Cement-based material reinforcing material and manufacturing method of same

Abstract

To provide a cement-based material reinforcing material that has high adhesive strength to a cement-based matrix and exhibits large frictional force at the interface with the cement-based matrix.SOLUTION: A fixing material 5 is applied to a fiber strand 4 formed by solidifying a reinforcing fiber bundle 2 with a synthetic resin material 3, and then cement particles 6 are attached to the surface of the fiber strand 4 and hardened to form a cement-based material reinforcing material 1.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a reinforcing material for reinforcing structures made of cement-based materials such as concrete and mortar. [Background technology]

[0002] Expressway bridges that have been in operation for more than 50 years are undergoing renovation work to reinforce the deck from above. One known method of reinforcing the top surface of a deck is the top surface thickening method, in which steel fiber concrete is poured onto the top surface of the deck, integrating the old and new concrete and increasing the thickness of the deck, thereby reinforcing it. However, it has been pointed out that the steel fibers mixed into the concrete tend to rust and damage the concrete's waterproofing layer, and furthermore, if cracks occur in the concrete, the steel fibers exposed to the atmosphere through the cracks will rust and lose strength, making the rusted areas more susceptible to brittle fracture.

[0003] As a means for solving the above-mentioned problems, there are known methods for preventing the occurrence of brittle fracture caused by the use of steel fibers by using a reinforcing material made of continuous inorganic fiber bundles solidified with a synthetic resin material instead of steel fibers, and further by bending the whole or part of this reinforcing material or by providing an uneven surface, and mixing this reinforcing material into concrete and pouring it into the reinforced part or forming a concrete structure (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-154853 [Patent Document 2] Japanese Patent Publication No. 2022-126885 Summary of the Invention [Problem to be solved by the invention]

[0005] It is possible to prevent the occurrence of brittle fracture caused by the use of steel fibers by mixing a reinforcing material made by solidifying the inorganic fiber bundles with a synthetic resin material into a cement matrix such as cement paste or mortar. However, there is a problem in that the adhesive strength between the reinforcing material and the cement paste or mortar is insufficient, making it prone to cracking and spreading on the concrete surface.

[0006] In view of the problems inherent in conventional techniques, an object of the present invention is to provide a reinforcing material for cement-based materials that has high adhesive strength to a cement-based matrix and generates large frictional force at the interface with concrete. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention includes the following aspects. [1] A reinforcing material for cement-based materials, characterized in that it has a structure in which cement particles are attached to the surface of a fiber strand formed by solidifying a reinforcing fiber bundle with a synthetic resin material. [2] A reinforcing material for cement-based materials according to [1] above, which has a structure in which cement particles are attached to a fiber strand having a surface coated with a fixing agent made of a resin-based primer. [3] The reinforcing material for cement-based materials according to [1] or [2], characterized in that the amount of cement particles attached is 10 to 80 mass %. [4] The reinforcing material for cement-based materials according to [2] or [3], characterized in that the amount of the resin-based primer attached is 1 to 20 mass %. [5] The cross-sectional area of ​​the fiber strand cut surface is 0.01 to 7.0 mm 2 The reinforcing material for cement-based materials according to any one of [1] to [4], characterized in that: [6] A reinforcing material for cement-based materials according to any one of [1] to [5], characterized in that the reinforcing fiber bundles are formed from any one of carbon fiber, aramid fiber, and glass fiber. [7] A method for producing a reinforcing material for cement-based materials, comprising the steps of impregnating a reinforcing fiber bundle with a thermosetting resin or a thermoplastic resin, solidifying the resin to form a fiber strand, applying a fixing agent consisting of a resin-based primer to the surface of the fiber strand, uniformly adhering cement particles to the surface of the fixing agent, and hardening the fixing agent to integrally adhere the cement particles to the surface of the fiber strand.

