Method for producing a fiber-reinforced mortar composition, and method for repairing concrete structures.

Abstract

To provide a method for producing a fiber-reinforced mortar composition that can suppress the sedimentation of steel fibers during mixing, and a method for repairing concrete structures using the mortar composition obtained by the method for producing the fiber-reinforced mortar composition. [Solution] The present invention relates to a method for producing a fiber-reinforced mortar composition comprising a binder containing Portland cement and silica fume fine powder, fine aggregate, steel fibers, organic fibers, and water, comprising a kneading step of adding the fine aggregate, steel fibers, organic fibers, and water to the binder and kneading, wherein in the kneading step, the organic fibers are added to the binder, and then the steel fibers are added.

Description

[Technical Field]

[0001] The present invention relates to a method for producing a fiber-reinforced mortar composition and a method for repairing concrete structures. [Background technology]

[0002] Fiber-reinforced mortar compositions, used as building materials for concrete structures such as skyscrapers and road structures, are known for their high compressive strength and high toughness, including tensile strength.

[0003] Fiber-reinforced mortar compositions generally consist of a binder containing Portland cement or ultrafast-setting cement, silica fume, slag powder, and admixtures (e.g., fly ash powder), fine aggregate, short fibers (e.g., organic fibers, steel fibers), a polycarboxylic acid-based water-reducing agent, and water. Here, fiber-reinforced mortar compositions are usually produced by mixing a binder and fine aggregate to obtain a premix powder, to which short fibers, a polycarboxylic acid-based water-reducing agent, and water are added and kneaded (see Non-Patent Documents 1 and 2). [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Study on the material properties of HFRCC using straight steel fibers and PVA fibers. Proceedings of the Architectural Institute of Japan Annual Meeting (Hokuriku), September 2010 (Takashi Kikuta, Hiromitsu Mihashi, Tomoya Nishiwaki) [Non-Patent Document 2] Effect of steel fiber shape on the tensile performance of fiber-reinforced cement composite materials containing steel fibers and synthetic fibers. Annual Proceedings of the Concrete Engineering Society, Vol. 34, No. 1, 2012 (Risa Yoshida, Takatsune Kikuta, Tomoya Nishiwaki, Hiromitsu Mihashi) [Overview of the project] [Problems that the invention aims to solve]

[0005] Incidentally, when steel fibers are used as short fibers in a fiber-reinforced mortar composition, they tend to settle during mixing because they have a higher specific gravity compared to other materials. Therefore, fiber-reinforced mortar compositions containing steel fibers have a problem in that the uniformity of the fibers is hindered, making them prone to cracking and other problems caused by differences in strength.

[0006] This invention has been made in view of the above circumstances, and aims to provide a method for producing a fiber-reinforced mortar composition that can suppress the settling of steel fibers during mixing, and a method for repairing concrete structures using the mortar composition obtained by the method for producing the fiber-reinforced mortar composition. [Means for solving the problem]

[0007] The present invention relates to a method for producing a fiber-reinforced mortar composition comprising a binder (B) containing Portland cement and silica fume powder, fine aggregate (S), steel fibers, organic fibers, and water (W), The process includes a kneading step in which the binder (B) is mixed with the fine aggregate (S), the steel fibers, the organic fibers, and the water (W). In the kneading process, the organic fibers are added to the binder (B), and then the steel fibers are added.

[0008] In the method for producing the fiber-reinforced mortar composition described above, by adding the organic fibers, which have a lower density than the steel fibers, first, the binder (B) and the organic fibers are uniformly mixed, and the organic fibers are uniformly dispersed in the binder (B). As a result, when the steel fibers are added to the mixture of the binder (B) and the organic fibers, the steel fibers become entangled with the organic fibers, thereby suppressing the settling of the steel fibers. Therefore, the method for producing the fiber-reinforced mortar composition can suppress the settling of steel fibers during mixing.

[0009] In the production method of the fiber-reinforced mortar composition according to the present invention, in the kneading step, after adding the water (W) to the binder (B) and kneading to obtain a slurry, the organic fibers may be added to the slurry.

[0010] According to such a configuration, in the production method of the fiber-reinforced mortar composition, since the organic fibers are uniformly dispersed in the slurry, sedimentation of the steel fibers during kneading can be further suppressed.

[0011] In the production method of the fiber-reinforced mortar composition according to the present invention, in the kneading step, after adding the organic fibers to the binder (B) and dry-kneading to obtain a powder mixture, the water (W) may be added to the powder mixture.

[0012] According to such a configuration, in the production method of the fiber-reinforced mortar composition, since a slurry in which the organic fibers are uniformly dispersed can be formed, sedimentation of the steel fibers during kneading can be further suppressed.

[0013] In the production method of the fiber-reinforced mortar composition according to the present invention, the specific surface area of the silica fume fine powder may be 15 m 2 / g or more and 20 m 2 / g or less.

[0014] According to such a configuration, in the production method of the fiber-reinforced mortar composition, a fiber-reinforced mortar composition excellent in crack generation strength can be produced.

[0015] In the production method of the fiber-reinforced mortar composition according to the present invention, the blending amount of the silica fume fine powder may be 5 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the Portland cement.

[0016] According to such a configuration, in the production method of the fiber-reinforced mortar composition, a fiber-reinforced mortar composition excellent in crack generation strength can be produced.

[0017] In the method for manufacturing the fiber reinforced mortar composition according to the present invention, the blending amount of the steel fiber may be 2.5% by volume or more and 4.5% by volume or less with respect to the entire fiber reinforced mortar composition.

