Mortar composition and mortar

Abstract

To provide a mortar composition that does not easily droop when applied onto a slope and exhibits excellent freeze-thaw resistance and compression strength.SOLUTION: The mortar composition includes cement, a pozzolan material, rubber powder, and fine aggregate, with the content of the rubber powder being from 3 to 55 pts.mass relative to 100 pts.mass of the cement, the total content of the pozzolan material and the rubber powder being from 10 to 70 pts.mass relative to 100 pts.mass of the cement, and a ratio of the total mass of the pozzolan material and the rubber powder relative to the total mass of the pozzolan material, the rubber powder and the fine aggregate, ([total mass of the pozzolan material and the rubber powder] / [total mass of the pozzolan material, the rubber powder and the fine aggregate]) being from 0.03 to 0.23.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a mortar composition and a mortar. [Background technology]

[0002] Concrete structures (for example, floor slabs, walls, and ceilings such as reinforced concrete (RC) floor slabs or the intermediate floor slabs of box culverts) are at risk of deterioration spreading due to external factors (water, chlorides, carbon dioxide, etc.) penetrating through cracks and other deterioration. In cold regions in particular, concrete structures are further deteriorated by frost damage and salt damage.

[0003] Therefore, polymer cement mortar has been proposed as a material that is resistant to such frost damage. Patent Document 1 discloses a mortar for slab track, containing 100 parts by mass of cement, 25 to 250 parts by mass of fine aggregate, 50 to 200 parts by mass of asphalt emulsion, rubber powder, and 10 to 200 parts by mass of water, wherein the rubber powder has a maximum particle size of 500 μm or less, an average particle size of 50 to 300 μm, and is contained at 3 to 25 volume % per mortar. Patent Document 2 discloses a polymer cement mortar containing rapid-setting cement, fine aggregate, a cement polymer, and water, wherein the content of the cement polymer is 31 to 52 parts by mass (solids content) and the content of water is 35 to 60 parts by mass per 100 parts by mass of the rapid-setting cement. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-203561 [Patent Document 2] Japanese Patent Application Publication No. 2019-163176 Summary of the Invention [Problem to be solved by the invention]

[0005] Repair materials with frost resistance are required to have both excellent freeze-thaw resistance and compressive strength. In addition, with the increasing variety of repair locations in recent years, repair materials that do not sag when applied to sloped sections are also required.

[0006] Therefore, an object of the present invention is to provide a mortar composition and a mortar that are less likely to sag even when applied to sloped sections and that exhibit excellent freeze-thaw resistance and compressive strength. [Means for solving the problem]

[0007] As a result of intensive research into the above-mentioned problems, the present inventors have found that by combining a pozzolanic substance, rubber powder, and fine aggregate in specific proportions, it is possible to obtain a mortar composition and a mortar that are less likely to sag and that exhibit excellent freeze-thaw resistance and compressive strength.

[0008] That is, the present invention relates to the following [1] to [6]. [1] A mortar composition comprising cement, a pozzolanic substance, rubber powder, and fine aggregate, wherein the content of the rubber powder is 3 to 55 parts by mass per 100 parts by mass of the cement, the total content of the pozzolanic substance and the rubber powder is 10 to 70 parts by mass per 100 parts by mass of the cement, and the ratio of the total mass of the pozzolanic substance and the rubber powder to the total mass of the pozzolanic substance, the rubber powder, and the fine aggregate ([total mass of the pozzolanic substance and the rubber powder] / [total mass of the pozzolanic substance, the rubber powder, and the fine aggregate]) is 0.03 to 0.23. [2] The mortar composition according to [1], wherein the rubber powder has a coarse particle ratio of 1 to 4. [3] The mortar composition according to [1] or [2], further comprising gypsum and calcium aluminates. [4] The mortar composition according to any one of [1] to [3], wherein the content of the fine aggregate is 130 to 400 parts by mass relative to 100 parts by mass of the cement. [5] The mortar composition according to any one of [1] to [4], further comprising a water-reducing agent. [6] A mortar comprising the mortar composition according to any one of [1] to [5] and water, wherein the content of the water is 30 to 60 parts by mass per 100 parts by mass of the cement. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a mortar composition and a mortar that are less likely to sag even when applied to a sloped section and that exhibit excellent freeze-thaw resistance and compressive strength. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, one embodiment of the present invention will be described in detail. In this specification, all contents and the like are expressed in terms of solid content and anhydrous content.

