Polymer cement mortar composition and polymer cement mortar

Abstract

To provide a polymer cement mortar composition that has excellent strength properties, causes low setting delay, and having good flowability, and to provide a polymer cement mortar.SOLUTION: A polymer cement mortar composition comprises: a binder containing a cement; a mixed aggregate comprising a clinker aggregate and a fine aggregate; and a polymer for cement, wherein the clinker aggregate contains 55 to 70 mass% of CaO and 15 to 30% of SiO2 as chemical components, and the cement content is 60 pts.mass or more based on 100 mass parts of the binder.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Cracks occur in concrete structures (for example, reinforced concrete (RC) decks, walls, ceilings, etc., such as decks, walls, and ceilings of box culverts, etc.) due to factors such as fatigue and drying shrinkage. As this type of deterioration progresses or the cracks become wedged together, the cracks widen, allowing deterioration factors such as water and chloride ions to penetrate into the concrete structure through the deteriorated area. This results in corrosion of the rebar embedded in the concrete structure. If damage caused by cracks in a concrete structure is left unattended, the internal rebar will eventually corrode, causing cross-sectional defects and making the structure unsafe. For this reason, repair and renovation work is carried out, in which the deteriorated areas are removed and the recesses are filled with repair or reinforcing materials.

[0003] Polymer cement mortars and pastes are increasingly being used as materials for various repair and renovation methods (for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-000820 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-015306 Summary of the Invention [Problem to be solved by the invention]

[0005] Polymer-cement mortar is expected to have improved adhesion and durability due to the effects of the polymers added. However, increasing the amount of polymer mixed in tends to delay setting and reduce compressive strength. For example, after cross-section repair work, appropriate curing is required until setting is complete before starting the next process, which can delay the entire construction project. Therefore, a method is needed to improve setting delay without compromising the workability and durability of polymer-cement mortar. Furthermore, considering the construction site, such as troweling work during cross-section repair, polymer-cement mortar is also required to have good fluidity.

[0006] Therefore, an object of the present invention is to provide a polymer cement mortar composition and a polymer cement mortar that are excellent in strength characteristics, are less likely to cause set retardation, and have good fluidity. [Means for solving the problem]

[0007] As a result of extensive research into the above-mentioned problems, the present inventors have found that by using a binder in a specific blending ratio and a clinker aggregate having a specific chemical composition, it is possible to obtain a polymer cement mortar composition and a polymer cement mortar that have good strength properties and fluidity while improving set retardation.

[0008] That is, the present invention includes the following [1] to [5]. [1] A polymer cement mortar composition comprising a binder containing cement, a mixed aggregate consisting of clinker aggregate and fine aggregate, and a cement polymer, wherein the clinker aggregate contains, as chemical components, 55 to 70 mass% of CaO and 15 to 30 mass% of SiO2, and the cement content is 60 parts by mass or more per 100 parts by mass of the binder. [2] The polymer cement mortar composition according to [1], wherein the content of the clinker aggregate is 10 to 95 parts by mass per 100 parts by mass of the mixed aggregate. [3] The polymer cement mortar composition according to [1] or [2], wherein the coarse particle ratio of the mixed aggregate is 1.5 to 4.3. [4] The polymer cement mortar composition according to any one of [1] to [3], wherein the content of the polymer for cement is 1 to 20 parts by mass in terms of solid content per 100 parts by mass of the binder. [5] A polymer cement mortar comprising the polymer cement composition according to any one of [1] to [4] and water, wherein the content of the water is 20 to 50 parts by mass per 100 parts by mass of the binder. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a polymer cement mortar composition and a polymer cement mortar that have excellent strength properties, are less likely to undergo set retardation, and have good fluidity. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described in detail, but the present invention is not limited thereto.

[0011] The polymer cement mortar composition of the present embodiment contains a binder containing cement, a mixed aggregate consisting of clinker aggregate and fine aggregate, and a cement polymer.

