JP7007964B2 - Polymer cement mortar composition and polymer cement mortar - Google Patents

Description

The present invention relates to polymer cement mortar compositions and polymer cement mortars.

Concrete structures (for example, floor slabs such as reinforced concrete (RC) floor slabs or box calvert mid-deck slabs, walls, and ceilings) are cracked due to factors such as fatigue and drying shrinkage. When the crack width becomes large due to the progress of this kind of deterioration or the rubbing of cracks, deterioration factors such as water and chloride ions invade the concrete structure from the deteriorated part. As a result, the reinforcing bars buried in the concrete structure are corroded. If the damage caused by cracks in the concrete structure is left unattended, the reinforcing bars inside will eventually corrode and the cross section will be damaged, making it impossible to maintain the safety of the structure. Therefore, after removing the deteriorated portion, the recess is filled with a repair material or a reinforcing material.

Polymer cement mortar has been proposed as the above-mentioned repair material or reinforcing material. However, when the difference in (static) elastic modulus between the existing concrete and the hardened body of the polymer cement mortar is large, shearing force is generated at the boundary surface between the existing concrete and the repair material due to fatigue due to repeated loading, and the boundary surface is regenerated. Deterioration may occur.

Patent Document 1 proposes a mortar kneaded product for tile attachment in which the elastic modulus is adjusted by the resin / cement mass ratio. Patent Document 2 proposes a rapid-hardening elastic composition containing rubber powder.

Japanese Unexamined Patent Publication No. 2010-76975 Japanese Unexamined Patent Publication No. 2-302350

However, since the mortar kneaded product for tile attachment described in Patent Document 1 is for tile attachment, fluidity is not required, and the rapid-hardening elastic composition described in Patent Document 2 is not excellent in strength development. There was a challenge.

Therefore, an object of the present invention is to provide a polymer cement mortar composition and a polymer cement mortar having excellent fluidity, good strength development at the time of curing, and a small static elastic modulus.

As a result of diligent studies on the above-mentioned problems, the present inventors have excellent fluidity and good strength development at the time of curing by adjusting the ratio of the fine aggregate and the rubber powder by using the alkali metal carbonate. It has been found that a polymer cement mortar composition and a polymer cement mortar having a small static elasticity coefficient can be obtained.

That is, the present invention is shown by the following [1] to [5].
[1] The mass ratio of the rubber powder to the total mass of the fine aggregate and the rubber powder, which includes cement, an alkali metal carbonate, a polymer for cement, a fine aggregate and a rubber powder ([mass of rubber powder]. ] / [Mass of fine aggregate + mass of rubber powder]) is 0.08 to 0.32, a polymer cement mortar composition.
[2] The polymer cement mortar composition according to [1], wherein the total content of the fine aggregate and the rubber powder is 60 to 250 parts by mass with respect to 100 parts by mass of the cement.
[3] The polymer cement mortar composition according to [1] or [2], wherein the content of the polymer for cement is 8 to 38 parts by mass in terms of solid content with respect to 100 parts by mass of cement.
[4] The particle size of the aggregate mixture in which the fine aggregate and the rubber powder are mixed is such that the mass ratio of the particles having a particle size of 0.6 mm or less to the mass of the aggregate mixture is 40% by mass or less [1]. ]-[3]. The polymer cement mortar composition according to any one of.
[5] A polymer containing the polymer cement mortar composition according to any one of [1] to [4] and water, and the content of water is 22 to 55 parts by mass with respect to 100 parts by mass of cement. Cement mortar.

According to the present invention, it is possible to provide a polymer cement mortar composition and a polymer cement mortar having excellent fluidity, good strength development at the time of curing, and a small static elastic modulus.

Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited thereto.

The polymer cement mortar composition of the present embodiment contains cement, an alkali metal carbonate, a polymer for cement, a fine aggregate, and a rubber powder.

Various cements can be used, and examples thereof include various Portland cements such as ordinary, early-strength, ultra-fast-strength, low-heat and moderate heat, eco-cement, and quick-hardening cement. As the cement, one type may be used alone, or two or more types may be used in combination.

