阅读说明：本技术 一种抗泥增粘缓释型聚羧酸减水剂及其制备和应用 (Anti-mud thickening slow-release polycarboxylate superplasticizer and preparation and application thereof ) 是由 胡志豪 汪源 汪苏平 文轩 于 2021-07-26 设计创作，主要内容包括：本发明提供一种抗泥增粘缓释型聚羧酸减水剂及其制备和应用,聚羧酸减水剂由三羟甲基丙烷与丙烯酸类化合物进行酯化反应合成的抗泥功能单体①,1,2,6-己三醇与衣康酸类化合物进行酯化反应合成的抗泥功能单体②,与异戊烯醇聚氧乙烯醚单体、丙烯酸、丙烯酸羟乙酯、丙烯酸羟丙酯在双氧水和维生素C氧化还原体系和链转移的作用下进行自由基聚合反应而制得。本发明制备的聚羧酸减水剂在抗泥功能单体的作用下形成空间网状立体结构,减少黏土吸附,提高减水剂的抗泥增粘效果,并在丙烯酸羟乙酯、丙烯酸羟丙酯两种缓释单体的作用下,缓慢释放出具有减水功能的减水剂。(The invention provides a mud-resistant tackifying slow-release polycarboxylate superplasticizer and preparation and application thereof, wherein the polycarboxylate superplasticizer is prepared by carrying out free radical polymerization reaction on a mud-resistant functional monomer synthesized by esterification reaction of trimethylolpropane and an acrylic compound, a mud-resistant functional monomer synthesized by esterification reaction of 1,2, 6-hexanetriol and an itaconic compound, an isopentenol polyoxyethylene ether monomer, acrylic acid, hydroxyethyl acrylate and hydroxypropyl acrylate under the action of a hydrogen peroxide and vitamin C redox system and chain transfer. The polycarboxylate water reducer prepared by the invention forms a spatial net-shaped three-dimensional structure under the action of the anti-mud functional monomer, reduces clay adsorption, improves the anti-mud tackifying effect of the water reducer, and slowly releases the water reducer with a water reducing function under the action of two slow-release monomers of hydroxyethyl acrylate and hydroxypropyl acrylate.)

1. The mud-resistant tackifying slow-release polycarboxylate superplasticizer is characterized by being prepared from the following raw materials in parts by mass: 300-380 parts of prenyl polyoxyethylene ether, 15-30 parts of acrylic acid, 30-60 parts of hydroxyethyl acrylate, 10-30 parts of a mud-resistant functional monomer, 10-40 parts of hydroxypropyl acrylate, 10-30 parts of a mud-resistant functional monomer, 1-4 parts of a chain transfer agent, 0.1-1 part of vitamin C, 1-6 parts of hydrogen peroxide and 200-500 parts of water; the mud-resistant functional monomer is synthesized by carrying out esterification reaction on trimethylolpropane and an acrylic acid compound; and the anti-mud functional monomer (II) is synthesized by esterification reaction of 1,2, 6-hexanetriol and an itaconic acid compound.

2. The anti-mud thickening slow-release type polycarboxylate superplasticizer according to claim 1, wherein the anti-mud functional monomer (i) is prepared by the following method: taking 120 parts of trimethylolpropane, 20-50 parts of a water-carrying agent and 0.1-2 parts of a polymerization inhibitor, heating to 60-70 ℃, adding 1-10 parts of solid acid and 230-280 parts of methacrylic acid after complete dissolution, heating to 70-80 ℃, and reacting for 6-10 hours to prepare the anti-mud functional monomer I; the water-carrying agent is carbon tetrachloride; the polymerization inhibitor is phenothiazine; the solid acid is a cation exchange resin.

