Fiber sheet material for reinforcing civil engineering and building structure

Abstract

To provide a fiber sheet material for reinforcing a civil engineering and building structure that exhibits excellent shear and toughness reinforcing effects in a civil engineering and building structure reinforcement method using continuous fiber sheets, and that demonstrates stable reinforcing effects regardless of a shape of a reinforced object.SOLUTION: A fiber sheet material for reinforcing a civil engineering and building structure is a fiber sheet material for reinforcement composed of high-strength organic multifilaments used for reinforcing the civil engineering and building structure, in which (a) retention of tensile strength of single yarn constituting the multifilaments after compression treatment is 90% or more, and (b) ultimate strain along an orientation of the reinforcing fibers of the fiber sheet material, as measured by a method described in JIS A1191:2021, is 3.0% or more.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a reinforcing fiber sheet material made of high-strength fibers for use in reinforcing civil engineering and architectural structures. [Background technology]

[0002] There are many concrete buildings, such as railway viaducts and highway viaducts, but there are problems with seismic reinforcement against destruction by earthquakes and improving durability due to increased traffic volume. In addition, there are historical structures, such as stone lighthouses, brick buildings, and concrete or brick chimneys, that require extension of their lifespan and seismic reinforcement.

[0003] Even if the earthquake resistance is sufficient, many concrete structures have cracks or parts that have spalled due to drying shrinkage or external pressure, and these have been repaired. Methods for reinforcing and repairing concrete structures include covering the concrete columns of the target railway viaduct with steel plates, and attaching or wrapping reinforcing fiber sheets such as aramid fiber or carbon fiber to 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. It also requires welding equipment and skilled workers. On the other hand, the method of wrapping reinforcing fiber sheet materials such as aramid fiber or carbon fiber (commonly known as the "continuous fiber reinforcement method" or "fiber sheet reinforcement method") does not require heavy machinery to handle heavy objects, is easy to install, can be easily installed in narrow spaces, and has the advantage of shortening the construction period, so it is becoming more widely used.

[0005] Reinforcement and repair methods using fiber sheet materials involve adhering reinforcing fiber sheet materials with high tensile strength, such as carbon fiber or aramid fiber, to the surface of concrete with an impregnating resin, such as epoxy resin, vinyl ester resin, unsaturated polyester resin, or phenolic resin. In this case, the impregnating resin not only adheres the fiber sheet material to the concrete, but also impregnates the fiber sheet material, improving the sheet's strength and acting as a medium to transmit the strength of the fiber sheet material 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 bars against lateral shaking during an earthquake, fiber sheets can be attached by wrapping them perpendicular to the axial direction, shifting the concrete column's destruction mode from a less viscous shear destruction mode to a more viscous bending destruction mode, making it possible to buy time before collapse (time to evacuate). It is known that the main required properties for fiber sheets in this type of shear reinforcement are strength and Young's modulus.

[0007] Also, 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 Sheet Materials (Japan Society of Civil Engineers)). The design ductility rate can be increased by reinforcing with fiber sheet materials, and the greater the ultimate strain of the fiber sheet materials, the better. Gamma i × μ rd / μ d (III) Gamma i : Structure coefficient (calculated at 1.0), μ rd :Design plasticity modulus, μ d : Design toughness factor

[0008] 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 impregnating resin into the fiber skeleton that constitutes the reinforcing fiber sheet material. However, a process of applying a surface treatment agent to the fiber skeleton in advance is required, and the breaking elongation as a reinforcing fiber sheet material is insufficient, resulting in poor dust performance.

[0009] Patent Document 2 proposes a reinforcing fiber sheet that has high reinforcing strength, is lightweight, and has excellent resin impregnation properties by using high-strength polyethylene fibers and appropriately allocating the warp cover factor and weft cover factor. However, high-strength polyethylene fibers have poor adhesion to epoxy resins and interfere with stress transmission, making it difficult to achieve various reinforcing functions.