As the cement, a fast-curing cement is preferable from the viewpoint of better strength development at an early stage. The fast-curing cement preferably contains calcium sulfates as an active ingredient, and contains 11CaO / 7Al _{2O 3} / CaX ₂ (X indicates a halogen atom) or 3CaO / 3Al ₂ O ₃ / CaSO ₄ (auyne). Those contained as an active ingredient are more preferable. _11CaO・ 7Al _2O3・ CaX ₂ is a so-called calcium aluminate halide-based cement. As the halogen atom, a fluorine atom is preferable. Hauyne is also referred to as calcium sulfoluminate-based cement (auyne-based cement). These are called ultrafast-hardening cements and are commercially available under the trade name Jet Cement or Super Jet Cement. As the quick-hardening cement, hauyne-based cement is most preferable.
In addition, as calcium aluminates, when CaO is indicated by C, Al ₂ O ₃ is indicated by A, and Fe ₂ O ₃ is indicated by F, C ₃ A, C ₂ A, C ₁₂ A ₇ , CA, Calcium aluminate having a mineral composition labeled as CA ₂ etc., calcium aluminoferrite labeled as C ₄ AF etc., alumina cement, and SiO ₂ , K ₂ O, Fe ₂ O ₃ , TIO ₂ etc. are solidified thereto. It includes those that have been melted or combined. The calcium aluminates may be either crystalline or amorphous, or may be such as a mixture of crystalline and amorphous. A quick-hardening admixture prepared by blending these calcium aluminates and an inorganic salt such as gypsum, which is added to Portland cement, can also be used as the quick-hardening cement.

The alkali metal carbonate is not particularly limited as long as it is a carbonate or percarbonate of an alkali metal (element of the first group of the periodic table excluding hydrogen atom). As the alkali metal carbonate, lithium carbonate, sodium carbonate and potassium carbonate are preferable from the viewpoint of further promoting the strength development. The alkali metal carbonate may be used alone or in combination of two or more.

The content of the alkali metal carbonate is preferably 0.3 to 3 parts by mass, more preferably 0.5 to 2 parts by mass, and 0.6 to 1.5 parts by mass with respect to 100 parts by mass of the cement. Most preferably, it is by mass. When the content of the alkali metal carbonate is within the above range, the strength development tends to be further excellent.

The polymer for cement is preferably the polymer specified in JIS A 6203: 2015 “Polymer dispersion for cement admixture and re-emulsified powder resin”. Examples of such a polymer for cement include polymer dispersions and re-emulsified powder resins. Examples of the polymer dispersion include synthetic rubber type such as styrene-butadiene rubber (SBR); natural rubber type; rubber asphalt type; ethylene vinyl acetate type; acrylic acid ester type; resin asphalt type and the like. Among the polymer dispersions, synthetic rubber-based, ethylene-vinyl acetate-based and acrylic acid ester-based are preferable, and specifically, synthetic rubber latex, polyacrylic acid ester and ethylene vinyl acetate are more preferable. Examples of the re-emulsified powder resin include synthetic rubber such as styrene-butadiene rubber; acrylic acid ester type; ethylene vinyl acetate type; vinyl acetate / versatic acid vinyl ester; vinyl acetate / versatic acid vinyl / acrylic acid ester and the like. As the polymer for cement, a polymer dispersion may be used, a re-emulsified powder resin may be used, or the polymer dispersion and the re-emulsified powder resin may be used in combination.
Among the polymers for cement, polymer dispersion of styrene-butadiene rubber and / or re-emulsified powder resin is preferable from the viewpoint of further improving the adhesiveness to concrete. Styrene-butadiene rubber is a kind of synthetic rubber obtained by copolymerizing styrene and butadiene, and its quality can be appropriately adjusted depending on the styrene content and the vulcanization amount. For cement admixture, the amount of bonded styrene is often 50 to 70% by mass, and it is used with improved stability and adhesiveness. As the cement polymer, one type may be used alone, or two or more types may be used in combination.

The content of the polymer for cement is preferably 8 to 38 parts by mass, more preferably 12 to 35 parts by mass, and 15 to 30 parts by mass with respect to 100 parts by mass of cement. Is the most preferable. When the content of the cement polymer is within the above range, better fluidity and strength development are likely to be obtained, and the static elastic modulus tends to be small.

Examples of the fine aggregate include river sand, silica sand, crushed sand, cold water stone, limestone sand, slag aggregate and the like. As the fine aggregate, it is preferable to use an aggregate such as silica sand or limestone whose particle size is adjusted so as not to contain fine powder or coarse aggregate. As the fine aggregate, one type may be used alone, or two or more types may be used in combination. As the fine aggregate, it is preferable to use a normally used material having a particle size of 5 mm or less (for passing through a 5 mm sieve).

