side recess 19A and the central back-side recess 17 have inner circumferential surfaces 12b formed to sandwich the end of the internal space 12a on the other width direction side W2 in the thickness direction T. In addition, in a cross-sectional view in the longitudinal direction L, in the region of the inner circumferential surface 12b of the back-side recess 12 on the other width direction side W2 of the reference line SL, the distance between the inner circumferential surface 12b and the reference line SL at the upper thickness direction side T1 is greater than the distance between the inner circumferential surface 12b and the reference line SL at the lower thickness direction side T2, among two different positions in the thickness direction T. Therefore, the four back-side recesses 12 located between the back-side recess 19A and the central back-side recess 17 correspond to the engagement recess and the second engagement recess.

[0149] The four back side recesses 12 located between the back side recess 19B and the central back side recess 17 have internal spaces 12a that, when viewed in the length direction L, form parallelogram shapes with diagonal lengths that differ, and more specifically, form parallelogram shapes that incline toward one width direction side W1 as they move toward the upper side T1 in the thickness direction.

[0150] The four back-side recesses 12 located between the back-side recess 19B and the central back-side recess 17 have inner circumferential surfaces 12b formed to sandwich the ends of their internal spaces 12a on one widthwise side W1 in the thickness direction T. In addition, in a cross-sectional view in the longitudinal direction L, in the region of the inner circumferential surface 12b of each back-side recess 12 on one widthwise side W1 of the reference line SL, the distance between the inner circumferential surface 12b and the reference line SL at the upper position in the thickness direction T is greater than the distance between the inner circumferential surface 12b and the reference line SL at the lower position T2 in the thickness direction. Therefore, the four back-side recesses 12 located between the back-side recess 19B and the central back-side recess 17 correspond to engagement recesses and first engagement recesses.

[0151] In this way, the shape of the internal space 13a of the engagement recess 13 as viewed in the length direction L is not limited to the shape of the first embodiment. However, in order to prevent the position of the paving material 1 from shifting, it is preferable that the main body 10 be provided with at least one first engagement recess and at least one second engagement recess.

[0152] Fourth Embodiment Next, a paving material 1 according to a fourth embodiment of the present disclosure will be described with reference to Fig. 7. The following description will focus on differences from the third embodiment, and the same components as those in the third embodiment will be denoted by the same reference numerals and description thereof will be omitted.

[0153] 7 , in the fourth embodiment, seven rear recesses 12 are provided in the main body 10. The seven rear recesses 12 are arranged at equal intervals in the width direction W. The central rear recess 12 of the seven rear recesses 12 is located in the center of the main body 10 in the width direction W.

[0154] In the fourth embodiment, the shape of the end portion on the lower side T2 in the thickness direction of each end portion in the width direction W of the main body portion 10 is different from that in the third embodiment. In the fourth embodiment, the end portion on the lower side T2 in the thickness direction of each end portion in the width direction W of the main body portion 10 is beveled.

[0155] In the fourth embodiment, the shape of the internal space 12a of the back side recess 12 located at the center of the width direction W among the seven back side recesses 12 is an isosceles trapezoid when viewed in the length direction L, with the width direction W dimension decreasing as it moves toward the upper side T1 in the thickness direction.

[0156] The dimension in the width direction W of the central back side recess 12 among the seven back side recesses 12 is larger than the dimension in the width direction W of the back side recesses 12 excluding the central back side recess 12 among the seven back side recesses 12. In this way, the dimensions in the width direction W of the multiple back side recesses 12 do not need to be the same.

[0157] In this case, the center of the width direction W of the main body 10 and the internal space 12a of the rear recess 12 overlap in the thickness direction T. The internal space 12a of the rear recess 12 that overlaps with the center of the width direction W of the main body 10 has a larger dimension in the width direction W than in the third embodiment. This makes it possible to prevent the main body 10 from becoming thicker around the center in the width direction W during molding over a wider area.

[0158] Fifth Embodiment Next, a paving material 1 according to a fifth embodiment of the present disclosure will be described with reference to Fig. 8. The following description will focus on differences from the eighth embodiment, and the same components as those in the fourth embodiment will be denoted by the same reference numerals and description thereof will be omitted.

