Retarding polycarboxylate superplasticizer and preparation method thereof

Abstract

The invention discloses a delayed coagulation type polycarboxylate superplasticizer and a preparation method thereof, and relates to the field of concrete admixtures. The retarding type polycarboxylic acid water reducing agent is prepared from 45 to 55 parts of unsaturated polyether monomer, 15 to 20 parts of quaternary ammonium salt cationic monomer, 10 to 15 parts of unsaturated sulfonic acid or unsaturated sulfonate monomer, 5.5 to 7.5 parts of unsaturated phosphate monomer, 4.8 to 6.2 parts of unsaturated hydroxy fatty acid ester monomer, 100 to 120 parts of acrylic acid, 1 to 2 parts of chain transfer agent, 1.5 to 2 parts of oxidizing agent, 0.75 to 1 part of reducing agent and 500 parts of water. The structural general formula of the unsaturated polyether monomer is R1CH2O (CH2CH2O) nR2, R1 is an alkenyl group, and R2 is any one of a phenyl group and a phenylalanine alkyl ester group. The delayed coagulation type polycarboxylate superplasticizer can effectively improve the delayed coagulation effect of a concrete mixture with the fine aggregate mud content larger than 1.5% in a high-temperature environment, and constructability is ensured.

Description

Technical Field

[0001] The present application relates to the field of concrete admixtures, and in particular to a slow-setting polycarboxylate water-reducing agent and a preparation method thereof. Background Art

[0002] Concrete mixtures that need to be used in high temperature seasons or need to be transported and pumped for a long time are usually required to have good retarding properties to ensure the convenience of construction.

[0003] At present, the way to improve the retarding performance of concrete is to add inorganic retarders or polycarboxylate water-reducing agents with retarding effect. Common inorganic retarders include phosphates, sulfates, borates, etc., but these inorganic retarders have the problem of large dosage and poor retarding effect. Common polycarboxylate water-reducing agents are usually made of unsaturated polyether monomers, unsaturated phosphates, unsaturated fatty acids, and unsaturated sulfonic acids or sulfonates. They can achieve retarding performance to a certain extent, but they are easily affected by the mud content of fine aggregates and the ambient temperature. For example, when the mud content of fine aggregates is higher than 1.5% and the ambient temperature is greater than 35°C, the retarding effect of the concrete mixture becomes worse, the dosage of polycarboxylate water-reducing agents increases, and the cost also increases accordingly. Summary of the invention

[0004] In order to improve the problem in the related art that the polycarboxylate water-reducing agent has poor retarding property for concrete admixtures with high fine aggregate mud content in a high temperature environment, the present application provides a retarding polycarboxylate water-reducing agent and a preparation method thereof.

[0005] In the first aspect, the present application provides a slow-setting polycarboxylate water-reducing agent using the following technical solution: A slow-setting polycarboxylate water-reducing agent comprises 45-55 parts by weight of an unsaturated polyether monomer, 15-20 parts by weight of a quaternary ammonium salt cationic monomer, 10-15 parts by weight of an unsaturated sulfonic acid or unsaturated sulfonate monomer, 5.5-7.5 parts by weight of an unsaturated phosphate monomer, 4.8-6.2 parts by weight of an unsaturated hydroxy fatty acid ester monomer, 100-120 parts by weight of acrylic acid, 1-2 parts by weight of a chain transfer agent, 1.5-2 parts by weight of an oxidant, 0.75-1 parts by weight of a reducing agent and 500 parts by weight of water, wherein the unsaturated polyether monomer has a general structural formula of R1CH2O(CH2CH2O): n R2, wherein R1 is an alkenyl group, and R2 is any one of a phenyl group and a phenylalanine alkyl ester group.

[0006] The slow-setting polycarboxylate water-reducing agent of the present application is obtained by reacting an unsaturated polyether monomer with a quaternary ammonium salt cationic monomer, an unsaturated sulfonic acid or unsaturated sulfonate monomer, an unsaturated phosphate monomer, an unsaturated hydroxy fatty acid ester monomer, acrylic acid, etc. in a specific ratio. The slow-setting polycarboxylate water-reducing agent has low sensitivity to mud in aggregates and has mud resistance. It can be evenly dispersed in a concrete mixture with a high fine aggregate mud content (more than 1.5%), and stably adsorbed on the surface of cement particles to form a layer of water film. The water film has good thermal stability and can prevent the problem of water easily accelerating the penetration of water into cement in a high temperature (>35°C) environment, thereby delaying the hydration rate of cement in a high temperature environment, and effectively improving the slow-setting effect of the slow-setting polycarboxylate water-reducing agent for a concrete mixture with a fine aggregate mud content greater than 1.5% in a high temperature environment.

[0007] In some specific embodiments, the unsaturated polyether monomer includes a first unsaturated polyether monomer and a second unsaturated polyether monomer, in which R2 is a phenyl group; in which R2 is a phenylalanine alkyl ester group, the weight ratio of the first unsaturated polyether monomer to the second unsaturated polyether monomer is (1-1.5):1.

