阅读说明：本技术 一种混凝土缓凝剂及其制备方法 (Concrete retarder and preparation method thereof ) 是由 张鑫 柳掌珀 任鹏飞 贾虎琛 于 2020-06-12 设计创作，主要内容包括：本发明属于建筑材料技术领域,尤其涉及一种混凝土缓凝剂及其制备方法。所述混凝土缓凝剂,由以下原料制成：3-6份改性微晶纤维素、1-3份丙烯酸、8-12份改性玻璃纤维、5-10份硼砂、6-10份聚氯乙烯树脂、2-4份无水硫酸钠、3-5份石英砂、8-12份三聚磷酸钠、1-3份羧甲基纤维素。本发明提供的混凝土缓凝剂具有良好的吸热性和散热性,能吸收混凝土生产的水化热；并使混凝土与外界环境形成良好的热交换作用,使混凝土内产成的水化热能散发出去；而且抑制混凝土中水泥的水化,具有较强的缓凝作用；同时具有良好的强度,对混凝土的强度、抗冲刷性能影响较小。(The invention belongs to the technical field of building materials, and particularly relates to a concrete retarder and a preparation method thereof. The concrete retarder is prepared from the following raw materials: 3-6 parts of modified microcrystalline cellulose, 1-3 parts of acrylic acid, 8-12 parts of modified glass fiber, 5-10 parts of borax, 6-10 parts of polyvinyl chloride resin, 2-4 parts of anhydrous sodium sulfate, 3-5 parts of quartz sand, 8-12 parts of sodium tripolyphosphate and 1-3 parts of carboxymethyl cellulose. The concrete retarder provided by the invention has good heat absorption and heat dissipation, and can absorb the hydration heat produced by concrete; the concrete and the external environment form good heat exchange effect, and the hydration heat energy generated in the concrete is dissipated; but also inhibits the hydration of cement in concrete and has stronger retardation; meanwhile, the concrete has good strength and has small influence on the strength and the anti-scouring performance of the concrete.)

1. The concrete retarder is characterized by being prepared from the following raw materials: 3-6 parts of modified microcrystalline cellulose, 1-3 parts of acrylic acid, 6-8 parts of modified glass fiber, 5-10 parts of borax, 6-10 parts of polyvinyl chloride resin, 2-4 parts of anhydrous sodium sulfate, 3-5 parts of quartz sand, 8-12 parts of sodium tripolyphosphate and 1-3 parts of carboxymethyl cellulose.

2. The concrete coagulant of claim 1, wherein the concrete retarder is made from the following raw materials: 5 parts of modified microcrystalline cellulose, 2 parts of acrylic acid, 6.5 parts of modified glass fiber, 6 parts of borax, 8 parts of polyvinyl chloride resin, 3 parts of anhydrous sodium sulfate, 4 parts of quartz sand, 10 parts of sodium tripolyphosphate and 1 part of carboxymethyl cellulose.

3. The concrete retarder of claim 1 or 2, wherein the modified microcrystalline cellulose is prepared by: adding microcrystalline cellulose into 80% ethanol solution with the mass 10 times of that of the microcrystalline cellulose, adding sodium hydroxide with the mass 10% of that of the microcrystalline cellulose, stirring and reacting at 45-50 ℃ for 6 hours, and cooling; adding carboxymethyl cellulose 20% of microcrystalline cellulose, and stirring at 30-35 deg.C for 2 hr to obtain modified coarse material; and drying the modified coarse material to obtain the modified microcrystalline cellulose.

4. The concrete coagulant according to claim 1 or 2, wherein the modified glass fiber is prepared by: mixing short glass fiber with KHH50 water solution with concentration of 40% and 5 times of the short glass fiber, adding sodium hydroxide with concentration of 5% of the short glass fiber, mixing well, stirring at 30 deg.C for 20min, and oven drying at 100 deg.C to obtain modified glass fiber.

5. The method for preparing a concrete retarder according to claim 1 or 2, comprising the steps of:

(1) adding modified microcrystalline cellulose into polysaccharide aqueous solution with the mass 8 times of that of the modified microcrystalline cellulose, adding a proper amount of potassium chloride, and reacting for 0.5h in a water bath at the temperature of 80 ℃ to obtain modified microcrystalline cellulose sol;

(2) dissolving acrylic acid in 10 times of 10% ammonia water solution, adding aluminum hydroxide 0.1% by mass of acrylic acid and potassium disulfate 0.1% by mass of acrylic acid, and reacting in 80 deg.C water bath for 0.5h to obtain acrylic acid sol;

(3) mixing the modified microcrystalline cellulose sol and the acrylic sol, and reacting for 1h in a water bath at the temperature of 80 ℃ to prepare composite hydrogel;

(4) grinding borax and quartz sand, adding hydrochloric acid solution for soaking treatment for 20-22min, washing, and drying to obtain inorganic mixture;

(5) and (3) mixing the composite hydrogel with glass fiber, polyvinyl chloride resin, sodium tripolyphosphate and carboxymethyl cellulose, stirring and mixing at 30 ℃ for 10min, adding an inorganic mixture, and uniformly stirring and mixing to obtain the retarder.