[0008] (reinforced fiber bundles) In the reinforcing material for cement-based materials (hereinafter also simply referred to as "reinforcing material") having the above-mentioned configuration, the reinforcing fiber bundles can be made of one or more types of reinforcing fibers such as inorganic fibers, organic fibers, and metal fibers. Examples of inorganic fibers include glass fibers, carbon fibers, boron fibers, silicon carbide fibers, and alumina fibers. Examples of organic fibers include polyparaphenylenebenzoxazole fibers (PBO fibers), high-strength polyethylene fibers, polypropylene fibers, aramid fibers, polyamide fibers such as aliphatic polyamide fibers and semi-aromatic polyamide fibers, polyester fibers, vinylon fibers, and self-reinforced fibers obtained by stretching and reinforcing these fibers. Examples of metal fibers include aluminum fibers, alumina fibers, SUS fibers, and copper fibers. Among these, carbon fibers, aramid fibers, and glass fibers, which have a higher elastic modulus than the cement matrix, are more preferred. The diameter of the monofilament used in the reinforcing fiber bundle is not particularly limited, but is preferably 5 to 20 μm, which is suitable for fiber production. In the case of carbon fiber, it is more preferably 5 to 10 μm, which provides high strength and high elastic modulus. The reinforcing fiber bundle is composed of several hundred to several hundred thousand of the monofilaments. The desired number of filaments can be obtained by separating or doubling commercially available fiber bundles.

[0009] (synthetic resin material) The synthetic resin material with which the reinforcing fiber bundle is impregnated is not particularly limited, and examples thereof include thermosetting resins, thermoplastic resins, moisture-curing resins, etc. Among these, thermosetting resins are preferred, and epoxy resins, vinyl ester resins, urethane resins, and urea resins are more preferred, and thermosetting resins containing epoxy resins or vinyl ester resin components are more preferred from the viewpoint of ease of production of the fiber strand bundle.

[0010] (fiber strand) There is no particular limit to the thickness of the fiber strand, but the cross-sectional area must be 0.01 to 7.0 mm. 2 The range is preferred. Cross-sectional area is 0.01 mm 2 If the cross-sectional area is smaller than 7.0 mm, it becomes difficult to attach cement particles to the surface. Also, it becomes more susceptible to damage when mixed with cementitious materials. Furthermore, since the surface area increases relatively and the contact area with the cementitious material increases, when cracks occur in the cementitious material due to external stress, the cementitious material reinforcement is less likely to come out of the cementitious material, and stress is more likely to be applied, making it more likely to break brittle. On the other hand, if the cross-sectional area is 7.0 mm, 2 If the value is larger than this, the surface area is relatively reduced and the contact with the cement-based material is reduced, so when a crack occurs in the cement-based material due to external stress, the reinforcing material for cement-based materials becomes too easily pulled out of the cement-based material, leading to a decrease in toughness, so the above range is preferable. The proportion of the synthetic resin material in the fiber strand is not particularly limited, but is preferably in the range of 10 to 60 mass %. If the resin content is less than 10% by mass, it is difficult to remove the air present between the monofilaments during fiber strand production, which makes voids likely to form, preventing the fiber strand from having normal strength and reducing the mechanical properties of the cement material.On the other hand, if the resin content is more than 60% by mass, the elastic modulus of the fiber strand decreases, reducing the elastic modulus of the cement material, so the above range is preferred.

[0011] (cement particles) The cement to be attached to the surface of the fiber strand can be any hydraulic material, and preferred examples include ordinary Portland cement, high-early-strength Portland cement, ultra-high-early-strength Portland cement, moderate-heat Portland cement, sulfate-resistant cement, blast-furnace cement, silica cement, fly ash cement, alumina cement, and expansion cement. Of these, ordinary Portland cement is preferred because it is inexpensive and easily available. It is also possible to use cement particles mixed with fine aggregate such as sand. The amount of cement particles attached to the reinforcing material is not particularly limited, but is preferably in the range of 10 to 80% by mass. If it is less than 10% by mass, the adhesive strength between the reinforcing material and the cement matrix cannot be effectively increased. On the other hand, if it is more than 80% by mass, the volume ratio of the fiber strands decreases when the volume fraction of the reinforcing material in the concrete molded body is constant, and the reinforcing effect is reduced, so the above range is preferable.

