Fiber-reinforced mortar

Abstract

To provide a fiber-reinforced mortar composition that exhibits low mortar residue on devices such as mixers, excellent workability, and high strength development, and to provide a mortar thereof.SOLUTION: A fiber-reinforced mortar composition comprises: a binder consisting of cement, calcium aluminates, gypsum, and a pozzolanic substance; a metallic fiber; and a fine aggregate, wherein a content of the pozzolanic substance is 1 to 20 pts.mass to 100 pts.mass of the binder, a content of the metallic fibers is 3 to 30 pts.mass to 100 pts.mass of the binder, and a content of the fine aggregate is 110 to 330 pts.mass to 100 pts.mass of the binder.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a fiber-reinforced mortar composition and the mortar thereof. [Background technology]

[0002] In recent years, the demand for super-high-rise, large-scale, and highly durable buildings and civil engineering structures has become increasingly clear. To realize such structures, high-strength mortars are being developed. As an example of high-strength mortar, an ultra-high-strength mortar has been disclosed that contains at least cement, pozzolanic fine powder, fine aggregate with a particle size of 3.5 mm or less, a water-reducing agent, and water (Patent Document 1).

[0003] Concrete used in various structures is inherently durable, but depending on the structure and usage environment, parts of it may deteriorate. When such deterioration occurs, the function of the structure may decrease, so repair and reinforcement of the deteriorated parts are necessary. For repair and reinforcement of deteriorated parts, for example, a fiber-reinforced mortar composition containing cement, fly ash, fine aggregate coated with a liquid shrinkage reducing agent, a fluidizer, an expansive agent, a powdered polymer, a thickener, and short fibers is used (Patent Document 2). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2004-043234 [Patent Document 2] Japanese Patent Publication No. 2011-121795 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, increasing the strength of mortar often leads to increased viscosity due to factors such as increased cement content, the addition of pozzolanic substances, and the use of high-performance water-reducing agents to enable mixing with a low water-to-binder ratio. As a result, problems arise such as reduced workability and residual mortar remaining in the mixer when the mixed mortar is discharged. In addition, with high-strength mortar that has been given rapid-setting properties, residual mortar in the mixer may harden, potentially affecting the mixer's performance.

[0006] Therefore, the present invention aims to provide a fiber-reinforced mortar composition and mortar that exhibit low mortar residue on equipment such as mixers, good workability, and high strength development. [Means for solving the problem]

[0007] As a result of diligent research into the above-mentioned problems, the inventors have found that by adjusting the composition of the binder and appropriately blending metal fibers and fine aggregates, it is possible to reduce the amount of mortar remaining on equipment such as mixers, and to obtain a fiber-reinforced mortar composition and mortar with excellent workability and strength development.

[0008] In other words, the present invention is as follows. [1] A fiber-reinforced mortar composition comprising a binder consisting of cement, calcium aluminates, gypsum, and a pozzolanic substance, metal fibers, and fine aggregate, wherein the pozzolanic substance content is 1 to 20 parts by mass per 100 parts by mass of the binder, the metal fibers content is 3 to 30 parts by mass per 100 parts by mass of the binder, and the fine aggregate content is 110 to 330 parts by mass per 100 parts by mass of the binder. [2] The fiber-reinforced mortar composition according to [1], wherein the aspect ratio of the metal fibers is 25 to 150. [3] The fiber-reinforced mortar composition according to [1] or [2], wherein the ends of the metal fibers are hook-shaped. [4] The fiber-reinforced mortar composition according to [1] or [2], further comprising an expansive agent. A fiber-reinforced mortar comprising the fiber-reinforced mortar composition described in [5] [1] or [2] and water, wherein the water content is 25 to 45 parts by mass per 100 parts by mass of the binder. [6] Fiber-reinforced mortar as described in [5], wherein the ratio of the flow values ​​of 0-powder and 15-powder measured in a 20°C environment ([15-powder flow value (mm)] / [0-powder flow value (mm)]) is 1.3 to 1.8, in accordance with JIS R 5201:2015 "Physical Testing Methods for Cement" 12. Flow Test. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a fiber-reinforced mortar composition and mortar that exhibit low mortar residue on equipment such as mixers, good workability, and high strength development. [Modes for carrying out the invention]

[0010] The following describes one embodiment of the present invention.

[0011] The fiber-reinforced mortar composition of this embodiment comprises a binder consisting of cement, calcium aluminates, gypsum, and pozzolanic substances, metal fibers, and fine aggregate.