The particle size of the fine aggregate is not particularly limited, and can be adjusted within the range of the required particle size of the fine aggregate. The particle size of the fine aggregate can be taken into consideration from the coarse grain ratio specified by JIS A 1102: 2014 “Aggregate Sifting Test Method”. From the viewpoint that better fluidity can be easily obtained and bleeding can be easily suppressed at the time of mortar, the coarse grain ratio of the fine aggregate is preferably 1 to 4, preferably 1.5 to 3.8. It is more preferable, and it is most preferably 2 to 3.5.

The content of the fine aggregate can be appropriately adjusted within the range of the mass ratio of the fine aggregate and the rubber powder described later. The content of the fine aggregate is preferably 35 to 280 parts by mass, more preferably 40 to 250 parts by mass, and most preferably 45 to 200 parts by mass with respect to 100 parts by mass of cement. When the content of the fine aggregate is within the above range, it is easy to obtain more appropriate fluidity that is neither too soft nor too hard at the time of mortar.

The material of the rubber powder is not particularly limited, and examples thereof include natural rubber and synthetic rubber specified in JIS K 6397: 2005 “Abbreviations for raw rubber and latex”. As the rubber powder, rubber classified into the R group such as natural rubber (NR), butadiene rubber (BR), butyl rubber (IIR), isoprene rubber (IR), and styrene butadiene rubber (SBR) is preferable, and butyl rubber is more preferable. .. As the rubber powder, one type may be used alone, or two or more types may be used in combination. In the present specification, the "rubber powder" is a water-insoluble resin, which is different from the re-emulsified powder resin used in the above-mentioned cement polymer.

The particle size of the rubber powder is not particularly limited, and can be adjusted within the range of the required particle size of the rubber powder. The grain size of the rubber powder can be taken into consideration from the same method as the coarse grain ratio specified by JIS A 1102: 2014 “Aggregate Sifting Test Method”. At the time of mortar, the coarse grain ratio of the rubber powder is preferably 1 to 4, preferably 1.5 to 3.8, from the viewpoint that better fluidity can be easily obtained and bleeding can be easily suppressed. Is more preferable, and 2 to 3.5 is even more preferable.

The content of the rubber powder can be appropriately adjusted within the range of the mass ratio of the fine aggregate and the rubber powder described later. The content of the rubber powder is preferably 3 to 80 parts by mass, more preferably 5 to 45 parts by mass, and even more preferably 7 to 40 parts by mass with respect to 100 parts by mass of cement. Most preferably, it is 10 to 34 parts by mass. When the content of the rubber powder is within the above range, the fluidity at the time of mortar tends to be better and the electrostatic modulus tends to be smaller.

In the polymer cement mortar composition of the present embodiment, the mass ratio of the rubber powder to the total mass of the fine aggregate and the rubber powder ([mass of the rubber powder] / [mass of the fine aggregate + mass of the rubber powder]) is 0. It is .08 to 0.32. If the mass ratio of the rubber powder to the total mass of the fine aggregate and the rubber powder is out of the above range, good fluidity and strength development, and a small static elastic modulus cannot be achieved. The mass ratio of the rubber powder to the total mass of the fine aggregate and the rubber powder may be 0.09 to 0.32 from the viewpoint that good fluidity can be easily obtained and the static elastic modulus can be easily reduced. It is preferably 0.10 to 0.30, and more preferably 0.10 to 0.30.

In the polymer cement mortar composition of the present embodiment, the total content of the fine aggregate and the rubber powder is preferably 60 to 250 parts by mass and 65 to 225 parts by mass with respect to 100 parts by mass of the cement. Is more preferable, and 70 to 200 parts by mass is most preferable. When the total content of the fine aggregate and the rubber powder is within the above range, good fluidity can be easily obtained and the static elastic modulus can be easily reduced.

