Composite water reducing agent for machine-made sand concrete and preparation method of composite water reducing agent

Abstract

The invention relates to the field of concrete admixtures, in particular to a composite water reducing agent for machine-made sand concrete and a preparation method of the composite water reducing agent, and aims to solve the problems that an existing water reducing agent is not ideal enough in water reducing effect and poor in adaptability to cement, the quality and construction efficiency of concrete are affected, and application of machine-made sand in higher-performance concrete is limited. According to the composite water reducing agent for the machine-made sand concrete, the water consumption of the machine-made sand concrete can be remarkably reduced through an optimized chemical component ratio and a preparation process, an excellent water reducing effect is achieved, the flowability and working performance of the machine-made sand concrete can be remarkably improved, the hydration effect of the machine-made sand concrete can be improved, and the service life of the machine-made sand concrete is prolonged. The uniform distribution of the internal structure of the machine-made sand concrete is promoted, so that the water-retaining property, the flowability and the pumpability of the machine-made sand concrete are improved, the water-binder ratio is reduced, the early-stage and later-stage strength of the machine-made sand concrete is enhanced, and the durability of the machine-made sand concrete is remarkably improved.

Description

Technical Field

[0001] The invention relates to the field of concrete admixtures, and in particular to a composite water reducing agent for machine-made sand concrete and a preparation method thereof. Background Art

[0002] With the continuous development of the construction industry, machine-made sand has gradually become one of the important sources of concrete aggregate. Machine-made sand is mainly made by crushing rocks. Compared with natural river sand, its particle shape, gradation and surface properties are significantly different. These differences lead to poor fluidity of machine-made sand concrete, which faces many challenges in the processes of mixing, pumping, and hardening. Therefore, it is necessary to use efficient water reducers to improve its working performance. Although the water reducers on the market can improve the fluidity of machine-made sand concrete to a certain extent, there are still some shortcomings, such as unsatisfactory water reduction effect and poor compatibility with cement, which affect the quality and construction efficiency of concrete, and limit the application of machine-made sand in higher performance concrete. Therefore, it is of great significance to develop a composite water reducer for machine-made sand concrete and a preparation method thereof. Summary of the invention

[0003] In order to overcome the above-mentioned technical problems, the object of the present invention is to provide a composite water reducer for machine-made sand concrete and a preparation method thereof, wherein a siloxane-modified water-reducing polymer, triethanolamine, sodium sulfate, sodium hexametaphosphate, potassium hydroxide, tartaric acid, sodium dodecylbenzene sulfonate and aluminum stearate are added to a high-speed mixer and mixed evenly to obtain a composite water reducer for machine-made sand concrete, thereby solving the problem that the existing water reducer has an unsatisfactory water-reducing effect and poor adaptability to cement, which affects the quality and construction efficiency of concrete, thereby limiting the application of machine-made sand in higher performance concrete.

[0004] The purpose of the present invention can be achieved through the following technical solutions:

[0005] A composite water reducing agent for machine-made sand concrete, comprising the following components in parts by weight:

[0006] 60-70 parts of siloxane-modified water-reducing polymer, 5-13 parts of triethanolamine, 0.5-1.1 parts of sodium sulfate, 0.3-0.5 parts of sodium hexametaphosphate, 1-3 parts of potassium hydroxide, 0.4-0.8 parts of tartaric acid, 0.5-0.9 parts of sodium dodecylbenzene sulfonate and 0.2-0.6 parts of aluminum stearate;

[0007] Wherein, the siloxane-modified water-reducing polymer is prepared by the following steps:

[0008] Step a1: Add vinylbenzyl chloride, hexadecyldimethyl tertiary amine and petroleum ether into a three-necked flask equipped with a stirrer, a thermometer and an inlet tube, introduce nitrogen protection, stir and react for 10-15 minutes at a temperature of 25-30° C. and a stirring rate of 300-400 r / min, then heat to 60-65° C. and continue stirring and reacting for 3-5 hours. After the reaction is completed, the reaction product is cooled to room temperature, and then the solvent is removed by rotary evaporation to obtain a cationic monomer;

