Fiber sheet material for reinforcing civil engineering and building structures

Abstract

To provide a fiber sheet material for reinforcing civil engineering and architectural structures, showing excellent and stable high-level strength (Young's modulus) and final strain in a reinforcing method for civil engineering and architectural structures using a continuous fiber sheet, and showing excellent and stable reinforcing effect even when workability and productivity are required.SOLUTION: A fiber sheet material used for reinforcing civil engineering and architectural structures is composed of reinforcing cloth formed of high strength fiber and matrix resin. The high strength fiber is formed of polyparaphenylene terephthalamide fiber, and has a final strain of 3.0% or more along the reinforcing fiber orientation of the fiber sheet material, measured by a method described in JIS A1191.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a fiber sheet material used for reinforcing civil engineering and architectural structures, which is composed of a reinforcing fabric made of high-strength fibers and a matrix resin. [Background technology]

[0002] There are many concrete buildings, such as railway viaducts and highway viaducts, but they face problems such as earthquake reinforcement to protect against destruction in earthquakes and improving durability to cope with increasing traffic volumes. In addition, there are historical structures, such as stone lighthouses, brick buildings, and concrete or brick chimneys, that require extending their lifespan and earthquake reinforcement.

[0003] Even if the earthquake resistance is sufficient, there are many cracks and parts that have spalled due to drying shrinkage of concrete and external pressure, and these are also being repaired.Methods of reinforcing and repairing concrete structures include covering the concrete columns of the target railway viaduct with steel plates, or attaching or wrapping reinforcing fiber sheets such as aramid fiber or carbon fiber on the concrete surface.

[0004] The method of covering with steel plates requires the use of heavy steel plates, and therefore requires heavy machinery and sturdy scaffolding for construction. It also requires welding equipment and skilled workers. On the other hand, the method of wrapping reinforcing fiber sheets made of aramid fiber or carbon fiber (commonly referred to as the "continuous fiber reinforcement method" or "fiber sheet reinforcement method") does not require heavy machinery to handle heavy loads, is easy to construct, can be easily constructed in narrow spaces, and has the advantage of shortening the construction period, making it increasingly popular.

[0005] Fiber sheet reinforcement and repair methods involve adhering high-tensile strength reinforcing fiber sheets, such as carbon fiber or aramid fiber, to the surface of concrete using a matrix resin, such as epoxy resin, vinyl ester resin, unsaturated polyester resin, or phenolic resin. The epoxy resin not only adheres the fiber sheet to the concrete, but also impregnates the fiber sheet, improving its strength and acting as a medium for transferring the strength of the fiber sheet to the concrete.

[0006] There are various methods for reinforcing concrete with fiber sheets depending on the purpose. For example, for concrete columns that have been assessed to have insufficient shear reinforcement steel against lateral shaking during an earthquake, attaching fiber sheets by wrapping them perpendicular to the axial direction can shift the concrete column's failure mode from a shear failure mode with low ductility to a flexural failure mode with high ductility, making it possible to buy time before collapse (time to evacuate). It is known that the main required properties of fiber sheets for this shear reinforcement are strength and Young's modulus.

[0007] Furthermore, even for concrete columns that are subject to bending failure mode, it is considered important for safety design that the ductility shown in the following formula (III) be 1.0 or less (see Concrete Library 101, Guidelines for Repair and Reinforcement of Concrete Structures Using Continuous Fiber Sheets (Japan Society of Civil Engineers)). The design ductility rate can be increased by fiber sheet reinforcement, and the greater the ultimate strain of the fiber sheet, i.e., the greater the breaking elongation of the fiber sheet, the better.

[0008] gamma i ×μ ud / μ d (III) gamma i : structural coefficient (calculated at 1.0), μ rd : Design plasticity modulus, μ d : Design toughness factor

[0009] In Patent Document 1, the resin impregnation of the reinforcing fiber sheet and the yield strength of the resin-impregnated sheet are improved by penetrating and impregnating a compatibilizer containing the same oligomer as the matrix resin into the fiber skeleton that constitutes the reinforcing fiber sheet material. However, this requires a process of applying a surface treatment agent to the fiber skeleton in advance, which results in poor productivity. Furthermore, the breaking elongation as a reinforcing fiber sheet material is insufficient, resulting in poor toughness performance.

[0010] Patent Document 2 proposes a reinforcing fiber sheet that has high reinforcing strength, is lightweight, and has excellent resin impregnation properties, achieved by using high-strength polyethylene fibers and appropriately allocating the warp cover factor and weft cover factor. However, high-strength polyethylene fibers have poor adhesive properties with epoxy resins, which hinders stress transmission, making it difficult for the fiber to exhibit various reinforcing functions.