[0011] The mortar composition of this embodiment contains cement, a pozzolanic substance, rubber powder, and fine aggregate.

[0012] Various cements can be used, including, for example, various Portland cements such as normal, early strength, ultra-early strength, low heat and medium heat, ecocement, and rapid hardening cement. Of these, normal Portland cement and early strength Portland cement are preferred. One type of cement may be used alone, or two or more types may be used in combination. From the viewpoint of achieving even better fluidity and strength development, the fineness of the cement is 2500 to 5500 cm in terms of Blaine specific surface area. 2 / g is preferred.

[0013] Examples of pozzolanic substances include fly ash, silica fume, ground slag, volcanic ash, acid clay, activated clay, aluminosilicate clay minerals such as kaolin minerals, and their calcined products. One type of pozzolanic substance may be used alone, or two or more types may be used in combination. From the viewpoint of high fluidity and non-segregation in water, the fineness of the pozzolanic substance should be 1,500 to 200,000 cm in terms of Blaine specific surface area.2 / g is preferred, and 2000 to 50,000 cm 2 / g is more preferred.

[0014] The content of the pozzolanic substance is preferably 1 to 65 parts by mass, more preferably 2 to 50 parts by mass, even more preferably 3 to 30 parts by mass, and most preferably 4 to 20 parts by mass, relative to 100 parts by mass of cement. If the content of the pozzolanic substance is within the above range, the mixability tends to be good and sagging is even less likely to occur.

[0015] The rubber powder is not particularly limited in terms of its material, and examples include natural rubber, synthetic rubber, and reclaimed rubber made primarily from these rubbers, as defined in JIS K 6397:2005, "Abbreviations for Raw Rubber and Latex." The primary raw material for the rubber powder is preferably rubber classified as group R, such as natural rubber (NR), butadiene rubber (BR), butyl rubber (IIR), isoprene rubber (IR), and styrene-butadiene rubber (SBR), with butyl rubber being more preferred. One type of rubber powder may be used alone, or two or more types may be used in combination. In this specification, "rubber powder" refers to a water-insoluble resin and is different from the polymer for cement admixture defined in JIS A 6203:2015, "Polymer dispersions and re-emulsifiable powdered resins for cement admixture." From the viewpoint of making sagging even less likely to occur, it is preferable that the mortar composition of this embodiment does not contain a polymer for cement admixture defined in JIS A 6203:2015 "Polymer dispersions and re-emulsifiable powdered resins for cement admixture."

[0016] The particle size of the rubber powder is not particularly limited and can be adjusted within the required particle size range. The particle size of the rubber powder can be considered using a method similar to the coarse particle ratio specified in JIS A 1102:2014 "Sieving Test Method for Aggregates." From the viewpoint of easily achieving better fluidity and suppressing bleeding when mixed into mortar, the coarse particle ratio of the rubber powder is preferably 1 to 4, more preferably 1.5 to 3.8, and even more preferably 2 to 3.5.

[0017] The content of the rubber powder is 3 to 55 parts by mass relative to 100 parts by mass of cement. If the content of the rubber powder is outside this range, the mixing property decreases and sagging occurs. From the viewpoints of easily improving the mixing property, further reducing the occurrence of sagging, and further improving the freeze-thaw resistance during hardening, the content of the rubber powder is preferably 4 to 40 parts by mass, more preferably 5 to 30 parts by mass, and even more preferably 5 to 25 parts by mass relative to 100 parts by mass of cement.

[0018] The total content of the pozzolanic substance and rubber powder is 10 to 70 parts by mass per 100 parts by mass of cement. If the total content of the pozzolanic substance and rubber powder is outside this range, the mixability decreases. From the viewpoint of further improving the mixability and compressive strength, the total content of the pozzolanic substance and rubber powder is preferably 11 to 60 parts by mass, more preferably 12 to 50 parts by mass, and even more preferably 13 to 40 parts by mass per 100 parts by mass of cement.