[0012] The binder according to this embodiment consists of four components: cement, calcium aluminates, gypsum, and pozzolanic substances.

[0013] Various types of cement can be used, including, for example, various types of Portland cement such as ordinary, rapid-hardening, ultra-rapid-hardening, low-heat, and moderate-heat cements, as well as eco-cement and fast-setting cement. From the viewpoint of easily achieving both fast-setting properties and fluidity, ordinary Portland cement and rapid-hardening Portland cement are preferred. One type of cement may be used alone, or two or more types may be used in combination.

[0014] The cement content is preferably 50 to 75 parts by mass, more preferably 55 to 70 parts by mass, and still more preferably 60 to 65 parts by mass with respect to 100 parts by mass of the binder. If the cement content is within the above range, the strength development property will be further improved.

[0015] As calcium aluminates, when CaO is represented by C, Al2O3 by A, Na2O by N, and Fe2O3 by F, calcium aluminates having a mineral composition represented by C3A, C2A, C 12 A7, CA, or CA2, calcium aluminoferrites represented by C4AF, etc., calcium haloaluminates containing calcium fluoroaluminates represented by C3A3·CaF2 or C 11 A7·CaF2, etc., calcium sodium aluminates represented by C8NA3 or C3N2A5, calcium lithium aluminates, alumina cement, and calcium sulfoaluminates represented by C3A3·CaSO4, etc. are collectively referred to. Any of these calcium aluminates, whether crystalline, non-crystalline, or a mixture of amorphous and crystalline, can be used. The calcium aluminates may be used alone or in combination of two or more. From the viewpoint of further improving the initial strength development property, the fineness of the calcium aluminates is preferably 3000 cm 2 / g or more in terms of Blaine specific surface area, and more preferably 5000 cm 2 / g or more. Also, the fineness of the calcium aluminates is preferably 8000 cm 2 / g or less in terms of Blaine specific surface area.

[0016] The content of the calcium aluminates is preferably 10 to 35 parts by mass, more preferably 12 to 30 parts by mass, and still more preferably 14 to 25 parts by mass with respect to 100 parts by mass of the binder. If the content of the calcium aluminates is within the above range, the quick-setting property is likely to be more excellent.

[0017] Examples of the gypsum materials include anhydrous gypsum, hemihydrate gypsum, dihydrate gypsum, etc. From the perspective of further improving the strength development property, anhydrous gypsum is preferred as the gypsum material. The gypsum materials may be used alone or in combination of two or more kinds.

[0018] As the content of the gypsum materials, it is preferably 7 to 23 parts by mass in terms of anhydride conversion with respect to 100 parts by mass of the binder, more preferably 8 to 20 parts by mass, and still more preferably 9 to 15 parts by mass. If the content of the gypsum materials is within the above range, the long-term strength development property will be further improved. From the perspective of further improving the long-term strength development property, the fineness of the gypsum materials is preferably 4500 cm [[ID=⑤]] 2 [[ID=⑥]] / g or more in terms of the Blaine specific surface area, and more preferably 6000 cm[[ID=⑦]] 2 [[ID=⑧]] / g or more. Also, the fineness of the gypsum materials is preferably 15000 cm[[ID=⑨]] 2 [[ID=⑩]] / g or less in terms of the Blaine specific surface area.

[0019] Examples of the pozzolanic substances include various fly ashes described in JIS A 6201:2015, silica fume, slag powder, amorphous aluminosilicate described in JIS A 6207:2016, etc. From the perspective of being more excellent in long-term strength development property and workability, silica fume and amorphous aluminosilicate are preferred as the pozzolanic substances. The pozzolanic substances may be used alone or in combination of two or more kinds.

[0020] The content of the pozzolanic substances is 1 to 20 parts by mass with respect to 100 parts by mass of the binder. If the content of the pozzolanic substances is outside the above range, the strength development property will decrease, and the workability such as the kneading property and fluidity of the mortar will also decrease. From the perspective of further improving the workability and strength development property and further reducing the remaining amount of the mortar on the equipment, the content of the pozzolanic substances is preferably 3 to 15 parts by mass with respect to 100 parts by mass of the binder, and more preferably 5 to 10 parts by mass. From the perspective of further improving the long-term strength development property, the fineness of the pozzolanic substances is preferably 5 m 2 / g or more in terms of the BET specific surface area, and 10 m 2It is more preferable that the amount be 30 m² or more. Furthermore, the powderiness of the pozzolanic material should be 30 m² in terms of BET specific surface area. 2 It is preferable that the value be less than or equal to / g.