[0011] Patent Document 3 proposes a reinforcing fiber sheet using vinylon fiber that is excellent in alkali resistance, reinforcing effect, and workability. However, vinylon fiber itself has low strength, making it difficult to achieve sufficient sheet strength, and requires ingenuity such as laminating multiple sheets. In addition, the fiber itself has a low elastic modulus, so the shear reinforcement effect is insufficient.

[0012] Patent Document 4 describes a reinforced fiber sheet using a three-component para-aramid fiber (copolyparaphenylene-3,4'-oxydiphenylene terephthalamide fiber), but this is more expensive than a reinforced fiber sheet using a two-component para-aramid fiber (polyparaphenylene terephthalamide fiber). [Prior art documents] [Patent documents]

[0013] [Patent Document 1] Japanese Patent Application Publication No. 2018-172823 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-88652 [Patent Document 3] Japanese Patent Application Laid-Open No. 2004-238757 [Patent Document 4] Japanese Patent Application Publication No. 10-37051 Summary of the Invention [Problem to be solved by the invention]

[0014] The present invention has been made in consideration of the above circumstances, and aims to provide a fiber sheet material for reinforcing civil engineering and building structures that exhibits very good and stable high levels of strength (Young's modulus) and ultimate strain, and also has excellent workability and productivity, in a civil engineering and building reinforcement method using a continuous fiber sheet. [Means for solving the problem]

[0015] As a result of earnest research into achieving the above-mentioned object, the inventors have discovered that in a civil engineering and building reinforcement method using a continuous fiber sheet, by using a continuous fiber sheet that combines high levels of strength (Young's modulus) and ultimate strain, it is possible to obtain excellent shear reinforcement effects and improved ductility, and further to provide a fiber sheet material for reinforcing civil engineering and building structures that is easy to work with and productive, and have thereby arrived at the present invention.

[0016] That is, the present invention provides a reinforcing fiber sheet material used for reinforcing civil engineering and architectural structures, which is composed of a reinforcing fabric made of high-strength fibers and a matrix resin, The high strength fiber The breaking elongation measured according to the method described in JIS L1013 is 4.0% or more, the tensile strength is 23 cN / dtex or more, and the tensile modulus is 400 cN / dtex or more. Consists of polyparaphenylene terephthalamide fibers It is something that and the ultimate strain along the orientation of the reinforcing fibers of the fiber sheet material measured by the method described in JIS A1191. of 3.0% or more By doing so, the toughness of the fiber sheet material can be obtained. The present invention provides a fiber sheet material for reinforcing civil engineering and building structures, characterized by the above-mentioned. [Effects of the Invention]

[0017] According to the present invention, in a civil engineering and building reinforcement method using a continuous fiber sheet, by using a continuous fiber sheet that combines high levels of strength (Young's modulus) and ultimate strain, it is possible to obtain excellent shear reinforcement effects and improved toughness, and it is also possible to provide a fiber sheet material for reinforcing civil engineering and building structures that is easy to work with and productive. [Brief explanation of the drawings]

[0018] [Figure 1] A photo of one-way fabric. [Figure 2] Photo of two-way fabric (plain weave). [Figure 3] A photo of two-way fabric (NCF (non-crimp fabric)). DETAILED DESCRIPTION OF THE INVENTION

[0019] The fiber sheet material for reinforcing civil engineering and architectural structures of the present invention is characterized in that it is composed of a reinforcing fabric made of polyparaphenylene terephthalamide fiber and a matrix resin, and has an ultimate strain of 3.0% or more along the orientation of the reinforcing fibers of the fiber sheet material, measured according to the method described in JIS A1191.

[0020] <High-strength fiber> Fiber materials used to repair and reinforce concrete structures must be strong, elastic, and tough because they must be able to withstand extremely large amounts of energy. Examples of such materials include organic fibers such as para-aramid fiber, polyarylate fiber, and PBO (polybenzobisoxazole) fiber, as well as inorganic fibers such as carbon fiber. Among these, para-aramid fiber is preferred for its flexibility, light weight, resistance to breakage, insulating properties, and ease of handling at construction sites. Examples of para-aramid fibers include polyparaphenylene terephthalamide fibers (such as Kevlar (registered trademark) manufactured by Toray DuPont and Twaron (registered trademark) manufactured by Teijin Limited), and copolyparaphenylene-3,4'-oxydiphenylene terephthalamide fibers (such as Technora (registered trademark) manufactured by Teijin Limited). Of these para-aramid fibers, it is extremely important in the present invention to use polyparaphenylene terephthalamide (hereinafter sometimes abbreviated as "PPTA") fibers, which have high strength, high elasticity, high toughness and an excellent cost balance.

