JP2023149566A - Cement mortar composition and cement mortar - Google Patents

Abstract

To provide a cement mortar composition and a cement mortar having chloride ion osmosis resistance and excellent strength development property, crack resistance, and workability.SOLUTION: A cement mortar composition includes a cement, amorphous aluminosilicate, a fly ash, an expansive admixture, and a fine aggregate, wherein a total content of the amorphous aluminosilicate and the fly ash is 3-35 pts.mass to 100 pts.mass of the cement and the content of the expansive admixture is 1-25 pts.mass to 100 pts.mass of the cement.SELECTED DRAWING: None

Description

The present invention relates to mortar compositions and mortars.

In recent years, there has been an increasing demand for extending the lifespan of concrete structures from the viewpoints of reducing environmental impact and reducing life cycle costs. Salt damage is one of the causes of deterioration of concrete structures. Salt damage reduces the performance of concrete structures by allowing chloride ions to penetrate into concrete and promoting corrosion of reinforcing steel. As a means to suppress salt damage, there is a method of imparting chloride ion penetration resistance to concrete.

One method for imparting chloride ion penetration resistance to concrete structures is to reduce the water-cement ratio. However, the method of reducing the water-cement ratio has poor workability and may lead to poor pouring, and does not provide a fundamental solution. Other methods include adding an admixture. Examples of admixtures include fly ash, silica fume, and pulverized blast furnace slag that have pozzolanic reaction and latent hydraulic properties. Adding these admixtures to concrete improves its durability and watertightness, and suppresses the penetration of chloride ions.

Other admixtures include calcium aluminates and amorphous aluminosilicates. Patent Document 1 describes a calcium aluminate compound having a CaO/Al ₂ O ₃ molar ratio of 0.15 to 0.7 and a Blaine specific surface area value of 2000 to 7000 cm ² /g, and a pozzolan substance, A cement admixture is disclosed in which the blending ratio of a calcium aluminate compound and a pozzolan substance is 10/1 to 1/10 in mass ratio. Patent Document 2 describes an admixture for mortar and concrete containing silica fume and metakaolin, in which the mass ratio of the silica fume and the metakaolin is 3:7 to 7:3, and the content of mullite in 100 parts by mass of the metakaolin is disclosed. A mortar/concrete admixture is disclosed in which the amount of kaolinite is 5 parts by mass or less and the content of kaolinite is 0.1 part by mass or more.

Japanese Patent Application Publication No. 2010-100473 Japanese Patent Application Publication No. 2021-008375

However, the method of adding calcium aluminate to a cement composition has the disadvantage that as the cement composition progresses to neutralization, the composition containing detoxified chloride ions is decomposed, and the chloride ions become harmful again. There was an issue. Further, the method of adding amorphous aluminosilicate and silica fume has the problem that drying shrinkage increases and cracks are more likely to occur.

Therefore, an object of the present invention is to provide a mortar composition and mortar that have resistance to chloride ion penetration and are excellent in strength development, cracking resistance, and workability.

As a result of intensive studies on the above-mentioned problems, the present inventors have found that by adjusting the content of the combination of amorphous aluminosilicate and fly ash, and the content of the expanding material, the present inventors have achieved resistance to chloride ion penetration. In addition, it has been found that a mortar composition and mortar that are excellent in strength development, crack resistance, and workability can be obtained.

That is, the present invention is as follows.
[1] Contains cement, amorphous aluminosilicate, fly ash, expansive material, and fine aggregate, and the total content of amorphous aluminosilicate and fly ash is based on 100 parts by mass of cement, 3 to 35 parts by mass, and the content of the expanding agent is 1 to 25 parts by mass based on 100 parts by mass of cement.
[2] The mortar composition according to [1], further comprising a cement polymer.
[3] The mortar composition according to [1] or [2], further comprising a thickener.
[4] The mortar composition according to any one of [1] to [3], further comprising a shrinkage reducing agent.
[5] A mortar containing the cement composition according to any one of [1] to [4] and water, the water content being 30 to 80 parts by mass based on 100 parts by mass of cement.

According to the present invention, it is possible to provide a mortar composition and mortar that have resistance to chloride ion penetration and are excellent in strength development, cracking resistance, and workability.

Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited thereto. In this specification, all contents are expressed in terms of anhydride and solid content.

The mortar composition of this embodiment includes cement, amorphous aluminosilicate, fly ash, expansive material, and fine aggregate.