In the polymer cement mortar composition of the present embodiment, the particle size of the aggregate mixture obtained by mixing the fine aggregate and the rubber powder is such that the mass ratio of the particles having a particle size of 0.6 mm or less to the mass of the aggregate mixture is 40. It is preferably 1% by mass or less, more preferably 35% by mass or less, and most preferably 30% by mass or less. When the mass ratio of the particles having a particle size of 0.6 mm or less is within the above range, better fluidity can be easily obtained at the time of mortar.
In the present specification, the particle size of the aggregate mixture is determined by sieving the entire amount of the aggregate mixture, and the particles passed through the 0.6 mm sieve are particles having a particle size of 0.6 mm or less.

The polymer cement mortar composition of the present embodiment may contain a water reducing agent. The water reducing agent includes a high performance water reducing agent, a high performance AE water reducing agent, an AE water reducing agent and a fluidizing agent. Examples of such a water reducing agent include water reducing agents specified in JIS A 6204: 2011 “Chemical admixture for concrete”. Examples of the water reducing agent include a polycarboxylic acid-based water reducing agent, a naphthalene sulfonic acid-based water reducing agent, a lignin sulfonic acid-based water reducing agent, a melamine-based water reducing agent, and an acrylic water-reducing agent. Among these, a naphthalene sulfonic acid-based water reducing agent is preferable. As the water reducing agent, one type may be used alone, or two or more types may be used in combination.

The content of the water reducing agent is preferably 0.3 to 5 parts by mass, more preferably 0.5 to 3 parts by mass, and 0.7 to 2 parts by mass with respect to 100 parts by mass of the cement. Is most preferable. When the content of the water reducing agent is within the above range, better fluidity can be easily obtained when the mortar is used, and strength development at the time of curing is also likely to be improved.

The polymer cement mortar composition of the present embodiment may contain a setting retarder. By containing the setting retarder, it is easy to secure the pot life even in the summer when the kneading temperature of the polymer cement mortar is high. Examples of the setting retarder include organic acids such as citric acid, gluconic acid, malic acid and tartrate or salts thereof; borates such as boric acid and sodium borate, phosphates, alkali metal carbonates and alkali metal weights. Inorganic salts such as carbonates; saccharides and the like. Among these, citric acid, citrate, tartaric acid, tartaric acid and alkali metal carbonate are preferable. The setting retarder may be a powder or a liquid (for example, in the form of an aqueous solution, an emulsion or a suspension). As the condensation retarder, one type may be used alone, or two or more types may be used in combination.

The content of the setting retarder is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 3 parts by mass, and 0.3 to 1 part by mass with respect to 100 parts by mass of the cement. It is more preferable to have. When the content of the setting retarder is within the above range, it is easy to secure the pot life, and the initial strength development tends to be difficult to decrease.

Various admixtures (materials) may be added to the polymer cement mortar composition of the present embodiment as long as the effects of the present invention are not impaired. Examples of the admixture (material) include defoaming agents, waterproofing agents, rust preventives, shrinkage reducing agents, thickeners, water retaining agents, pigments, water repellents, efflorescence inhibitors, and fibers.

The polymer cement mortar composition of the present embodiment can be prepared by mixing each of the above-mentioned components with a commonly used kneading device, and the device is not particularly limited. Examples of the kneading device include a mortar mixer, a hand mixer, a tilting mixer, a twin-screw mixer, and the like.

The polymer cement mortar composition of the present embodiment can be mixed with water to prepare a polymer cement mortar, and the content of the water may be appropriately adjusted according to the intended use. The water content is preferably 22 to 55 parts by mass, more preferably 25 to 50 parts by mass, and most preferably 25 to 45 parts by mass with respect to 100 parts by mass of cement. When the water content is within the above range, it is easier to secure fluidity, it is easier to suppress the occurrence of material separation, the increase in shrinkage of the cured product, and the decrease in the initial strength development, and the static elastic modulus tends to be smaller. It is in.

The preparation of the polymer cement mortar of the present embodiment can use the same kneading equipment as the ordinary polymer cement mortar, and is not particularly limited. As the kneading tool, for example, the above-mentioned one can be used.

The polymer cement mortar composition and the polymer cement mortar of the present embodiment have excellent fluidity, good strength development at the time of curing, and a small static elastic modulus. Therefore, such a polymer cement mortar composition and a polymer cement mortar can be used, for example, as a repair / reinforcing material for concrete structures, steel / concrete composite structures, roads, etc., and further, narrow gaps such as grout. It can also be used as a mortar for filling gaps as a material for repairing, reinforcing, and filling cavities. The method of using the polymer cement mortar of the present embodiment can be appropriately selected. For example, a method of filling the recess with a trowel, a method of smoothing the recess with a vibrator and then finishing with a trowel, a method of spraying on a repaired portion, and a gap portion. You can select the method of pouring and filling in.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited thereto. In addition, No. The polymer cement mortar compositions of 7, 10 and 14 are used as reference examples.

