JP7110017B2 - Composite sheet for reinforcement - Google Patents

Description

Article 30, Paragraph 2 of the Patent Act applies [Publisher name] Hokkaido Branch of the Japan Society of Civil Engineers [Publication name, volume number, issue number] 2017 Paper Report No. 74 [Date of issue] January 27, 2018

The present invention relates to a reinforcing composite sheet. More particularly, it relates to a reinforcing composite sheet suitable for reinforcing floors and walls of concrete structures.

In recent years, there have been an increasing number of incidents in which structures are subjected to collisions, such as debris flows, falling rocks and tornadoes due to abnormal weather, cinders due to volcanic activity, and bombings due to terrorism. Until now, EPS (Expanded Polystyrene) has been used as a cushioning material as one of the countermeasures for mitigating the impact force. In addition, as a method of effectively exerting its cushioning performance, a two-layer cushioning structure in which an RC plate is placed on EPS and a three-layer cushioning structure in which sand is further placed have been developed and put into practical use (non-patent literature). 1).

However, these buffer structures use a highly rigid member such as an RC plate as a surface layer material to disperse the impact force, but because of their heavy weight, heavy machinery is required for construction.

On the other hand, it is considered possible to develop a cushioning structure that can be transported by human power by adopting a material that is lightweight and has excellent impact resistance for the surface layer material. Until now, it has been clarified that the impact resistance of wood can be dramatically improved by bending and reinforcing wood with an aramid fiber sheet (Non-Patent Document 2).

Therefore, it is conceivable that a lightweight and high-performance multi-layer cushioning structure can be constructed by arranging a surface layer material such as a wooden board whose lower surface is reinforced with a high-strength fiber sheet such as aramid fiber on EPS.

Hisashi Konno, Hiroaki Nishi, Yuji Ushiwatari, Yusuke Kurihashi, Tokumitsu Kishi: Numerical Analysis of Impact Resistant Behavior of RC Rock Shed with Three-layer Buffer Structure, Journal of Structural Engineering, Vol.61A, pp.1024-1033 ,2015.3 Kazutaka Ikeda, Yusuke Kurihashi, Masato Komuro, Hidetoshi Sakai, Taiichi Okada, Tomohisa Saito: Impact Loading Test of Wood Adhered with Aramid Fiber Sheet Using Thermoplastic Resin, Journal of Japan Society of Civil Engineers Hokkaido Branch, No.73, CD-ROM, A-48, 2017.

SUMMARY OF THE INVENTION An object of the present invention is to provide a reinforcing composite sheet having a lightweight, high-performance multilayer cushioning structure and excellent impact resistance.

In order to achieve the above object, the present inventors conducted extensive studies, and as a result, found that a reinforcing composite sheet having light weight and excellent impact resistance can be obtained with the following configuration, and completed the present invention.

That is, the present invention is as follows.

(1) Surface layer material and at least one selected from the group consisting of organic fibers and inorganic fibers having a tensile strength of 16 cN / dtex or more measured according to JIS L 1013 8.5. 1. A composite sheet for reinforcing a concrete structure, comprising a fiber sheet made of fabric containing strength fibers (excluding glass fibers) and a cushioning material, which are laminated in order via an adhesive.
(2) The composite sheet for reinforcing a concrete structure according to (1) above, wherein the surface layer material is a wooden material.
(3) The concrete structure according to (1) or (2) above, wherein the fabric includes at least one selected from the group consisting of woven fabric, knitted fabric, nonwoven fabric, felt and unidirectional sheet (UD). Composite sheet for reinforcement.
(4) The composite sheet for reinforcing a concrete structure according to any one of (1) to (3), wherein the fabric has a basis weight of 50 g/m ² to 1,000 g/m ² per sheet.
(5) The cushioning material is a foam made of at least one synthetic resin material selected from polyethylene, polystyrene, acrylonitrile/styrene copolymer, acrylonitrile/butadiene/styrene copolymer, polyester, and polyurethane. A composite sheet for reinforcing a concrete structure according to any one of 1) to (4).
(6) The composite sheet for reinforcing a concrete structure according to (5) above, wherein the foam is a polystyrene-based resin foam produced by a bead method.
(7) The composite sheet for reinforcing a concrete structure according to any one of (1) to (6) above, wherein the adhesive is an epoxy resin.
(8) Concrete characterized by placing the composite sheet for reinforcing a concrete structure according to (1) above in a concrete layer so that the cushioning material constituting the reinforcing composite sheet is placed on the upper surface of the concrete layer. Reinforcement method for steel structures.