[0012] Various cements can be used, including various types of Portland cement such as ordinary, early-strength, ultra-early-strength, low-heat, and moderate-heat, ecocement, and rapid-hardening cement. Ordinary Portland cement and early-strength Portland cement are preferred because they ensure fluidity and usable life even in high-temperature environments. One type of cement may be used alone, or two or more types may be used in combination.

[0013] The cement content is 60 parts by mass or more relative to 100 parts by mass of the binder. If the cement content is outside this range, it becomes difficult to achieve both rapid setting and good strength properties. The cement content is preferably 70 parts by mass or more, and more preferably 80 parts by mass or more, relative to 100 parts by mass of the binder. The cement content may be the total mass (100 parts by mass) of the binder. If the cement content is within the above range, good strength properties are likely to be obtained while suppressing delay in setting.

[0014] The binder may include, in addition to cement, gypsum, expansive materials, ground granulated blast furnace slag, silica fume, fly ash, and the like.

[0015] The mixed aggregate according to this embodiment is composed of clinker aggregate and fine aggregate. The clinker aggregate and fine aggregate are preferably those having a particle size of 5 mm or less (passing a 5 mm sieve), which are commonly used. The coarse particle ratio of the mixed aggregate is preferably 1.0 to 4.3, more preferably 1.2 to 4.1, and even more preferably 1.7 to 3.8, from the viewpoints of easily obtaining good fluidity and preventing material segregation.

[0016] The content of the mixed aggregate is preferably 100 to 450 parts by mass, more preferably 150 to 400 parts by mass, and even more preferably 200 to 350 parts by mass, relative to 100 parts by mass of the binder. When the content of the mixed aggregate is within the above range, good strength characteristics are likely to be obtained.

[0017] Clinker aggregate is obtained by pulverizing various cement clinkers, such as various Portland cements including normal, early strength, extra early strength, low heat, and medium heat, and ecocement, and adjusting them to a predetermined particle size. From the viewpoint of easily obtaining good fluidity and preventing material separation, the coarse particle ratio of the clinker aggregate is preferably 1.0 to 4.0, more preferably 1.2 to 3.8, and even more preferably 1.7 to 3.5.

[0018] The clinker aggregate contains 55 to 70 mass% CaO and 15 to 30 mass% SiO2 as chemical components. If the chemical components of the clinker aggregate are outside the above ranges, there is a possibility that the setting time will not be sufficient and the strength characteristics will not be excellent. From the viewpoint of easily obtaining better strength characteristics, the chemical components of the clinker aggregate preferably contain 58 to 68 mass% CaO and 16 to 28 mass% SiO2, and more preferably 60 to 65 mass% CaO and 17 to 25 mass% SiO2. The chemical components of the clinker aggregate can be calculated using the Borg formula.

[0019] The content of the clinker aggregate is preferably 10 to 95 parts by mass, more preferably 10 to 90 parts by mass, and even more preferably 20 to 80 parts by mass, relative to 100 parts by mass of the mixed aggregate. If the content of the clinker aggregate is within the above range, it is easy to achieve both good fluidity and good strength properties.

[0020] Examples of fine aggregate include river sand, silica sand, crushed sand, kansui stone, limestone sand, and slag aggregate. Of these, it is preferable to use silica sand, limestone sand, etc., 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. The coarse particle ratio of the fine aggregate is preferably 1.0 to 5.0, more preferably 1.2 to 4.5, and even more preferably 1.7 to 3.8, from the viewpoints of easily obtaining good fluidity and preventing material separation.