[0009] Step a2: adding methyl allyl polyoxyethylene ether, acrylic acid, sodium p-styrene sulfonate, cationic monomer and deionized water into a three-necked flask equipped with a stirrer, a thermometer, an air guide tube and a constant pressure dropping funnel, introducing nitrogen protection, stirring and reacting for 20-30 minutes at a temperature of 25-30° C. and a stirring rate of 300-400 r / min, then adding ammonium persulfate solution dropwise while stirring, controlling the dropping rate to 1-2 drops / s, and continuing to stir and react for 1-2 hours under the condition of heating to 65-70° C. after the dropwise addition is completed, cooling the reaction product to room temperature, then adjusting the pH to 7-8 with sodium hydroxide solution, and then removing the solvent by rotary evaporation to obtain a water-reducing polymer;

[0010] Step a3: adding a water-reducing polymer and dichloromethane to a three-necked flask equipped with a stirrer and a thermometer, stirring the mixture for 20-30 min at a temperature of 25-30° C. and a stirring rate of 300-400 r / min, then adding chloromethyl octyl ether and tin tetrachloride and continuing to stir the mixture for 20-30 min, then heating the mixture to 50-55° C. and continuing to stir the mixture for 2-3 h, after the reaction is completed, cooling the reaction product to room temperature, then adding the product to anhydrous ethanol and allowing the mixture to stand for precipitation, then vacuum filtering the product, placing the filter cake in a vacuum drying oven, and drying the filter cake at 50-55° C. for 5-7 h to obtain a chloromethyl-modified water-reducing polymer;

[0011] Step a4: Add the chloromethyl modified water-reducing polymer, 3-aminopropyltriethoxysilane, anhydrous potassium carbonate, potassium iodide and N, N-dimethylacetamide to a three-necked flask equipped with a stirrer, a thermometer and an inlet tube, introduce nitrogen protection, stir the reaction for 10-15 minutes at a temperature of 25-30°C and a stirring rate of 300-400r / min, then heat the temperature to 80-85°C and continue stirring the reaction for 5-7 hours. After the reaction is completed, the reaction product is cooled to room temperature, then vacuum filtered, and the filtrate is rotary evaporated to remove the solvent, then washed with anhydrous ethanol 3-5 times, and then placed in a vacuum drying oven and dried at a temperature of 50-55°C for 6-8 hours to obtain a siloxane-modified water-reducing polymer.

[0012] As a further solution of the present invention: the usage ratio of the vinylbenzyl chloride, hexadecyldimethyl tertiary amine and petroleum ether in step a1 is 10 mmol: 10 mmol: 40-50 mL.

[0013] As a further solution of the present invention: the usage ratio of the methyl allyl polyoxyethylene ether, acrylic acid, sodium p-styrene sulfonate, cationic monomer, deionized water and ammonium persulfate solution in step a2 is 15-20g: 3-5g: 1.3-3.9g: 0.8-1.6g: 30-35mL: 10-12mL.

[0014] As a further solution of the present invention: the methyl allyl polyoxyethylene ether in step a2 is HPEG-2400.

[0015] As a further solution of the present invention: the mass fraction of the ammonium persulfate solution in step a2 is 3-5%.

[0016] As a further solution of the present invention: the mass fraction of the sodium hydroxide solution in step a2 is 30-35%.

[0017] As a further solution of the present invention: the usage ratio of the water-reducing polymer, dichloromethane, chloromethyl octyl ether and tin tetrachloride in step a3 is 10g:80-100mL:18-24g:1-2mL.

[0018] As a further solution of the present invention: the usage ratio of the chloromethyl modified water-reducing polymer, 3-aminopropyltriethoxysilane, anhydrous potassium carbonate, potassium iodide and N,N-dimethylacetamide in step a4 is 10g:2.5-7.5g:1.5-3.5g:0.3-0.7g:100-120mL.

[0019] As a further solution of the present invention: a method for preparing a composite water reducing agent for machine-made sand concrete comprises the following steps:

[0020] Step 1: Weigh 60-70 parts of siloxane-modified water-reducing polymer, 5-13 parts of triethanolamine, 0.5-1.1 parts of sodium sulfate, 0.3-0.5 parts of sodium hexametaphosphate, 1-3 parts of potassium hydroxide, 0.4-0.8 parts of tartaric acid, 0.5-0.9 parts of sodium dodecylbenzene sulfonate and 0.2-0.6 parts of aluminum stearate according to weight parts, and set aside;

[0021] Step 2: Add siloxane-modified water-reducing polymer, triethanolamine, sodium sulfate, sodium hexametaphosphate, potassium hydroxide, tartaric acid, sodium dodecylbenzene sulfonate and aluminum stearate into a high-speed mixer and mix evenly to obtain a composite water-reducing agent for machine-made sand concrete.