According to the present invention, it is possible to provide a reinforcing composite sheet that is lightweight and has excellent impact resistance. This type of reinforcing composite sheet can be used at high-rise building construction sites in place of the conventional multi-layer cushioning structure, which was difficult to install and remove due to its heavy weight. It can be a protective measure. By taking protective measures on sites where construction was limited to nighttime due to the danger of falling materials, construction can be done during the daytime, and construction costs can be greatly reduced.

1 is an explanatory diagram of a reinforcing composite sheet according to the present invention; FIG. It is a schematic diagram of a test body subjected to a weight drop. It is a figure which shows various response waveforms. It is a figure which shows the damage condition of a composite board. It is a figure which shows the condition of the center part cut surface of an EPS block.

As shown in FIG. 1, the reinforcing composite sheet 1 of the present invention includes (A) a surface layer material 2, (B) a fiber sheet 3 made of one or more pieces of fabric containing high-strength fibers, and (C) a cushioning material. It is composed of three layers of 4, which are laminated in order via an adhesive.

(A) The surface layer material is formed on the opposite side of the cushioning material with the fiber sheet sandwiched therebetween. The surface layer material preferably has excellent impact resistance, and various materials can be used depending on the application of the reinforcing composite sheet. Examples thereof include wood materials, resin materials such as polycarbonate resin, fiber-reinforced resin materials, and non-wood materials such as gypsum board. A wooden material is preferable from the viewpoint of lightness, workability, and the like.

Although the thickness of the surface layer material is not particularly limited, it is preferably 2 mm or more, more preferably 7 mm or more, in order to obtain impact resistance. Although there is no particular upper limit, the thickness is preferably 50 mm or less because excessive thickness increases the weight.

Examples of the above wooden materials include veneer, laminated veneer lumber (LVL), plywood in which veneers are bonded with an adhesive, particle board (PB), fiberboard (MDF, etc.), OSB (Oriented Strand Board), laminated wood, block board, wooden composite material, and the like.
Laminated veneer lumber is a wooden board obtained by laminating a plurality of veneers obtained by thinly slicing wood with the fiber direction facing the same direction and bonding them by heat and pressure.
Plywood is a wooden board obtained by laminating a plurality of veneers obtained by thinly slicing a piece of wood so that the fiber directions are staggered, and bonding them by heat and pressure. Plywood includes softwood plywood and hardwood plywood.
A particle board is a wooden board obtained by mixing small pieces obtained by cutting or crushing wood with an adhesive to form a mat, and then hot-pressing the mat.
A fiberboard is a wooden board obtained by mixing small pieces obtained by steaming or defibrating wood with an adhesive to form a mat, and then hot-pressing the mixture. Fiberboards include MDF (medium density fiberboard), hardboard (HB), and insulation board.
OSB is made by orienting, laminating and bonding thin flake-shaped raw materials.
Laminated lumber is obtained by laminating sawn boards or small rectangular lumbers parallel to each other in the fiber direction and laminating them in the length, width, and thickness directions.
A block board is made by gluing block-shaped pieces into a plate.

A wooden composite material is obtained by bonding a surface decorative material, a fiber mat, or the like to one or both surfaces of the wooden board via an adhesive. Examples of shapes include films, sheets, and plates. Examples of the surface decorative material include sliced veneer, paper, olefin resin sheet, vinyl chloride resin sheet, and melamine impregnated paper. Examples of nonwoven mats include nonwoven mats made of fiber materials including cotton fiber, hemp fiber such as kenaf fiber and jute fiber, bamboo fiber, and vegetable fiber such as palm fiber such as oil palm and coco palm.