[0010] In addition, in both the above-mentioned shear reinforcement and ductility reinforcement, the fiber sheet material is wrapped around the column-shaped object to be reinforced. However, in the case of polygonal columns, the fiber sheet material will bend at the corners, which can lead to a decrease in the strength of the fiber sheet material depending on the fibers, and ultimately may not achieve the designed reinforcement effect.

[0011] Patent Document 3 describes a reinforced fiber sheet using para-aramid fiber (copolyparaphenylene-3,4'-oxydiphenylene terephthalamide fiber) containing a copolymer component. However, the para-aramid fiber containing the copolymer component is said to be weaker in radial compression than the para-aramid fiber (polyparaphenylene terephthalamide fiber) obtained by polycondensation of paraphenylenediamine and terephthalic acid chloride, and the reinforcing effect may decrease depending on the shape of the object to be reinforced. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] JP 2018-172823 A [Patent Document 2] JP 2014-88652 A [Patent Document 3] Japanese Patent Application Publication No. 10-37051 Summary of the Invention [Problem to be solved by the invention]

[0013] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a fiber sheet material for reinforcing civil engineering and building structures, which exhibits excellent shear reinforcement and ductility reinforcement effects in a civil engineering and building reinforcement method using continuous fiber sheet material, and can provide a stable reinforcement effect regardless of the shape of the object to be reinforced. [Means for solving the problem]

[0014] As a result of sincere research by the inventors in order to achieve the above-mentioned objective, they have discovered that in a civil engineering and building reinforcement method using a continuous fiber sheet, a continuous fiber sheet material which achieves both high levels of strength (Young's modulus) and ultimate strain, and which can maintain a high level of strength retention after compression treatment, shows excellent shear and ductility reinforcement effects, and can be used as a fiber sheet material for reinforcing civil engineering and building structures which exerts a stable reinforcement effect regardless of the shape of the object to be reinforced, thus arriving at the present invention.

[0015] That is, the present invention provides a fiber sheet material for reinforcing civil engineering and architectural structures, which is made of a high-strength organic multifilament and is used for reinforcing civil engineering and architectural structures, in which (a) the tensile strength retention rate of the single yarns constituting the multifilament after compression treatment is 90% or more, and (b) the ultimate strain along the orientation of the reinforcing fibers of the fiber sheet material, as measured by the method described in JIS A1191:2021, is 3.0% or more. Effect of the Invention

[0016] According to the present invention, in a civil engineering / architectural reinforcement method using continuous fiber sheet material, by using a continuous fiber sheet material that can achieve both high levels of strength (Young's modulus) and ultimate strain and maintain a high level of strength retention after compression treatment, it is possible to provide a fiber sheet material for reinforcing civil engineering / architectural structures that exhibits excellent shear reinforcement and ductility reinforcement effects and can exert a stable reinforcement effect regardless of the shape of the object to be reinforced. [Brief description of the drawings]

[0017] [Figure 1] A photo of one-way fabric. [Diagram 2] Photo of two-way fabric (plain weave). [Diagram 3] A photo of two-way fabric (NCF (Non-Crimp Fabric)). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The fiber sheet material for reinforcing civil engineering and architectural structures of the present invention is a reinforcing fiber sheet material made of high-strength organic multifilament used to reinforce civil engineering and architectural structures, characterized in that the tensile strength retention rate of the single yarns constituting the high-strength multifilament after compression treatment is 90% or more, and the ultimate strain along the orientation of the reinforcing fibers of the fiber sheet material, as measured by the method described in JIS A1191:2021, is 3.0% or more.