[0012] (fixing agent) Examples of fixing agents for adhering cement particles to the surface of fiber strands include thermosetting resin-based primers such as epoxy resins, modified silicone resins, melamine resins, urea resins, phenolic resins, polyurethane resins, unsaturated polyesters, reactive acrylic resins, and silylated urethane resins. Among these, epoxy and modified silicone resin-based primers, which have alkali resistance, are preferred. Considering long-term durability and safety, epoxy resin-based primers are more preferred. The cement particles can be attached by applying the resin-based primer to the surface of the fiber strand, then sprinkling the cement particles on the surface, and allowing the resin to harden and solidify. The amount of resin-based primer applied to the reinforcing material is not particularly limited, but is preferably in the range of 1 to 20% by mass. If it is less than 1% by mass, the cement particles will not be sufficiently fixed, and the adhesive strength between the fiber strand and the cement matrix will not be effectively increased. On the other hand, if it is more than 20% by mass, the cement particles will be coated with the resin-based primer, and the hardening reaction between the base mortar and the cement particles will not occur. Also, the degree of surface roughening will be reduced, making it impossible to effectively increase adhesiveness. Therefore, the above range is preferable.

[0013] The reinforcing material having the above-described configuration is formed by adhering cement particles to the surface of a fiber strand formed into a long rod shape, and may be used in its long form or cut to a predetermined length. The fiber strand may be rod-shaped and be bent in whole or in part. Furthermore, the fiber strands may be cut to a predetermined length and dispersed in concrete or mortar for use. There are no particular restrictions on the cut length, but a range of 5 to 30 mm is preferred. If the cut length is shorter than 5 mm, the adhesive area with the matrix cement decreases, resulting in a reduced reinforcing effect and reduced toughness, making the fiber more susceptible to cracking. Furthermore, the cutting process becomes more difficult, leading to increased costs. On the other hand, if the cut length is longer than 30 mm, the fiber strands tend to entangle with each other when mixed into concrete or mortar, resulting in poor dispersion, and as a result, the mechanical properties of the concrete molded body decrease. Therefore, the above range is preferred.

[0014] (Manufacturing method of reinforcing material) The reinforcing material having the above-mentioned structure can be produced, for example, by the following processing steps. First, a glass fiber strand or a carbon fiber strand having a monofilament diameter of 5 to 20 μm and a strand thickness of 350 to 37,500 dtex is prepared. The strand is then passed through an impregnation die filled with a thermosetting resin or a thermoplastic resin, and is drawn out from the die outlet while being heated in the case of a thermosetting resin, or while being cooled in the case of a thermoplastic resin, to form the strand, which is then cut to the desired length to produce a fiber strand 4 as shown in Figures 1 and 2. The cross-sectional shape and area of ​​the reinforcing material are determined by the shape of the die outlet. Here, in the fiber strand 4 produced as described above, as shown in FIG. 2, the monofilaments 2 are aligned parallel to the length direction of the fiber strand 4 and are dispersed almost uniformly in the cross-sectional direction. Furthermore, when a thermoplastic resin is used, by using a press mold or gears immediately after drawing out from the outlet of the impregnation die and before or during cooling, or by changing the drawing speed from the outlet of the die, it is possible to produce an indented reinforcing material having multiple bulges, an indented reinforcing material having multiple recesses, an indented shape having multiple protrusions, or a dumbbell-shaped reinforcing material having bulges on both ends. [Effects of the Invention]

[0015] When the reinforcing material of the present invention is mixed into a cementitious matrix, a hydration reaction occurs between the cement particles attached to the surface of the fiber strand and the cementitious matrix, thereby increasing the adhesive strength between the fiber strand and the cementitious matrix. By using concrete mixed with the reinforcing material of the present invention to reinforce concrete decks and structures, cracks are less likely to occur in the reinforced parts, and even if cracks do occur, their toughness is improved, preventing their propagation and making brittle fracture less likely. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is an external view of one embodiment of a reinforcing material for cement-based materials of the present invention. FIG. [Figure 2] 1 is an enlarged cross-sectional view of a reinforcing material for cement-based materials according to the present invention. [Figure 3]FIG. 1 is an external view of a testing machine used to verify the performance of the reinforcing material for cement-based materials of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] The present invention will be described in detail below based on preferred embodiments. Note that the present invention is not limited to the following embodiments. The embodiments are merely examples and can be appropriately modified and implemented within the scope of the present invention.