[0021] The polyparaphenylene terephthalamide fiber used in the fiber sheet material for reinforcing civil engineering and building structures of the present invention preferably has a breaking elongation of 4.0% or more, as measured by the method described in JIS L1013:2010, "Testing Methods for Chemical Fiber Filament Yarns." The fiber sheet material for reinforcing civil engineering and building structures of the present invention is composed of polyparaphenylene terephthalamide fiber and a matrix resin, and the polyparaphenylene terephthalamide fiber is responsible for most of the mechanical properties of the fiber sheet material for reinforcing civil engineering and building structures. Therefore, if the breaking elongation of the polyparaphenylene terephthalamide fiber is less than 4.0%, depending on the composition of the fiber sheet, the reinforcing effect may be reduced, resulting in the fiber sheet material for reinforcing civil engineering and building structures having a breaking elongation of less than 3.0%, which is an inconvenience.

[0022] On the other hand, if the breaking elongation of the polyparaphenylene terephthalamide fiber is 4.0% or more, when a fiber sheet material for reinforcing civil engineering and building structures is prepared, the fiber sheet material can exhibit sufficient toughness (ultimate strain). The breaking elongation of the polyparaphenylene terephthalamide fiber is preferably 4.1% or more, more preferably 4.2% or more. If the breaking elongation of the polyparaphenylene terephthalamide fiber is thus high, the thickness of the fiber sheet material for reinforcing civil engineering and building structures can be reduced, making it easier to reduce the cost of the fiber sheet material.

[0023] The polyparaphenylene terephthalamide (PPTA) in the present invention is a polymer obtained by polycondensation of terephthalic acid and paraphenylenediamine, but it is also possible to use one copolymerized with small amounts of dicarboxylic acid and diamine, and the number average molecular weight of the obtained polymer or copolymer is preferably usually within the range of 20,000 to 25,000.

[0024] Ordinary polyparaphenylene terephthalamide fibers are produced by dissolving polyparaphenylene terephthalamide in concentrated sulfuric acid, extruding the resulting viscous solution through a spinneret, and spinning it into air or water to form filaments, which are then neutralized with an aqueous sodium hydroxide solution and finally dried and heat-treated at 120 to 500°C. An oil is then applied and allowed to penetrate the fibers (see U.S. Patent No. 3,767,756).

[0025] Examples of the oil agent include fatty acid esters, polyoxyethylene polyoxypropylene copolymers or derivatives thereof, and mineral oils. Among these, an oil agent containing at least one polyether compound selected from polyoxyethylene polyoxypropylene copolymers and derivatives thereof in an amount of at least 50% by mass based on the total amount of the oil agent is preferred. The polyether compounds often have excellent affinity with various matrix resins, and have the advantage of being easily washed away with an aqueous solvent during the refining process.

[0026] It is more preferable that the oil contains a component having a reactive functional group, such as a curable epoxy compound (aliphatic epoxy compound or aromatic epoxy compound). The use of such an oil can further improve the adhesion between the polyparaphenylene terephthalamide fiber and the matrix resin.

[0027] The curable epoxy compound is preferably blended in a proportion of 20 to 80% by mass, with the total amount of the oil agent being 100% by mass. It is more preferably 30 to 70% by mass, and even more preferably 35 to 55% by mass. By using such blended oil agents, polyparaphenylene terephthalamide fibers can be obtained that have good adhesion to the matrix resin and are excellent in productivity and bundling ability. Increased adhesive strength between the polyparaphenylene terephthalamide fibers and the matrix resin leads to improved interfacial adhesion between the polyparaphenylene terephthalamide fibers and the matrix resin, further improving the mechanical properties of the reinforcing fiber sheet material.

[0028] The polyparaphenylene terephthalamide fiber used in the present invention may be a continuous fiber, and the fiber thickness is not particularly limited as long as it is thick enough to function as a fiber sheet material for reinforcing civil engineering and building structures. On the other hand, the single fiber fineness is preferably 0.5 to 7.0 dtex from the viewpoints of resin impregnation and ease of handling, such as cutting at the construction site, and more preferably 1.0 to 5.0 dtex.