Various types of cement can be used, such as ordinary, early-strength, ultra-early-strength, low-heat and moderate-heat Portland cements, ecocements, quick-hardening cements, and the like. The cement is preferably ordinary Portland cement, early-strength Portland cement, ultra-early strength Portland cement, or ecocement, from the viewpoint that high strength development properties are easily obtained. One type of cement may be used alone, or two or more types may be used in combination.

The amorphous aluminosilicate is not particularly limited as long as it is derived from clay minerals and contains an amorphous portion, and any aluminosilicate can be used. Examples of clay minerals that are raw materials include (1) kaolin minerals, (2) mica clay minerals, (3) smectite minerals, and mixed layer minerals produced by mixing these minerals. Amorphous aluminosilicate can be obtained by, for example, firing and dehydrating these crystalline aluminosilicates to make them amorphous. As the amorphous aluminosilicate, those derived from kaolin minerals such as kaolinite, hallosite, and dickite are preferable, and metakaolin obtained by calcining kaolinite is more preferable, from the viewpoint of even better resistance to chloride ion penetration. . One type of amorphous aluminosilicate may be used alone, or two or more types may be used in combination. The BET specific surface area of the amorphous aluminosilicate is preferably 10,000 to 40,000 cm ² /g, more preferably 15,000 to 30,000 cm ² /g.
In this specification, "amorphous" means that peaks derived from clay minerals, which are raw materials, are almost not observed when measured using a powder X-ray diffractometer. The amorphous aluminosilicate mineral powder according to the present embodiment may have an amorphous content of 70% by mass or more, preferably 90% by mass or more, more preferably 100% by mass, that is, measured by a powder X-ray diffraction device. It is most preferable that no peak be observed at all. Here, the amorphous ratio is a value determined by the standard addition method. Aluminosilicate with a high proportion of amorphous, that is, aluminosilicate with a low proportion of crystalline, tends to have better strength development properties at the same mixing amount than aluminosilicate with a low proportion of amorphous. Examples of heating for amorphizing aluminosilicate include firing in an external heating kiln, internal heating kiln, electric furnace, etc., and melting using a melting furnace.

The content of amorphous aluminosilicate is preferably 1 to 30 parts by mass, more preferably 2 to 25 parts by mass, and even more preferably 3 to 20 parts by mass, based on 100 parts by mass of cement. preferable. If the content of amorphous aluminosilicate is within the above range, the chloride ion penetration resistance and adhesive strength will be even better.

Any fly ash may be used as long as it is generally used as an admixture for concrete (JIS ash: defined in JIS A 6201:2015). The fly ash is preferably JIS ash of type I or type II from the viewpoint of obtaining even better strength development in a low-temperature environment. The Blaine specific surface area of fly ash is preferably 2,500 to 6,000 cm ² /g, more preferably 3,000 to 5,000 cm ² /g.

The content of fly ash is preferably 1 to 30 parts by mass, more preferably 2 to 25 parts by mass, and even more preferably 3 to 20 parts by mass, based on 100 parts by mass of cement. If the fly ash content is within the above range, cracking resistance and workability will be even better.

The total content of amorphous aluminosilicate and fly ash is 3 to 35 parts by mass based on 100 parts by mass of cement. If the total content of amorphous aluminosilicate and fly ash is outside the above range, it will not be possible to achieve both chloride ion penetration resistance and cracking resistance, and the adhesive strength will not be excellent. From the viewpoint of having a high chloride ion penetration suppressing effect, ensuring high strength, and easy to ensure good workability, the total content of amorphous aluminosilicate and fly ash is set to 100 parts by mass of cement. It is preferably 8 to 30 parts by weight, more preferably 12 to 28 parts by weight.

The expansion material may be any expansion material as long as it is a JIS-compliant expansion material (JIS A 6202:2008) that is generally used as an expansion material for concrete. Examples of the expanding material include an expanding material whose main component is free quicklime (quicklime-based expanding material), an expanding material whose main component is Irwin (ettringite-based expanding material), and a composite expanding material of free quicklime and ettringite-forming substances. Can be mentioned. One type of expansion material may be used alone, or two or more types may be used in combination. It is preferable to use an expanding material having a Blaine specific surface area of 2000 to 6000 cm ² /g.

The content of the expanding agent is 1 to 25 parts by mass based on 100 parts by mass of cement. If the content of the expanding material is outside the above range, cracking resistance and strength development will not be excellent. From the viewpoint of better dimensional stability and strength development, the content of the expanding agent is preferably 3 to 20 parts by mass, more preferably 5 to 15 parts by mass, based on 100 parts by mass of cement. .