[0019] <High-strength organic multifilament> Fiber materials (multifilaments) used to repair and reinforce concrete structures are required to have high strength, high elasticity, and high toughness because they need to withstand very large amounts of energy. Specifically, organic fibers such as para-aramid fibers, polyarylate fibers, and PBO (polybenzobisoxazole) fibers; and inorganic fibers such as carbon fibers can be mentioned. Among them, para-aramid fibers, polyarylate fibers, and PBO fibers are preferred because they are flexible, lightweight, hard to break, insulating, easy to handle at the construction site, and have a fiber structure that is strong against compression in the fiber diameter direction. Among them, para-aramid fibers are particularly preferred because they have an excellent balance of high strength, high elasticity, high toughness, and cost. Examples of para-aramid fibers include polyparaphenylene terephthalamide fibers (such as "Kevlar®" manufactured by Toray DuPont and "Twaron®" manufactured by Teijin Limited), and copolyparaphenylene-3,4'-oxydiphenylene terephthalamide fibers (such as "Technora®" 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 are particularly excellent in compressive properties in the fiber diameter direction.

[0020] The polyparaphenylene terephthalamide (PPTA) is a polymer obtained by polycondensation of terephthalic acid and paraphenylenediamine, but it is also possible to use one copolymerized with a small amount of dicarboxylic acid and diamine. The number average molecular weight of the obtained polymer or copolymer is preferably usually within the range of 20,000 to 25,000.

[0021] Ordinary polyparaphenylene terephthalamide fibers are produced by dissolving polyparaphenylene terephthalamide in concentrated sulfuric acid, extruding the viscous solution from a spinneret and spinning it into air or water to form filaments, neutralizing the filaments with an aqueous sodium hydroxide solution, and finally drying and heat treating the filaments at 120 to 500° C. An oil is then applied and allowed to penetrate the fibers to produce the fibers (see U.S. Patent No. 3,767,756).

[0022] Examples of the oil agent include fatty acid esters, polyoxyethylene polyoxypropylene copolymers or derivatives thereof, and mineral oils. Among them, 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 in the refining process.

[0023] It is more preferable that the oil contains a component having a reactive functional group, such as a curable epoxy compound (aliphatic epoxy compound, aromatic epoxy compound). By using such an oil, the adhesion between the polyparaphenylene terephthalamide fiber and the matrix resin can be further improved.

[0024] The curable epoxy compound is preferably blended at a ratio of 20 to 80% by mass, based on 100% by mass of the entire oil agent. More preferably, it is 30 to 70% by mass, and even more preferably, it is 35 to 55% by mass. By using such blended oil agent, it is possible to obtain polyparaphenylene terephthalamide fibers that have good adhesion to the matrix resin and are excellent in productivity and bundling ability. When the adhesive strength between the polyparaphenylene terephthalamide fibers and the matrix resin is increased, it leads to improvement in the interfacial adhesion between the polyparaphenylene terephthalamide fibers and the matrix resin, and therefore the mechanical properties of the reinforcing fiber sheet material are further improved.

[0025] The polyparaphenylene terephthalamide fiber used in the present invention may be a continuous fiber, and the thickness of the fiber 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 in terms of resin impregnation and ease of handling such as cutting at the construction site, and more preferably 1.0 to 5.0 dtex.

[0026] The high-strength organic multifilament 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 method for chemical fiber filament yarn". In the fiber sheet material for reinforcing civil engineering and building structures of the present invention, the organic high-strength multifilament 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 high-strength organic multifilament is less than 4.0%, there is a risk of the ultimate strain of the fiber sheet material for reinforcing civil engineering and building structures being less than 3.0%.

[0027] On the other hand, if the breaking elongation of the high strength organic multifilament is 4.0% or more, when a fiber sheet material for reinforcing civil engineering and architectural structures is prepared, the fiber sheet material can exhibit sufficient toughness (ultimate strain). The breaking elongation of the high strength organic multifilament is preferably 4.1% or more, more preferably 4.2% or more.