[0022] Beneficial effects of the present invention:

[0023] A composite water reducer for machine-made sand concrete of the present invention and a preparation method thereof, by adding siloxane-modified water-reducing polymer, triethanolamine, sodium sulfate, sodium hexametaphosphate, potassium hydroxide, tartaric acid, sodium dodecylbenzene sulfonate and aluminum stearate into a high-speed mixer and mixing evenly, a composite water reducer for machine-made sand concrete is obtained; the composite water reducer for machine-made sand concrete can significantly reduce the water consumption of machine-made sand concrete through optimized chemical composition ratio and preparation process, has excellent water reduction effect, can significantly improve the fluidity and working performance of machine-made sand concrete, can improve the hydration effect of machine-made sand concrete, promote the uniform distribution of the internal structure of machine-made sand concrete, thereby improving the water retention, fluidity and pumpability of machine-made sand concrete, reducing the water-cement ratio, enhancing the early and late strength of machine-made sand concrete, and significantly improving its durability. The preparation method of the composite water reducer is simple and efficient, can greatly improve efficiency and reduce costs, adapts to a variety of machine-made sand concrete construction scenes, is widely used in buildings, bridges, tunnels and other fields, significantly enhances the safety and economy of engineering structures, and realizes a comprehensive upgrade of the performance of machine-made sand concrete.

[0024] In the process of preparing a composite water-reducing agent for machine-made sand concrete, a siloxane-modified water-reducing polymer is first prepared. First, vinylbenzyl chloride and hexadecyl dimethyl tertiary amine are reacted, and the chlorine atom on the vinylbenzyl chloride reacts with the tertiary amine group on the hexadecyl dimethyl tertiary amine to form a quaternary ammonium group to obtain a cationic monomer. Then, methyl allyl polyoxyethylene ether, acrylic acid, sodium p-styrene sulfonate, and a cationic monomer are used as polymerization monomers to obtain a water-reducing polymer. Then, chloromethyl octyl ether is used to modify the water-reducing polymer. A chloromethyl group is introduced into the benzene ring of the molecular chain of the water-reducing polymer to obtain a chloromethyl-modified water-reducing polymer. Then, the chloromethyl-modified water-reducing polymer and 3-aminopropyltriethoxysilane react. The chlorine atoms on the chloromethyl-modified water-reducing polymer react with the amino groups on the 3-aminopropyltriethoxysilane to introduce a large number of siloxane groups to obtain a siloxane-modified water-reducing polymer. The siloxane-modified water-reducing polymer uses carboxyl and sulfonic acid groups as anionic functional groups. After being adsorbed on the surface of cement particles, the cement particles are charged with the same sign, and the same charges are generated. Electrostatic repulsion, under the action of this repulsive force, can reduce the flocculation and friction resistance between cement particles, so that the flocculation structure disintegrates, releases free water between the flocculation structure, achieves water reduction effect, and allows cement particles to be fully dispersed, and introduces quaternary ammonium groups as cationic groups in the molecular chain, so that it can also be adsorbed on the surface of negatively charged cement minerals, with stronger adsorption, further improving its dispersion performance, and introducing siloxanes into the molecular structure. The silanols generated by hydrolysis can undergo dehydration condensation with the hydroxyls on the surface of other substances, and can often bond two substances of different properties together, thereby improving the material properties, further improving its adsorption performance in cement, and reducing the retarding effect; therefore, under the synergistic effect of anionic groups, cationic groups and siloxane groups, the siloxane-modified water-reducing polymer can significantly improve the working performance and physical and chemical properties of concrete, achieve lower water consumption and water retention, and at the same time promote cement hydration reaction, enhance the interaction between it and cement, accelerate the early strength growth of machine-made sand concrete, and enhance its later strength and durability. DETAILED DESCRIPTION

[0025] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] Embodiment 1:

[0027] This embodiment is a method for preparing a composite water reducing agent for machine-made sand concrete, comprising the following steps:

[0028] Step S1: 10 mmol vinylbenzyl chloride, 10 mmol hexadecyldimethyl tertiary amine and 40 mL petroleum ether are added to a three-necked flask equipped with a stirrer, a thermometer and an inlet tube, and nitrogen is introduced for protection. The mixture is stirred for reaction at a temperature of 25° C. and a stirring rate of 300 r / min for 10 min, and then the temperature is raised to 60° C. and the stirring reaction is continued for 3 h. After the reaction is completed, the reaction product is cooled to room temperature, and then the solvent is removed by rotary evaporation to obtain a cationic monomer;

[0029] Step S2: 15g of methyl allyl polyoxyethylene ether HPEG-2400, 3g of acrylic acid, 1.3g of sodium p-styrene sulfonate, 0.8g of cationic monomer and 30mL of deionized water are added to a three-necked flask equipped with a stirrer, a thermometer, an air guide tube and a constant pressure dropping funnel, and nitrogen is introduced for protection. The mixture is stirred and reacted for 20min at a temperature of 25°C and a stirring rate of 300r / min. Then, 10mL of a 3% ammonium persulfate solution is added dropwise while stirring, and the dropping rate is controlled to be 1 drop / s. After the dropwise addition is completed, the mixture is heated to 65°C and the stirring reaction is continued for 1h. After the reaction is completed, the reaction product is cooled to room temperature, and then the pH is adjusted to 7 with a 30% sodium hydroxide solution, and then the solvent is removed by rotary evaporation to obtain a water-reducing polymer;

[0030] Step S3: 10 g of a water-reducing polymer and 80 mL of dichloromethane were added to a three-necked flask equipped with a stirrer and a thermometer, and the mixture was stirred at 25° C. and 300 r / min for 20 min, and then 18 g of chloromethyl octyl ether and 1 mL of tin tetrachloride were added for 20 min, and then the mixture was heated to 50° C. and stirred for 2 h. After the reaction, the reaction product was cooled to room temperature, and then added to anhydrous ethanol and allowed to stand for precipitation, and then vacuum filtered. The filter cake was placed in a vacuum drying oven and dried at 50° C. for 5 h to obtain a chloromethyl-modified water-reducing polymer.

[0031] Step S4: 10 g of chloromethyl modified water-reducing polymer, 2.5 g of 3-aminopropyltriethoxysilane, 1.5 g of anhydrous potassium carbonate, 0.3 g of potassium iodide and 100 mL of N, N-dimethylacetamide were added to a three-necked flask equipped with a stirrer, a thermometer and an introduction tube, and nitrogen was introduced for protection. The mixture was stirred for reaction at a temperature of 25° C. and a stirring rate of 300 r / min for 10 min, and then the mixture was heated to 80° C. and continued to stir for 5 h. After the reaction was completed, the reaction product was cooled to room temperature, and then vacuum filtered. The filtrate was rotary evaporated to remove the solvent, and then washed with anhydrous ethanol for 3 times, and then placed in a vacuum drying oven and dried at a temperature of 50° C. for 6 h to obtain a siloxane modified water-reducing polymer;

[0032] Step S5: weigh 60 parts of siloxane-modified water-reducing polymer, 5 parts of triethanolamine, 0.5 parts of sodium sulfate, 0.3 parts of sodium hexametaphosphate, 1 part of potassium hydroxide, 0.4 parts of tartaric acid, 0.5 parts of sodium dodecylbenzene sulfonate and 0.2 parts of aluminum stearate according to weight parts, and set aside;

[0033] Step S6: adding the siloxane-modified water-reducing polymer, triethanolamine, sodium sulfate, sodium hexametaphosphate, potassium hydroxide, tartaric acid, sodium dodecylbenzene sulfonate and aluminum stearate into a high-speed mixer and mixing them evenly to obtain a composite water-reducing agent for machine-made sand concrete.