(B) The fiber sheet is composed of one or more fabrics. The fabric is a fabric containing high-strength fibers, and fibers other than high-strength fibers, such as nylon fibers, polyester fibers, rayon fibers, etc., are included as long as they do not affect the impact resistance of the reinforcing composite sheet of the present invention. It may be The fibers or fabrics described above may contain various additives that are commonly used to improve the productivity or properties in the manufacturing process or processing process of the raw yarn. For example, heat stabilizers, antioxidants, light stabilizers, smoothing agents, antistatic agents, plasticizers, thickeners, pigments, flame retardants, oils and the like can be contained or attached.

The high-strength fiber preferably has a tensile strength of 16 cN/dtex or more, more preferably 18 cN/dtex or more, and still more preferably 19 cN/dtex or more, in order to obtain a fabric with high yield strength. Tensile strength is a value measured according to JIS L 1013 8.5.

Examples of high-strength fibers include organic fibers such as para-aramid fibers, polyarylate fibers, PBO (polybenzobisoxazole) fibers, and high-strength polyethylene fibers; inorganic fibers such as carbon fibers. At least one selected from the group is used. Among these high-strength fibers, para-aramid fibers are preferred in terms of flexibility, light weight, resistance to breakage, and ease of handling at construction sites. Examples of para-aramid fibers include polyparaphenylene terephthalamide fibers and copolyparaphenylene-3,4'-oxydiphenylene terephthalamide fibers. Among these para-aramid fibers, high elasticity Polyparaphenylene terephthalamide fibers are particularly preferred in terms of their modulus.

The high-strength fibers preferably have a single filament fineness of 0.5 to 7 dtex in terms of resin impregnation and ease of handling such as cutting at construction sites. Further, the yarn fineness of the fabric is preferably 1,500 to 5,000 dtex in consideration of the fiber density per unit width for impregnating the adhesive and the balance between maintaining the strength of the fabric. If it is 1,500 dtex or more, it is possible to obtain a fabric with good adhesive impregnation and high yield strength.

A fabric can be produced using the fibers described above and used as a material for a fiber sheet. The fabric preferably includes at least one selected from the group consisting of woven fabrics, knitted fabrics, non-woven fabrics, felts and unidirectional sheets (UD; fibers aligned in one direction). A unidirectional sheet laminate in which the UDs are laminated at different angles in the alignment direction, for example, a unidirectional sheet laminate laminated at 0 ° / 90 ° (when the alignment direction of a certain UD is 0 °, the following It means that the UD alignment direction of the layers is laminated by 90°.) can be preferably used. A woven fabric is more preferably used in terms of dimensional stability and strength.

Examples of the weaving structure of the fabric include plain weave, twill weave, satin weave, basket weave, satin weave, cedar weave, ribbed weave, and double weave. Woven fabrics are preferred. The knitting structure of the fabric may be either weft knitting or warp knitting, and plain knitting, rubber knitting, pearl knitting, multiaxial knitting, and the like are preferable.

Also, if a fabric is used, it preferably includes at least one fabric selected from the group consisting of bi-directional fabrics and multi-directional (three-way, four-way, etc.) fabrics. In particular, bidirectional fabrics have good resin impregnation properties even for fabrics with a relatively high crossing ratio of warp and weft, and have the advantage of being less likely to cause misalignment of warp and weft when handling reinforcing fabrics. There is The density of the warp and weft threads in the bidirectional fabric is preferably between 8 and 18 threads/cm. If the thread density is 8 threads/cm or more, the woven fabric can be imparted with yield strength, and if the thread density is 18 threads/cm or less, it is possible to impart good adhesive impregnating properties.

From the standpoint of strength, it is preferable to use two or more layers of the fabric, but it is also possible to use only one layer. For example, a fabric obtained by laminating a woven fabric and a woven fabric, a woven fabric and a knitted fabric, a woven fabric and a non-woven fabric, or a woven fabric and UD can be used.

When a plurality of fabrics are laminated and used, it is possible to prevent the fabrics from coming apart and to improve the yield strength of the fabrics by using the fabrics that are bonded in advance with an adhesive or the like. As the adhesive, an adhesive to be described later can be used.