[0028] In addition, the high-strength organic multifilament used in the fiber sheet material for reinforcing civil engineering and building structures of the present invention preferably has a tensile strength of 17.0 cN / dtex or more, as measured by the method described in JIS L1013:2010 "Testing method for chemical fiber filament yarn", and a tensile modulus of elasticity of 400 cN / dtex or more, as measured by the same method. By using a high-strength organic multifilament having such characteristics, it is possible to provide the fiber sheet material for reinforcing civil engineering and building structures with sufficient tensile strength and modulus of elasticity. The tensile strength of the high-strength organic multifilament is preferably 20.0 cN / dtex or more, more preferably 23.0 cN / dtex or more. The tensile modulus of the high-strength organic multifilament is preferably 420 cN / dtex or more, more preferably 450 cN / dtex or more.

[0029] In addition, it is important that the single yarn constituting the high-strength organic multifilament of the present invention has a single yarn strength that is maintained at 90% or more of the single yarn strength before compression deformation after compression deformation to half the radial direction using the device and method described in Experimental investigation of the transverse mechanical properties of a single Kevlar(R) KM2 fiber, International Journal of Solids and Structures 41 (2004). The tensile strength retention rate of the single yarn after compression treatment is more preferably 91% or more, even more preferably 92% or more, and particularly preferably 93% or more.

[0030] If the strength retention rate of the single yarn after compression deformation is high, when a reinforcing fiber sheet made of high-strength organic fiber multifilament composed of the single yarn is used to reinforce civil engineering and architectural structures, the reinforcing fiber sheet has improved resistance to compressive force, providing a stable reinforcing effect, which enables safe design.

[0031] <Reinforcing fiber sheet material> The form of the reinforcing fiber sheet material of the present invention can be at least one selected from the group consisting of woven fabric, knitted fabric, and NCF (non-crimp fabric), and may be any form having gaps (holes) large enough to allow the resin to be impregnated. The reinforcing fabric may be, for example, a fabric obtained by laminating woven fabric and woven fabric, woven fabric and knitted fabric, woven fabric and NCF, knitted fabric and NCF, etc.

[0032] Furthermore, the reinforcing fiber sheet material is preferably 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 a sheet shape. There are no limitations on the shape of the auxiliary fibers as long as they can hold the sheet in a sheet shape.

[0033] As the auxiliary fibers, polyester fibers, nylon fibers, glass fibers, etc. can be used, and polyester fibers and glass fibers, which are particularly less susceptible to dimensional change due to humidity, are preferred. Since the reinforcing fibers are aligned in a specific direction, the unidirectional fabric has good resin impregnation and fiber strength expression, and is a more preferred form when handling at the construction site.

[0034] FIG. 1 shows a unidirectional fabric in which reinforcing fibers are arranged in parallel in one direction. To hold the fabric in a sheet, auxiliary fibers are arranged in a vertical direction. FIG. 2 shows a bidirectional fabric in which reinforcing fibers are arranged in two directions. Since the warp and weft threads are interlaced to form a plain weave fabric, auxiliary fibers are not used. FIG. 3 shows a bidirectional fabric in which reinforcing fibers are arranged in two directions without crimping. To hold the fabric in a sheet, auxiliary fibers are sewn at the intersections. Each of FIGS. 1 to 3 shows a preferred example of a reinforcing fiber sheet material, and the present invention is not limited to these examples.

[0035] The reinforcing fiber sheet material may contain fibers other than high-strength fibers depending on the purpose, and the proportion of fibers other than high-strength 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 decreases, which is not desirable.

[0036] The density of the warp threads of the unidirectional fabric and the density of the warp threads / weft threads of the bidirectional fabric can be appropriately selected according to the purpose, but it is preferable that the density is 25 to 35 threads / 25.4 mm in order to effectively reinforce the fabric. Since the fabric of the present invention uses high-strength organic multifilaments with high breaking strength, a thread density of 25 threads / 25.4 mm or more can impart sufficient strength to the fabric. In addition, a thread density of 35 threads / 25.4 mm or less can impart good resin impregnation. The thread density is more preferably 26 to 34 threads / 25.4 mm, and even more preferably 27 to 33 threads / 25.4 mm.