Examples of the fine aggregate include river sand, silica sand, crushed sand, kansui stone, limestone sand, and slag aggregate. Among these fine aggregates, it is preferable to use aggregates such as silica sand and limestone that have been adjusted to a particle size that does not contain fine powder or coarse aggregates. One type of fine aggregate may be used alone, or two or more types may be used in combination. As the fine aggregate, it is preferable to use a commonly used particle size of 5 mm or less (the amount that passes through a 5 mm sieve).

The particle size of the fine aggregate is not particularly limited, and can be adjusted within the required particle size range of the fine aggregate. The particle size of fine aggregate can be considered from the coarse particle ratio specified by JIS A 1102:2014 "Sieving test method for aggregate". From the viewpoint of easily obtaining better fluidity and suppressing bleeding during mortar, the coarse particle ratio of the fine aggregate is preferably 1 to 4, and 1.5 to 3.5. The number is more preferably 2 to 3, and even more preferably 2 to 3.

The content of fine aggregate is preferably 150 to 400 parts by mass, more preferably 200 to 350 parts by mass, and even more preferably 240 to 340 parts by mass, based on 100 parts by mass of cement. If the content of fine aggregate is within the above range, sufficient strength development can be easily achieved while suppressing cracking.

The mortar composition of this embodiment may include a cement polymer. The polymer for cement is preferably a polymer defined in JIS A 6203:2015 "Polymer dispersion and re-emulsified powder resin for mixing with cement". Examples of such polymers for cement include polymer dispersions, re-emulsified powder resins, and the like. Examples of the polymer dispersion include synthetic rubber systems such as styrene butadiene rubber (SBR); natural rubber systems; rubber asphalt systems; ethylene vinyl acetate systems; acrylic ester systems; and resin asphalt systems. Among the polymer dispersions, synthetic rubber-based, ethylene-vinyl acetate-based, and acrylic ester-based ones are preferable, and specifically, synthetic rubber latex, polyacrylic ester, and ethylene-vinyl acetate are more preferable. Examples of the re-emulsified powder resin include synthetic rubbers such as styrene-butadiene rubber; acrylic esters; ethylene vinyl acetate; vinyl acetate/vinyl versatate; vinyl acetate/vinyl versatate/acrylic ester. As the polymer for cement, a polymer dispersion may be used, a re-emulsified powdered resin may be used, or a polymer dispersion and a re-emulsified powdered resin may be used in combination.
Among polymers for cement, acrylic ester-based polymer dispersions and/or re-emulsified powder resins are preferred from the viewpoint of further improving chloride ion penetration resistance and adhesion to concrete. One type of polymer for cement may be used alone, or two or more types may be used in combination.

The content of the polymer for cement is preferably 1 to 18 parts by mass, more preferably 2 to 15 parts by mass, and even more preferably 3 to 12 parts by mass, based on 100 parts by mass of cement. When the content of the cement polymer is within the above range, construction is easy and strength development and adhesive strength are further improved.

The mortar composition of this embodiment may also contain fibers. Examples of fibers include organic fibers such as vinylon fibers, polypropylene fibers, nylon fibers, acrylic fibers, polyethylene fibers, and cellulose fibers. From the viewpoint of better dispersibility, the fibers are preferably organic fibers, and more preferably nylon fibers, vinylon fibers, and polypropylene fibers. One type of fibers may be used alone, or two or more types may be used in combination.

The length of the fibers is preferably 1 to 20 mm, more preferably 2 to 15 mm, and even more preferably 3 to 12 mm. If the length of the fibers is within the above range, mortar will be easier to prepare.

The content of fibers is preferably 0.05 to 5 parts by mass, more preferably 0.1 to 4 parts by mass, and 0.2 to 3 parts by mass based on 100 parts by mass of cement. More preferably. If the content of fibers is within the above range, it can be mixed more uniformly during mortar preparation, and even better cracking resistance can be obtained.

The mortar composition of this embodiment may include a shrinkage reducing agent. As the shrinkage reducing agent, for example, a polyoxyalkylene compound, a polyether compound, an alkylene oxide compound, etc. can be used. Specific examples of shrinkage reducing agents include polyoxyethylene/alkyl allyl ether, polypropylene glycol, lower alcohol alkylene oxide adduct, glycol ether/amino alcohol derivative, polyether, polyoxyalkylene glycol, ethylene oxide methanol adduct, and ethylene oxide. - Propylene oxide polymer, phenyl ethylene oxide polymer, cycloalkylene ethylene oxide polymer, dimethylamine ethylene oxide polymer, etc. One type of shrinkage reducing agent may be used alone, or two or more types may be used in combination.