The fabric preferably has a basis weight of 50 g/m ² to 1,000 g/m ² , more preferably 100 to 800 g/m ² , still more preferably 150 to 600 g/m ² . If the basis weight is too large, it becomes difficult to impregnate the adhesive in a short period of time, which may lead to poor adhesion. On the other hand, if the basis weight is too small, the resulting reinforcing composite sheet may have insufficient impact absorption. The fabric preferably has gaps (pores) large enough to be impregnated with the adhesive.

(C) As the cushioning material, synthetic resin foam, thermosetting elastomer (rubber), thermoplastic elastomer, fiber mat material, etc. can be used. , a synthetic resin foam can be preferably used. The density of the synthetic resin foam is preferably 10 kg/m ³ or more and 40 kg/m ³ or less, and more preferably 15 kg/m ³ or more and 30 kg/m ³ or less, in order to obtain good load resistance and breaking strength. It is more preferable to have

Since the synthetic resin foam has feeder marks and filling holes on the surface when it is removed from the molding die, remove these and grind one or both sides of the foamed resin so that the thickness deviation value is 1 mm or less. It is preferably homogenized as follows.

The method for foaming the synthetic resin composition is not particularly limited, but it is preferable to use the bead method because a homogeneous synthetic resin foam can be obtained. In the bead method, foamed resin particles made of a foamed resin composition impregnated with a foaming agent are filled into a cavity of a mold, and the filled foamed resin particles are subjected to secondary expansion with steam while the pre-expanded particles are heated. In this method, a resin foam is obtained by integrating by fusion.

Synthetic resins include polyolefin resins such as polyethylene and polypropylene, polystyrene resins such as polystyrene, acrylonitrile-styrene copolymer, and acrylonitrile-butadiene-styrene copolymer, polyester resins such as polyethylene terephthalate, polyurethane resins, and polyamide resins. or a mixed resin of these thermoplastic resins. Among these resins, polyolefin-based resins or polystyrene-based resins are preferable, and polystyrene-based resins are more preferable, in consideration of the strength of the resin itself.

The thickness of the cushioning material is preferably 5 mm or more, more preferably 10 mm or more, in order to obtain good load resistance and breaking strength. Moreover, if the thickness is too large, the handleability is deteriorated, so from the viewpoint of the balance between handleability and impact resistance, the thickness is preferably 50 mm or less.

In the reinforcing composite sheet according to the present invention, a surface layer material and a fiber sheet (one sheet or a plurality of sheets) are bonded with an adhesive to produce a composite plate, and then an adhesive is applied to the fiber sheet surface of the composite plate. It can be manufactured by using and adhering a cushioning material. When the fiber sheet is composed of a plurality of fabrics, each fabric is impregnated or coated with an adhesive, and then the fabrics impregnated and coated with the adhesive are laminated in order, and the adhesive is cured to produce a fiber sheet. When a nonwoven fabric is used as the fabric, the laminated nonwoven fabric can be impregnated with an adhesive. Alternatively, it can also be produced by bonding the fiber sheet and the cushioning material with an adhesive, then superimposing the surface layer material on the opposite side of the fiber sheet from the cushioning material, and bonding the cushioning material with an adhesive.

As the type of adhesive used for forming the adhesive layer, it is generally preferable to use a synthetic adhesive. For example, acrylic resin system, urethane resin system, α-olefin system, ether system, ethylene-vinyl acetate resin system, epoxy resin system, vinyl chloride resin system, chloroprene rubber system, cyanoacrylate system, silicone system, styrene-butadiene rubber system , phenolic resins, polyamide resins, polyimide resins, and polyolefin resins. It is possible to make suitable changes according to the types of fibers, surface layer materials and cushioning materials. Among the adhesives described above, epoxy resins are preferred from the viewpoint of excellent handleability and adhesiveness to high-strength fibers. The epoxy resin may contain a rubber component (carboxyl-modified nitrile rubber, acrylic rubber, etc.) for imparting flexibility, or a tackifier.

The thickness of the adhesive layer is preferably in the range of 10-500 μm, more preferably 50-200 μm. When the thickness is 10 μm or more, the effect of the adhesive is exerted, and peeling between the surface layer material and the fiber sheet can be prevented. Further, if the thickness is 500 μm or less, the effort and weight reduction during application are not significantly impaired.