[0037] The basis weight (weight per unit area) of the reinforcing fiber sheet material 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 reinforcing 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 fiber 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.

[0038] The reinforcing fiber sheet material preferably has a weave shrinkage ratio of 1.5% or less, more preferably 1.3% 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 architectural structures can be increased, and a sufficient reinforcing effect can be exhibited. Weaving shrinkage rate = [(yarn length - fabric length) / fabric length] x 100 (I)

[0039] When preparing a reinforcing fiber sheet material, it is desirable to align high-strength organic multifilament single yarns and twist them together to improve the processability and strength development rate during fabric preparation, and the twist factor shown in the following formula (II) is preferably 0.2 to 1.4, and more preferably in the range of 0.3 to 1.2. If the twist factor exceeds 1.4, the fabric thickness increases and the resin impregnation property is significantly reduced. If the twist factor is less than 0.2, the processability deteriorates and the fabric strength decreases. TM=T×√D / 303 (II) Where TM: twist factor, T: number of twists (t / 10cm), D: total fineness (dtex)

[0040] The fiber sheet material for reinforcing civil engineering and architectural structures of the present invention is characterized in that the sheet ultimate strain measured by the method described in JIS A1191 is 3.0% or more. 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 effect of improving toughness when the fiber sheet is wrapped around concrete becomes insufficient, and the yield strength of the concrete member must be large in design, which increases the amount of fiber sheet used, and therefore increases costs and labor.

[0041] In addition, the reinforcing fiber sheet material preferably has a sheet tensile strength of 2,000 MPa or more along the orientation direction of the reinforcing fiber, measured by the method described in (c) JIS A1191. If the sheet tensile strength is less than 2,000 MPa, the reinforcing effect will be insufficient when the fiber sheet material for civil engineering and building reinforcement is used for shear reinforcement purposes, so in order to obtain the desired shear resistance, the total cross-sectional area of ​​the continuous fiber sheet needs to be increased, which will increase the amount of fiber sheet used and the number of steps. The sheet tensile strength is preferably 2,200 MPa or more, and more preferably 2,400 MPa or more.

[0042] Furthermore, the reinforcing fiber sheet material desirably has a Young's modulus of 60 GPa or more as measured by the method described in (d) JIS A1191. If the Young's modulus is less than 60 GPa, the reinforcing effect of the fiber sheet material for civil engineering and building reinforcement when used for shear reinforcement purposes will be insufficient, so in order to obtain the desired shear resistance, the total cross-sectional area of ​​the continuous fiber sheet needs to be increased, which will increase 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.

[0043] In the fiber sheet material for reinforcing civil engineering and architectural structures of the present invention, it is preferable that at least one of (c) a tensile strength of 2,000 MPa or more and (d) a Young's modulus of 60 GPa or more is satisfied. Since this affects the amount of the fiber sheet material used and the increase in the number of steps, it is more preferable that both are satisfied.

[0044] <Reinforcement method using fiber sheet material for civil engineering and building reinforcement> When the fiber sheet material for reinforcing civil engineering and architectural structures of the present invention is applied to the surface of concrete, the application method is not particularly limited and may be any known method. That is, for example, the procedure for attaching the fiber sheet for reinforcing to the surface of concrete is as follows: first, the concrete surface is appropriately chipped, the weak layer of the surface is removed by grinding, etc., and in some cases, the corners are scraped and rounded appropriately, and the recessed parts are filled with putty or the like to adjust the unevenness. After such a surface preparation, a resin called a primer is applied to the surface of the concrete and dried. The primer is usually the same type of resin as the resin impregnated into the fiber sheet. Therefore, when an epoxy resin is used as the impregnating resin, an epoxy resin with viscosity adjusted so that it can easily penetrate into the concrete is used as the primer. After the primer applied to the concrete surface is sufficiently dried, the impregnating resin is applied on top of it. After application, the reinforcing fiber sheet is cut to the required length (for example, in the case of a concrete pillar, the circumference plus 20 cm of joint length) and immediately attached so that the warp threads run in the circumferential direction, and the fiber sheet is thoroughly impregnated with the resin using a roller or similar. Reinforcing fiber sheet materials with widths of 10 cm to 50 cm are generally used.