[0018] According to such a configuration, the method for manufacturing the fiber reinforced mortar composition can manufacture a fiber reinforced mortar composition excellent in crack generation strength.

[0019] In the method for manufacturing the fiber reinforced mortar composition according to the present invention, the fiber diameter of the steel fiber may be 100 μm or more and 400 μm or less.

[0020] According to such a configuration, the method for manufacturing the fiber reinforced mortar composition can manufacture a fiber reinforced mortar composition excellent in crack generation strength.

[0021] In the method for manufacturing the fiber reinforced mortar composition according to the present invention, the fiber length of the steel fiber may be 10 mm or more and 20 mm or less.

[0022] According to such a configuration, the method for manufacturing the fiber reinforced mortar composition can manufacture a fiber reinforced mortar composition excellent in crack generation strength.

[0023] In the method for manufacturing the fiber reinforced mortar composition according to the present invention, the blending amount of the organic fiber may be 0.2% by volume or more and 2.0% by volume or less with respect to the entire fiber reinforced mortar composition.

[0024] According to such a configuration, the method for manufacturing the fiber reinforced mortar composition can manufacture a fiber reinforced mortar composition excellent in crack generation strength.

[0025] In the method for manufacturing the fiber reinforced mortar composition according to the present invention, the fiber diameter of the organic fiber may be 10 μm or more and 200 μm or less.

[0026] According to such a configuration, the method for manufacturing the fiber reinforced mortar composition can manufacture a fiber reinforced mortar composition excellent in crack generation strength.

[0027] The method for producing the fiber-reinforced mortar composition according to the present invention may also involve organic fibers having a fiber length of 6 mm or more and 15 mm or less.

[0028] The method for producing the fiber-reinforced mortar composition described above allows for the production of a fiber-reinforced mortar composition with excellent crack-initiating strength.

[0029] The method for producing the fiber-reinforced mortar composition according to the present invention may also involve a maximum particle size of 2.5 mm for the fine aggregate (S).

[0030] The method for producing the fiber-reinforced mortar composition described above allows for the stable production of a fiber-reinforced mortar composition with minimal variation.

[0031] The method for producing the fiber-reinforced mortar composition according to the present invention may also involve a fine aggregate (S) with a coarseness ratio of 1.3 to 3.0.

[0032] The method for producing the fiber-reinforced mortar composition described above allows for the production of a fiber-reinforced mortar composition with excellent crack-initiating strength.

[0033] The method for repairing concrete structures according to the present invention involves filling or applying a fiber-reinforced mortar composition, manufactured by the method for manufacturing the fiber-reinforced mortar composition described above, to the repair area of ​​the concrete structure.

[0034] The aforementioned concrete structure repair method, by using the fiber-reinforced mortar composition, makes it less likely for differences in crack formation strength to occur at the repair site. [Effects of the Invention]

[0035] According to the present invention, it is possible to provide a method for producing a fiber-reinforced mortar composition that can suppress the settling of steel fibers during mixing, and a method for repairing concrete structures using the mortar composition obtained by the method for producing the fiber-reinforced mortar composition. [Modes for carrying out the invention]

[0036] The following describes a method for producing a fiber-reinforced mortar composition according to this embodiment, and a method for repairing concrete structures.

[0037] <Method for producing fiber-reinforced mortar composition> The method for producing a fiber-reinforced mortar composition according to this embodiment is a method for producing a fiber-reinforced mortar composition comprising a binder (B) containing Portland cement and silica fume fine powder, fine aggregate (S), steel fibers, organic fibers, and water (W), the method comprising a kneading step of adding the fine aggregate (S), the steel fibers, the organic fibers, and the water (W) to the binder (B) and kneading them together.

[0038] In the mixing process, the organic fibers are added to the binder (B), and then the steel fibers are added.

[0039] In the method for producing the fiber-reinforced mortar composition according to this embodiment, the kneading step, in one embodiment, involves adding water (W) to the binder (B) and kneading to obtain a slurry, and then adding the organic fibers to the slurry.

[0040] Specifically, first, a premix powder obtained by mixing a binder (B) and fine aggregate (S) is mixed with water (W) to obtain a slurry. Then, organic fibers are added to the slurry and mixed, and subsequently steel fibers are added and mixed to carry out the mixing process.

[0041] In the kneading step of the above embodiment, the timing for adding steel fibers is preferably 2 to 6 minutes after the start of kneading the premix powder and water (W), and more preferably 2 to 4 minutes after the start of kneading, from the viewpoint of uniformly dispersing the organic fibers and steel fibers.

[0042] In the kneading process of the above embodiment, the kneading time after adding the steel fibers is preferably 2 minutes or more and 6 minutes or less, and more preferably 2 minutes or more and 4 minutes or less, from the viewpoint of uniformly dispersing the organic fibers and steel fibers.

[0043] In the method for producing the fiber-reinforced mortar composition according to this embodiment, in another embodiment, the kneading step involves adding the organic fibers to the binder (B) and dry-kneading to obtain a powder mixture, and then adding the water (W) to the powder mixture.

[0044] Specifically, first, the organic fibers are added to a premixed powder obtained by mixing the binder (B) and the fine aggregate (S), and the mixture is dry-kneaded to obtain a powder mixture. Then, the water (W) is added to the powder mixture and kneaded, and subsequently the steel fibers are added and kneaded to perform the kneading process.