[0021] The metal fibers are not particularly limited as long as they are made of metal, and examples include steel fibers, stainless steel fibers, amorphous metal fibers, and those that have been chemically or physically treated on their surface. As for the metal fibers, steel fibers are preferred from the viewpoint of achieving both good mixability and hardening properties of the mortar and further reducing the amount of mortar remaining on the equipment. One type of metal fiber may be used alone, or two or more types may be used in combination. The shape of the metal fibers is not particularly limited, and examples include straight, hook-shaped with a bent tip, etc. From the viewpoint of further reducing the amount of mortar remaining on the equipment, the shape of the metal fibers is preferably hook-shaped. In hook-shaped metal fibers, the bent portion may be on only one side of the tip or on both sides, but from the viewpoint of further reducing the amount of mortar remaining on the equipment, it is preferable to have it on both sides.

[0022] The metal fiber content is 3 to 30 parts by mass per 100 parts by mass of binder. If the metal fiber content is outside this range, workability such as the dispersibility and fluidity of the metal fibers, as well as the initial strength development, will decrease. From the viewpoint of further reducing the amount of mortar remaining on the equipment and providing higher toughness, the metal fiber content is preferably 4 to 25 parts by mass, and more preferably 5 to 20 parts by mass, per 100 parts by mass of binder.

[0023] The total length of the metal fibers is preferably 10 to 50 mm, more preferably 13 to 45 mm, and even more preferably 20 to 40 mm. If the total length of the metal fibers is within the above range, the mixability and workability of the mortar will be further improved.

[0024] The aspect ratio (total length / diameter) of the metal fibers is preferably 25 to 150, more preferably 30 to 100, and even more preferably 40 to 65. If the aspect ratio is within the above range, the mixability and workability of the mortar will be further improved, and sagging will be less likely to occur.

[0025] The fine aggregate is not particularly limited and can include river sand, silica sand, crushed sand, granite, limestone sand, slag aggregate, lightweight aggregate, etc. These fine aggregates may be used individually or in combination of two or more types.

[0026] The fine aggregate content is 110 to 330 parts by mass per 100 parts by mass of binder. If the fine aggregate content is outside this range, the mixability of the mortar will decrease and the mortar will adhere to the equipment. From the viewpoint of further reducing the amount of mortar remaining on the equipment, the fine aggregate content is preferably 150 to 300 parts by mass, and more preferably 200 to 270 parts by mass, per 100 parts by mass of binder.

[0027] The fiber-reinforced mortar composition of this embodiment may also contain an expansive agent. The inclusion of an expansive agent in the fiber-reinforced mortar composition results in superior compressive strength and dimensional change rate of the mortar. Any expansive agent conforming to JIS standards (JIS A 6202:2008), commonly used as an expansive agent for concrete, may be used. Examples of expansive agents include those primarily composed of free quicklime (quicklime-based expansive agents), those primarily composed of hauyne (ettringite-based expansive agents), and composite expansive agents of free quicklime and ettringite-producing substances. The expansive agent may be used alone or in combination of two or more types. The expansive agent should have a Blaine specific surface area of ​​2000 to 6000 cm². 2 It is preferable to use the product that is priced per gram.

[0028] The content of the expansive agent is preferably 0.1 to 5 parts by mass, more preferably 0.5 to 4 parts by mass, and even more preferably 1 to 3 parts by mass, per 100 parts by mass of the binder. If the content of the expansive agent is within the above range, the compressive strength, dimensional change rate, etc. will be even better.

[0029] The fiber-reinforced mortar composition of this embodiment may contain a water-reducing agent. The water-reducing agent may include high-performance water-reducing agents, high-performance AE water-reducing agents, AE water-reducing agents, and fluidizers. Examples of such water-reducing agents include those specified in JIS A 6204:2011 "Chemical admixtures for concrete". Examples of water-reducing agents include polycarboxylic acid-based water-reducing agents, naphthalene sulfonic acid-based water-reducing agents, lignin sulfonic acid-based water-reducing agents, and melamine-based water-reducing agents. Among these water-reducing agents, polycarboxylic acid-based water-reducing agents are preferred from the viewpoint of easily ensuring fluidity retention time even with a small amount of additive. One type of water-reducing agent may be used alone, or two or more types may be used in combination.