The method of applying and curing the adhesive can be changed according to the recommended conditions for use according to the type of adhesive used, but the method of application is not particularly limited. Also, the surface to which the adhesive is applied can be any of the surface layer material, the fiber sheet, and the cushioning material. This is a preferred embodiment. Moreover, it is preferable that the adhesive is applied to all the adherends after the temperature has been cooled down to room temperature. Such coating can prevent the material to be adhered from warping during the cooling process.

In the reinforcing composite sheet of the present invention, it is presumed that the surface layer material has a shock reducing action, the fiber sheet has a shock dispersing action, and the cushioning material has a shock absorbing action. From this point of view, it is desirable to use the cushioning material of the reinforcing composite sheet placed on the upper surface of the concrete layer, so that the concrete layer will not be destroyed by the impact caused by the fall of heavy objects, the collision of high-speed flying objects, etc. can be prevented or mitigated.

In addition, in the reinforcing composite sheet of the present invention, the impact resistance is improved by bonding the fiber sheet to the surface layer material, and resin foam (particularly, bead method polystyrene resin foam (EPS )) reduces and localizes the shear resistance. Therefore, since the surface layer material, the fiber sheet and the cushioning material form a double cushioning structure, the sheet has excellent impact resistance.

EXAMPLES The present invention will be described in more detail with reference to Examples below, but the present invention is not limited to them.

[Materials used in experiments]
1) EPS (Expanded Poly Styrene; bead method expanded polystyrene)
Product name: Styrodiablock, model D-20 (JSP Co., Ltd.)
Main component: Polystyrene Expansion ratio: 50
Unit volume weight (kN/m ³ ); 0.212
2) Commercial concrete formwork plywood (JAS standard, thickness 9mm)
Size: 900 mm square 3) Rolled steel for general structure (SS400, thickness 3.2 mm)
Size: 914 mm square 4) Bi-directional para-aramid fiber (Kevlar (R)) sheet (hereinafter "AFRP sheet")
Size; 1,000 mm square Weight per area (g/m ² ); 435/435
Guaranteed yield strength (kN/m); 588/588
Thickness (mm); 0.286/0.286
Tensile strength (GPa); 2.06
Elastic modulus (GPa); 118
Breaking strain (%); 1.75
Polyparaphenylene terephthalamide fiber (total fineness 3,160 dtex, single yarn fineness 1.58 dtex, filament number 2,000, single yarn strength 20.8 cN/dtex) manufactured by Toray DuPont Co., Ltd. is used as warp and weft. , a four-ply satin (4x4) fabric was woven using a rapier loom. The warp density of the fabric is 13 threads/cm, the weft density is 13 threads/cm.
5) Epoxy adhesive; Gripbond GB-35 manufactured by Sumitomo Rubber Industries, Ltd.

(Example 1)
When adhering to a concrete formwork plywood, use sandpaper to roughen the AFRP sheet adhesion area, remove impurities and degrease with a rag containing acetone, and then apply a primer to the sheet adhesion area. After confirming that the primer was dry to the touch, the AFRP sheet was placed on the reinforced area and adhered using an epoxy-based impregnated adhesive resin. The curing period is about 7 days. When adhering to the steel material, no primer was used, and other than that, the same procedure as in the case of formwork plywood was used to perform the adhesion work.

Table 1 shows a list of specimens.

[Weight drop test]
A steel weight having a mass of 300 kg and a tip diameter of 200 mm was allowed to freely fall from a predetermined height through a linear rail to the center of the specimen (see FIG. 2). The weight drop height was 0.5 m, 1.0 m, and 1.5 m.
The measurement items in this experiment are weight impact force and weight penetration amount. The amount of penetration of the weight was evaluated by installing a laser displacement gauge vertically upward and measuring the distance from the L-shaped angle attached to the weight. These measured values were collectively recorded at a sampling frequency of 10 kHz using a memory recorder. During the weight drop experiment, a high-speed camera was used to confirm the deformation and fracture properties of the specimen. After the experiment was completed, the state of adhesion of the composite plate was checked, and the foam material was cut at the center to observe residual deformation.