[0045] In the kneading process of the other embodiment described above, the timing for adding steel fibers is preferably 2 to 6 minutes after the start of kneading the powder mixture and the water (W), and more preferably 2 to 4 minutes after the start of kneading, from the viewpoint of uniformly dispersing the organic fibers and steel fibers.

[0046] In the kneading process of the other embodiment described above, the kneading time after adding the steel fibers is preferably 2 minutes or more and 6 minutes or less, and more preferably 2 minutes or more and 4 minutes or less, from the viewpoint of uniformly dispersing the organic fibers and steel fibers.

[0047] In addition, the kneading step may be carried out in another embodiment by adding steel fibers to the powder mixture and kneading dry, and then adding water (W) and kneading.

[0048] Furthermore, the method for producing the fiber-reinforced mortar composition according to this embodiment may include admixtures as described later, if necessary. Preferably, these admixtures are added at the same time as the water (W).

[0049] Furthermore, the method for producing the fiber-reinforced mortar composition according to this embodiment may be carried out using a premixed powder obtained by mixing a binder (B), fine aggregate (S), and organic fibers.

[0050] Furthermore, the mixing machine used in the method for producing the fiber-reinforced mortar composition according to this embodiment is not particularly limited, and examples include a twin-screw forced mixer, a pan-type mixer, a fiber-reinforced material mixer, a hand mixer, and the like.

[0051] The binder (B) contains Portland cement and silica fume powder.

[0052] Examples of Portland cement include ordinary Portland cement, rapid-hardening Portland cement, ultra-rapid-hardening Portland cement, moderate-heat Portland cement, low-heat Portland cement, sulfate-resistant Portland cement, and white Portland cement, as specified in JIS R 5210.

[0053] Silica fume fine powder refers to fine particles (specifically amorphous spherical fine particles) mainly composed of silicon dioxide, collected from exhaust gases etc. generated when metallic silicon or ferrosilicon is manufactured in an arc electric furnace, as defined in JIS A 6207. It means silica fume in its collected state, without any processing to increase the unit volume mass or suspension in water.

[0054] The composition of the silica fume fine powder may, for example, be 85% to 98% by mass of silicon dioxide and 0.6% to 2.0% by mass of magnesium oxide.

[0055] From the viewpoint of obtaining excellent crack-initiating strength, the specific surface area of ​​silica fume fine powder is preferably 15 m². 2 / g or more 20m 2 / g or less, more preferably 16m 2 / g or more 19m 2 It is less than or equal to / g, and more preferably 17m2 18 m or more per g 2 It is 18 m or less per g. The specific surface area of the silica fume fine powder is measured by the method specified in JIS A 6207 "Silica Fume for Concrete, 7 Test Methods, 7.9 Specific Surface Area".

[0056] The bulk density of the silica fume is not particularly limited. For example, from the viewpoint of reducing the autogenous shrinkage of concrete, it may be 0.25 g / cm 3 or more and 0.50 g / cm 3 or less. The bulk density means the density when a powder is filled in a container of a certain volume and the internal volume is taken as the volume, and is synonymous with the apparent density specified in JIS Z 8901.

[0057] From the viewpoint of obtaining excellent cracking generation strength, the content of the silica fume fine powder is preferably 5 parts by mass or more and 30 parts by mass or less, more preferably 5 parts by mass or more and 25 parts by mass or less, and still more preferably 5 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the Portland cement.

[0058] In addition to the Portland cement, the binder (B) may include, for example, blended cements such as blast furnace cement, fly ash cement, silica cement; known cements such as high - early strength cement, alumina cement, etc.

[0059] Furthermore, the binder (B) may also contain admixtures. Examples of admixtures include inorganic powders such as fly ash, cement kiln dust, blast furnace fume, blast furnace granulated slag powder, blast furnace decooked slag powder, converter slag powder, hemihydrate gypsum, expansive agents, limestone powder, quicklime powder, dolomite powder, sodium-type bentonite, calcium-type bentonite, attapulgite, sepiolite, activated clay, acid clay, allophane, imogolite, shirasu (volcanic ash), shirasu balloon, kaolinite, metakaolin (calcined clay), synthetic zeolite, artificial zeolite, mordenite, clinoptilolite, and other inorganic fillers. Note that one type of admixture may be used alone, or two or more types may be used in combination.

[0060] Fine aggregate (S) refers to aggregate that, as defined in JIS A 0203:2019, completely passes through a 10mm mesh sieve and passes through a 5mm mesh sieve by mass at a rate of 85% or more. Examples of fine aggregate (S) include sands derived from natural materials such as river sand, land sand, mountain sand, sea sand, crushed sand, and crushed limestone sand, as defined in Annex JA of JIS A 5308:2024 for ready-mixed concrete, as well as sands derived from slags such as blast furnace slag, electric furnace oxidized slag, and ferronickel slag, recycled aggregate, artificial lightweight aggregate, and recovered aggregate. Silica sand produced by crushing and classifying silica can also be used. Fine aggregate may be used alone or in combination of two or more types.

[0061] The maximum particle size of the fine aggregate (S) is preferably 2.5 mm, from the viewpoint of obtaining a stable fiber-reinforced mortar composition with low variability. The maximum particle size of the fine aggregate (S) refers to the largest mesh opening of the sieve that the fine aggregate (S) remains in when the fine aggregate (S) is sieved in accordance with the method described in JIS A 1102.

[0062] The coarseness ratio of the fine aggregate (S) is preferably 1.3 to 3.0, and more preferably 1.5 to 2.5, from the viewpoint of obtaining excellent crack initiation strength. The coarseness ratio of the fine aggregate (S) can be measured according to the method described in JIS A 1102.