[0029] The fiber sheet material for reinforcing civil engineering and building structures of the present invention is composed of polyparaphenylene terephthalamide fiber and a matrix resin, with the polyparaphenylene terephthalamide fiber responsible for most of the mechanical properties of the fiber sheet material for reinforcing civil engineering and building structures of the present invention. Therefore, it is desirable that the polyparaphenylene terephthalamide fiber have a tensile strength of 17 cN / dtex or more and a tensile modulus of elasticity of 400 cN / dtex or more, as measured by the method described in JIS L1013:2010, "Testing Methods for Chemical Fiber Filament Yarns." Using polyparaphenylene terephthalamide fiber with such characteristics enables the fiber sheet material for reinforcing civil engineering and building structures to exhibit sufficient tensile strength and modulus of elasticity. The tensile strength of the polyparaphenylene terephthalamide fiber is preferably 20 cN / dtex or more, more preferably 23 cN / dtex or more. The tensile modulus of the polyparaphenylene terephthalamide fiber is preferably 420 cN / dtex or more, more preferably 450 cN / dtex or more.

[0030] <Reinforcement fabric> The form of the reinforcing fabric can be selected from at least one form selected from the group consisting of woven fabric, knitted fabric, and NCF (non-crimp fabric), and it is sufficient if it has gaps (pores) large enough to allow the resin to be impregnated. The reinforcing fabric may be a laminated fabric, such as woven fabric and woven fabric, woven fabric and knitted fabric, woven fabric and NCF, or knitted fabric and NCF.

[0031] Furthermore, the reinforcing fabric is selected from the group consisting of unidirectional fabrics and bidirectional fabrics. The terms "unidirectional" and "bidirectional" refer to the direction of the fiber group in which the reinforcing fibers are arranged in parallel, and do not include auxiliary fibers used to hold the sheet in place. The auxiliary fibers are not limited in their form as long as they can fulfill their role of holding the sheet in place. Polyester fibers, nylon fibers, etc. can be used as auxiliary fibers, and polyester fibers, which are particularly prone to dimensional change due to humidity, are preferred. Furthermore, since the reinforcing fibers are aligned in a specific direction, unidirectional fabrics have good resin impregnation properties and fiber strength development rates, making them a more preferred form for handling at construction sites.

[0032] Figure 1 shows a unidirectional fabric with parallel reinforcing fibers in the "one direction." It is made with vertically aligned auxiliary fibers to hold it in a sheet. Figure 2 shows a bidirectional fabric with vertically aligned reinforcing fibers in the "two directions." Because the warp and weft yarns intertwine to form a plain weave, no auxiliary fibers are used. Figure 3 shows a bidirectional fabric with vertically aligned reinforcing fibers in the "two directions" without crimping, with auxiliary fibers stitched at the intersections to hold it in a sheet.

[0033] The reinforcing fiber sheet material may contain fibers other than high-strength fibers depending on the purpose, and the proportion of such fibers is 20% by weight or less, preferably 15% by weight, and more preferably 10% by weight or less, when the weight of the entire fiber sheet material is 100% by weight. If the proportion of fibers other than high-strength fibers exceeds 20% by weight, the reinforcing effect of the reinforcing fiber sheet material will be reduced, which is undesirable.

[0034] The warp density of unidirectional fabrics and the warp / weft density of bidirectional fabrics are preferably 25 to 35 threads / 25.4 mm. Since the fabric of the present invention uses polyparaphenylene terephthalamide fibers with high breaking strength, a thread density of 25 threads / 25.4 mm or more can impart sufficient strength to the fabric. Furthermore, a thread density of 35 threads / 25.4 mm or less can impart good resin impregnation properties. The thread density is more preferably 26 to 34 threads / 25.4 mm, and even more preferably 27 to 33 threads / 25.4 mm.

[0035] The weight per unit area of ​​the reinforcing fabric is 250 to 500 g / m2, from the viewpoint of providing sufficient strength and rigidity while suppressing the thickness of the resulting civil engineering and building reinforcement fiber sheet material. 2 is preferable, and more preferably 300 to 450 g / m 2 The weight is within the range of 250g / m 2 If the weight is more than 500 g / m, sufficient strength and rigidity can be imparted to the fiber sheet material. 2 If the thickness is less than this, the problem of resin impregnation being significantly impaired due to an increase in the thickness of the fiber sheet material is unlikely to occur.