[0034] Embodiment 2:

[0035] This embodiment is a method for preparing a composite water reducing agent for machine-made sand concrete, comprising the following steps:

[0036] Step S1: 10 mmol vinylbenzyl chloride, 10 mmol hexadecyldimethyl tertiary amine and 45 mL petroleum ether are added to a three-necked flask equipped with a stirrer, a thermometer and an introduction tube, and nitrogen is introduced for protection. The mixture is stirred for reaction at a temperature of 28° C. and a stirring rate of 350 r / min for 12 min, and then the temperature is raised to 62° C. and the stirring reaction is continued for 4 h. After the reaction is completed, the reaction product is cooled to room temperature, and then the solvent is removed by rotary evaporation to obtain a cationic monomer;

[0037] Step S2: 18 g of methyl allyl polyoxyethylene ether HPEG-2400, 4 g of acrylic acid, 2.6 g of sodium p-styrene sulfonate, 1.2 g of cationic monomer and 32 mL of deionized water are added to a three-necked flask equipped with a stirrer, a thermometer, an air guide tube and a constant pressure dropping funnel, and nitrogen is introduced for protection. The mixture is stirred for reaction for 25 min at a temperature of 28° C. and a stirring rate of 350 r / min. Then, 11 mL of a 4% ammonium persulfate solution is added dropwise while stirring, and the dropping rate is controlled to be 1 drop / s. After the addition is completed, the mixture is heated to 68° C. and the stirring reaction is continued for 1.5 h. After the reaction is completed, the reaction product is cooled to room temperature, and then the pH is adjusted to 7.5 with a 32% sodium hydroxide solution, and then the solvent is removed by rotary evaporation to obtain a water-reducing polymer;

[0038] Step S3: 10 g of a water-reducing polymer and 90 mL of dichloromethane were added to a three-necked flask equipped with a stirrer and a thermometer, and the mixture was stirred for reaction at a temperature of 28° C. and a stirring rate of 350 r / min for 25 min, and then 21 g of chloromethyl octyl ether and 1.5 mL of tin tetrachloride were added and the stirring reaction was continued for 25 min, and then the mixture was heated to 52° C. and the stirring reaction was continued for 2.5 h. After the reaction was completed, the reaction product was cooled to room temperature, and then added to anhydrous ethanol and allowed to stand for precipitation, and then vacuum filtered, and the filter cake was placed in a vacuum drying oven and dried at a temperature of 52° C. for 6 h to obtain a chloromethyl-modified water-reducing polymer;

[0039] Step S4: 10 g of chloromethyl modified water-reducing polymer, 5 g of 3-aminopropyltriethoxysilane, 2.5 g of anhydrous potassium carbonate, 0.5 g of potassium iodide and 110 mL of N, N-dimethylacetamide were added to a three-necked flask equipped with a stirrer, a thermometer and an introduction tube, and nitrogen was introduced for protection. The mixture was stirred for reaction at a temperature of 28° C. and a stirring rate of 350 r / min for 12 min, and then the mixture was heated to 82° C. and stirred for reaction for 6 h. After the reaction was completed, the reaction product was cooled to room temperature, and then vacuum filtered. The filtrate was rotary evaporated to remove the solvent, and then washed with anhydrous ethanol for 4 times. Then, the mixture was placed in a vacuum drying oven and dried at a temperature of 52° C. for 7 h to obtain a siloxane modified water-reducing polymer;

[0040] Step S5: weigh 65 parts of siloxane-modified water-reducing polymer, 9 parts of triethanolamine, 0.8 parts of sodium sulfate, 0.4 parts of sodium hexametaphosphate, 2 parts of potassium hydroxide, 0.6 parts of tartaric acid, 0.7 parts of sodium dodecylbenzene sulfonate and 0.4 parts of aluminum stearate according to weight parts, and set aside;

[0041] Step S6: adding the siloxane-modified water-reducing polymer, triethanolamine, sodium sulfate, sodium hexametaphosphate, potassium hydroxide, tartaric acid, sodium dodecylbenzene sulfonate and aluminum stearate into a high-speed mixer and mixing them evenly to obtain a composite water-reducing agent for machine-made sand concrete.