[0063] The fine aggregate-to-binder ratio (S / B) is preferably 0.25 to 0.70, more preferably 0.25 to 0.60, and even more preferably 0.25 to 0.50, from the viewpoint of obtaining excellent crack initiation strength.

[0064] The steel fibers are not particularly limited and include, for example, steel cord (SC fiber), cut wire (CW fiber), straight steel fiber (OL fiber), hooked steel fiber (DR fiber), embossed steel fiber, three-dimensional corrugated steel fiber, piano wire, etc. Straight steel fibers are preferably those without end processing. Hooked steel fibers may have only one end hooked, or both ends may have hook processing.

[0065] From the viewpoint of obtaining excellent crack-initiating strength, the fiber diameter of the steel fibers is preferably 100 μm to 400 μm, and more preferably 150 μm to 250 μm.

[0066] From the viewpoint of obtaining excellent crack-initiating strength, the fiber length of the steel fibers is preferably 10 mm to 20 mm, and more preferably 13 mm to 15 mm.

[0067] The tensile strength of the steel fiber is not particularly limited; for example, it may be 1,800 MPa or more, or 2,300 MPa or more. Alternatively, the tensile strength of the steel fiber may be 4,000 MPa or less, or 3,500 MPa or less.

[0068] From the viewpoint of obtaining excellent crack-initiating strength, the steel fiber content is preferably 2.5% to 4.5% by volume, more preferably 3.0% to 4.5% by volume, and even more preferably 3.0% to 3.5% by volume, relative to the entire fiber-reinforced mortar composition.

[0069] Examples of organic fibers include polyvinyl alcohol fibers (PVA fibers), polyethylene fibers, aramid fibers, polypropylene fibers, and nylon fibers. Among these, from the viewpoint of obtaining excellent crack-initiating strength, the organic fiber is preferably at least one selected from the group consisting of polyvinyl alcohol fibers, polyethylene fibers, aramid fibers, and nylon fibers, and more preferably at least one selected from the group consisting of polyvinyl alcohol fibers, polyethylene fibers, and aramid fibers. The shape of the organic fiber is preferably a straight shape without end processing. Furthermore, the surface of the organic fiber may be embossed.

[0070] From the viewpoint of obtaining excellent crack-initiating strength, the fiber diameter of the organic fiber is preferably 10 μm to 200 μm, and more preferably 12 μm to 200 μm.

[0071] From the viewpoint of obtaining excellent crack-initiating strength, the fiber length of the organic fiber is preferably 6 mm to 15 mm, and more preferably 6 mm to 12 mm.

[0072] The tensile strength of the organic fiber is not particularly limited; for example, it may be 900 MPa or more, or 2,000 MPa or more. Alternatively, the tensile strength of the organic fiber may be 4,000 MPa or less, or 3,500 MPa or less.

[0073] From the viewpoint of obtaining excellent crack-initiating strength, the content of organic fibers is preferably 0.2% to 2.0% by volume, more preferably 0.2% to 1.5% by volume, and even more preferably 0.2% to 1.0% by volume, relative to the entire fiber-reinforced mortar composition.

[0074] The water (W) is not particularly limited, and for example, tap water, industrial water, recovered water, groundwater, river water, rainwater, etc. can be used. Preferably, the water does not contain organic matter, chloride ions, sodium ions, potassium ions, etc. that adversely affect the hydration reaction of the cement composition and concrete, or if it does contain them, it is in extremely small amounts. It is more preferable that the water be tap water or industrial water of stable quality.

[0075] From the viewpoint of obtaining excellent cracking strength, the water-to-binder ratio (W / B) is preferably 16% to 22%, more preferably 17% to 21%, and even more preferably 18% to 20%.

[0076] Examples of admixtures include air-entraining agents, air-entraining water-reducing agents, high-performance air-entraining water-reducing agents, fluidizing agents, separation-reducing agents, thickeners, thixotropic agents, setting retarders (e.g., tartaric acid), setting accelerators (e.g., aluminum sulfate), rapid setting agents, shrinkage-reducing agents, foaming agents, defoaming agents, and waterproofing agents. Note that admixtures may be used individually or in combination of two or more.

[0077] The fiber-reinforced mortar composition produced by the method for producing the fiber-reinforced mortar composition according to this embodiment can be used, for example, as building material for concrete structures such as skyscrapers and road structures, or as a repair material for such concrete structures.

[0078] The method for producing the fiber-reinforced mortar composition according to this embodiment is a method for producing a fiber-reinforced mortar composition comprising a binder (B) containing Portland cement and silica fume fine powder, fine aggregate (S), steel fibers, organic fibers, and water (W), The process includes a kneading step in which the binder (B) is mixed with the fine aggregate (S), the steel fibers, the organic fibers, and the water (W). In the kneading process, the organic fibers are added to the binder (B), and then the steel fibers are added.

[0079] In the method for producing the fiber-reinforced mortar composition described above, by adding the organic fibers, which have a lower density than the steel fibers, first, the binder (B) and the organic fibers are uniformly mixed, and the organic fibers are uniformly dispersed in the binder (B). As a result, when the steel fibers are added to the mixture of the binder (B) and the organic fibers, the steel fibers become entangled with the organic fibers, thereby suppressing the settling of the steel fibers. Therefore, the method for producing the fiber-reinforced mortar composition can suppress the settling of steel fibers during mixing.