3. The anti-mud thickening slow-release type polycarboxylate superplasticizer according to claim 1, wherein the anti-mud functional monomer (II) is prepared by the following method: taking 130 parts of 1,2, 6-hexanetriol, 20-50 parts of water-carrying agent and 0.1-2 parts of polymerization inhibitor, heating to 60-70 ℃, adding 1-10 parts of solid acid and 380 parts of itaconic acid after complete dissolution, heating to 70-80 ℃ and reacting for 6-10 hours to prepare the anti-mud functional monomer II; the water-carrying agent is carbon tetrachloride; the polymerization inhibitor is phenothiazine; the solid acid is a cation exchange resin.

4. The anti-mud thickening slow-release type polycarboxylate superplasticizer according to claim 1, wherein the mass ratio of the anti-mud functional monomer (i) to the anti-mud functional monomer (ii) is 1: 1.

5. The anti-mud thickening slow-release type polycarboxylate water reducer according to claim 1, wherein the chain transfer agent is mercaptopropionic acid.

6. The anti-mud thickening slow-release type polycarboxylate water reducer as claimed in claim 1, wherein the molecular structure of the polycarboxylate water reducer is a spatial network three-dimensional structure.

7. A preparation method of the anti-mud thickening slow-release type polycarboxylate water reducer is used for preparing the anti-mud thickening slow-release type polycarboxylate water reducer disclosed by any one of claims 1-6, and is characterized by comprising the following steps:

(1) adding acrylic acid, hydroxyethyl acrylate and an anti-mud functional monomer into water, and stirring and dissolving to prepare a liquid A;

(2) adding hydroxypropyl acrylate and an anti-mud functional monomer into water, and stirring and dissolving to obtain liquid B;

(3) adding a chain transfer agent and vitamin C into water, and stirring and dissolving to obtain liquid C;

(4) adding prenyl polyoxyethylene ether into water, stirring and dissolving to obtain a liquid D;

(5) adding hydrogen peroxide into the liquid D prepared in the step (4), stirring for 5-10 min, then simultaneously dropwise adding the liquid A prepared in the step (1) and the liquid C prepared in the step (3), dropwise adding the liquid A for 1.5 hours, and dropwise adding the liquid C for 3.5 hours; after the liquid A is dripped, dripping the liquid B prepared in the step (2), and dripping the liquid B for 1.5 hours; after the liquid C is dripped, preserving the heat for 1-1.5 hours; and (3) after the heat preservation is finished, adding alkali to adjust the pH value to 6-8, adding water to adjust the solid content of the solution to 40%, and thus obtaining the anti-mud thickening slow-release polycarboxylate water reducer.

8. The preparation method of the anti-mud thickening slow-release type polycarboxylate superplasticizer according to claim 7, wherein the initial reaction temperature of the step (5) is 20-30 ℃, the reaction temperature is maintained at 55-60 ℃ when the liquid A is dripped, and the reaction temperature is maintained at 60-65 ℃ when the liquid B is dripped.

9. Use of the anti-mud thickening slow-release type polycarboxylate water reducer as defined in any one of claims 1-6 as a concrete admixture.

Technical Field

The invention belongs to the field of preparation of concrete admixtures, and particularly relates to a mud-resistant tackifying slow-release type polycarboxylate superplasticizer as well as a preparation method and application thereof.

Background

In the 1980 s, the invention of a polycarboxylic acid high-efficiency water reducing agent (PCE) represented one of the most significant breakthroughs in the history of concrete admixtures. The PCE serving as a third-generation concrete high-efficiency water reducing agent has the characteristics of high water reducing rate, high strength, good compactness, good stability, low viscosity, convenience in operation, good self-leveling property, environmental friendliness and the like, and is widely applied to high-performance concrete such as high-strength concrete, premixed concrete, self-compacting concrete, pump concrete and the like. However, as more and more capital construction projects are made, the consumption of raw materials is increased, natural high-quality sand and stone materials are gradually replaced by artificial and inferior sand and stone materials and machine-made sand, which mainly reflects the sudden increase of mud content in the sand and stone, poor gradation of machine-made sand and more edges and corners. High mud content in the sand not only affects the mixing performance of the concrete, but also results in rapid slump loss, and even directly affects the later strength of the concrete, mainly due to the high sensitivity of the PCE to the soil. The reduction of the fluidity of the concrete doped with the mud is attributed to four factors: firstly, forming surface competitive adsorption between mud and cement; secondly, the side chain of the polycarboxylic acid water reducing agent is easily inserted into the interlayer of mud particles to lose the dispersing activity; thirdly, the soil absorbs water to reduce the actual water content; fourthly, the water absorption expansion of the soil leads to the increase of the viscosity coefficient of the whole system. Poor mobility of concrete, poor wrapping property of concrete, segregation of concrete and other problems caused by poor mechanical sand grade distribution and more edges and corners.