[0045] After it has been confirmed that the undercoat resin has been sufficiently impregnated, a top coat of the same resin is applied. The impregnating resin is then evenly applied over the entire surface of the reinforcing fiber sheet material, and the material is left to cure until the resin has completely hardened. Depending on the level of reinforcement, multiple layers of reinforcing fiber sheets may be attached. In this case, the above process will be repeated. Once the top layer of sheet has been attached and it has been confirmed that the impregnating 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, a mortar paint may also be applied.

[0046] The type of impregnating resin used here is not particularly limited, and at least one selected from thermosetting resins and thermoplastic resins can be used depending on the purpose. Since thermosetting resins do not have plasticity due to heat, the use of thermosetting resins 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, since thermoplastic resins show plasticity when heated, the use of thermoplastic resins can provide a fiber sheet material for reinforcing civil engineering and building structures that can be bent on-site.

[0047] Examples of the thermosetting resin include unsaturated polyester resin, phenol resin, vinyl ester resin, thermosetting epoxy resin, and urea resin. 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, polycyclohexane dimethylene terephthalate resin, and thermoplastic epoxy resin.

[0048] Among the above resins, thermosetting resins such as unsaturated polyester resins and thermosetting epoxy resins, which have good adhesion to high-strength organic multifilaments and excellent mechanical properties, are preferred. By using these thermosetting resins, it is possible to maximize the reinforcing effect of the fiber sheet material for reinforcing civil engineering and building structures of the present invention.

[0049] The above-mentioned impregnated resin may be blended with various additives as necessary within a range that does not impair the effects of the present invention. Examples of additives include heat stabilizers, light stabilizers, ultraviolet absorbers, hydrolysis inhibitors, antioxidants, lubricants, nucleating agents, plasticizers, coloring 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, and one or more selected from these additives may be blended. The blending amounts of these additives may be the amounts normally used.

[0050] 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 columns 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 conventional methods such as attaching to the structure to be reinforced, wrapping around it, or placing it in cracks in concrete. EXAMPLES

[0051] 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 mass" is abbreviated to "parts" unless otherwise specified. The evaluation methods described in the examples are as follows.

[0052] (1) Tensile properties of high-strength organic multifilament 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.

[0053] (2) Single yarn strength retention rate after compression treatment A compressive deformation in the single fiber diameter direction was applied using the apparatus and method described in Experimental investigation of the transverse mechanical properties of a single Kevlar(R) KM2 fiber, International Journal of Solids and Structures 41 (2004), and the tensile strength retention rate before and after the treatment was calculated. Specifically, the strength of each single yarn constituting the multifilament was measured after compressive deformation to half the diameter of the single yarn (nominal strain: 0.5) at a nominal strain rate of 0.075 / sec using a Lenzing Technik automatic single fiber fineness and strength / elongation measuring instrument "VIBRODYN400" in accordance with ASTM D3379, and the strength retention rate before and after the compressive deformation was calculated as a percentage. The measured value was the average value of 10 single yarns randomly taken from each sample.

[0054] (3) Weaving density and basis weight of reinforcing fiber sheet material The method described in JIS L1096:2020 "Testing methods for woven and knitted fabrics" was followed.

[0055] (4) Shrinkage rate of reinforcing fiber sheet material 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. Weaving shrinkage rate = [(yarn length - woven fabric length) / woven fabric length] x 100

[0056] (5) The twist factor of the high-strength organic multifilament 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 factor, T: number of twists (t / 10cm), D: total fineness (dtex)

[0057] (6) Ultimate strain, tensile strength and Young's modulus of fiber sheet material for reinforcing civil engineering and building structures The test was conducted in accordance with the method described in JIS A1191:2021 "Tensile test method for FRP sheets for concrete reinforcement."