[0080] In the method for producing the fiber-reinforced mortar composition according to this embodiment, in the mixing step, water (W) is added to the binder (B) and mixed to obtain a slurry, and then the organic fibers are added to the slurry. As a result, the organic fibers are uniformly dispersed in the slurry, and the settling of steel fibers during mixing can be further suppressed.

[0081] In the method for producing the fiber-reinforced mortar composition according to this embodiment, in the mixing step, the organic fibers are added to the binder (B) and dry-mixed to obtain a powder mixture, and then water (W) is added to the powder mixture to form a slurry in which the organic fibers are uniformly dispersed, thereby further suppressing the settling of steel fibers during mixing.

[0082] The method for producing the fiber-reinforced mortar composition according to this embodiment is such that the specific surface area of ​​the silica fume fine powder is 15 m². 2 / g or more 20m 2 By having a concentration of less than / g, it is possible to produce a fiber-reinforced mortar composition with excellent crack initiation strength.

[0083] In the method for producing the fiber-reinforced mortar composition according to this embodiment, the amount of silica fume fine powder added is 5 parts by mass or more and 30 parts by mass or less per 100 parts by mass of Portland cement, thereby enabling the production of a fiber-reinforced mortar composition with excellent crack initiation strength.

[0084] The method for producing the fiber-reinforced mortar composition according to this embodiment allows for the production of a fiber-reinforced mortar composition with excellent crack-initiating strength, provided that the amount of steel fibers included is 2.5% by volume or more and 4.5% by volume or less of the total fiber-reinforced mortar composition.

[0085] The method for producing the fiber-reinforced mortar composition according to this embodiment allows for the production of a fiber-reinforced mortar composition with excellent crack initiation strength, provided that the fiber diameter of the steel fibers is 100 μm or more and 400 μm or less.

[0086] The method for producing the fiber-reinforced mortar composition according to this embodiment allows for the production of a fiber-reinforced mortar composition with excellent crack initiation strength, provided that the fiber length of the steel fibers is 10 mm or more and 20 mm or less.

[0087] The method for producing the fiber-reinforced mortar composition according to this embodiment allows for the production of a fiber-reinforced mortar composition with excellent crack-initiating strength, provided that the amount of organic fibers blended is 0.2% to 2.0% by volume relative to the entire fiber-reinforced mortar composition.

[0088] The method for producing the fiber-reinforced mortar composition according to this embodiment allows for the production of a fiber-reinforced mortar composition with excellent crack initiation strength, provided that the fiber diameter of the organic fibers is 10 μm or more and 200 μm or less.

[0089] The method for producing the fiber-reinforced mortar composition according to this embodiment allows for the production of a fiber-reinforced mortar composition with excellent crack-initiating strength, provided that the fiber length of the organic fibers is 6 mm or more and 15 mm or less.

[0090] The method for producing the fiber-reinforced mortar composition according to this embodiment allows for the stable production of a fiber-reinforced mortar composition with minimal variation, as the maximum particle size of the fine aggregate (S) is 2.5 mm.

[0091] The method for producing the fiber-reinforced mortar composition according to this embodiment allows for the production of a fiber-reinforced mortar composition with excellent crack-initiating strength, provided that the coarseness ratio of the fine aggregate (S) is 1.3 or more and 3.0 or less.

[0092] <Repair methods for concrete structures> The concrete structure repair method according to this embodiment involves filling or applying a fiber-reinforced mortar composition to the repair area of ​​the concrete structure.

[0093] The fiber-reinforced mortar composition is a fiber-reinforced mortar composition produced by the method for producing the fiber-reinforced mortar composition according to the present embodiment.

[0094] The method of filling or applying is not particularly limited and includes, for example, filling methods, plastering methods, and spraying methods. In the filling method, a formwork is assembled at the repair site and an appropriate amount of fiber-reinforced mortar composition is poured in. In the plastering method, a craftsman places an appropriate amount of fiber-reinforced mortar composition on a trowel board and applies the mortar composition to the repair site of the concrete structure using a trowel or similar tool. In the spraying method, the fiber-reinforced mortar composition is sprayed onto the repair site of the concrete structure using a device such as a mortar pump.

[0095] Furthermore, in the concrete structure repair method according to this embodiment, before filling or applying the fiber-reinforced mortar composition to the repair area of ​​the concrete structure, the repair area may be pre-treated by removing corroded or deteriorated parts.

[0096] The concrete structure repair method according to this embodiment involves filling or applying the fiber-reinforced mortar composition, manufactured by the above-described method for manufacturing fiber-reinforced mortar compositions, to the repair area of ​​the concrete structure, thereby minimizing the occurrence of strength differences at the repair area.

[0097] Furthermore, the method for producing the fiber-reinforced mortar composition and the method for repairing concrete structures according to the present invention are not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the present invention.