[0030] The water-reducing agent content is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 3 parts by mass, and even more preferably 0.3 to 1 part by mass, based on solid content, per 100 parts by mass of binder. If the water-reducing agent content is within the above range, it is easier to ensure a longer pot life and the fluidity is further improved.

[0031] The fiber-reinforced mortar composition of this embodiment may contain a setting retarder. The inclusion of a setting retarder in the fiber-reinforced mortar composition makes it easier to ensure a longer pot life, even when the mixing temperature of the polymer cement mortar is high, such as during the summer. Examples of setting retarders include organic acids or their salts, such as citric acid, gluconic acid, malic acid, and tartaric acid; borates such as boric acid and sodium borate; phosphates; inorganic salts such as alkali metal carbonates and alkali metal bicarbonates; and sugars. Among these, citric acid, citrates, tartaric acid, tartarates, and alkali metal carbonates are preferred. The setting retarder may be in powder form or liquid form (e.g., aqueous solution, emulsion, or suspension). One type of setting retarder may be used alone, or two or more types may be used in combination.

[0032] The content of the setting retarder is preferably 0.1 to 7.5 parts by mass, more preferably 0.3 to 5 parts by mass, and most preferably 0.5 to 3.5 parts by mass, based on solid content, per 100 parts by mass of the binder. If the content of the setting retarder is within the above range, it is easier to further secure the pot life and the initial strength development is less likely to decrease.

[0033] The fiber-reinforced mortar composition of this embodiment may contain various admixtures, provided that the effects of the present invention are not impaired. Examples of admixtures include foaming agents, defoaming agents, thickeners, cement polymers, waterproofing agents, rust inhibitors, shrinkage reducing agents, water-retaining agents, pigments, fibers, water-repellent agents, efflorescence inhibitors, rapid setting agents, rapid hardening agents, stone powder, volcanic ash, air-entraining agents, and surface hardening agents.

[0034] The method for producing the fiber-reinforced mortar composition of this embodiment is not particularly limited, and can be produced by mixing the above components using a mixer such as a gravity mixer such as a V-type mixer or a tiltable concrete mixer, a Henschel mixer, a jet mixer, a ribbon mixer, or a paddle mixer.

[0035] The fiber-reinforced mortar composition of this embodiment can be prepared as fiber-reinforced mortar by mixing it with water, and the water content can be appropriately adjusted depending on the application. The water content is preferably 25 to 45 parts by mass, more preferably 28 to 40 parts by mass, and even more preferably 30 to 35 parts by mass per 100 parts by mass of binder. If the water content is within the above range, the kneadability of the metal fibers and the initial and long-term strength development will be even better.

[0036] In this embodiment, the fiber-reinforced mortar preferably has a ratio of the flow values ​​of 0-strand and 15-strand ([15-strand flow value (mm)] / [0-strand flow value (mm)]) measured in accordance with JIS R 5201:2015 "Physical Testing Methods for Cement" 12. Flow Test at a 20°C environment of 1.3 to 1.8, more preferably 1.32 to 1.6, and even more preferably 1.35 to 1.5. If the ratio of the flow values ​​of the mortar is within the above range, the mortar will have good elongation and even better workability.

[0037] The preparation of the fiber-reinforced mortar in this embodiment can be done using the same mixing equipment as for ordinary mortar compositions, and is not particularly limited. Examples of mixing equipment include mortar mixers, hand mixers, tilting drum mixers, twin-shaft mixers, pan-type mixers, and the like.

[0038] The fiber-reinforced mortar composition and fiber-reinforced mortar of this embodiment are high-strength mortars that also exhibit excellent metal fiber dispersibility. Therefore, they can be suitably used for repair and reinforcement of various structures and construction sites where high strength development is required. The application method is not particularly limited, and methods such as creating a formwork and filling it, trowel application, and spreading and leveling using a vibrator can be selected. [Examples]

[0039] The present invention will be described below based on embodiments, but the present invention is not limited to these embodiments.