[0058] (7) Resin impregnation of fiber sheet materials for reinforcing civil engineering and building structures Konishi Bond E2500S (epoxy resin) was mixed with the base agent and hardener according to the specifications, and a release film was coated with resin 1.4 times the weight of the fiber sheet. A 20 x 20 cm fiber sheet was placed on top of the resin, and a 10 cm wide metal roller was used to roll it back and forth three times under a load of 2 kg, and then the sheet was left to stand. The resin seeped out from the underside of the fiber sheet toward the surface, and the sheet surface became wet. After 5 minutes, the resin impregnation of the sheet surface was observed and judged according to the following criteria. ○: Resin seepage onto the sheet surface is 90% or more. ×: Resin seepage onto the sheet surface was less than 90% of the sheet surface.

[0059] (8) Dustproofing effect of fiber sheet materials for civil engineering and building reinforcement Since the effect of improving toughness performance depends on the ultimate strain of the sheet, it was evaluated according to the following criteria based on the ultimate strain of the sheet. ○: Sheet ultimate strain is 3.0% or more ×: Sheet ultimate strain is less than 3.0%

[0060] (9) Shear reinforcement effect of fiber sheet materials for civil engineering and building reinforcement Based on the 2021 Revised Edition Guidelines for the Design and Construction of Seismic Reinforcement 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 )

[0061] [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 having 1,000 holes with a diameter of 0.1 mm at a shear rate of 30,000 sec -1 The fiber was extruded so that the fiber resembled a fiber shape, and spun into water at 25°C. The fiber was then neutralized with a 10% by weight aqueous solution of sodium hydroxide at 10°C for 15 seconds. The fiber was then heated and dried at 170°C for 15 seconds, and an oil agent was then applied to the fiber to obtain polyparaphenylene terephthalamide fiber with a moisture content of 7.0% by weight (total fineness 3,300 dtex, specific gravity 1.44).

[0062] [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.×30 seconds, to obtain polyparaphenylene terephthalamide fibers (total fineness 3,300 dtex, specific gravity 1.44) having a moisture content of 6.8% by weight.

[0063] [Example 3] The same procedure as in Production Example 1 was repeated 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, specific gravity 1.44) with a moisture content of 7.0% by weight.

[0064] [Comparative Example 1] The material used was "Kevlar(R) 49" (polyparaphenylene terephthalamide fiber; 3,300 dtex, specific gravity 1.45) manufactured by Toray DuPont.

[0065] [Comparative Example 2] Teijin's "Technora(R)" (copolyparaphenylene-3,4'-oxydiphenylene terephthalamide fiber, total fineness 1,670 dtex, specific gravity 1.39) was used.

[0066] [Comparative Example 3] Toray Industries, Inc.'s "TORAYCA(R) T300" (PAN-based carbon fiber, total fineness 3,690 dtex, specific gravity 1.76) was used.

[0067] Table 1 shows the tensile properties and the single yarn strength retention rate after compression treatment of Examples 1 to 3 and Comparative Examples 1 to 3.

[0068] [Table 1]

[0069] From Table 1, it can be seen that copolyparaphenylene-3,4'-oxydiphenylene terephthalamide fiber (Comparative Example 2) and carbon fiber (Comparative Example 3) have low single-yarn strength retention after compression treatment and lack performance stability. For Examples 1 to 3 and Comparative Example 1, which have high single-yarn strength retention after compression treatment, unidirectional fiber sheet materials were produced with the following configuration and various evaluations were carried out.