[0036] The reinforcing fabric preferably has a weave shrinkage ratio of 1.5% or less, as shown in the following formula (I): If the weave shrinkage ratio is 1.5% or less, the structural elongation of the fabric can be kept small, and as a result, the Young's modulus of the reinforcing fiber sheet material for civil engineering and building construction can be increased, and a sufficient reinforcing effect can be achieved. Weave shrinkage rate = [(yarn length - fabric length) / fabric length] x 100 (I)

[0037] When producing a reinforcing fabric, it is desirable to align single yarns of multifilament polyparaphenylene terephthalamide fiber and twist them together to improve processability and strength development during fabric production. The twist coefficient, as shown in the following formula (II), is preferably 0.2 to 1.4, and more preferably 0.3 to 1.2. If the twist coefficient exceeds 1.4, the fabric thickness increases, significantly reducing resin impregnation. If the twist coefficient is less than 0.2, the processability deteriorates and the fabric strength decreases. TM=T×√D / 303 (II) Where TM: twist coefficient, T: number of twists (t / 10cm), D: total fineness (dtex)

[0038] The tensile strength of the reinforcing fabric along the orientation direction of the reinforcing fibers, measured by the method described in JIS L1096, is preferably 60 to 100 kN / 10 cm, more preferably 70 to 90 kN / 10 cm, from the viewpoint of imparting sufficient strength and rigidity to the resulting civil engineering and architectural reinforcement fiber sheet material. If the tensile strength is less than 60 kN / 10 cm, the various reinforcing effects will be reduced, and more fiber sheets will need to be used to compensate. If the tensile strength exceeds 100 kN / 10 cm, the fiber density of the fiber sheet will increase, resulting in poor resin impregnation.

[0039] <Matrix resin> In the present invention, the matrix resin is an essential component of the fiber sheet material for reinforcing civil engineering and building structures of the present invention, and is used by impregnating a reinforcing fabric made of polyparaphenylene terephthalamide fiber. The type of matrix resin is not particularly limited, and at least one selected from thermosetting resins and thermoplastic resins can be used depending on the purpose. Because thermosetting resins do not become plastic when heated, using a thermosetting resin can provide a fiber sheet material for reinforcing civil engineering and building structures that has excellent heat resistance and fire resistance. On the other hand, because thermoplastic resins become plastic when heated, using a thermoplastic resin can provide a fiber sheet material for reinforcing civil engineering and building structures that can be bent on site.

[0040] Examples of thermosetting resins include unsaturated polyester resins, phenolic resins, vinyl ester resins, thermosetting epoxy resins, and urea resins. Examples of thermoplastic resins include polypropylene resin, polyethylene resin, ABS resin, polyvinyl chloride resin, polycarbonate resin, polyacetal resin, polyethylene terephthalate resin, polybutylene terephthalate resin, polyphenylene sulfide resin, polyamide resin, modified polyphenylene ether resin, liquid crystal polyester resin, polyimide resin, syndiotactic polystyrene resin, polycyclohexanedimethylene terephthalate resin, and thermoplastic epoxy resin.

[0041] Among the above resins, thermosetting resins such as unsaturated polyester resins and thermosetting epoxy resins are preferred, as they have good adhesion to polyparaphenylene terephthalamide fibers and excellent mechanical properties. By using these thermosetting resins, the reinforcing effect of the fiber sheet material for reinforcing civil engineering and building structures of the present invention can be maximized.

[0042] The matrix resin preferably has a tensile strength of 30 MPa or more as measured by the method described in JIS K7161, a flexural strength of 40 MPa or more as measured by the method described in JIS K7171, and a tensile shear strength of 10 MPa or more as measured by the method described in JIS K6850, and more preferably a tensile strength of 40 MPa or more, a flexural strength of 50 MPa or more, and a tensile shear strength of 20 MPa or more. When the tensile strength, flexural modulus, and tensile shear strength are within these ranges, a fiber sheet material for reinforcing civil engineering and building structures having excellent strength and rigidity can be obtained.

[0043] The matrix resin used in the present invention can be blended with various additives as needed, as long as they do not impair the effects of the present invention. Examples of additives include heat stabilizers, light stabilizers, UV absorbers, hydrolysis inhibitors, antioxidants, lubricants, nucleating agents, plasticizers, color inhibitors, matting agents, flame retardants, antistatic agents, mold release agents, fillers (fillers such as glass fiber, carbon fiber, glass beads, hollow glass, and talc), pigments, and dyes. One or more additives selected from these additives can be blended. The amounts of these additives may be those typically used.

[0044] <Fiber sheet material for reinforcing civil engineering and building structures> The fiber sheet material for reinforcing civil engineering and architectural structures of the present invention is composed of a reinforcing fabric using polyparaphenylene terephthalamide fiber and a matrix resin, and is characterized by having a sheet ultimate strain of 3.0% or more as measured by the method described in JIS A1191. This allows for sufficient toughness (sheet elongation) as a fiber sheet material for reinforcing civil engineering and architectural structures. The sheet ultimate strain is preferably 3.2% or more, and more preferably 3.4% or more. If the sheet ultimate strain is less than 3.0%, the toughness improvement effect when the fiber sheet is wrapped around concrete will be insufficient, forcing the design of concrete members to have a high yield strength, which increases the amount of fiber sheet used and, accordingly, increases costs and labor.