[0098] The present invention includes the following embodiments. [1] A method for producing a fiber-reinforced mortar composition comprising a binder (B) containing Portland cement and silica fume powder, fine aggregate (S), steel fibers, organic fibers, and water (W), The process includes a kneading step in which the binder (B) is mixed with the fine aggregate (S), the steel fibers, the organic fibers, and the water (W). A method for producing a fiber-reinforced mortar composition, wherein in the kneading step, the organic fibers are added to the binder (B), and then the steel fibers are added. [2] The method for producing the fiber-reinforced mortar composition according to [1], wherein in the kneading step, water (W) is added to the binder (B) and kneaded to obtain a slurry, and then the organic fibers are added to the slurry. [3] The method for producing the fiber-reinforced mortar composition according to [1], wherein in the mixing step, the organic fibers are added to the binder (B) and dry-kneaded to obtain a powder mixture, and then the water (W) is added to the powder mixture. [4] The specific surface area of ​​the silica fume fine powder is 15 m². 2 / g or more 20m 2 A method for producing a fiber-reinforced mortar composition according to any one of [1] to [3], wherein the amount is less than or equal to / g. [5] A method for producing a fiber-reinforced mortar composition according to any one of [1] to [4], wherein the amount of silica fume fine powder added is 5 parts by mass or more and 30 parts by mass or less per 100 parts by mass of the Portland cement. [6] A method for producing a fiber-reinforced mortar composition according to any one of [1] to [5], wherein the amount of steel fibers added is 2.5% by volume or more and 4.5% by volume or less with respect to the entire fiber-reinforced mortar composition. [7] A method for producing a fiber-reinforced mortar composition according to any one of [1] to [6], wherein the fiber diameter of the steel fibers is 100 μm or more and 400 μm or less. [8] A method for producing a fiber-reinforced mortar composition according to any one of [1] to [7], wherein the fiber length of the steel fibers is 10 mm or more and 20 mm or less. [9] A method for producing a fiber-reinforced mortar composition according to any one of [1] to [8], wherein the amount of organic fibers blended is 0.2% by volume or more and 2.0% by volume or less with respect to the entire fiber-reinforced mortar composition.

[10] A method for producing a fiber-reinforced mortar composition according to any one of [1] to [9], wherein the fiber diameter of the organic fiber is 10 μm or more and 200 μm or less.

[11] A method for producing a fiber-reinforced mortar composition according to any one of [1] to

[10] , wherein the fiber length of the organic fiber is 6 mm or more and 15 mm or less.

[12] A method for producing a fiber-reinforced mortar composition according to any one of [1] to

[11] , wherein the maximum particle size of the fine aggregate (S) is 2.5 mm.

[13] A method for producing a fiber-reinforced mortar composition according to any one of [1] to

[12] , wherein the coarseness ratio of the fine aggregate (S) is 1.3 or more and 3.0 or less. A method for repairing a concrete structure, comprising filling or applying a fiber-reinforced mortar composition, manufactured by the method for manufacturing a fiber-reinforced mortar composition described in any one of items

[14] [1] to

[13] , to a repair site of the concrete structure. [Examples]

[0099] The following describes embodiments of the present invention, but the present invention is not limited to the following embodiments.

[0100] (Preparation of fiber-reinforced mortar composition) [Examples 1-9] Using the materials shown in Table 1, the fiber-reinforced mortar compositions of Examples 1 to 9 were prepared according to the formulations shown in Table 2. Specifically, the mixture was first prepared using a mixing machine (Makita Corporation 550 min)... -1Using a premix powder (100 parts by mass of Portland cement, 15 parts by mass of silica fume, and 50 parts by mass of fine aggregate (S)) which was prepared by mixing a binder (B) (Portland cement and silica fume) and fine aggregate (S), water (W) and an admixture were added and mixed for 2 minutes to obtain a slurry. Organic fibers were added to the slurry and mixed for 0.5 minutes, and then steel fibers were added and mixed for 2 minutes to obtain a fiber-reinforced mortar composition.

[0101] [Example 10] Using the materials shown in Table 1, the fiber-reinforced mortar composition of Example 10 was prepared according to the formulation shown in Table 2. Specifically, first, the mixture was mixed using a Makita 550 min mixer. -1 Using a premix powder (100 parts by mass of Portland cement, 15 parts by mass of silica fume, and 50 parts by mass of fine aggregate (S)) which was prepared by mixing a binder (B) (Portland cement and silica fume) and fine aggregate (S) with organic fibers and dry-mixing for 0.25 minutes to obtain a powder mixture. Water (W) and admixtures were added to the powder mixture and mixed for 2 minutes, and then steel fibers were added and mixed for 2 minutes to obtain a fiber-reinforced mortar composition.

[0102] [Example 11] Using the materials shown in Table 1, the fiber-reinforced mortar composition of Example 11 was prepared according to the formulation shown in Table 2. Specifically, first, the mixture was mixed using a Makita 550 min mixer. -1 Using a premix powder (100 parts by mass of Portland cement, 15 parts by mass of silica fume, and 50 parts by mass of fine aggregate (S)) which was prepared by mixing a binder (B) (Portland cement and silica fume) and fine aggregate (S), organic fibers were added and the mixture was dry-kneaded for 0.25 minutes to obtain a powder mixture. Steel fibers were added to the powder mixture and kneaded for 0.25 minutes, and then water (W) and admixtures were added and kneaded for 4 minutes to obtain a fiber-reinforced mortar composition.

[0103] [Examples 12-13] Using the materials shown in Table 1, the fiber-reinforced mortar compositions of Examples 12-13 were prepared according to the formulations shown in Table 2. Specifically, the mixture was first prepared using a mixing machine (Makita Corporation 550 min)... -1 Using a premix powder (100 parts by mass of Portland cement, 15 parts by mass of silica fume, and 50 parts by mass of fine aggregate (S)) which was prepared by mixing a binder (B) (Portland cement and silica fume) and fine aggregate (S), water (W) and an admixture were added and mixed for 4 minutes to obtain a slurry. Organic fibers were added to the slurry and mixed for 0.5 minutes, and then steel fibers were added and mixed for 4 minutes to obtain a fiber-reinforced mortar composition.