[0159] As shown in FIG. 8, in the fifth embodiment, the shape of each rear recess 12 is different from that in the fourth embodiment.

[0160] Of the seven back-side recesses 12, six, excluding the central back-side recess 12, have a shape, as viewed in the length direction L of the internal space 12a of the back-side recess 12, that is the inverse of the shape, as viewed in the length direction L, of the internal space 12a of the back-side recess 12 in the fourth embodiment, in the width direction W. Therefore, of the seven back-side recesses 12, three back-side recesses 12 located on one width direction side W1 of the central back-side recess 12 correspond to first engagement recesses. Of the seven back-side recesses 12, three back-side recesses 12 located on the other width direction side W2 of the central back-side recess 12 correspond to second engagement recesses.

[0161] The back-side recesses 12 provided in the region of the main body 10 closer to the one widthwise side W1 are not limited to the second engagement recesses, but may be the first engagement recesses or the second engagement recesses. The back-side recesses 12 provided in the region of the main body 10 closer to the other widthwise side W2 are not limited to the first engagement recesses, but may be the first engagement recesses or the second engagement recesses. The multiple back-side recesses 12 provided in the region of the main body 10 closer to the one widthwise side W1 may have first engagement recesses and second engagement recesses. The multiple back-side recesses 12 provided in the region of the main body 10 closer to the other widthwise side W2 may have first engagement recesses and second engagement recesses. For example, the first engagement recesses and second engagement recesses may be arranged alternately at intervals in the width direction W.

[0162] The internal space 12a of the central back recess 12 among the seven back recesses 12 has an isosceles trapezoidal shape in which the width W dimension increases toward the upper side T1 in the thickness direction when viewed in the length direction L.

[0163] In this case, in adjacent back-side recesses 12, the region of the inner circumferential surface 12b of one back-side recess 12 facing the other back-side recess 12 and the region of the inner circumferential surface 12b of the other back-side recess 12 facing the one back-side recess 12 extend parallel to each other in a cross section perpendicular to the longitudinal direction L. This makes it easier to ensure the spacing between adjacent back-side recesses 12, thereby making it easier to ensure the strength of the paving material 1. The central back-side recess 12 of the seven back-side recesses 12 corresponds to the engagement recess, the first engagement recess, the second engagement recess, and the dovetail groove.

[0164] Although one embodiment of the paving material of the present disclosure has been described above, the configuration of the paving material of the present disclosure can be modified as appropriate.

[0165] For example, the back side recess 12, the front side recess 15, and the side side recess 16 may be formed by recessing the outer surface of the main body 10, or may be formed by being sandwiched between two protruding portions protruding from the main body 10.

[0166] In each of the above embodiments, the main body 10 has a generally rectangular plate shape overall, but there are no particular limitations on the shape of the main body 10. Furthermore, there are no particular limitations on the shape of the main body 10 in a plan view in the thickness direction T, and it may be, for example, a square or a rectangle.

[0167] The main body 10 may have at least one hollow portion. In other words, the main body 10 may have a hollow structure. In this case, the hollow portion extends in the length direction L. This makes it possible to suppress warping of the main body 10 in the length direction L. It is preferable that multiple hollow portions are provided in the main body 10, lined up in the width direction W. In this case, it is possible to suppress warping of the main body 10 in the width direction W. It is preferable that the hollow portion penetrates the main body in the length direction L. In this case, the hollow portion can be easily formed in the main body 10 by extrusion molding. The cross-sectional shape of the internal space of the hollow portion in the length direction L is not particularly limited. However, it is preferable that the inner peripheral surface of the hollow portion be formed in a curved shape. In this case, it is possible to suppress stress concentration on the angular portions of the inner peripheral surface of the hollow portion.

[0168] The shape of the engagement recess 13 is not limited to that of the above-described embodiments. The inner peripheral surface 13b of the engagement recess 13 may include a flat portion, a curved portion, or a stepped portion. The shape of the internal space 13a of the engagement recess 13 as viewed in the length direction L may be various shapes such as a circle, an ellipse, a polygon, or a combination thereof.