[0045] The fiber sheet material for reinforcing civil engineering and architectural structures of the present invention preferably has a sheet tensile strength of 2,000 MPa or more along the orientation direction of the reinforcing fibers, as measured by the method specified in JIS A1191. If the sheet tensile strength is less than 2,000 MPa, the reinforcing effect when used for shear reinforcement purposes will be insufficient. Therefore, to achieve the desired shear strength, the total cross-sectional area of ​​the continuous fiber sheet must be increased, which increases the amount of fiber sheet used and the number of steps required. The sheet tensile strength is preferably 2,200 MPa or more, and more preferably 2,400 MPa or more.

[0046] The fiber sheet material for reinforcing civil engineering and architectural structures of the present invention desirably has a Young's modulus of 60 GPa or more, as measured by the method described in JIS A1191. If the Young's modulus is less than 60 GPa, the reinforcing effect of the fiber sheet material for reinforcing civil engineering and architectural structures when used for shear reinforcement purposes will be insufficient. Therefore, to obtain the desired shear resistance, the total cross-sectional area of ​​the continuous fiber sheet must be increased, which increases the amount of fiber sheet used and the number of steps. The Young's modulus of the fiber sheet material is preferably 62 GPa or more, more preferably 64 GPa or more, even more preferably 69 GPa or more, and particularly preferably 71 GPa or more. On the other hand, as the sheet Young's modulus increases, the sheet ultimate strain may fall below the target 3.0%, so the Young's modulus is preferably 100 GPa or less, and more preferably 90 GPa or less.

[0047] <Reinforcement method for fiber sheet materials for civil engineering and building reinforcement> When applying the fiber sheet material for civil engineering and architectural reinforcement of the present invention to concrete surfaces, the application method is not particularly limited and can be any known method. For example, the procedure for attaching the fiber sheet to a concrete surface involves first appropriately chipping the concrete surface and removing any weak layers by polishing or other methods. In some cases, corners are scraped and rounded appropriately, and recesses are filled with putty or other materials to smooth out any unevenness. After this surface preparation, a resin called a primer is applied to the concrete surface and allowed to dry. The primer is typically the same type of resin as the resin impregnated into the fiber sheet. Therefore, when epoxy resin is used as the impregnating resin, the viscosity of the epoxy resin is adjusted to allow it to penetrate the concrete easily. After the primer applied to the concrete surface is allowed to dry sufficiently, the impregnating epoxy resin is applied on top. After application, the reinforcing fiber sheet is cut to the required length (for example, in the case of a concrete pillar, the circumference plus a 20 cm joint length) and immediately applied with the warp threads running along the circumference, and the resin is thoroughly impregnated into the fiber sheet using a roller or similar. Reinforcing fiber sheets generally have a width of 10 cm to 50 cm.

[0048] After ensuring that the undercoat resin has been sufficiently impregnated, a top coat is applied using the same resin. After applying epoxy resin evenly over the entire surface of the reinforcing fiber sheet, the sheet is left to cure until the resin has completely hardened. Depending on the level of reinforcement, multiple layers of reinforcing fiber sheet may be applied. In this case, the above process will be repeated. After the top layer of sheet has been applied and it has been confirmed that the epoxy resin on the surface has completely hardened, the surface is painted with a fluororesin or acrylic resin as a finishing touch to improve durability and fire resistance. In some cases, mortar paint is also applied.

[0049] The fiber sheet material for reinforcing civil engineering and architectural structures of the present invention forms a reinforcing layer by being impregnated with resin, and is therefore useful not only for general structures but also for reinforcing concrete viaduct piers and concrete decks on railways and expressways, concrete pillars and concrete walls of buildings, and can be suitably used to reinforce buildings that require an extension of their lifespan or earthquake resistance. Reinforcement using the fiber sheet material for reinforcing civil engineering and architectural structures of the present invention may be carried out in accordance with conventionally known methods, such as by attaching it to the structure to be reinforced, by wrapping it around the structure, or by placing it in cracks in concrete. [Example]

[0050] The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto. In the following examples, "parts by weight" will be abbreviated to "parts" unless otherwise specified. The evaluation methods described in the examples are as follows.

[0051] (1) Tensile properties of polyparaphenylene terephthalamide fibers The elongation at break (Section 13; Elongation at Break), tensile strength (Section 11; Breaking Strength), and tensile modulus (Section 15; Modulus) were measured according to the method described in ASTM D7269.