[0070] [Example 4] The fibers obtained in Example 1 were twisted at a twist factor of 0.78 for the warp yarns, and polyester fibers (550 dtex) manufactured by Toray Industries, Inc. were used for the weft yarns to weave a reinforcing fiber sheet material with a width of 30 cm, a warp density of 30 / 25.4 mm, a weft density of 12 / 25.4 mm, and a weaving pattern of imitation weaving. The shrinkage rate of the obtained fiber sheet material was 1.2%, and the basis weight was 403 g / m 2 It was.

[0071] [Example 5] The fibers obtained in Example 2 were twisted at a twist factor of 1.14, but the fibers were woven under the same conditions as in Example 4. The shrinkage rate of the obtained fiber sheet material was 1.1%, and the basis weight was 398 g / m 2 It was.

[0072] [Example 6] The fibers obtained in Example 3 were twisted at a twist factor of 0.78, but were woven under the same conditions as in Example 4. The shrinkage rate of the obtained fiber sheet material was 1.0%, and the basis weight was 402 g / m 2 It was.

[0073] [Comparative Example 4] The fibers obtained in Comparative Example 1 were twisted at a twist factor of 0.98, but were woven under the same conditions as in Example 4. The shrinkage rate of the obtained fiber sheet material was 1.0%, and the basis weight was 399 g / m 2 It was.

[0074] [Example 7] The fibers obtained in Example 1 were twisted at a twist factor of 1.51, but the same weaving conditions were used as in Example 4. The shrinkage rate of the obtained sheet was 1.3%, and the basis weight was 391 g / m 2 It was.

[0075] [Example 8] The weft density was 32 threads / 25.4 mm, and the other conditions were the same as in Example 4. The shrinkage rate of the obtained sheet was 1.5%, and the basis weight was 422 g / m 2 It was.

[0076] Table 2 shows the evaluation results of the fiber sheet materials for reinforcing civil engineering and building structures obtained by impregnating the unidirectional fiber sheet materials obtained in Examples 4 to 8 and Comparative Example 4 with Konishi Bond E2500S (two-component curing epoxy resin).

[0077] [Table 2]

[0078] From Table 2, it can be seen that the fiber sheet material of Comparative Example 4, which has a low breaking elongation of the multifilament, also has a low ultimate strain in the sheet properties and a low effect of improving the dust performance. On the other hand, Examples 4 to 8 show a high ultimate strain of 3.0% or more, and are also excellent in the effect of improving the dust performance. [Industrial Applicability]

[0079] The fiber sheet material for reinforcing civil engineering and architectural structures of the present invention is ideal for reinforcing the shear and ductility of not only general structures but also elevated bridge piers and decks, and especially polygonal columnar structures. [Explanation of symbols]

[0080] 10 High-strength organic multifilament 11 Supplementary Fibers

Claims

1. A reinforcing fiber sheet material made of high-strength organic multifilaments for use in reinforcing civil engineering and architectural structures, (a) the tensile strength retention rate of the single yarn constituting the multifilament after compression treatment is 90% or more; (b) The ultimate strain along the orientation of the reinforcing fibers of the fiber sheet material, measured by the method described in JIS A1191:2021, is 3.0% or more; Fiber sheet material for reinforcing civil engineering and building structures.

2. 2. The fiber sheet material for reinforcing civil engineering and architectural structures according to claim 1, wherein the high-strength organic multifilament is at least one type of fiber selected from the group consisting of para-aramid fiber, polyarylate fiber, and polybenzobisoxazole (PBO) fiber.

3. 2. The fiber sheet material for reinforcing civil engineering and architectural structures according to claim 1, wherein the high-strength organic multifilament is a polyparaphenylene terephthalamide fiber.

4. The reinforcing fiber sheet material is (c) a tensile strength in the orientation direction of the reinforcing fibers measured by the method described in JIS A1191:2021 of 2,000 MPa or more; (d) a Young's modulus measured by JIS A1191:2021 of 60 GPa or more; The fiber sheet material for reinforcing civil engineering and architectural structures according to claim 1.

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

6. 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 5.

7. The civil engineering / architectural structure according to claim 6, which is a concrete structure.

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