[0040] [Materials used] • Cement (C): High-early-strength cement, specific surface area 4500 cm² 2 / g Calcium aluminate (CA): CaO / Al2O3 = 1.4, vitrification rate: 40%, Blaine specific surface area: 5000 cm² 2 / g • Gypsum (CS): Blaine specific surface area 7000 cm² 2 / g • Pozzolanic substance (SF): Silica fume BET specific surface area: 15m² 2 / g • Fine aggregate: Silica sand (S) (grain size adjusted) • Fiber: Steel fiber (F1): Fiber length 30mm, aspect ratio 45, hooked ends. Polypropylene fiber (F2): Fiber length 12mm, Aspect ratio 280 Steel fiber (F3): Fiber length 13mm, aspect ratio 62, linear shape • Expansion agent: Quicklime-based expansion agent, specific surface area 3200 cm² 2 / g • Water-reducing agent: High-performance polycarboxylic acid-based water-reducing agent • Delaying agent: Citrate

[0041] [Formulation design for fiber-reinforced mortar compositions] The binder, consisting of cement, calcium aluminates, gypsum, and pozzolanic substances, was used in the proportions shown in Table 1. For every 100 parts by mass of the binder, the mix was designed with 2 parts by mass of metal fibers, fine aggregate, and expansive agent, 0.5 parts by mass of water-reducing agent, and 0.6 parts by mass of setting retarder, as shown in Table 1 for the content and types of metal fibers and fine aggregate.

[0042] [Mortar preparation] At 20°C, 32 parts by mass of water were added to 100 parts by mass of binder, and each material (except for the fibers) of the mortar composition designed in Table 1 was added. The mixture was kneaded for 90 seconds in a pan-type forced mixer, and then the fibers were added and kneaded for another 60 seconds to produce approximately 25 L of mortar.

[0043] [Table 1]

[0044] [Evaluation Method] Each item was evaluated using the following method. The evaluation results are shown in Table 2. 1) Freshness (consistency) In accordance with JIS R 5201:2015 "Physical Testing Methods for Cement," Section 12, Flow Test, the pull-out (0-strand) and 15-strand flow values ​​of mortar were measured under a 20°C environment, and these were evaluated as consistency. 2) Compressive strength The compressive strength of concrete was measured at 4 hours and 28 days of age in accordance with JIS A 1108:2018 "Test Method for Compressive Strength of Concrete". The dimensions of the test specimens were 100 mm in diameter and 200 mm in height. The 28-day-old specimens were demolded the following day and cured in water until the end of the curing period. Curing was always carried out in a constant temperature bath at 20°C. 3) Emission loss rate Mortar prepared in a mortar mixer was discharged into a container without scraping or other methods, its weight was measured, and the mortar discharge rate was calculated as the weight ratio to the weight of the materials added. The discharge loss rate was calculated by subtracting the calculated mortar discharge rate from 100%. A discharge loss rate of 8% by mass or less was considered good, and a rate exceeding 8% by mass was considered poor.

[0045] [Table 2]

[0046] The fiber-reinforced mortar in the example exhibited low discharge loss, a good ratio of 0-strand flow to 15-strand flow, resulting in excellent mortar elongation, superior workability, and high compressive strength. On the other hand, the fiber-reinforced mortars in the comparative examples, including mortars No. 4, 8, and 14, which were difficult to mix, did not perform well in terms of workability, compressive strength, and mortar discharge loss.

Claims

1. A fiber-reinforced mortar comprising a binder consisting of rapid-hardening Portland cement, calcium aluminates, gypsum, and silica fume, metal fibers, fine aggregate, and water, The content of the aforementioned rapid-hardening Portland cement is 50 to 75 parts by mass per 100 parts by mass of the binder. The calcium aluminate content is 10 to 25 parts by mass per 100 parts by mass of the binder. The amount of gypsum in the aforementioned gypsum is 7 to 15 parts by mass per 100 parts by mass of the binder. The silica fume content is 1 to 20 parts by mass per 100 parts by mass of the binder. The content of the metal fibers is 3 to 30 parts by mass per 100 parts by mass of the binder. The content of the fine aggregate is 110 to 330 parts by mass per 100 parts by mass of the binder. The water content is 25 to 45 parts by mass per 100 parts by mass of the binder. Fiber-reinforced mortar, measured in accordance with JIS R 5201:2015 "Physical Testing Methods for Cement" 12. Flow Test, with a ratio of flow values ​​of 0 to 15 sq. m ([15 sq. m flow value (mm)] / [0 sq. m flow value (mm)]) of 1.3 to 1.8 in a 20°C environment.

2. The fiber-reinforced mortar according to claim 1, wherein the aspect ratio of the metal fibers is 25 to 150.

3. The fiber-reinforced mortar according to claim 1 or 2, wherein the ends of the metal fibers are hook-shaped.

4. The fiber-reinforced mortar according to claim 1 or 2, further comprising an expansive material.

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