[Experimental result]
Waveforms related to (a) weight impact force, (b) weight penetration amount, and (c) impact force-penetration amount relationship of each specimen were obtained for each weight drop height. In addition, (d) the state of the specimen after the weight drop test was observed.

(a) Weight impact force Fig. 3(a) shows the weight impact force waveform of each specimen. At a weight drop height of 0.5 m, the weight impact force waveform of the N-IS test piece without the composite plate shows waveform characteristics with a maximum amplitude of about 15 kN and a duration of about 180 ms. On the other hand, the WA/SA-IC specimen on which the composite plate is installed exhibits waveform characteristics with a maximum amplitude of about 55 to 60 kN and a duration of about 50 ms. From this, it can be seen that the weight impact force increases by about 3.5 to 4.0 times by installing the composite plate.
At a weight drop height of 1.0 m, the maximum impact force of the WA-IC specimen is about 80 kN, while the maximum impact force of the SA-IC specimen is about 50 kN. As will be described later, in the case of the SA-IC specimen, this is presumed to be due to the separation of the AFRP sheet from the steel plate.
In the case of the WA-IC test piece at a weight drop height of 1.5 m, the impact force drops sharply after reaching the maximum weight impact force, but shows a constant value at about 35 kN. As will be described later, this is presumed to be due to EPS absorbing the impact energy after the composite wood plate was damaged and lost its resistance. Similar properties were also confirmed in the case of a single-loaded WA-IS2.0 specimen with a drop height of 2.0 m.

(b) Weight Penetration Amount FIG. 3(b) shows the weight penetration amount waveform of each specimen. At a weight drop height of 0.5 m, the maximum penetration amount of the N-IS test specimen without the composite plate was about 160 mm, which is 64% in terms of penetration strain. On the other hand, in the case of the WA/SA-IC specimen with the composite plate installed, the maximum penetration depth was about 40 mm. From this, it can be seen that penetration into the EPS is suppressed by installing the composite plate.
At a weight drop height of 1.0 m, both the WA-IC specimen and the SA-IC specimen have a maximum penetration depth of about 60 mm, but their restoring characteristics are different. That is, the recovery speed of the SA-IC specimen is slower than that of the WA-IC specimen. This is presumably because the delamination of the AFRP sheet lowered the restoration performance.
The maximum penetration depth of the WA-IC/IS test specimen increased as the weight drop height increased, and was about 90 mm in the case of 2.0 m. However, as will be described later, almost no residual deformation occurs in the EPS.

(c) Impact Force-Penetration Amount Relationship FIG. 3(c) shows the impact force-penetration amount relationship of each specimen. At a weight drop height of 0.5 m, in the case of the N-IS specimen without the composite plate, the weight impact force is small and the penetration amount is large. On the other hand, in the case of the WA/SA-IC test body in which the composite plate was installed, the weight impact force was large and the amount of penetration was small, indicating that the rigidity was large.
Comparing the SA-IC and WA-IC specimens at a weight drop height of 1.0 m, the former has a higher initial stiffness, but a smaller maximum impact force. It is presumed that this is due to the peeling of the AFRP sheet placed on the SA-IC test body.
At a weight drop height of 1.5 m, the impact force decreases after the maximum weight impact force impacts, but the displacement passes through a constant value and decreases from a certain load. This is presumed to be due to EPS absorbing the impact energy after the wood composite plate installed on the WA-IC test piece was damaged. Similar properties were confirmed in the case of a single load with a drop height of 2.0 m.
The reason why the weight impact force increased by installing the composite plate is presumed to be that after the weight collided with the highly rigid composite plate, the impact force was dispersed and the response area of the EPS expanded. be. On the other hand, as will be described later, since the deformation of the EPS is slight, it is presumed that the transmitted impact stress is small (about 0.2 MPa).

(d) Situation after weight drop test In the case of the N-IC0.5 specimen without the composite plate, it was confirmed that the weight penetrated the EPS. On the other hand, in the case of the SA-IC1.0 test body in which the steel + AFRP sheet composite plate (hereinafter referred to as the steel composite plate) was installed, it was confirmed that the steel plate around the weight collision lifted up and the AFRP sheet was peeled off. In the case of the WA-IC1.5 specimen using the wood composite board, it is confirmed that the form plywood cracks and rises. However, the AFRP sheet was not peeled off.