[0169] For example, the shape of the internal space 13a of the engagement recess 13 as viewed in the length direction L may include a rectangular region formed including the opening of the engagement recess 13 and a circular region formed on the upper side T1 of the rectangular region in the thickness direction and having a width W dimension larger than the width W dimension of the rectangular region. In this case, the internal space 13a of the engagement recess 13 is narrower on the opening side than on the back side, thereby preferably generating an anchor effect. Furthermore, this can prevent the main body 10 from becoming sharp near the opening of the engagement recess 13 and suppress stress concentration on the inner circumferential surface 13b of the engagement recess 13, thereby improving the durability of the main body 10.

[0170] In the above-described embodiments, the rear recesses 12 are arranged at equal intervals, but they do not necessarily have to be arranged at equal intervals.

[0171] In each of the above embodiments, the main body 10 is provided with a front-side recess 15, but the front-side recess 15 is not an essential component. The number of front-side recesses 15 provided in the main body 10 is not particularly limited. The size and shape of the front-side recess 15 provided in the main body 10 are not particularly limited. Furthermore, when the main body 10 is provided with multiple front-side recesses 15, the multiple front-side recesses 15 may each have a different size or shape.

[0172] In each of the above embodiments, the main body 10 is provided with a side recess 16, but the side recess 16 is not a required component. The number of side recesses 16 provided on the main body 10 is not particularly limited. Alternatively, one of the pair of side surfaces F3 may be provided with a side recess 16, and the other side surface F3 may be provided with a side protrusion that is convex in the width direction W and can be inserted into the side recess 16. In this case, for paving materials 1 adjacent to each other in the width direction W, inserting the side protrusion 18 of one paving material 1 into the side recess 16 of the other paving material 1 can suppress warping of the paving materials 1. Furthermore, shifting of the paving materials 1 can be suppressed.

[0173] In the above embodiments, the paving material 1 includes a low-melting resin and non-low-melting resin particles and wood particles dispersed in the low-melting resin, the melting point of the low-melting resin being in the range of 80°C or higher but lower than 190°C, and the non-low-melting resin particles including at least one of a high-melting resin having a melting point of 190°C or higher and a thermosetting resin having a melting point of 190°C or higher, but the material of the paving material 1 is not particularly limited. For example, the paving material 1 does not need to include wood particles or various resin materials.

[0174] In the above embodiments, the paving material 1 is used with the back surface F2 facing the ground, with the adhesive in contact with the back surface F2. However, this is not limited to this. For example, the paving material 1 may be used with a portion of it buried in the ground. Even in this case, as long as soil or the like has penetrated into the back recess 12 and hardened to the extent that an anchoring effect can be generated, warping of the paving material 1 can be suppressed. However, the configurations of the above embodiments are preferred because they can generate an anchoring effect more reliably.

[0175] The application method of the paving material 1 is not limited to the methods of the above-described embodiments. The application method of the paving material 1 is not limited to the improved pressure-bonding method.

[0176] In the construction method of the above embodiment, a first base 51 and a second base 52 were placed on the ground G, but the base placed on the ground G may be one layer or three or more layers.

[0177] The step of applying the second adhesive to the back surface F2 of the paving material 1 is not a required step in the application method of the paving material 1. For example, the application method of the paving material 1 may include a step of applying the paving material 1 without adhesive on top of a paste-like adhesive applied to a substrate. The application method of the paving material 1 can be modified as needed as long as it is possible to achieve a state in which the adhesive is contained within the engagement recesses 13 of the main body 10 when the paving material 1 is in use.

[0178] The first adhesive 53 and the second adhesive 54 may be made of the same material or different materials. The materials of the first adhesive 53 and the second adhesive 54 are not particularly limited.

[0179] The present disclosure will be described in more detail below based on examples. The present disclosure is not limited to these examples. In these examples, wastes 1 to 4 were used as plastic waste, with the low-melting-point resin and non-low-melting-point resin contents shown in Table 1 below. Wastes 1 to 4 are waste plastic residues derived from general waste that remain after the low-melting-point resin is separated and recovered from general waste. The ratio of low-melting-point resin content to non-low-melting-point resin content of wastes 1 to 4 is lower than that of general waste. This makes material recycling difficult. Material recycling is particularly difficult for wastes with a low-melting-point resin content / non-low-melting-point resin content ratio of less than 1.00. Recycled resin is low-melting-point resin separated and recovered from general waste. Recycled resin has a high low-melting-point resin content / non-low-melting-point resin content ratio and is used for material recycling.