The polycarboxylate superplasticizer (PCE) is an additive prepared from a surfactant, Wangziming and the like and used for inhibiting side effects of clay. The Zhao Chun Li and other synthetic cationic functional group mud-resistant sacrificial agents, but the mud-resistant sacrificial agents need to be compounded with a water reducing agent in application, the use cost of the admixture is increased, and the performance of the polycarboxylic acid water reducing agent is influenced by some mud-resistant sacrificial agents. The cationic sacrificial agents are preferred in the above studies, and the modification of the polycarboxylate water reducing agent molecules by redesign or modification is not involved.

Disclosure of Invention

In view of the defects of the prior art, the invention aims to provide the mud-resistant tackifying slow-release type polycarboxylic acid water reducer, which introduces a mud-resistant functional monomer into a molecular structure to form a net-shaped three-dimensional structure and slowly releases the water reducer with a water reducing function, so that the adverse effect on concrete caused by mud-containing sand and machine-made sand is better solved, and the mud-resistant tackifying performance of the product is improved.

In order to achieve the purpose, the invention is realized by the following technical scheme:

the mud-resistant tackifying slow-release polycarboxylate superplasticizer is prepared from the following raw materials in parts by mass: 300-380 parts of prenyl alcohol polyoxyethylene ether, 15-30 parts of acrylic acid, 30-60 parts of hydroxyethyl acrylate, 10-30 parts of a mud-resistant functional monomer, 10-40 parts of hydroxypropyl acrylate, 10-30 parts of a mud-resistant functional monomer, 1-4 parts of a chain transfer agent, 0.1-1 part of vitamin C, 1-6 parts of hydrogen peroxide and 200-500 parts of water; the mud-resistant functional monomer is synthesized by carrying out esterification reaction on trimethylolpropane and an acrylic acid compound; the anti-mud functional monomer (II) is synthesized by esterification reaction of 1,2, 6-hexanetriol and itaconic acid compounds.

Further, the mud-resistant functional monomer is prepared by the following method: taking 120 parts of trimethylolpropane, 20-50 parts of a water-carrying agent and 0.1-2 parts of a polymerization inhibitor, heating to 60-70 ℃, adding 1-10 parts of solid acid and 230-280 parts of methacrylic acid after complete dissolution, heating to 70-80 ℃, and reacting for 6-10 hours to prepare the anti-mud functional monomer I; the water carrying agent is carbon tetrachloride, and water generated in the reaction is carried out of the reaction through the water carrying agent, so that the reaction conversion rate is improved; the polymerization inhibitor is phenothiazine; the solid acid is a cation exchange resin.

Further, the anti-mud functional monomer is prepared by the following method: taking 130 parts of 1,2, 6-hexanetriol, 20-50 parts of water-carrying agent and 0.1-2 parts of polymerization inhibitor, heating to 60-70 ℃, adding 1-10 parts of solid acid and 380 parts of itaconic acid after complete dissolution, heating to 70-80 ℃ and reacting for 6-10 hours to prepare the anti-mud functional monomer II; the water carrying agent is carbon tetrachloride, and water generated in the reaction is carried out of the reaction through the water carrying agent, so that the reaction conversion rate is improved; the polymerization inhibitor is phenothiazine; the solid acid is a cation exchange resin.

Furthermore, the mass ratio of the mud resistant functional monomer I to the mud resistant functional monomer II is 1: 1.