The content of the shrinkage reducing agent is preferably 0.1 to 5 parts by mass, more preferably 0.3 to 3 parts by mass, and 0.5 to 2 parts by mass based on 100 parts by mass of cement. It is even more preferable that there be. If the content of the shrinkage reducing agent is within the above range, it is possible to suppress drying shrinkage after curing and further improve durability without causing almost any setting delay.

The mortar composition of this embodiment may also contain a thickener. The type of thickener is not particularly limited, and examples thereof include cellulose thickeners, acrylic thickeners, and guar gum thickeners. As the thickener, cellulose thickeners are preferred. Examples of cellulosic thickeners include carboxymethylcellulose, methylcellulose, hydroxypropylmethylcellulose, hydroxyethylcellulose, and hydroxypropylcellulose. One type of thickener may be used alone, or two or more types may be used in combination.

The content of the thickener is preferably 0.005 to 3 parts by mass, more preferably 0.01 to 2 parts by mass, and more preferably 0.015 to 2 parts by mass in terms of solid content per 100 parts by mass of cement. More preferably, it is 1 part by mass. If the content of the thickener is within the above range, better water retention and workability can be easily obtained when made into mortar, and compressive strength can also be improved.

The mortar composition of this embodiment may also contain a water reducing agent. Water reducers include superplasticizers, super AE water reducers, AE water reducers, and superplasticizers. Examples of such water reducing agents include water reducing agents specified in JIS A 6204:2011 "Chemical admixtures for concrete". Examples of the water reducing agent include polycarboxylic acid water reducing agents, naphthalene sulfonic acid water reducing agents, lignin sulfonic acid water reducing agents, and melamine water reducing agents. Among these, naphthalenesulfonic acid water reducing agents are preferred. One type of water reducing agent may be used alone, or two or more types may be used in combination.

The content of the water reducing agent is preferably 0.1 to 5 parts by mass, more preferably 0.15 to 3 parts by mass, and more preferably 0.2 to 1 parts by mass in terms of solid content per 100 parts by mass of cement. More preferably, it is parts by mass. If the content of the water reducing agent is within the above range, better kneading properties (water compatibility) are likely to be obtained when mortar is prepared, and compressive strength is also likely to be improved.

The mortar composition of this embodiment may also contain an organic admixture. Organic admixtures include the above-mentioned shrinkage reducers, thickeners, and water reducers, and others include antifoaming agents, foaming agents, waterproofing agents, water repellents, dust reducing agents, etc. . One type of organic admixture may be used alone, or two or more types may be used in combination. Among these, the organic admixture is preferably at least two or more types selected from shrinkage reducing agents, water reducing agents, thickening agents, and antifoaming agents.

The content of the organic admixture is preferably 0.01 to 3 parts by mass, more preferably 0.02 to 2 parts by mass, and 0.05 to 1.8 parts by mass based on 100 parts by mass of cement. It is more preferable that it is part. If the content of the organic admixture is within the above range, it is easy to ensure good workability.

The mortar composition of this embodiment may contain various admixtures (materials) as long as the effects of the present invention are not impaired. Examples of admixtures (materials) include foaming agents, rust inhibitors, pigments, and efflorescence inhibitors.

The method for producing the mortar composition of this embodiment is not particularly limited, and examples include gravity mixers such as V-type mixers and tilting concrete mixers, Henschel mixers, injection mixers, ribbon mixers, paddle mixers, etc. It can be manufactured by mixing with a mixer.

The mortar composition of this embodiment can be mixed with water to form a mortar, and the water content may be adjusted as appropriate depending on the application. The content of water is preferably 35 to 80 parts by mass, more preferably 35 to 75 parts by mass, and even more preferably 40 to 70 parts by mass, based on 100 parts by mass of cement. If the water content is within the above range, workability will be more easily ensured, and resistance to chloride ion penetration, adhesion, and strength development will also be more excellent.

The mortar of this embodiment can be prepared using the same kneading equipment as used for the mortar composition described above, and is not particularly limited. Examples of the kneading device include gravity mixers such as V-type mixers and tilting concrete mixers, mixers such as Henschel mixers, jet mixers, ribbon mixers, and paddle mixers.