[0018] 1 and 2 show a reinforcing material according to one embodiment of the present invention. The reinforcing material 1 shown in the figure is constructed by impregnating a reinforcing fiber bundle 2 consisting of numerous monofilaments with a synthetic resin material 3 such as epoxy resin, solidifying it to form a fiber strand 4, applying a fixing agent 5 consisting of a resin-based primer to the surface of this fiber strand 4, and uniformly adhering cement particles 6 to the surface of this fixing agent 5, and then hardening the fixing agent 5 to integrally adhere the cement particles 6 to the surface of the fiber strand 4.

[0019] The reinforcing material 1 has an appropriate size, for example, a cross-sectional area of ​​0.1 to 12.0 mm 2 They are formed into a shape of about 5 to 30 mm in length, and several pieces are mixed into concrete or mortar, which are used to construct or repair concrete or mortar structures. Although there is no particular limitation on the amount of reinforcing material 1 mixed into concrete or mortar, a volume fraction of 0.1 to 5% is preferred. If it is less than 0.1%, the reinforcing effect is small and the purpose cannot be achieved, while if it is more than 5%, the effect becomes saturated or the reinforcing materials become entangled with each other, forming defects that lead to a decrease in mechanical properties. Therefore, the above range is preferred. [Example]

[0020] The performance of the reinforcing material 1 shown in FIG. 1 was examined. (reinforcement material) The following materials were used to make the reinforcements for testing: Reinforcing fiber bundle: Carbon fiber bundle, product name "Pyrofil (registered trademark) TR505S15L" (15,000 filaments, strand strength 4900 MPa, strand modulus 242 GPa), manufactured by Mitsubishi Chemical Corporation Synthetic resin material: Epoxy resin. Base agent: jER (registered trademark) 828, manufactured by Mitsubishi Chemical Corporation. Hardener: Kayahard (registered trademark) MCD, manufactured by Nippon Kayaku Co., Ltd. Fixing agent: Product name "Bond (registered trademark) Microcrack Repair Primer" manufactured by Konishi Co., Ltd. Cement particles: Product name "Instant Cement", manufactured by Katei Kagaku Kogyo Co., Ltd. Cement matrix for fixing reinforcement: Product name "Plystar 100", manufactured by Pacific Materials Co., Ltd.

[0021] The test reinforcement was prepared as follows. The reinforcing fiber bundle was impregnated with an epoxy resin as a synthetic resin material according to the strand preparation method described in JIS R7608, and cured to form a continuous fiber strand. The resin content at this time was 40 wt %. Next, the continuous fiber strand was cut into a length of 100 mm, and then 5 mg of an adhesion promoter was applied to the surface of each fiber strand. Before the adhesive hardened, cement particles were attached in an amount twice the weight of the carbon fiber strands, and the strands were left to stand for one day to harden the adhesive.

[0022] The axial half of the reinforcing material was inserted into a 50 mm long nut (screw diameter W3 / 8, see reference number 11 in Figure 3) and integrated. The integration was performed by first filling half of the inside of the nut with paper waste (trade name "Kimtowel (registered trademark)" manufactured by Nippon Paper Crecia Co., Ltd.) and plugging it, then filling the remaining half of the nut with the cement-based matrix for fixing the reinforcing material, inserting the fiber strand into this, and leaving it to harden for 24 hours.

[0023] Five test reinforcing members each having a long nut integrated on one side of the axial direction were fabricated, and an adhesion force experiment was carried out on these reinforcing members according to the following procedure.