6. The concrete coagulant according to claim 5, wherein in the step (1), the aqueous polysaccharide solution is trehalose solution with a concentration of 0.6%, and the amount of potassium chloride is 0.2% of the mass of the modified microcrystalline cellulose.

7. The concrete coagulant according to claim 1, wherein in the step (4), the concentration of the hydrochloric acid solution is 15%, and the temperature of the dipping treatment is 30-40 ℃.

Technical Field

The invention belongs to the technical field of building materials, and particularly relates to a concrete retarder and a preparation method thereof.

Background

The retarder is a common additive for prolonging the setting time of concrete, and in the summer construction process, a proper amount of the retarder can be added into the coagulant to ensure that the newly stirred concrete can keep better plasticity for a long time, thereby being convenient for construction and improving the working efficiency, and especially in the mass concrete construction process, in order to ensure that the concrete can not generate temperature cracks due to over concentration of hydration heat, the addition of the retarder becomes one of important means; and aiming at high-temperature seasons, a proper amount of retarder can prevent the concrete from being too quickly collapsed to cause workability. Therefore, the retarder has very practical economic value and technical value in modern concrete technology.

Substances currently used as retarders mainly include molasses, lignosulfonate, carboxylic acid and salts thereof, inorganic salts and the like; in the practical engineering application process, most of the retarders meet the requirement of concrete setting time, but the performance indexes of concrete such as strength and the like are influenced. Therefore, the research of the novel retarder is of great significance to the application of concrete.

For example, patent publication No. CN111116081A discloses a graphene modified concrete retarder, which comprises: 10-40 parts of graphene, 5-35 parts of ethylene diamine tetraacetate, 10-30 parts of formate, 10-35 parts of calcium bromide and 10-20 parts of urea. The graphene has good heat-conducting property, when cement in the concrete is gasified to release heat, the graphene conducts the heat to each position in the concrete, the hydration degree of each position in the concrete is improved, and the cement hydration in the area is promoted. In the patent technology, the graphene achieves the coagulation effect through the heat conduction effect, but the graphene is high in cost and is not suitable for wide application.

Also, for example, patent publication No. CN110590218A discloses a concrete retarder, which comprises the following raw materials in parts by weight: 10-16 parts of sodium lignosulfonate, 6-8 parts of slag, 3-5 parts of cane sugar, 2-5 parts of disodium hydrogen phosphate, 3-6 parts of magnesium sulfate, 6-9 parts of organic acid, 16-20 parts of vinyl acrylate copolymer emulsion, 3-5 parts of aminotrimethylene phosphonic acid and 6-10 parts of glyceride. The slag is finely ground into particles with the range of 1-10 microns and then used as a raw material of a concrete additive, and can be subjected to hydration reaction with calcium hydroxide generated by cement hydration under compound excitation to form a corresponding hydration projection product, so that the release of heat in the hydration process is reduced, cracks caused by hydration heat release in large-volume concrete are obviously reduced, and the strength of the concrete is increased. And after the slag is added and other components are reasonably proportioned, the use amount of cement in concrete can be reduced, and the engineering cost is saved. According to the technical scheme, the reaction heat is reduced by the hydration reaction of the slag and calcium hydroxide in the concrete, although the reaction heat is reduced, the reduction range is small, and the anti-scouring performance of the concrete is influenced.

Disclosure of Invention

In order to solve the technical problems in the prior art, the invention provides a concrete retarder and a preparation method thereof, and particularly the concrete retarder is realized through the following technical scheme.

The concrete retarder is characterized by being prepared from the following raw materials: 3-6 parts of modified microcrystalline cellulose, 1-3 parts of acrylic acid, 6-8 parts of modified glass fiber, 5-10 parts of borax, 6-10 parts of polyvinyl chloride resin, 2-4 parts of anhydrous sodium sulfate, 3-5 parts of quartz sand, 8-12 parts of sodium tripolyphosphate and 1-3 parts of carboxymethyl cellulose.