[0042] Embodiment 3:

[0043] This embodiment is a method for preparing a composite water reducing agent for machine-made sand concrete, comprising the following steps:

[0044] Step S1: 10 mmol vinylbenzyl chloride, 10 mmol hexadecyldimethyl tertiary amine and 50 mL petroleum ether are added to a three-necked flask equipped with a stirrer, a thermometer and an inlet tube, and nitrogen is introduced for protection. The mixture is stirred at a temperature of 30° C. and a stirring rate of 400 r / min for 15 min, and then the mixture is heated to 65° C. and stirred for 5 h. After the reaction is completed, the reaction product is cooled to room temperature, and then the solvent is removed by rotary evaporation to obtain a cationic monomer;

[0045] Step S2: 20 g of methyl allyl polyoxyethylene ether HPEG-2400, 5 g of acrylic acid, 3.9 g of sodium p-styrene sulfonate, 1.6 g of cationic monomer and 35 mL of deionized water are added to a three-necked flask equipped with a stirrer, a thermometer, an air guide tube and a constant pressure dropping funnel, and nitrogen is introduced for protection. The mixture is stirred and reacted for 30 min at a temperature of 30° C. and a stirring rate of 400 r / min. Then, 12 mL of a 5% ammonium persulfate solution is added dropwise while stirring, and the dropping rate is controlled to be 2 drops / s. After the dropwise addition is completed, the mixture is heated to 70° C. and the stirring reaction is continued for 2 h. After the reaction is completed, the reaction product is cooled to room temperature, and then adjusted to pH 8 with a 35% sodium hydroxide solution, and then the solvent is removed by rotary evaporation to obtain a water-reducing polymer;

[0046] Step S3: 10 g of a water-reducing polymer and 100 mL of dichloromethane were added to a three-necked flask equipped with a stirrer and a thermometer, and the mixture was stirred for reaction at a temperature of 30° C. and a stirring rate of 400 r / min for 30 min, and then 24 g of chloromethyl octyl ether and 2 mL of tin tetrachloride were added and the mixture was stirred for reaction for 30 min, and then the mixture was heated to 55° C. and stirred for reaction for 3 h. After the reaction was completed, the reaction product was cooled to room temperature, and then added to anhydrous ethanol and allowed to stand for precipitation, and then vacuum filtered, and the filter cake was placed in a vacuum drying oven and dried at a temperature of 55° C. for 7 h to obtain a chloromethyl-modified water-reducing polymer;

[0047] Step S4: 10 g of chloromethyl modified water-reducing polymer, 7.5 g of 3-aminopropyltriethoxysilane, 3.5 g of anhydrous potassium carbonate, 0.7 g of potassium iodide and 120 mL of N, N-dimethylacetamide were added to a three-necked flask equipped with a stirrer, a thermometer and an introduction tube, and nitrogen was introduced for protection. The mixture was stirred for reaction at a temperature of 30° C. and a stirring rate of 400 r / min for 15 min, and then the mixture was heated to 85° C. and continued to stir for reaction for 7 h. After the reaction was completed, the reaction product was cooled to room temperature, and then vacuum filtered. The filtrate was rotary evaporated to remove the solvent, and then washed with anhydrous ethanol for 5 times, and then placed in a vacuum drying oven and dried at a temperature of 55° C. for 8 h to obtain a siloxane modified water-reducing polymer;

[0048] Step S5: weigh 70 parts of siloxane-modified water-reducing polymer, 13 parts of triethanolamine, 1.1 parts of sodium sulfate, 0.5 parts of sodium hexametaphosphate, 3 parts of potassium hydroxide, 0.8 parts of tartaric acid, 0.9 parts of sodium dodecylbenzene sulfonate and 0.6 parts of aluminum stearate according to weight parts, and set aside;

[0049] Step S6: adding the siloxane-modified water-reducing polymer, triethanolamine, sodium sulfate, sodium hexametaphosphate, potassium hydroxide, tartaric acid, sodium dodecylbenzene sulfonate and aluminum stearate into a high-speed mixer and mixing them evenly to obtain a composite water-reducing agent for machine-made sand concrete.

[0050] Comparative Example 1:

[0051] This comparative example is a method for preparing a composite water reducing agent for machine-made sand concrete, comprising the following steps:

[0052] Step S1: weigh 13 parts of triethanolamine, 1.1 parts of sodium sulfate, 0.5 parts of sodium hexametaphosphate, 3 parts of potassium hydroxide, 0.8 parts of tartaric acid, 0.9 parts of sodium dodecylbenzene sulfonate and 0.6 parts of aluminum stearate according to weight parts, and set aside;

[0053] Step S2: adding triethanolamine, sodium sulfate, sodium hexametaphosphate, potassium hydroxide, tartaric acid, sodium dodecylbenzene sulfonate and aluminum stearate into a high-speed mixer and mixing them evenly to obtain a composite water reducing agent for machine-made sand concrete.