[0052] (2) Weaving density and basis weight of reinforcing fabric The method described in JIS L1096:2020 "Testing methods for woven and knitted fabrics" was followed.

[0053] (3) Shrinkage of polyparaphenylene terephthalamide fiber constituting the reinforcing fabric According to the method described in JIS L1096:2020 "Fabric testing methods for woven and knitted fabrics," the shrinkage rate was calculated using the following formula. Woven shrinkage rate = [(yarn length - fabric length) / fabric length] x 100

[0054] (4) Twist coefficient of polyparaphenylene terephthalamide fiber constituting the reinforcing fabric According to the method described in ASTM D123, the twist factor (TM) was calculated using the following formula. TM=T×√D / 303 TM: twist coefficient, T: number of twists (t / 10cm), D: total fineness (dtex)

[0055] (5) Ultimate strain, tensile strength and Young's modulus of fiber sheet materials for civil engineering and building reinforcement The test was conducted in accordance with the method described in JIS A1191 "Tensile test method for FRP sheets for concrete reinforcement."

[0056] (6) Resin impregnation of fiber sheet materials for civil engineering and building reinforcement Konishi Bond E2500S (epoxy resin) was mixed with the base resin and curing agent according to the specifications, and a base coat of resin 1.4 times the weight of the fiber sheet was applied to a release film. A 20 x 20 cm fiber sheet was placed on top of this, and a 10 cm wide metal roller was used to roll it back and forth three times under a 2 kg load, and then the sheet was left to stand. The resin seeped from the underside of the fiber sheet toward the surface, causing the sheet surface to become wet. After five minutes, the resin impregnation of the sheet surface was observed and the results were judged according to the following criteria. ○: Resin seepage onto the sheet surface covers 90% or more of the sheet surface. ×: Resin seepage onto the sheet surface was less than 90% of the sheet surface.

[0057] (7) Dustproof performance improvement effect of fiber sheet material for civil engineering and building reinforcement Since the effect of improving toughness performance depends on the ultimate strain of the sheet, it was evaluated as follows based on the ultimate strain of the sheet. ○: Sheet ultimate strain is 3.0% or more ×: Sheet ultimate strain is less than 3.0%

[0058] (8) Shear reinforcement effect of fiber sheet materials for civil engineering and building reinforcement Based on the 2021 revised edition of the Guidelines for the Design and Construction of Earthquake-Resistant Reinforcements of Existing Reinforced Concrete and Steel-Reinforced Concrete Buildings Using Continuous Fiber Reinforcement (Japan Building Disaster Prevention Association), the shear design tensile strength of the fiber sheet was calculated according to the formula below. min[E fd ×ε fd ,(2 / 3)×σ f ] (N / mm 2 ) E fd : Young's modulus of fiber sheet material (N / mm 2 ) ε fd : Effective strain of fiber sheet material (calculated at 0.01) σ f : Tensile strength of fiber sheet material (N / mm 2 ) (In the formula, min[E fd ×ε fd ,(2 / 3)×σ f ] is E fd ×ε fd and (2 / 3)×σ f )

[0059] [Manufacturing Example 1] 1 kg of paraphenylene terephthalamide (molecular weight approximately 20,000) obtained by a conventional method was dissolved in 4 kg of concentrated sulfuric acid, and the solution was passed through a die with 1,000 holes of 0.1 mm diameter at a shear rate of 30,000 sec -1The mixture was discharged so that the fiber became spun into water at 25°C, and then neutralized with a 10 wt% aqueous sodium hydroxide solution at 10°C for 15 seconds. After that, the mixture was dried by heating at 170°C for 15 seconds, and then an oil was added to obtain polyparaphenylene terephthalamide fiber (total fineness 3,300 dtex) with a moisture content of 7.0 wt%.

[0060] [Manufacturing Example 2] The same procedure as in Production Example 1 was carried out except that the heating and drying conditions were changed to 200°C for 30 seconds, to obtain polyparaphenylene terephthalamide fibers (total fineness 3,300 dtex) with a moisture content of 6.8% by weight.

[0061] [Manufacturing Example 3] The same procedure as in Production Example 1 was carried out except that the spinning temperature was 4°C and the heat drying conditions were 150°C x 30 seconds, to obtain polyparaphenylene terephthalamide fibers (total fineness 3,300 dtex) with a moisture content of 7.0% by weight.