Preferably, the concrete retarder is prepared from the following raw materials: 5 parts of modified microcrystalline cellulose, 2 parts of acrylic acid, 6.5 parts of modified glass fiber, 6 parts of borax, 8 parts of polyvinyl chloride resin, 3 parts of anhydrous sodium sulfate, 4 parts of quartz sand, 10 parts of sodium tripolyphosphate and 1 part of carboxymethyl cellulose.

Preferably, the modified microcrystalline cellulose is prepared by: adding microcrystalline cellulose into 80% ethanol solution with the mass 10 times of that of the microcrystalline cellulose, adding sodium hydroxide with the mass 10% of that of the microcrystalline cellulose, stirring and reacting at 45-50 ℃ for 6 hours, and cooling; adding carboxymethyl cellulose 20% of microcrystalline cellulose, and stirring at 30-35 deg.C for 2 hr to obtain modified coarse material; and drying the modified coarse material to obtain the modified microcrystalline cellulose.

Preferably, the modified glass fiber is prepared by: mixing short glass fiber with KHH50 water solution with concentration of 40% and 5 times of the short glass fiber, adding sodium hydroxide with concentration of 5% of the short glass fiber, mixing well, stirring at 30 deg.C for 20min, and oven drying at 100 deg.C to obtain modified glass fiber.

Preferably, the preparation method of the concrete retarder comprises the following steps:

(1) adding modified microcrystalline cellulose into polysaccharide aqueous solution with the mass 8 times of that of the modified microcrystalline cellulose, adding a proper amount of potassium chloride, and reacting for 0.5h in a water bath at the temperature of 80 ℃ to obtain modified microcrystalline cellulose sol;

(2) dissolving acrylic acid in 10 times of 10% ammonia water solution, adding aluminum hydroxide 0.1% by mass of acrylic acid and potassium disulfate 0.1% by mass of acrylic acid, and reacting in 80 deg.C water bath for 0.5h to obtain acrylic acid sol;

(3) mixing the modified microcrystalline cellulose sol and the acrylic sol, and reacting for 1h in a water bath at the temperature of 80 ℃ to prepare composite hydrogel;

(4) grinding borax and quartz sand, adding hydrochloric acid solution for immersion treatment for 20-22min, washing, drying, cooling, and mixing with anhydrous sodium sulfate to obtain inorganic mixture;

(5) and (3) mixing the composite hydrogel with glass fiber, polyvinyl chloride resin, sodium tripolyphosphate and carboxymethyl cellulose, stirring and mixing at 30 ℃ for 10min, adding an inorganic mixture, and uniformly stirring and mixing to obtain the retarder.

Preferably, in the step (1), the polysaccharide aqueous solution is trehalose solution with the concentration of 0.6%, and the amount of potassium chloride is 0.2% of the mass of the modified microcrystalline cellulose.

Preferably, in the step (4), the concentration of the hydrochloric acid solution is 15%, and the temperature of the dipping treatment is 30-40 ℃.

The invention has the beneficial effects that:

the dispersion characteristic of the microcrystalline cellulose can be improved by treating the microcrystalline cellulose and the short glass fiber, so that the microcrystalline cellulose can be fully dispersed in the organic material in the retarder. The composite hydrogel prepared from the modified microcrystalline cellulose and the acrylic acid has good heat absorption and heat dissipation performance, and can absorb the hydration heat produced by concrete; and the concrete and the external environment form good heat exchange effect, so that the hydration heat energy generated in the concrete is dissipated. After the borax, the polyvinyl chloride resin, the anhydrous sodium sulfate, the quartz sand and the composite hydrogel are compounded for use, the composite hydrogel has a synergistic effect, has better heat absorption and heat dissipation performance, and can enhance the strength of the retarder through the quartz sand and the borax.The hydrochloric acid is adopted to treat the quartz sand and the borax, so that the wettability of the quartz sand and the borax can be effectively improved, and the quartz sand and the borax can have good compatibility and processing dispersibility with organic materials in the retarder. Sodium tripolyphosphate can form complex salt with calcium ion in concrete to reduce Ca in solution²⁺Concentration of ions hindering Ca (OH)₂The complex is adsorbed on the surface of cement particles, and hydration of cement is inhibited. The carboxymethyl cellulose can further improve the compatibility and the dispersibility among the raw materials of the retarder.

The concrete retarder provided by the invention has good heat absorption and heat dissipation, and can absorb the hydration heat produced by concrete; the concrete and the external environment form good heat exchange effect, and the hydration heat energy generated in the concrete is dissipated; but also inhibits the hydration of cement in concrete and has stronger retardation; meanwhile, the concrete has good strength and has small influence on the strength and the anti-scouring performance of the concrete.

Detailed Description

The technical solution of the present invention is further limited by the following specific embodiments, but the scope of the claims is not limited to the description.