[0021] The cement polymer is preferably a polymer specified in JIS A 6203:2015, "Polymer dispersions and re-emulsifiable powdered resins for cement admixture." Examples of such cement polymers include polymer dispersions and re-emulsifiable powdered resins. Examples of polymer dispersions include synthetic rubbers such as styrene-butadiene rubber (SBR); natural rubbers; rubber asphalts; ethylene vinyl acetates; acrylic esters; styrene-acrylic esters; vinyl acetate-acrylic esters; and resin asphalts. Among these, synthetic rubbers, ethylene vinyl acetates, acrylic esters, styrene-acrylic esters, and vinyl acetate-acrylic esters are preferred polymer dispersions. Specifically, synthetic rubber latex, polyacrylic esters, and ethylene vinyl acetates are more preferred. Examples of re-emulsifiable powdered resins include synthetic rubbers such as styrene butadiene rubber, acrylic esters, styrene-acrylic esters, vinyl acetate-acrylic esters, ethylene vinyl acetates, vinyl acetate / vinyl versatate esters, vinyl acetate / vinyl versatate / acrylic esters, etc. As the polymer for cement, a polymer dispersion may be used, a re-emulsifiable powdered resin may be used, or a polymer dispersion and a re-emulsifiable powdered resin may be used in combination. Among polymers for cement, styrene-butadiene rubber, acrylic ester-based polymer dispersions and / or re-emulsified powdered resins are preferred from the viewpoint of further improving adhesion to concrete. Styrene-butadiene rubber is a type of synthetic rubber obtained by copolymerizing styrene and butadiene, and its quality can be appropriately adjusted by adjusting the styrene content and vulcanization amount. For cement admixture, most have a bound styrene content of 50 to 70% by mass, and are used to improve stability and adhesiveness. One type of polymer for cement may be used alone, or two or more types may be used in combination.

[0022] The content of the cement polymer is preferably 1 to 20 parts by mass, more preferably 2 to 15 parts by mass, and even more preferably 3 to 12 parts by mass, in terms of solid content, relative to 100 parts by mass of the binder. If the content of the cement polymer is within the above range, better fluidity and trowel properties are likely to be obtained when the mortar is made into a mortar.

[0023] The polymer cement 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, naphthalene sulfonic acid-based water reducing agents, lignin sulfonic 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.

[0024] The content of the water-reducing agent 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 the binder. If the content of the water-reducing agent is within the above range, better fluidity and trowel properties are likely to be obtained when the mortar is made into a mortar.

[0025] The polymer cement mortar composition of this embodiment may contain various admixtures within the range that does not impair the effects of the present invention. Examples of admixtures include set retarders, antifoaming agents, waterproofing agents, rust inhibitors, shrinkage reducing agents, thickeners, water retention agents, pigments, water repellents, anti-efflorescence agents, and fibers.

[0026] The polymer cement mortar composition of the present embodiment can be prepared by mixing the above-described components using a commonly used mixer, and the mixer may be, for example, a Hobart mixer, a hand mixer, a tilting mixer, or a twin-shaft mixer.

[0027] The polymer cement mortar composition of the present 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 20 to 50 parts by mass, more preferably 25 to 45 parts by mass, and even more preferably 30 to 40 parts by mass, per 100 parts by mass of binder. If the water content is within the above range, it is easier to ensure fluidity and to suppress the occurrence of material separation, increased shrinkage of the hardened body, and a decrease in early strength development.

[0028] The polymer cement mortar of this embodiment can be prepared using the same kneading equipment as that used for ordinary polymer cement mortars, and is not particularly limited. For example, the kneading equipment described above can be used.

[0029] The polymer cement mortar composition and polymer cement mortar of the present embodiment are resistant to set retardation, have good fluidity, and exhibit excellent strength properties. Therefore, such polymer cement mortar compositions and polymer cement mortars prepared using the same can be used, for example, as repair and reinforcing materials for concrete structures, steel-concrete composite structures, roads, etc. The polymer cement mortar composition and polymer cement mortar of the present embodiment can be used in a variety of ways, including filling recesses with a trowel, filling and then leveling with a vibrator or the like and then finishing with a trowel, and spraying onto the repair area. [Example]