The mortar composition and mortar of this embodiment have good workability, and upon hardening, exhibit excellent resistance to chloride ion penetration, strength development, and cracking resistance. Therefore, the mortar composition and mortar of this embodiment can be suitably used for repairing reinforced concrete structures, building structures, and the like. The construction method is not particularly limited, and can be selected from a plastering method in which the material is filled with a trowel, a wet spraying method using a pump, a formwork method in which the material is filled into a formwork, and the like.

EXAMPLES Hereinafter, the present invention will be explained in detail with reference to Examples, but the present invention is not limited thereto. All contents in the table are in terms of anhydride and solid content.

[material]
Cement: Ordinary Portland cement Fly ash: Blaine specific surface area 4100cm ² /g
Metakaolin: BET specific surface area 21000 cm ² /g
Silica fume: BET specific surface area 180000cm ² /g
Fine aggregate: Silica sand Fine aggregate A: Coarse particle ratio 2.46
Fine aggregate B: Coarse particle ratio 2.53
Fine aggregate C: Coarse particle ratio 2.21
Fine aggregate D: Coarse particle ratio 2.50
Expanding material: quicklime-based expanding material, Blaine specific surface area 4100 cm ² /g
Polymer for cement Resin A: Acrylic ester re-emulsified powder resin Resin B: SBR emulsion Resin C: Acrylic ester emulsion Fiber: Nylon fiber, fiber length 5 mm
Shrinkage reducer: Alkylene oxide adduct of lower alcohol Thickener: Methylcellulose thickener Water reducer: Naphthalenesulfonic acid water reducer

[Mortar composition and mortar production]
Each material was put into a Henschel mixer at the mixing ratio shown in Tables 1 and 2, and mixed for 3 minutes to prepare a mortar composition. In Table 1, the numerical values of each material are shown in parts by mass based on 100 parts by mass of cement. The mortar composition and water were mixed for 90 seconds using a cage-type high-speed hand mixer (1000 pm) to prepare a mortar. The blending ratio of water is as shown in Tables 1 and 2.

[Measurement condition]
Various measurement conditions are as follows. The measurement results are shown in Tables 1 and 2.
- Apparent diffusion coefficient The apparent diffusion coefficient was measured based on JSCE-G573-2003 "Method for measuring total chloride ion distribution in concrete in actual structures (draft)" and evaluated as chloride ion penetration resistance. . Those with an apparent diffusion coefficient of 1 cm ² /year or less were evaluated as good.
- Crack resistance Based on JIS A 1129-3:2010 "Length change measurement method for mortar and concrete Part 3: Dial gauge method", the length change rate at 28 days of material age was measured. The rate of change in length was evaluated as cracking resistance. Those with a length change rate of 0.1% or less were evaluated as good.
- Compressive strength Based on JIS A 1171:2016 "Testing method for polymer cement mortar", compressive strength was measured for a 28-day-old specimen. For curing, the hardened specimen was removed from the mold 24 hours after molding, and air-cured in a constant temperature room at 20° C. until the material was 28 days old. Those with a compressive strength of 35 N/m ² or more were evaluated as good.
- Adhesive strength Based on JIS A 1171:2016 "Test method for polymer cement mortar", the adhesive strength was measured for a 28-day old specimen. For curing, the hardened specimen was removed from the mold 24 hours after molding, and air-cured in a constant temperature room at 20° C. until the material was 28 days old. Those with adhesive strength of 1.0 N/m ² or more were evaluated as good.
・Workability: ○ means that the trowel work (trowel elongation, trowel cutting, surface smoothness) is excellent when applying mortar to the wall, and the trowel elongation is poor, it sticks to the trowel, and the surface is difficult to smooth. No was marked as ×.

The mortar of the example was excellent in chloride ion penetration resistance, cracking resistance, strength development, adhesive strength, and workability. On the other hand, the mortar of the comparative example was insufficient in any of the measurement items.

Claims (5)

Contains cement, amorphous aluminosilicate, fly ash, expansive material, and fine aggregate,
The total content of the amorphous aluminosilicate and the fly ash is 3 to 35 parts by mass based on 100 parts by mass of the cement,
A mortar composition, wherein the content of the expanding agent is 1 to 25 parts by mass based on 100 parts by mass of the cement. The mortar composition of claim 1 further comprising a cementitious polymer. The mortar composition according to claim 1 or 2, further comprising a thickener. Mortar composition according to any one of claims 1 to 3, further comprising a shrinkage reducing agent. comprising the cement composition according to any one of claims 1 to 4 and water,
A mortar, wherein the water content is 30 to 80 parts by mass based on 100 parts by mass of the cement.