[0054] Comparative Example 2:

[0055] This comparative example is a method for preparing a composite water reducing agent for machine-made sand concrete, comprising the following steps:

[0056] Step S1: weigh 70 parts of sodium p-styrene sulfonate, 13 parts of triethanolamine, 1.1 parts of sodium sulfate, 0.5 parts of sodium hexametaphosphate, 3 parts of potassium hydroxide, 0.8 parts of tartaric acid, 0.9 parts of sodium dodecylbenzene sulfonate and 0.6 parts of aluminum stearate according to weight parts, and set aside;

[0057] Step S2: adding sodium p-styrene sulfonate, triethanolamine, sodium sulfate, sodium hexametaphosphate, potassium hydroxide, tartaric acid, sodium dodecylbenzene sulfonate and aluminum stearate into a high-speed mixer and mixing evenly to obtain a composite water reducing agent for machine-made sand concrete.

[0058] Comparative Example 3:

[0059] This comparative example is HD-SS3 polycarboxylic acid high performance water reducing agent.

[0060] Comparative Example 4:

[0061] This comparative example is SK-5 early strength water reducing agent.

[0062] Performance Testing:

[0063] Weigh 215 parts of PO 42.5 ordinary Portland cement, 172 parts of water, 552 parts of machine-made sand, 237 parts of river sand, 1046 parts of crushed stone, 61 parts of fly ash, 68 parts of slag powder and the water reducer from Examples 1-3 or Comparative Examples 1-4 according to weight;

[0064] Ordinary Portland cement, water, machine-made sand, river sand, crushed stone, fly ash, slag powder and water reducing agent were mixed evenly to form cement mortar. The water reduction rate and 28d compressive strength of the cement mortar were measured when the slump was 180±5mm. The test results are shown in the following table:

[0065]

[0066] Referring to the data in the above table, according to the comparison between Examples 1-3 and Comparative Examples 1-4, it can be known that the water reducer of the present invention can significantly reduce the water consumption of machine-made sand concrete and improve the compressive strength of machine-made sand concrete.

[0067] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0068] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A composite water reducing agent for machine-made sand concrete, characterized in that: It includes the following components by weight: 60-70 parts of siloxane-modified water-reducing polymer, 5-13 parts of triethanolamine, 0.5-1.1 parts of sodium sulfate, 0.3-0.5 parts of sodium hexametaphosphate, 1-3 parts of potassium hydroxide, 0.4-0.8 parts of tartaric acid, 0.5-0.9 parts of sodium dodecylbenzene sulfonate and 0.2-0.6 parts of aluminum stearate; Wherein, the siloxane-modified water-reducing polymer is prepared by the following steps: Step a1: Add vinylbenzyl chloride, hexadecyldimethyl tertiary amine and petroleum ether into a three-necked flask equipped with a stirrer, a thermometer and an inlet tube, introduce nitrogen protection, stir and react for 10-15 minutes at a temperature of 25-30° C. and a stirring rate of 300-400 r / min, then heat to 60-65° C. and continue stirring and reacting for 3-5 hours. After the reaction is completed, the reaction product is cooled to room temperature, and then the solvent is removed by rotary evaporation to obtain a cationic monomer; Step a2: adding methyl allyl polyoxyethylene ether, acrylic acid, sodium p-styrene sulfonate, cationic monomer and deionized water into a three-necked flask equipped with a stirrer, a thermometer, an air guide tube and a constant pressure dropping funnel, introducing nitrogen protection, stirring and reacting for 20-30 minutes at a temperature of 25-30° C. and a stirring rate of 300-400 r / min, then adding ammonium persulfate solution dropwise while stirring, controlling the dropping rate to 1-2 drops / s, and continuing to stir and react for 1-2 hours under the condition of heating to 65-70° C. after the dropwise addition is completed, cooling the reaction product to room temperature, then adjusting the pH to 7-8 with sodium hydroxide solution, and then removing the solvent by rotary evaporation to obtain a water-reducing polymer; Step a3: adding a water-reducing polymer and dichloromethane to a three-necked flask equipped with a stirrer and a thermometer, stirring the mixture for 20-30 min at a temperature of 25-30° C. and a stirring rate of 300-400 r / min, then adding chloromethyl octyl ether and tin tetrachloride and continuing to stir the mixture for 20-30 min, then heating the mixture to 50-55° C. and continuing to stir the mixture for 2-3 h, after the reaction is completed, cooling the reaction product to room temperature, then adding the product to anhydrous ethanol and allowing the mixture to stand for precipitation, then vacuum filtering the product, placing the filter cake in a vacuum drying oven, and drying the filter cake at 50-55° C. for 5-7 h to obtain a chloromethyl-modified water-reducing polymer; Step a4: Add the chloromethyl modified water-reducing polymer, 3-aminopropyltriethoxysilane, anhydrous potassium carbonate, potassium iodide and N, N-dimethylacetamide to a three-necked flask equipped with a stirrer, a thermometer and an inlet tube, introduce nitrogen protection, stir the reaction for 10-15 minutes at a temperature of 25-30°C and a stirring rate of 300-400r / min, then heat the temperature to 80-85°C and continue stirring the reaction for 5-7 hours. After the reaction is completed, the reaction product is cooled to room temperature, then vacuum filtered, and the filtrate is rotary evaporated to remove the solvent, then washed with anhydrous ethanol 3-5 times, and then placed in a vacuum drying oven and dried at a temperature of 50-55°C for 6-8 hours to obtain a siloxane-modified water-reducing polymer.