[0019] Examples of fine aggregate include river sand, silica sand, crushed sand, kansui stone, limestone sand, and slag aggregate. Among these, it is preferable to use fine aggregate such as silica sand or limestone adjusted to a particle size that does not contain fine powder or coarse aggregate. One type of fine aggregate may be used alone, or two or more types may be used in combination. It is preferable to use fine aggregate with a particle size of 5 mm or less (passing through a 5 mm sieve), which is the size commonly used.

[0020] The particle size of the fine aggregate is not particularly limited and can be adjusted within the required particle size range. The particle size of the fine aggregate can be determined based on the coarse particle ratio specified in JIS A 1102:2014 "Sieving Test Method for Aggregates." From the viewpoint of achieving better fluidity and suppressing bleeding during mortar formation, the coarse particle ratio of the fine aggregate is preferably 1 to 4, more preferably 1.5 to 3.8, and most preferably 2 to 3.5.

[0021] The content of the fine aggregate is preferably 130 to 400 parts by mass, more preferably 160 to 350 parts by mass, and even more preferably 200 to 300 parts by mass, relative to 100 parts by mass of cement. If the content of the fine aggregate is within the above range, the mixing property tends to be good, and sagging is further prevented from occurring.

[0022] The ratio of the total mass of the pozzolanic substance and rubber powder to the total mass of the pozzolanic substance, rubber powder, and fine aggregate ([total mass of the pozzolanic substance and rubber powder] / [total mass of the pozzolanic substance, rubber powder, and fine aggregate]) is 0.03 to 0.23. If this ratio is outside the above range, the mixability decreases. From the viewpoint of further improving the mixability and compressive strength, the ratio of the total mass of the pozzolanic substance and rubber powder to the total mass of the pozzolanic substance, rubber powder, and fine aggregate is preferably 0.04 to 0.21, more preferably 0.05 to 0.20, and even more preferably 0.05 to 0.19.

[0023] The mortar composition of the present embodiment may contain calcium aluminates. Examples of calcium aluminates include C3A, C2A, C, where CaO is C, Al2O3 is A, Na2O is N, and Fe2O3 is F. 12 Calcium aluminate with a mineral composition indicated as A7, CA, or CA2, calcium aluminoferrite indicated as C4AF, calcium aluminate with halogen as a solid solution or substituted, C3A3·CaF2, and C 11This is a general term for calcium haloaluminates, including calcium fluoroaluminates such as A7·CaF2, calcium sodium aluminates such as C8NA3 and C3N2A5, calcium lithium aluminate, alumina cement, and calcium sulfoaluminates such as C3A3·CaSO4. These calcium aluminates can be crystalline, amorphous, or a mixture of amorphous and crystalline. One type of calcium aluminate can be used alone, or two or more types can be used in combination. The fineness of calcium aluminates is set to a Blaine specific surface area of ​​3000 cm in order to further improve the initial compressive strength. 2 / g or more, and 2 / g or more. The fineness of calcium aluminates is preferably 8000 cm2 in terms of Blaine specific surface area. 2 / g or less is preferable.

[0024] The content of calcium aluminates is preferably 10 to 40 parts by mass, more preferably 15 to 35 parts by mass, and even more preferably 20 to 32 parts by mass, relative to 100 parts by mass of cement. If the content of calcium aluminates is within the above range, the initial compressive strength is further improved.

[0025] The mortar composition of the present embodiment may contain gypsum. Examples of gypsum include anhydrous gypsum, hemihydrate gypsum, and dihydrate gypsum. As the gypsum, anhydrous gypsum is preferred from the viewpoint of further improving compressive strength. One type of gypsum may be used alone, or two or more types may be used in combination.

[0026] The content of gypsum is preferably 10 to 40 parts by mass, more preferably 12 to 35 parts by mass, and even more preferably 15 to 30 parts by mass, relative to 100 parts by mass of cement. If the content of gypsum is within the above range, the compressive strength is further improved.