Further, the chain transfer agent is mercaptopropionic acid.

The invention also aims to provide a preparation method of the anti-mud thickening slow-release type polycarboxylate superplasticizer.

The invention provides a preparation method of an anti-mud thickening slow-release type polycarboxylate superplasticizer, which comprises the following steps:

(1) adding acrylic acid, hydroxyethyl acrylate and an anti-mud functional monomer into water, and stirring and dissolving to prepare a liquid A;

(2) adding hydroxypropyl acrylate and an anti-mud functional monomer into water, and stirring and dissolving to obtain liquid B;

(3) adding a chain transfer agent and vitamin C into water, and stirring and dissolving to obtain liquid C;

(4) adding prenyl polyoxyethylene ether into water, stirring and dissolving to obtain a liquid D;

(5) adding hydrogen peroxide into the liquid D prepared in the step (4), stirring for 5-10 min, then simultaneously dropwise adding the liquid A prepared in the step (1) and the liquid C prepared in the step (3), dropwise adding the liquid A for 1.5 hours, and dropwise adding the liquid C for 3.5 hours; after the liquid A is dripped, dripping the liquid B prepared in the step (2), and dripping the liquid B for 1.5 hours; after the liquid C is dripped, preserving the heat for 1-1.5 hours; and (3) after the heat preservation is finished, adding alkali to adjust the pH value to 6-8, adding water to adjust the solid content of the solution to 40%, and thus obtaining the anti-mud thickening slow-release polycarboxylate water reducer.

The initial reaction temperature of the reaction is 20-30 ℃, the reaction temperature is maintained at 55-60 ℃ when the liquid A is dripped, and the reaction temperature is maintained at 60-65 ℃ when the liquid B is dripped.

The invention also provides the application of the anti-mud thickening slow-release type polycarboxylate superplasticizer as a concrete admixture.

The mud-resistant functional monomer prepared by the invention is an ester monomer containing a plurality of double bonds, trimethylolpropane and methacrylic acid are subjected to esterification reaction to synthesize a mud-resistant functional monomer I, and the component providing the double bonds is mainly trimethylolpropane trimethyl acrylate; esterification reaction is carried out on 1,2, 6-hexanetriol and an itaconic acid compound to synthesize an anti-mud functional monomer II, wherein the component providing double bonds is mainly hexanetriol itaconate; the monomer and the prenyl polyoxyethylene ether are subjected to free radical polymerization under the action of oxydol and vitamin C redox systems and chain transfer, the molecular structure of the synthesized water reducer is a spatial net-shaped three-dimensional structure, the steric hindrance of the water reducer is increased, the adsorption effect of clay on the water reducer can be reduced, and the anti-mud tackifying effect of the water reducer is improved; and the water reducing agent with the water reducing function can be slowly released under the action of two slow-release monomers of hydroxyethyl acrylate and hydroxypropyl acrylate.

Detailed Description

The technical solutions of the present invention will be described in detail and fully with reference to the following specific embodiments, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without any inventive step, are within the scope of the present invention.

Example 1

The mud-resistant tackifying slow-release polycarboxylate superplasticizer is prepared from the following raw materials in parts by mass: 330 parts of prenyl alcohol polyoxyethylene ether, 20 parts of acrylic acid, 40 parts of hydroxyethyl acrylate, 10 parts of a mud-resistant functional monomer, 20 parts of hydroxypropyl acrylate, 10 parts of a mud-resistant functional monomer, 2 parts of mercaptopropionic acid, 0.7 part of vitamin C, 4 parts of hydrogen peroxide and 450 parts of water.

The mud-resistant functional monomer is prepared by the following method: adding 120 parts of trimethylolpropane, 20 parts of carbon tetrachloride and 0.2 part of phenothiazine into a three-neck flask, heating to 60 ℃, adding 6 parts of solid acid and 250 parts of methacrylic acid after complete dissolution, heating to 80 ℃, and reacting for 8 hours to obtain the mud-resistant functional monomer I.