[0030] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0031] [material] A: Ordinary Portland cement B: Ground blast furnace slag (blaine specific surface area 4000 cm 2 / g) C1: Clinker aggregate (CaO content 63.3% by mass, SiO2 content 21.1% by mass, coarse grain ratio 3.2) C2: Clinker aggregate (Al2O3 content 39.5% by mass, CaO content 38% by mass, coarse particle ratio 3.2) C3: Standard sand for cement strength testing (coarse grain ratio 2.8), Cement Association of Japan C4: Crushed sand (coarse grain ratio 5.0) D: Polycarboxylic acid water reducing agent E1: SBR emulsion E2: Acrylate ester emulsion E3: Acrylic ester-based re-emulsified powder resin

[0032] [Mixture design of polymer cement mortar composition] The mix was designed so that the ratios of aggregate, water-reducing agent, and cement polymer (solid content equivalent) per 100 parts by mass of binder were as shown in Table 1.

[0033] [Preparation of polymer cement mortar] In a 20°C environment, the materials for the polymer cement mortar composition designed according to the formulation shown in Table 1 and water were added to a cylindrical container and mixed for 60 seconds with a hand mixer to produce approximately 3 L of polymer cement mortar. The water content was 35 parts by mass per 100 parts by mass of binder.

[0034] [Table 1]

[0035] [Evaluation method] Each item was evaluated by the following method. The evaluation results are shown in Table 2. For Comparative Example 2, no evaluation was performed because the setting was too rapid. Fluidity test The fluidity test was conducted in accordance with the flow test of JIS R 5201:2015 "Physical Testing Methods for Cement." The flow value was measured after 15 strokes. Compression strength The compressive strength of the hardened mortar at 28 days of age was measured in accordance with the Japan Society of Civil Engineers standard JSCE-G 505-2018, "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 specimens were wet-cured in the formwork at 20°C for 24 hours. After 24 hours, the formwork was removed, and the specimens were then underwater-cured until they reached the specified age. Bending strength The flexural strength at 28 days of age was measured in accordance with JIS A 1106:2018 "Testing Method for Flexural Strength of Concrete." The dimensions of the specimen were 100 mm wide, 100 mm high, and 400 mm long. The specimens were demolded the following day and then cured underwater for 28 days. Curing was always carried out in a thermostatic chamber at 20°C. -Torone workability Polymer cement mortar was poured onto wood (300mm length x 300mm width x 5mm height), and the mortar was leveled with a trowel to a thickness of 5mm, and the trowelability was evaluated. Those that were difficult to trowel evenly were rated as poor (×), those that took time to finish (more than 2 minutes from pouring to completing the finishing work) but could be troweled evenly were rated as good (○), and those that could be troweled without any problems were rated as excellent (◎).

[0036] [Table 2]

[0037] The polymer cement mortars of the Examples had good fluidity and trowelability, set quickly, and exhibited excellent strength properties such as compressive strength and flexural strength, whereas the polymer cement mortars of the Comparative Examples had problems such as insufficient strength, insufficient fluidity, and taking too long to set.

Claims

1. The method includes the steps of: a binder containing cement; a mixed aggregate containing clinker aggregate and fine aggregate; and a polymer for cement; The clinker aggregate contains, as chemical components, 55 to 70 mass % of CaO, SiO 2 Contains 15 to 30 mass% of The coarse particle ratio of the mixed aggregate is 1.5 to 4.3, A polymer cement mortar composition, wherein the content of the cement is 60 parts by mass or more per 100 parts by mass of the binder.

2. 2. The polymer cement mortar composition according to claim 1, wherein the content of the clinker aggregate is 10 to 95 parts by mass per 100 parts by mass of the mixed aggregate.

3. 3. The polymer cement mortar composition according to claim 1, wherein the content of the cement polymer is 1 to 20 parts by mass in terms of solid content per 100 parts by mass of the binder.

4. A method for producing a cement-based polymer composition comprising the polymer cement composition of any one of claims 1 to 3 and water, The polymer cement mortar has a water content of 20 to 50 parts by mass per 100 parts by mass of the binder.

Images