[0104] [Examples 14-15] Using the materials shown in Table 1, the fiber-reinforced mortar compositions of Examples 14-15 were prepared according to the formulations shown in Table 2. Specifically, the mixture was first mixed using a Makita 550 min mixer. -1 Using a premix powder (100 parts by mass of Portland cement, 15 parts by mass of silica fume, and 50 parts by mass of fine aggregate (S)) which was prepared by mixing a binder (B) (Portland cement and silica fume) and fine aggregate (S), water (W) and an admixture were added and mixed for 6 minutes to obtain a slurry. Organic fibers were added to the slurry and mixed for 0.5 minutes, and then steel fibers were added and mixed for 6 minutes to obtain a fiber-reinforced mortar composition.

[0105] [Example 16] Using the materials shown in Table 1, the fiber-reinforced mortar composition of Example 16 was prepared according to the formulation shown in Table 2. Specifically, first, a mixing machine (Makita Corporation 550 min) was used to mix the materials. -1Using a premix powder (100 parts by mass of Portland cement, 15 parts by mass of silica fume, and 50 parts by mass of fine aggregate (S)) which was prepared by mixing a binder (B) (Portland cement and silica fume) and fine aggregate (S) with organic fibers and dry-mixing for 0.25 minutes to obtain a powder mixture. Water (W) and admixtures were added to the powder mixture and mixed for 4 minutes, and then steel fibers were added and mixed for 4 minutes to obtain a fiber-reinforced mortar composition.

[0106] [Example 17] Using the materials shown in Table 1, the fiber-reinforced mortar composition of Example 17 was prepared according to the formulation shown in Table 2. Specifically, first, the mixture was mixed using a Makita 550 min mixer. -1 Using a premix powder (100 parts by mass of Portland cement, 15 parts by mass of silica fume, and 50 parts by mass of fine aggregate (S)) which was prepared by mixing a binder (B) (Portland cement and silica fume) and fine aggregate (S) with organic fibers and dry-mixing for 0.25 minutes to obtain a powder mixture. Water (W) and admixtures were added to the powder mixture and mixed for 6 minutes, and then steel fibers were added and mixed for another 6 minutes to obtain a fiber-reinforced mortar composition.

[0107] [Comparative Example 1] A fiber-reinforced mortar composition of Comparative Example 1 was prepared using the materials shown in Table 1 and according to the formulation shown in Table 2. Specifically, the mixture was first mixed using a Makita 550 min mixer. -1 Using a premix powder (100 parts by mass of Portland cement, 15 parts by mass of silica fume, and 50 parts by mass of fine aggregate (S)) which was prepared by mixing a binder (B) (Portland cement and silica fume) and fine aggregate (S), water (W) and an admixture were added and mixed for 2 minutes to obtain a slurry. Steel fibers were added to the slurry and mixed for 0.5 minutes, and then organic fibers were added and mixed for 2 minutes to obtain a fiber-reinforced mortar composition.

[0108] [Comparative Example 2] Using the materials shown in Table 1, a fiber-reinforced mortar composition of Comparative Example 2 was prepared according to the formulation shown in Table 2. Specifically, the mixture was first mixed using a Makita 550 min mixer. -1 Using a premix powder (100 parts by mass of Portland cement, 15 parts by mass of silica fume, and 50 parts by mass of fine aggregate (S)) which was prepared by mixing binder (B) (Portland cement and silica fume) and fine aggregate (S), steel fibers were added and the mixture was dry-kneaded for 0.25 minutes to obtain a powder mixture. Water (W) and admixtures were added to the powder mixture and kneaded for 2 minutes, and then organic fibers were added and kneaded for 2 minutes to obtain a fiber-reinforced mortar composition.

[0109] [Comparative Example 3] Using the materials shown in Table 1, a fiber-reinforced mortar composition of Comparative Example 3 was prepared according to the formulation shown in Table 2. Specifically, the mixture was first mixed using a Makita 550 min mixer. -1 Using a premix powder (100 parts by mass of Portland cement, 15 parts by mass of silica fume, and 50 parts by mass of fine aggregate (S)) which was prepared by mixing binder (B) (Portland cement and silica fume) and fine aggregate (S), steel fibers were added and the mixture was dry-kneaded for 0.25 minutes to obtain a powder mixture. Organic fibers were added to the powder mixture and kneaded for 0.25 minutes, and then water (W) and admixtures were added and kneaded for 4 minutes to obtain a fiber-reinforced mortar composition.

[0110] (Preparation of test specimens) The fiber-reinforced mortar compositions of each example and comparative example were poured in a single layer into cylindrical formwork (φ100 × h200 mm), and test specimens were prepared by vibrating compaction for 60 seconds using a table vibrator as specified in JIS R 5201. The obtained test specimens were sealed and cured at 20°C from immediately after pouring until 28 days of age. The cured test specimens were used for the evaluation of the unit volume mass ratio and the crack initiation strength ratio as described below.