The anti-mud functional monomer is prepared by the following method: adding 130 parts of 1,2, 6-hexanetriol, 30 parts of carbon tetrachloride and 0.3 part of phenothiazine into a three-neck flask, heating to 60 ℃, adding 6 parts of solid acid and 320 parts of itaconic acid after complete dissolution, heating to 80 ℃, and reacting for 8 hours to obtain the anti-mud functional monomer II.

The preparation method of the anti-mud thickening slow-release polycarboxylate superplasticizer comprises the following steps:

(1) adding 20 parts of acrylic acid, 40 parts of hydroxyethyl acrylate, 10 parts of a mud-resistant functional monomer and 50 parts of water into a beaker, and stirring and dissolving to obtain a liquid A;

(2) adding 20 parts of hydroxypropyl acrylate, 10 parts of anti-mud functional monomer and 50 parts of water into a beaker, and stirring and dissolving to obtain liquid B;

(3) adding 2 parts of mercaptopropionic acid, 0.7 part of vitamin C and 50 parts of water into a beaker, and stirring for dissolving to obtain liquid C;

(4) adding 330 parts of prenyl alcohol polyoxyethylene ether and 300 parts of water into a four-neck flask, heating to 25 ℃, stirring and dissolving to prepare a liquid D;

(5) adding 4 parts of hydrogen peroxide into the liquid D prepared in the step (4), stirring for 5-10 min, simultaneously dropwise adding the liquid A prepared in the step (1) and the liquid C prepared in the step (3) into a four-neck flask, keeping the reaction temperature at 55-60 ℃ when the liquid A is dropwise added for 1.5 hours, and dropwise adding the liquid C for 3.5 hours; after the liquid A is dripped, the liquid B prepared in the step (2) is dripped, the liquid B is dripped for 1.5 hours, and the reaction temperature is maintained at 60-65 ℃; after the liquid C is dripped, keeping the temperature in the four-neck flask for 1 hour; and (3) after the heat preservation is finished, adding alkali to adjust the pH value to 6-8, adding water to adjust the solid content of the solution to 40%, and thus obtaining the anti-mud thickening slow-release polycarboxylate superplasticizer liquid E.

Weight average molecular weight was 84000 by GPC.

Example 2

The mud-resistant tackifying slow-release polycarboxylate superplasticizer is prepared from the following raw materials in parts by mass: 340 parts of prenyl alcohol polyoxyethylene ether, 20 parts of acrylic acid, 30 parts of hydroxyethyl acrylate, 20 parts of a mud-resistant functional monomer, 30 parts of hydroxypropyl acrylate, 20 parts of a mud-resistant functional monomer, 2 parts of mercaptopropionic acid, 0.7 part of vitamin C, 4 parts of hydrogen peroxide and 450 parts of water.

The mud-resistant functional monomer is prepared by the following method: adding 120 parts of trimethylolpropane, 20 parts of carbon tetrachloride and 0.5 part of phenothiazine into a three-neck flask, heating to 60 ℃, adding 4 parts of solid acid and 260 parts of methacrylic acid after complete dissolution, heating to 70 ℃, and reacting for 7 hours to obtain the mud-resistant functional monomer I.

The anti-mud functional monomer is prepared by the following method: adding 130 parts of 1,2, 6-hexanetriol, 35 parts of carbon tetrachloride and 5 parts of phenothiazine into a three-neck flask, heating to 60 ℃, adding 5 parts of solid acid and 330 parts of itaconic acid after complete dissolution, heating to 80 ℃, and reacting for 8 hours to obtain the anti-mud functional monomer II.