[0180]

[0181] Example 1 (Production of Resin Composition Powder) Waste 1 was placed in a crusher and crushed. The crushed material obtained was subjected to a high-magnetic pulley-type magnetic separator with a magnetic force of 2000 Gauss on the belt surface to remove iron-containing materials. The crushed material from which the iron-containing materials had been removed was then crushed in a uniaxial coarse crusher until it passed through a 50 mm mesh sieve, yielding plastic fragments (crushing step). The magnetic materials contained in the resulting plastic fragments were removed and recovered using a hanging magnetic separator and a pulley-type magnetic separator (magnetic material removal process). Next, non-magnetic metals contained in the plastic fragments were removed and recovered using a non-magnetic metal separator (non-magnetic metal removal process). Next, the plastic fragments were washed and removed while being crushed using a wet crusher and washer until they passed through a 12 mm mesh sieve, yielding coarse plastic particles (water washing process). Next, the coarse plastic particles obtained in the wet grinding and washing machine were compressed and dehydrated using a volume reduction and compression dehydrator to reduce the volume, resulting in a coarse plastic powder with a moisture content of 0.5% by mass (volume reduction process). Finally, the coarse plastic powder was pulverized using a cutter mill-type pulverizer until it passed through a sieve with 2 mm openings (pulverization process). In this way, a resin composition powder was obtained. The presence or absence of the magnetic substance removal process, non-magnetic metal removal process, water washing process, and volume reduction process, and the opening diameter of the sieve used in the pulverization process are shown in Table 2 below.

[0182] (Production of wood flour) Waste wood was fed into a crusher and crushed using a uniaxial coarse crusher until it passed through a sieve with 50 mm openings, obtaining wood chips (crushing process). Magnetic materials contained in the obtained wood chips were removed and recovered using a hanging magnetic separator and a pulley magnetic separator (magnetic material removal process). Next, the wood chips were crushed using a cutter mill-type crusher until they passed through a sieve with 1 mm openings (crushing process). In this way, wood powder was obtained. The opening diameters of the sieves used in the crushing process are shown in Table 2 below.

[0183] (Method for manufacturing resin composition molded body) 60 parts by mass of resin composition powder, 30 parts by mass of wood powder, and 10 parts by mass of additives (a mixture containing a pigment, a compatibilizer, an inorganic filler, a lubricant, and a weathering material) were mixed at 150°C using a heater mixer. The resulting mixture was molded using an extruder equipped with a rectangular cross-sectional mold 30 mm thick and 300 mm wide to obtain a plate-shaped resin composition molded body. During extrusion molding, a backside recess having an engaging recess was formed in the resin composition molded body. The composition of the obtained resin composition molded body is shown in Table 3 below.

[0184] The resulting molded resin composition articles were evaluated for bending strength, water resistance, and mildew resistance by the following methods, and the results are shown in Table 3 below.

[0185] (Bending strength) Bending strength (three-point bending) is measured using a full-scale test specimen in accordance with Method B specified in JIS A 5741:2016 (recycled wood-plastic composite material). Bending strength of 20 MPa or more is rated as "S", 15 MPa or more but less than 20 MPa is rated as "A", 10 MPa or more but less than 15 MPa is rated as "B", and less than 10 MPa is rated as "C".

[0186] (Water Resistance) The sample is immersed in warm water adjusted to 60°C. The sample is taken out of the warm water every day and the thickness of the sample is measured. The change rate of thickness compared to the thickness of the sample on the previous day is calculated using the following formula (1): Change rate of sample thickness (%) = (sample thickness - sample thickness on the previous day) / sample thickness on the previous day x 100 (1)

[0187] When the change in thickness of the sample becomes 0.5% or less, it is assumed that the expansion rate of the sample's thickness due to water absorption has reached equilibrium, and the equilibrium expansion rate of the sample's thickness is calculated using the following formula (2). The sample thickness was determined as the average of the thicknesses at five locations: the center of the plane and the areas near each of the four corners. Equilibrium expansion rate (%) = {(Tf - Ti) / Ti} × 100 (2) In formula (2), Tf (unit: mm) is the thickness of the resin composition molded article when the change in thickness becomes 0.5% or less, and Ti (unit: mm) is the thickness of the resin composition molded article before immersion in warm water. Water resistance is evaluated as "S" when the equilibrium expansion rate is 5% or less, "A" when it is 10% or less, "B" when it is more than 10% and 20% or less, and "C" when it is more than 20%.