[0027] The mortar composition of the present embodiment may contain a water-reducing agent. Examples of water-reducing agents include high-performance water-reducing agents, high-performance air-entraining water-reducing agents, air-entraining water-reducing agents, and superplasticizers. 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, naphthalenesulfonic acid-based water-reducing agents, ligninsulfonic acid-based water-reducing agents, melamine-based water-reducing agents, and acrylic-based water-reducing agents. Among these, polycarboxylic acid-based 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.

[0028] The content of the water-reducing agent is preferably 0.1 to 5 parts by mass, more preferably 0.3 to 3 parts by mass, and most preferably 0.5 to 1.5 parts by mass, relative to 100 parts by mass of cement. If the content of the water-reducing agent is within the above range, better fluidity is likely to be obtained when the mortar is made into, and compressive strength is also likely to be improved.

[0029] The mortar composition of this embodiment may contain a set retarder. By incorporating a set retarder, it becomes easier to ensure a sufficient working life, even in the summer when the temperature of the mixed mortar is high. Examples of set retarders include organic acids or salts thereof, such as citric acid, gluconic acid, malic acid, and tartaric acid; boric acid, borates such as sodium borate, phosphates, inorganic salts, such as alkali metal carbonates and alkali metal bicarbonates; and sugars. Among these, citric acid, citrates, tartaric acid, tartrates, and alkali metal carbonates are preferred. The set retarder may be in the form of a powder or a liquid (for example, an aqueous solution, emulsion, or suspension). One type of set retarder may be used alone, or two or more types may be used in combination.

[0030] The content of the set retarder 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, relative to 100 parts by mass of cement. If the content of the set retarder is within the above range, it is easier to ensure a longer pot life and the initial compressive strength is less likely to decrease.

[0031] The mortar composition of this embodiment may contain various admixtures (materials) within the range that does not impair the effects of the present invention. Examples of admixtures (materials) include expansive agents, antifoaming agents, waterproofing agents, rust inhibitors, shrinkage reducing agents, thickeners, water retention agents, pigments, water repellents, efflorescence inhibitors, and fibers.

[0032] The mortar composition of the present embodiment can be prepared by mixing the above-described components using a commonly used kneading tool, which is not particularly limited. Examples of the kneading tool include a mortar mixer, a hand mixer, a tilting mixer, and a twin-shaft mixer.

[0033] The mortar composition of this embodiment can be prepared as a mortar by mixing with water, and the water content can be adjusted appropriately depending on the application. The water content is preferably 30 to 60 parts by mass, more preferably 35 to 55 parts by mass, and most preferably 40 to 52 parts by mass, per 100 parts by mass of cement. If the water content is within the above range, good fluidity and reduced sagging tend to be achieved at the same time.

[0034] The preparation of the mortar of this embodiment can be carried out using the same kneading equipment as that used for ordinary mortar, and is not particularly limited. For example, the kneading equipment described above can be used.

[0035] The mortar composition and mortar of this embodiment are resistant to sagging even when applied to sloped sections, and exhibit excellent freeze-thaw resistance and compressive strength. Therefore, they can be used as repair and reinforcement materials in cold regions prone to frost damage or in sloped areas. The mortar of this embodiment can be used in a variety of ways, including filling recesses with a trowel, smoothing the surface with a vibrator or the like after filling and then finishing with a trowel, or spraying the area to be repaired. [Example]

[0036] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0037] The materials and abbreviations used in the examples are as follows: Materials used Cement (C): High-early-strength Portland cement, Blaine specific surface area 4500 cm 2 / g Pozzolanic material (FA): Fly ash, Blaine specific surface area 2000cm 2 / g Rubber powder (G): Reclaimed rubber, bulk density 0.38g / cm 3 , average particle size 0.6~1.5mm, coarse particle ratio 2.9 Fine aggregate (S): Silica sand, particle size adjusted, coarse particle ratio 3.2 Calcium aluminate: Blaine specific surface area 5000cm 2 / g Gypsum: anhydrous gypsum, blaine specific surface area 7000 cm 2 / g Water reducing agent: Polycarboxylic acid-based high-performance water reducing agent ·Set retarder: citrate

[0038] [Mixture design of mortar composition] The mix was designed so that, per 100 parts by mass of cement, the pozzolanic substance, rubber powder, and fine aggregate were used in the proportions shown in Table 1, with 28 parts by mass of calcium aluminate, 22 parts by mass of gypsum, 0.7 parts by mass of water-reducing agent, and 0.7 parts by mass of setting retarder. All blend amounts in the examples are calculated on an anhydrous basis and solid content basis.