2. The composite water reducing agent for machine-made sand concrete according to claim 1, characterized in that: The usage ratio of the vinylbenzyl chloride, hexadecyldimethyl tertiary amine and petroleum ether in step a1 is 10mmol:10mmol:40-50mL.

3. The composite water reducing agent for machine-made sand concrete according to claim 1, characterized in that: The usage ratio of the methyl allyl polyoxyethylene ether, acrylic acid, sodium p-styrene sulfonate, cationic monomer, deionized water and ammonium persulfate solution in step a2 is 15-20g: 3-5g: 1.3-3.9g: 0.8-1.6g: 30-35mL: 10-12mL.

4. The composite water reducing agent for machine-made sand concrete according to claim 1, characterized in that: The methyl allyl polyoxyethylene ether in step a2 is HPEG-2400.

5. The composite water reducing agent for machine-made sand concrete according to claim 1, characterized in that: The mass fraction of the ammonium persulfate solution in step a2 is 3-5%.

6. The composite water reducing agent for machine-made sand concrete according to claim 1, characterized in that: The mass fraction of the sodium hydroxide solution in step a2 is 30-35%.

7. The composite water reducing agent for machine-made sand concrete according to claim 1, characterized in that: The usage ratio of the water-reducing polymer, dichloromethane, chloromethyl octyl ether and tin tetrachloride in step a3 is 10g:80-100mL:18-24g:1-2mL.

8. The composite water reducing agent for machine-made sand concrete according to claim 1, characterized in that: The usage ratio of the chloromethyl modified water-reducing polymer, 3-aminopropyltriethoxysilane, anhydrous potassium carbonate, potassium iodide and N,N-dimethylacetamide in step a4 is 10g: 2.5-7.5g: 1.5-3.5g: 0.3-0.7g: 100-120mL.

9. A method for preparing a composite water reducing agent for machine-made sand concrete, characterized in that: The following steps are involved: Step 1: Weigh 60-70 parts of siloxane-modified water-reducing polymer, 5-13 parts of triethanolamine, 0.5-1.1 parts of sodium sulfate, 0.3-0.5 parts of sodium hexametaphosphate, 1-3 parts of potassium hydroxide, 0.4-0.8 parts of tartaric acid, 0.5-0.9 parts of sodium dodecylbenzene sulfonate and 0.2-0.6 parts of aluminum stearate according to weight parts, and set aside; Step 2: Add siloxane-modified water-reducing polymer, triethanolamine, sodium sulfate, sodium hexametaphosphate, potassium hydroxide, tartaric acid, sodium dodecylbenzene sulfonate and aluminum stearate into a high-speed mixer and mix evenly to obtain a composite water-reducing agent for machine-made sand concrete.

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