The preparation method of the anti-mud thickening slow-release polycarboxylate superplasticizer comprises the following steps:

(1) adding 20 parts of acrylic acid, 30 parts of hydroxyethyl acrylate, 20 parts of a mud-resistant functional monomer and 50 parts of water into a beaker, and stirring and dissolving to obtain a liquid A;

(2) adding 30 parts of hydroxypropyl acrylate, 20 parts of anti-mud functional monomer and 50 parts of water into a beaker, and stirring and dissolving to obtain liquid B;

(3) adding 2 parts of mercaptopropionic acid, 0.7 part of vitamin C and 50 parts of water into a beaker, and stirring for dissolving to obtain liquid C;

(4) adding 340 parts of prenyl alcohol polyoxyethylene ether and 300 parts of water into a four-neck flask, heating to 25 ℃, stirring and dissolving to prepare a liquid D;

(5) adding 4 parts of hydrogen peroxide into the liquid D prepared in the step (4), stirring for 5-10 min, simultaneously dropwise adding the liquid A prepared in the step (1) and the liquid C prepared in the step (3) into a four-neck flask, keeping the reaction temperature at 55-60 ℃ when the liquid A is dropwise added for 1.5 hours, and dropwise adding the liquid C for 3.5 hours; after the liquid A is dripped, the liquid B prepared in the step (2) is dripped, the liquid B is dripped for 1.5 hours, and the reaction temperature is maintained at 60-65 ℃; after the liquid C is dripped, keeping the temperature in the four-neck flask for 1 hour; and (3) after the heat preservation is finished, adding alkali to adjust the pH value to 6-8, adding water to adjust the solid content of the solution to 40%, and thus obtaining the anti-mud thickening slow-release polycarboxylate superplasticizer liquid E.

PC detected its weight average molecular weight of 105000.

Example 3

The mud-resistant tackifying slow-release polycarboxylate superplasticizer is prepared from the following raw materials in parts by mass: 330 parts of prenyl alcohol polyoxyethylene ether, 20 parts of acrylic acid, 20 parts of hydroxyethyl acrylate, 25 parts of a mud-resistant functional monomer, 40 parts of hydroxypropyl acrylate, 25 parts of a mud-resistant functional monomer, 2 parts of mercaptopropionic acid, 0.6 part of vitamin C, 5 parts of hydrogen peroxide and 450 parts of water.

The mud-resistant functional monomer is prepared by the following method: adding 120 parts of trimethylolpropane, 30 parts of carbon tetrachloride and 1 part of phenothiazine into a three-neck flask, heating to 60 ℃, adding 7 parts of solid acid and 270 parts of methacrylic acid after complete dissolution, heating to 80 ℃, and reacting for 8 hours to obtain the mud-resistant functional monomer I.

The anti-mud functional monomer is prepared by the following method: adding 130 parts of 1,2, 6-hexanetriol, 30 parts of carbon tetrachloride and 1.3 parts of phenothiazine into a three-neck flask, heating to 60 ℃, adding 6 parts of solid acid and 350 parts of itaconic acid after complete dissolution, heating to 80 ℃, and reacting for 8 hours to obtain the anti-mud functional monomer II.

The preparation method of the anti-mud thickening slow-release polycarboxylate superplasticizer comprises the following steps:

(1) adding 20 parts of acrylic acid, 20 parts of hydroxyethyl acrylate, 25 parts of a mud-resistant functional monomer and 50 parts of water into a beaker, and stirring and dissolving to obtain a liquid A;

(2) adding 40 parts of hydroxypropyl acrylate, 25 parts of anti-mud functional monomer and 50 parts of water into a beaker, and stirring and dissolving to prepare liquid B;

(3) adding 2 parts of mercaptopropionic acid, 0.6 part of vitamin C and 50 parts of water into a beaker, and stirring for dissolving to obtain liquid C;

(4) adding 330 parts of prenyl alcohol polyoxyethylene ether and 300 parts of water into a four-neck flask, heating to 25 ℃, stirring and dissolving to prepare a liquid D;

(5) adding 5 parts of hydrogen peroxide into the liquid D prepared in the step (4), stirring for 5-10 min, simultaneously dropwise adding the liquid A prepared in the step (1) and the liquid C prepared in the step (3) into a four-neck flask, keeping the reaction temperature at 55-60 ℃ when the liquid A is dropwise added for 1.5 hours, and dropwise adding the liquid C for 3.5 hours; after the liquid A is dripped, the liquid B prepared in the step (2) is dripped, the liquid B is dripped for 1.5 hours, and the reaction temperature is maintained at 60-65 ℃; after the liquid C is dripped, keeping the temperature in the four-neck flask for 1 hour; and (3) after the heat preservation is finished, adding alkali to adjust the pH value to 6-8, adding water to adjust the solid content of the solution to 40%, and thus obtaining the anti-mud thickening slow-release polycarboxylate superplasticizer liquid E.