[0039] [Mortar preparation] In an environment of 20°C, water was added to the mortar composition formulated in Table 1 so that the ratio was 48 parts by mass of water to 100 parts by mass of cement, and the mixture was mixed with a hand mixer for 120 seconds to produce approximately 3 L of mortar.

[0040] [Table 1]

[0041] [Evaluation method] Each item was evaluated using the following methods. The evaluation results are shown in Table 2. 1) Fresh properties a) Consistency According to JIS R 5201:2015 "Physical Testing Methods for Cement" 12. Flow test, the flow value of the mortar was measured in a 20°C environment and evaluated as consistency. b) Droopiness A concrete slab (300mm x 300mm x 60mm) was placed at a 3% gradient, and mortar was applied to a thickness of 20mm. The mortar was then leveled with a trowel and visually inspected for sagging. Cases where sagging occurred were rated as poor (×), and cases where no sagging occurred were rated as good (○). 2) Compressive strength The compressive strength at 28 days of age was measured in accordance with the Japan Society of Civil Engineers standard JSCE-G 5050-2010, "Test method for compressive strength of mortar or cement paste using cylindrical specimens (draft)." The specimen dimensions were 50 mm in diameter and 100 mm in height. The 28-day-old specimens were demolded the following day and cured in water until the end of their maturity. Curing was always carried out in a thermostatic chamber at 20°C. 3) Freeze-thaw resistance The specimens were rectangular columns measuring 100mm x 100mm x 400mm. After molding, the specimens were demolded the next day and cured in water until they reached a material age of 28 days. Curing was always carried out in a constant temperature bath at 20°C. Using the cured specimens, the relative dynamic modulus of elasticity of the specimens was measured in accordance with JIS A 1148:2010 "Freeze-thaw test method for concrete" to evaluate their freeze-thaw resistance. After 300 cycles, a value of "Good" was given if the relative dynamic modulus of elasticity was 60% or higher, and a value of "Poor" if it was less than 60%.

[0042] [Table 2]

Claims

1. The composition includes cement, a pozzolanic substance, rubber powder, fine aggregate, gypsum, and calcium aluminates, The content of the pozzolan substance is 1 to 65 parts by mass per 100 parts by mass of the cement, The content of the rubber powder is 3 to 55 parts by mass per 100 parts by mass of the cement, The content of the fine aggregate is 200 to 400 parts by mass relative to 100 parts by mass of the cement, The content of the gypsum is 10 to 40 parts by mass relative to 100 parts by mass of the cement, the content of the calcium aluminates is 10 to 40 parts by mass relative to 100 parts by mass of the cement, a total content of the pozzolan substance and the rubber powder is 10 to 70 parts by mass per 100 parts by mass of the cement, a ratio of the total mass of the pozzolan substance and the rubber powder to the total mass of the pozzolan substance, the rubber powder, and the fine aggregate ([total mass of the pozzolan substance and the rubber powder] / [total mass of the pozzolan substance, the rubber powder, and the fine aggregate]) of 0.03 to 0.23; The rubber powder is insoluble in water, A mortar composition that does not contain coarse aggregate.

2. The mortar composition according to claim 1, wherein the rubber powder has a coarse particle ratio of 1 to 4.

3. The mortar composition according to claim 1 or 2, further comprising a water-reducing agent.

4. A mortar composition comprising the mortar composition according to any one of claims 1 to 3 and water, The mortar has a water content of 30 to 60 parts by mass per 100 parts by mass of the cement.

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