[0188] (Mold resistance) According to Method A specified in Appendix A (Testing of plastic products) of JIS Z 2911:2018 (Mold resistance test method), the area of ​​the sample on which mycelia have grown after two weeks is measured. Mold resistance is rated as "A" if the growth area is less than 25%, "B" if it is 25% or more but less than 50%, and "C" if it is 50% or more.

[0189] [Examples 2 to 16] Resin composition powders and wood flour were produced in the same manner as in Example 1, except that the conditions for producing the resin composition powder and wood flour were changed as shown in Table 2, and resin composition molded articles were produced using the obtained resin composition powders and wood flour. Table 3 shows the bending strength, water resistance, and mold resistance of the obtained resin composition molded articles.

[0190]

[0191]

[0192] The results shown in Table 3 demonstrate that resin composition powders obtained in Examples 1 to 16, which were subjected to the magnetic material removal treatment, non-magnetic metal removal treatment, water washing treatment, and volume reduction treatment, can be used to obtain resin composition molded articles with excellent bending strength, water resistance, and mold resistance. In particular, the resin composition molded articles obtained in Examples 2 and 11, in which the sieve mesh size of the pulverizer used in the production of the resin composition powder was 1 mm, and in Examples 8 and 16, in which the sieve mesh size was 500 μm, exhibited improved bending strength. This is because the use of resin composition powder that passed through a 1 mm or 500 μm sieve resulted in the dispersion of fine, non-low-melting-point resin particles in the resin composition molded article in an island-like pattern. These results demonstrate that, from the perspective of bending strength of the resin composition molded article, it is preferable for the resin composition powder to be fine, i.e., to be finely ground. On the other hand, finely grinding the resin composition powder tends to reduce the processing capacity and long-term stability of the pulverizer, and it is therefore preferable to use a sieve mesh size of 1 mm or larger in the case of a cutter mill-type pulverizer. Furthermore, the resin composition molded bodies obtained in Examples 4 and 12, in which the sieve used in the mill to produce the wood flour had a mesh size of 500 μm, exhibited improved water resistance. This is because the use of fine wood flour that passed through a sieve with a mesh size of 500 μm as the wood flour, which is a water absorption factor in the water resistance test, allows the wood flour to be efficiently mixed and dispersed in the low-melting-point resin, thereby suppressing changes in water absorption in the resin composition molded body. The results of Examples 1 to 16 confirmed that waste plastic residues that were previously used for thermal recycling can be used for material recycling by performing the magnetic material removal process, non-magnetic metal removal process, water washing process, and volume reduction process according to the present disclosure.

[0193] [Aspect 1] A paving material comprising a main body having a mating front and back surfaces, wherein a thickness direction is defined as a direction perpendicular to the back surfaces, a thickness direction is defined as a direction in the thickness direction when the front surface is viewed from the back surface, a thickness direction is defined as a direction in the thickness direction when the back surface is viewed from the front surface, a thickness direction is defined as a direction in the thickness direction when the back surface is viewed from the front surface, a thickness direction is defined as a direction perpendicular to the thickness direction, and a width direction is defined as a direction perpendicular to the thickness direction and a length direction is defined as a direction perpendicular to the thickness direction and a width direction is defined as a direction perpendicular to the thickness direction and a length direction is defined as a direction perpendicular to the thickness direction and a width direction is defined as a direction perpendicular to the thickness direction and a length direction is defined as a direction [Aspect 3] The paving material according to Aspect 2, wherein the engaging recess is a dovetail groove. [Aspect 4] The paving material according to any one of Aspects 1 to 3, wherein the main body portion is provided with a plurality of the engaging recesses spaced apart in the width direction. [Aspect 5] The paving material according to Aspect 4, wherein at least the rear recesses at both ends in the width direction out of the plurality of rear recesses are the engaging recess. [Aspect 6] The paving material according to Aspect 4 or 5, wherein one engaging recess is provided on the opposite side of the center of the main body portion in the width direction from the other engaging recess. [Aspect 7] The paving material according to Aspect 4, wherein one of the width directions is defined as one width direction side and the other direction is defined as the other width direction side, and the plurality of rear recesses have at least one first engaging recess having the inner circumferential surface formed to sandwich the end of the internal space on the one width direction side in the thickness direction, and at least one second engaging recess having the inner circumferential surface formed to sandwich the end of the internal space on the other width direction side in the thickness direction. [Aspect 8] The paving material according to any one of Aspects 1 to 7, wherein the paving material includes wood particles.[Aspect 9] A paving material according to Aspect 8, comprising a low-melting resin, and non-low-melting resin particles and wood particles dispersed in the low-melting resin, wherein the low-melting resin has a melting point in the range of 80°C or higher but lower than 190°C, and the non-low-melting resin particles comprise at least one of a high-melting resin and a thermosetting resin having a melting point of 190°C or higher. [Aspect 10] The paving material according to any one of Aspects 1 to 9, which is used with the back surface facing the ground, with an adhesive in contact with the back surface. [Aspect 11] A paving application method comprising the steps of placing a substrate on the ground, placing a first adhesive on the substrate, placing a second adhesive on the back surface of the paving material according to any one of Aspects 1 to 10, and joining the first adhesive and the second adhesive.