FIG. 4 shows the state of damage to the composite plate. In the case of the SA-IC1.0 test piece, the steel material was greatly deformed in the out-of-plane direction, and the AFRP sheet completely peeled off. On the other hand, in the case of the WA-IC1.5 test piece, the form plywood cracked on the front surface, and the sheet partially broke on the back surface.

FIG. 5 shows the state of the central section of the EPS. In the case of the N-IS0.5 test piece without the composite plate, it is confirmed that there is a depression of the same size as the weight diameter and a crack is generated obliquely downward. On the other hand, in the case of SA-IC1.0 and WA-IC1.5 specimens on which the composite plate was installed, the maximum residual deformation was about 60 mm and 85 mm respectively, but it was found in the N-IS0.5 specimen. No cracks were found. From these facts, it was clarified that the cushioning effect was improved by placing the composite plate on the EPS. In particular, since the wood and the AFRP sheet have a high adhesion performance, it has been clarified that the cushioning performance can be improved by about four times. Also, referring to Table 1 above, the weight specific energy obtained by dividing the input energy by the weight of the cushioning structure is the N-IS0.5 specimen, the SA-IC1.0 specimen, the WA-IC1.5 specimen and the WA -24.0, 10.8, 49.7 and 65.4 (J/N) for IS2.0 test specimens, respectively. In addition, it is considered that the cushioning structure has an excellent cushioning effect.

A weight drop test was conducted for the purpose of examining the cushioning effect of a two-layer cushioning structure in which a composite plate made of wooden and steel plates reinforced with an AFRP sheet was placed on EPS. The findings obtained in this experiment are summarized as follows.
・Irrespective of the type of plate material, placing a composite plate reinforced with AFRP sheet on top of EPS can greatly improve its cushioning performance.
・When a steel material composite plate is used, the AFRP sheet peels off. On the other hand, when a wood sheet composite plate was used, the sheet was partially broken without peeling.
・The adhesion between the wood and the AFRP sheet is extremely high, and it can be applied to a double-layer cushioning structure as a composite board that is lightweight and has excellent impact resistance.

Since the reinforcing composite sheet of the present invention is lightweight and has excellent impact resistance, work efficiency and economic efficiency are required for concrete structures such as tunnels, bridge piers, floor slabs and walls of buildings. It is useful for reinforcing structures that are

1 Reinforcing composite sheet 2 Surface layer material 3 Fiber sheet 4 Cushioning material

Claims (8)

At least one high-strength fiber selected from the group consisting of a surface layer material and one or more organic fibers and inorganic fibers having a tensile strength of 16 cN / dtex or more measured according to JIS L 1013 8.5 ( 1. A composite sheet for reinforcing a concrete structure , characterized by comprising a fiber sheet made of a cloth containing glass fiber, excluding glass fiber, and a cushioning material, which are laminated in order via an adhesive. The composite sheet for reinforcing a concrete structure according to claim 1, wherein the surface layer material is a wooden material. The composite sheet for reinforcing a concrete structure according to claim 1 or 2, wherein said fabric comprises at least one selected from the group consisting of woven fabric, knitted fabric, non-woven fabric, felt and unidirectional sheet (UD). The composite sheet for reinforcing a concrete structure according to any one of claims 1 to 3, wherein the fabric has a basis weight of 50 g/m ² to 1,000 g/m ² per sheet. Claims 1 to 4, wherein the cushioning material is a foam made of at least one synthetic resin material selected from polyethylene, polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene copolymer, polyester, and polyurethane. The composite sheet for reinforcing a concrete structure according to any one of . The composite sheet for reinforcing a concrete structure according to claim 5, wherein the foam is a polystyrene-based resin foam produced by a bead method. The composite sheet for reinforcing a concrete structure according to any one of claims 1 to 6, wherein the adhesive is an epoxy resin. A concrete structure, characterized in that the composite sheet for reinforcing a concrete structure according to claim 1 is installed in a concrete layer so that the cushioning material constituting the reinforcing composite sheet is on the upper surface of the concrete layer. Reinforcement method.

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