[0111] [Table 1]

[0112] [Table 2]

[0113] (Evaluation of unit volume mass ratio) The unit volume mass ratio of cured specimens obtained using the fiber-reinforced mortar compositions of each example and comparative example was evaluated by the following method. Specifically, first, the cured specimen was cut in a direction perpendicular to the side surface using a dry cutter, dividing the cured specimen into two equal parts (hereinafter, the specimen piece on the upper side of the formwork will be referred to as the "upper specimen," and the specimen piece on the lower side of the formwork will be referred to as the "lower specimen"). The mass, diameter, and height of the upper and lower specimens were measured, and the unit volume mass was calculated using the following formula (I). Unit volume mass (g / cm³) 3 ) = Mass of the upper or lower part of the specimen (g) / Volume (cm³ 3 ) ···(I)

[0114] The ratio of the unit volume mass of the upper part of the specimen to the unit volume mass of the lower part of the specimen (hereinafter referred to as the unit volume mass ratio) was determined, and the determined unit volume mass ratio was evaluated based on the evaluation criteria shown below. The evaluation results are shown in Table 3. • Evaluation criteria ○: 0.97 or more and 1.00 or less △: 0.94 or higher and less than 0.97 ×: Less than 0.94

[0115] [Table 3]

[0116] (Evaluation of crack initiation strength ratio) The crack initiation strength ratio of cured specimens obtained using the fiber-reinforced mortar compositions of each example and comparative example was evaluated using the following method. Specifically, first, the crack initiation strength was measured for the upper and lower parts of the specimens obtained in the "Evaluation of Unit Volume Mass Ratio" above, in accordance with the method described in "Japan Society of Civil Engineers Concrete Library 113 Design and Construction Guidelines (Draft) for Ultra-High Strength Fiber-Reinforced Concrete: Method for Determining Crack Initiation Strength - Splitting Tensile Strength Test".

[0117] The ratio of the crack initiation strength at the top of the specimen to the crack initiation strength at the bottom of the specimen (hereinafter referred to as the crack initiation strength ratio) was determined, and the determined crack initiation strength ratio was evaluated based on the evaluation criteria shown below. The evaluation results are shown in Table 4. • Evaluation criteria ○: 0.90 or higher △: 0.80 or higher and less than 0.90 ×: Less than 0.80

[0118] [Table 4]

[0119] As can be seen from Tables 3 and 4, the fiber-reinforced mortar composition obtained using the method for producing a fiber-reinforced mortar composition that satisfies the configuration of the present invention showed excellent unit volume mass ratio and crack initiation strength ratio in the cured specimens. From this, it can be said that the method for producing a fiber-reinforced mortar composition that satisfies the configuration of the present invention yields a fiber-reinforced mortar composition in which fibers are uniformly dispersed, and suppresses the settling of steel fibers during mixing.

[0120] Furthermore, as can be seen from Table 4, the repair method for concrete structures that satisfies the configuration of the present invention shows excellent crack initiation strength ratio in cured specimens formed with the fiber-reinforced mortar composition that satisfies the configuration of the present invention, indicating that differences in crack initiation strength are unlikely to occur.

Claims

1. A method for producing a fiber-reinforced mortar composition comprising a binder (B) containing Portland cement and silica fume powder, fine aggregate (S), steel fibers, organic fibers, and water (W), The process includes a kneading step in which the binder (B) is mixed with the fine aggregate (S), the steel fibers, the organic fibers, and the water (W). A method for producing a fiber-reinforced mortar composition, wherein in the kneading step, the organic fibers are added to the binder (B), and then the steel fibers are added.

2. The method for producing a fiber-reinforced mortar composition according to claim 1, wherein in the kneading step, water (W) is added to the binder (B) and kneaded to obtain a slurry, and then the organic fibers are added to the slurry.

3. The method for producing a fiber-reinforced mortar composition according to claim 1, wherein in the kneading step, the organic fibers are added to the binder (B) and dry-kneaded to obtain a powder mixture, and then the water (W) is added to the powder mixture.

4. The specific surface area of ​​the aforementioned silica fume fine powder is 15 m². ２ / g or more 20m ２ A method for producing the fiber-reinforced mortar composition according to claim 1, wherein the amount is less than or equal to / g.

5. A method for producing a fiber-reinforced mortar composition according to claim 1, wherein the amount of silica fume fine powder blended is 5 parts by mass or more and 30 parts by mass or less per 100 parts by mass of the Portland cement.

6. A method for producing a fiber-reinforced mortar composition according to claim 1, wherein the amount of steel fibers blended is 2.5% by volume or more and 4.5% by volume or less of the entire fiber-reinforced mortar composition.

7. A method for producing a fiber-reinforced mortar composition according to claim 1, wherein the fiber diameter of the steel fibers is 100 μm or more and 400 μm or less.

8. A method for producing a fiber-reinforced mortar composition according to claim 1, wherein the fiber length of the steel fibers is 10 mm or more and 20 mm or less.

9. A method for producing a fiber-reinforced mortar composition according to claim 1, wherein the amount of the organic fiber blended is 0.2% by volume or more and 2.0% by volume or less relative to the entire fiber-reinforced mortar composition.

10. A method for producing a fiber-reinforced mortar composition according to claim 1, wherein the fiber diameter of the organic fiber is 10 μm or more and 200 μm or less.

11. A method for producing the fiber-reinforced mortar composition according to claim 1, wherein the fiber length of the organic fiber is 6 mm or more and 15 mm or less.

12. A method for producing a fiber-reinforced mortar composition according to claim 1, wherein the maximum particle size of the fine aggregate (S) is 2.5 mm.

13. A method for producing a fiber-reinforced mortar composition according to claim 1, wherein the coarseness ratio of the fine aggregate (S) is 1.3 or more and 3.0 or less.

14. A method for repairing a concrete structure, comprising filling or applying a fiber-reinforced mortar composition, manufactured by the method for manufacturing a fiber-reinforced mortar composition according to any one of claims 1 to 13, to a repair location on the concrete structure.

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