Weight average molecular weight was 84000 by GPC.

Comparative example

The preparation method of the polycarboxylic acid water reducing agent comprises the following steps:

(1) adding 20 parts of acrylic acid, 60 parts of hydroxyethyl acrylate and 50 parts of water into a beaker, and stirring and dissolving to obtain liquid A;

(2) taking 2 parts of mercaptopropionic acid, 0.5 part of vitamin C and 50 parts of water, adding into a beaker, and stirring for dissolving to obtain liquid B;

(3) adding 330 parts of prenyl alcohol polyoxyethylene ether and 300 parts of water into a four-neck flask, heating to 25 ℃, stirring and dissolving to prepare liquid C;

(4) adding 3 parts of hydrogen peroxide into the liquid C prepared in the step (3), stirring for 5-10 min, simultaneously dropwise adding the liquid A prepared in the step (1) and the liquid B prepared in the step (2) into a four-neck flask, dropwise adding the liquid A for 3 hours, dropwise adding the liquid B for 3.5 hours, and maintaining the reaction temperature to be 55-60 ℃; after the liquid B is dripped, keeping the temperature in the four-neck flask for 1 hour; and (3) after the heat preservation is finished, adding alkali to adjust the pH value to 6-8, adding water to adjust the solid content of the solution to 40%, and thus obtaining the polycarboxylic acid water reducing agent liquid D.

The weight average molecular weight was 56000 by GPC.

To further illustrate the technical effects, the following description will be given of the effects of the present invention in terms of the net paste fluidity, the concrete slump, and the water-reducing agent content.

1. Degree of fluidity of the paste

According to GB/T8077-2012 'concrete admixture homogeneity test method', the clear slurry fluidity test is carried out, the water-cement ratio W/C is 0.29, the water reducer fracture-solid mixing amount is 0.25%, wherein sodium bentonite with 3% of cement mass is added, and the result is shown in Table 1.

TABLE 1 Net paste fluidity and loss over time for different samples

2. Testing of concrete Properties

The concrete performance test is carried out according to GB/T50081-2002 ordinary concrete mechanical property test method standard and GB 8076-2008 concrete admixture, wherein the mud resistance of the water reducer is detected by adopting the externally-doped sodium bentonite, the formula of the concrete is shown in Table 2, the mixing amount of the water reducer is respectively 2.0 percent and 1.6 percent of the cementing material, and the test result is shown in Table 3.

TABLE 2C 30 concrete mixing ratio

Cement	Mineral powder	Fly ash	Stone (stone)	Machine-made sand	Bentonite clay	Water (W)
							200	65	80	1050	810	10	170

TABLE 3 comparison of C30 concrete workability

As can be seen from the data in Table 1, the net slurry fluidity of the water reducing agents of the examples 1 to 3 is obviously superior to that of the comparative example under the condition of the same water reducing agent mixing amount, and the water reducing agent of the invention has better mud resistance effect. As can be seen from the data in Table 3, under the condition that the mixing amount of the water reducing agent is the same, the slump and the expansion degree of the concrete are obviously superior to those of the comparative example by using the water reducing agent of the invention; meanwhile, under the condition that the using amount of the water reducing agent is obviously less than that of the comparative example, the working performance of the concrete is basically the same, and the compressive strength is basically the same in 7 days and 28 days. The water reducer has better mud resistance, viscosity increasing and water reducing performances, and can reduce the doping amount of the additive.

The above description is only for the specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention disclosed herein should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.