[0062] [Manufacturing Example 4] "Kevlar(R) 49" (registered trademark) (polyparaphenylene terephthalamide fiber; 3,300 dtex) manufactured by Toray DuPont Co., Ltd. was used.

[0063] [Manufacturing Example 5] "Kevlar(R) 119" (registered trademark) (polyparaphenylene terephthalamide fiber; 3,300 dtex) manufactured by Toray DuPont Co., Ltd. was used.

[0064] Details of the polyparaphenylene terephthalamide fibers obtained in Production Examples 1 to 5 are shown in Table 1.

[0065] [Table 1]

[0066] [Examples 1 to 3, Comparative Examples 1 to 3] Table 2 shows the evaluation results for unidirectional reinforcing fabrics made from the fiber types listed in Table 1, and for fiber sheet materials for reinforcing civil engineering and building structures, in which unidirectional reinforcing fabrics are impregnated with Bond E2500S (epoxy resin) manufactured by Konishi Co., Ltd. Examples 1 and 2 are reference examples.

[0067] [Table 2]

[0068] As shown in Table 2, a fiber sheet material for reinforcing civil engineering and building structures with an ultimate sheet strain of less than 3.0% cannot exert a ductility reinforcement effect (Comparative Example 1). On the other hand, even if the ultimate sheet strain is 3.0% or more, a fiber sheet material for reinforcing civil engineering and building structures with a Young's modulus of less than 60 GPa cannot exert a sufficient shear reinforcement effect (Comparative Examples 2 and 3).

[0069] In contrast, the fiber sheet material for reinforcing civil engineering and building structures of the present invention is excellent in terms of ultimate sheet strain, Young's modulus, and cost, and is also excellent in tensile strength, particularly in Example 3. This demonstrates that the fiber sheet material for reinforcing civil engineering and building structures of the present invention can improve deformation performance and shear strength in shear and toughness reinforcement methods, and that the present invention is useful. [Industrial Applicability]

[0070] The fiber sheet material for reinforcing civil engineering and architectural structures of the present invention is ideal for shear and ductility reinforcement not only for general structures but also for elevated bridge piers and decks, building columns and walls, etc. [Explanation of symbols]

[0071] 10 Reinforcing fibers 20 Supplementary Fiber

Claims

1. A reinforcing fiber sheet material used for reinforcing civil engineering and architectural structures, comprising a reinforcing fabric made of high-strength fibers and a matrix resin, The high-strength fiber is composed of polyparaphenylene terephthalamide fiber that simultaneously satisfies the following requirements: a breaking elongation of 4.0% or more, a tensile strength of 23 cN / dtex or more, and a tensile modulus of 400 cN / dtex or more, as measured by the method described in JIS L1013; and the toughness of the fiber sheet material is obtained by setting the ultimate strain along the orientation of the reinforcing fibers of the fiber sheet material to 3.0% or more, as measured by the method described in JIS A1191.

2. 2. The fiber sheet material for reinforcing civil engineering and architectural structures according to claim 1, wherein the fiber sheet material for reinforcing civil engineering and architectural structures has a tensile strength of 2,000 MPa or more along the orientation direction of the reinforcing fibers as measured by the method described in JIS A1191, and / or a Young's modulus of 60 GPa or more as measured by the same method.

3. 3. The fiber sheet material for reinforcing civil engineering and architectural structures according to claim 1, wherein the reinforcing fabric has a shrinkage rate of 1.5% or less as defined by the following formula (I) measured by the method described in JIS L1096: Weave shrinkage rate (%) = [(yarn length - fabric length) / fabric length] × 100 (I)

4. 4. The fiber sheet material for civil engineering and architectural reinforcement according to claim 1, wherein the polyparaphenylene terephthalamide fiber has a twist coefficient defined by the following formula (II), measured by the method specified in ASTM D123, in the range of 0.2 to 1.4: TM=T×√D / 303... (II) where TM is twist coefficient, T is twist number (t / 10 cm), and D is total fineness (dtex).

5. 5. The fiber sheet material for reinforcing civil engineering and architectural structures according to claim 1, wherein the reinforcing fabric is one selected from the group consisting of unidirectional and bidirectional.

6. The reinforcing fabric according to any one of claims 1 to 5, wherein the reinforcing fabric is a unidirectional fabric, and the warp yarn density of the unidirectional fabric measured by the method described in JIS L1096 is 25 to 35 yarns / 25.4 mm.

7. A civil engineering / architectural structure reinforced with the fiber sheet material for reinforcing civil engineering / architectural structures according to any one of claims 1 to 6.

8. 8. The civil engineering / architectural structure according to claim 7, wherein the civil engineering / architectural structure is a concrete structure.

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