[0024] First, as shown in FIG. 3, five holes 10a, each 10 mm in diameter and 55 mm deep, were drilled with a concrete drill in a plain concrete plate 10 made in accordance with JIS A5371. Next, 263 g of water was added to 1,754 g of dry mortar (manufactured by Yoko Bussan Co., Ltd.), and the mixture was stirred for 3 minutes using a tabletop mixer (trade name "Mixer-N-50", manufactured by Hobart Japan Co., Ltd.) to knead 1 L of mortar. The mixed mortar was filled into the drilled hole 10a, and as shown in the figure, the test reinforcement material was embedded 50 mm into the center of the filled mortar, with a long nut 11 protruding from the flat plate 10. At this time, an edge separator was placed between the mortar and the reinforcement material. The mortar was allowed to harden for 15 days, and the long nut 11 was connected to a tensile testing machine 12 (trade name "Techno Tester R10000ND", manufactured by Sanko Techno Co., Ltd.) placed on the flat plate 10. The handle of the tensile testing machine 12 was rotated at a speed of approximately 1 rotation per second to pull the test reinforcement material upward, thereby extracting the entire 50 mm shaft portion of the reinforcement material embedded in the hole 10a. During this operation, the maximum tensile load value displayed on the tensile tester 12 was recorded.

[0025] The results of the tensile test for the five test reinforcing members and the average bond stress calculated using the following formula are shown in Table 1.

[0026] TIFF2025151680000002.tif54170

[0027] As a comparative example, five fiber strands (without cement particles attached) were prepared in the same manner as in the above example and subjected to a tensile test in the same manner as in the above example. The average bond stress obtained from the measured values ​​and the calculation formula is shown in Table 1.

[0028] [Table 1]

[0029] According to the above test results, the reinforcing material of the Example, in which cement particles were attached to the surface of the fiber strand, had a higher bond stress to the mortar than the fiber strand of the Comparative Example, in which no cement particles were attached. This is presumably because the cement particles increased the surface roughness of the fiber, which in turn increased the frictional force with the matrix mortar. It is also presumed that a hardening reaction occurred between the matrix mortar and the cement particles, which increased the adhesion to the reinforcing material.

[0030] The configuration and form of the reinforcing material described and illustrated above are examples, and the present invention is not limited to the configuration and form described and illustrated, and other appropriate configurations and forms are possible. [Explanation of symbols]

[0031] 1 Reinforcement material for cement-based materials (reinforcement material), 2 Reinforcement fiber bundle, 33 Synthetic resin material, 4 Fiber strand, 5 Fixing material, 6 Cement particles

Claims

1. A reinforcing material for cement-based materials, characterized in that it has a structure in which cement particles are attached to the surface of a fiber strand formed by solidifying a reinforcing fiber bundle with a synthetic resin material.

2. 2. A reinforcing material for cement-based materials according to claim 1, which has a structure in which cement particles are attached to a fiber strand having a surface coated with a fixing agent made of a resin-based primer.

3. 3. The reinforcing material for cement-based materials according to claim 1, wherein the amount of cement particles attached is 10 to 80% by mass.

4. 3. The reinforcing material for cement-based materials according to claim 2, wherein the amount of the resin-based primer adhered is 1 to 20% by mass.

5. The cross-sectional area of ​​the fiber strand cut surface is 0.01 to 7.0 mm ２ 3. The reinforcing material for cement-based materials according to claim 1, wherein the reinforcing material is

6. 3. A reinforcing material for cement-based materials according to claim 1, wherein the reinforcing fiber bundles are formed from any one of carbon fiber, aramid fiber, and glass fiber.

7. A method for manufacturing a reinforcing material for cement-based materials, comprising the steps of impregnating a reinforcing fiber bundle with a thermosetting resin or a thermoplastic resin, solidifying the resin to form a fiber strand, applying a fixing agent consisting of a resin-based primer to the surface of the fiber strand, uniformly adhering cement particles to the surface of the fixing agent, and hardening the fixing agent to integrally adhere the cement particles to the surface of the fiber strand.

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