The materials and abbreviations used in the examples are as follows. Table 1 shows the particle sizes of the fine aggregate and rubber powder.
C: Fast-hardening cement S: Fine aggregate (quartz sand)
G: Rubber powder (butyl rubber)
A: Lithium carbonate P: Polymer for cement (SBR emulsion)
W: Water supply

[Compound design of polymer cement mortar composition]
Lithium carbonate, fine aggregate, rubber powder and cement polymer (in terms of solid content) are used in the amounts shown in Table 2 with respect to 100 parts by mass of cement, and 0.9 parts by mass of a water reducing agent (naphthalene sulfonic acid-based water reducing agent) is used. The setting was made by blending and designing a setting retarder (citric acid) in an amount of 0.3 parts by mass.

[Making polymer cement mortar]
In a 20 ° C environment, a polymer for cement (polymer dispersion) is added to a 10 L cylindrical container, each material and water of the polymer cement mortar composition formulated and designed in Table 2 are added, and the mixture is kneaded with a hand mixer for 90 seconds. About 3 L of polymer cement mortar was prepared.

[Evaluation methods]
Each item was evaluated by the following method. The evaluation results are shown in Table 3.
-Consistency JIS R 5201: 2015 "Physical test method for cement" 12. According to the flow test, the flow value (0 strokes) of the polymer cement mortar was measured in an environment of 20 ° C., and this was evaluated as consistency.
-Compressive strength According to the JSCE standard JSCE-G 505-2010 "Compressive strength test method for mortar or cement paste using columnar specimens (draft)", polymer cement mortar cured products at ages 1 and 28 days. The compressive strength was measured. The dimensions of the specimen were 50 mm in diameter and 100 mm in height. Curing was always performed in a constant temperature bath at 20 ° C.
-Static elastic modulus The static elastic modulus at 28 days of age was measured according to JIS A 1149: 2010 "Test method for static elastic modulus of concrete". The dimensions of the specimen were 100 mm in diameter and 200 mm in height. The specimen was demolded the day after preparation and then cured in the air until the age of the material. Curing was always performed in a constant temperature bath at 20 ° C.

Claims (6)

Containing cement, alkali metal carbonates, polymers for cement, fine aggregates, and rubber powder,
The polymer for cement is a polymer specified in JIS A 6203: 2015 "Polymer Dispersion for Cement Mixing and Reemulsified Powder Resin".
The coarse grain ratio of the rubber powder is 1 to 4, and the rubber powder has a coarse grain ratio of 1 to 4.
The content of the polymer for cement is 15 to 38 parts by mass in terms of solid content with respect to 100 parts by mass of the cement.
The total content of the fine aggregate and the rubber powder is 60 to 250 parts by mass with respect to 100 parts by mass of the cement.
The mass ratio of the rubber powder to the total mass of the fine aggregate and the rubber powder ([mass of rubber powder] / [mass of fine aggregate + mass of rubber powder]) is 0. Polymer cement mortar composition of more than 12 to 0.32. The polymer cement mortar composition according to claim 1 , wherein the content of the alkali metal carbonate is 0.3 to 3 parts by mass with respect to 100 parts by mass of the cement. The polymer cement mortar composition according to claim 1 or 2 , further comprising 0.3 to 5 parts by mass of a water reducing agent with respect to 100 parts by mass of the cement. The polymer cement mortar composition according to any one of claims 1 to 3, further comprising 0.1 to 5 parts by mass of a setting retarder with respect to 100 parts by mass of the cement. The particle size of the aggregate mixture obtained by mixing the fine aggregate and the rubber powder is such that the mass ratio of the particles having a particle size of 0.6 mm or less to the mass of the aggregate mixture is 40% by mass or less. The polymer cement mortar composition according to any one of 1 to 4 . The polymer cement mortar composition according to any one of claims 1 to 5 and water are included.
A polymer cement mortar having a water content of 22 to 55 parts by mass with respect to 100 parts by mass of the cement.