[0194] 1: Paving material, F1: surface F1, F2: back surface F2, 12, 13, 19A, 19B: back recess, engagement recess, first engagement recess and second engagement recess, 12a, 13a, 19Aa, 19Ba: internal space, 12b, 13b, 19Ab, 19Bb: inner surface, 53: first adhesive (adhesive), 54: second adhesive (adhesive).

Claims

1. A paving material comprising a main body portion having a mating front and back surface, wherein the direction perpendicular to the back surface is defined as the thickness direction, the direction in the thickness direction when looking at the front surface from the back surface is defined as the upper thickness direction, the direction in the thickness direction when looking at the back surface from the front surface is defined as the lower thickness direction, one direction perpendicular to the thickness direction is defined as the length direction, and the direction perpendicular to the thickness direction and the length direction is defined as the width direction, wherein the main body portion is provided with at least one back recess that extends in the length direction and opens downward in the thickness direction, and the back recess has at least one engaging recess having an inner surface formed so as to sandwich at least one of the width direction ends of the internal space in the thickness direction.

2. A paving material as described in claim 1, wherein the engaging recess is located at two different thickness-wise positions within the internal space, and the width dimension of the internal space at the upper thickness-wise position is larger than the width dimension of the internal space at the lower thickness-wise position.

3. The paving material according to claim 2, wherein the engaging recess is a dovetail groove.

4. A paving material according to any one of claims 1 to 3, wherein the main body portion has a plurality of engaging recesses spaced apart in the width direction.

5. A paving material as described in claim 4, wherein at least the rear recesses at both ends in the width direction among the plurality of rear recesses are each the engaging recesses.

6. A paving material as described in claim 4 or 5, wherein one of the engaging recesses is provided on the opposite side of the widthwise center of the main body portion from the other engaging recess.

7. A paving material as described in claim 4, wherein one of the width directions is defined as one width side and the other direction is defined as the other width side, and the multiple rear recesses have at least one first engaging recess having an inner surface formed to sandwich the end of the internal space on one width side in the thickness direction, and at least one second engaging recess having an inner surface formed to sandwich the end of the internal space on the other width side in the thickness direction.

8. A paving material according to any one of claims 1 to 7, wherein the paving material comprises wood particles.

9. A paving material as described in claim 8, comprising: a low melting point resin; and non-low melting point resin particles and wood particles dispersed in the low melting point resin, wherein the low melting point resin has a melting point in the range of 80°C or higher and lower than 190°C, and the non-low melting point resin particles comprise at least one of a high melting point resin and a thermosetting resin having a melting point of 190°C or higher.

10. The paving material according to any one of claims 1 to 9, which is used with the back surface facing the ground, with the adhesive in contact with the back surface.

11. A method for constructing a paving material, comprising the steps of: placing a base on the ground; placing a first adhesive on the base; placing a second adhesive on the back surface of the paving material described in any one of claims 1 to 10; and joining the first adhesive and the second adhesive.

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