[0008] In the present application, the unsaturated polyether monomer is preferably a composition of a first unsaturated polyether monomer and a second unsaturated polyether monomer in a specific ratio, wherein R2 in the first unsaturated polyether monomer is a phenyl group, and R2 in the second unsaturated polyether monomer is a phenylalanine alkyl ester group, which is beneficial to further improve the mud resistance of the slow-setting polycarboxylic acid water-reducing agent, and can further prolong the initial setting time of concrete with a high fine aggregate mud content in a high temperature environment.

[0009] In some specific embodiments, in the unsaturated polyether monomer, the value of n is 15-20.

[0010] In the present application, the value of n in the general formula of the unsaturated polyether monomer is preferably 15-20, which is beneficial to further improve the dispersibility of the slow-setting polycarboxylic acid water-reducing agent. Under the condition that other conditions remain unchanged, the initial setting time of concrete with high fine aggregate content in a high temperature environment can be further prolonged.

[0011] In some specific embodiments, the quaternary ammonium salt cationic monomer is at least one of dimethyldiallylammonium chloride, methacryloyloxyethyltrimethylammonium chloride, and methacryloyloxyethyldimethylbenzylammonium chloride.

[0012] In some specific embodiments, the quaternary ammonium salt cationic monomer is a composition of methacryloyloxyethyl trimethyl ammonium chloride and methacryloyloxyethyl dimethyl benzyl ammonium chloride, and the weight ratio of methacryloyloxyethyl trimethyl ammonium chloride to methacryloyloxyethyl dimethyl benzyl ammonium chloride is 1: (3-4).

[0013] In the present application, the quaternary ammonium salt cationic monomer is preferably a composition of methacryloyloxyethyl trimethyl ammonium chloride and methacryloyloxyethyl dimethyl benzyl ammonium chloride in a weight ratio of 1: (3-4), which is beneficial to further improve the mud resistance of the slow-setting polycarboxylate water-reducing agent. Under the condition that other conditions remain unchanged, the initial setting time of concrete with high fine aggregate mud content in a high temperature environment can be further prolonged.

[0014] In some specific embodiments, the unsaturated phosphate monomer is at least one of acrylic acid phosphate and methacrylic acid phosphate.

[0015] In some specific embodiments, the unsaturated sulfonic acid or unsaturated sulfonate monomer is at least one of 2-acrylamide-2-methylpropane sulfonic acid and sodium 2-acrylamide-2-methylpropane sulfonate.

[0016] In some specific embodiments, the unsaturated hydroxy fatty acid ester monomer is at least one of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, and hydroxypropyl methacrylate.

[0017] In some specific embodiments, the chain transfer agent is at least one of thioglycolic acid, mercaptoethanol, and mercaptopropionic acid.

[0018] In the second aspect, the present application provides a method for preparing a slow-setting polycarboxylate water-reducing agent using the following technical solution: A method for preparing a slow-setting polycarboxylate water-reducing agent, comprising the following steps: Add acrylic acid, quaternary ammonium salt cationic monomer, unsaturated sulfonic acid or unsaturated sulfonate monomer to water with a total weight of 20-25% of the water formula, stir evenly, and obtain liquid A; Add unsaturated polyether monomer, unsaturated phosphate monomer and unsaturated hydroxy fatty acid ester monomer to water with a total weight of 20-25% of the water formula, stir evenly to obtain liquid B; Adding an oxidant to water in an amount of 10-15% of the total weight of the water formula to obtain liquid C; Add the reducing agent to water in an amount of 10-15% of the total weight of the water formula to obtain liquid D; Add the chain transfer agent to the remaining amount of water to obtain liquid E; Add part of liquid C and liquid D dropwise to liquid A, the amount of liquid C and liquid D added is 40-45% of their respective total weights, the dropwise acceleration ratio of liquid C and liquid D is (1.5-2.5):1, and the dropwise addition time is controlled at 100-120 min to obtain liquid F; Add liquid B, the remaining liquid C and the remaining liquid D to liquid F at the same time, and control the dropping time to 120-150 minutes. Then add liquid E and stir the reaction for 1-2 hours to obtain a slow-setting polycarboxylate water-reducing agent.

[0019] In the present application, liquid A and liquid E are prepared separately, and part of liquid C and liquid D are first added to liquid A to react to obtain liquid F, and then liquid B, the remaining liquid C and the remaining liquid D are added to liquid F to continue the reaction, and finally liquid E is added to react to obtain a slow-setting polycarboxylate water-reducing agent. Among them, the use of this method to prepare a slow-setting polycarboxylate water-reducing agent is conducive to further improving the slow-setting effect of the slow-setting polycarboxylate water-reducing agent on a concrete mixture with a fine aggregate mud content greater than 1.5% in a high temperature environment.

[0020] In summary, this application at least includes the following beneficial technical effects: (1) The slow-setting polycarboxylate water-reducing agent of the present application is obtained by reacting an unsaturated polyether monomer with a quaternary ammonium salt cationic monomer, an unsaturated sulfonic acid or unsaturated sulfonate monomer, an unsaturated phosphate monomer, an unsaturated hydroxy fatty acid ester monomer, acrylic acid, etc. in a specific ratio. The slow-setting polycarboxylate water-reducing agent has low sensitivity to mud in aggregates and has mud resistance. It can be evenly dispersed in a concrete mixture with a high fine aggregate mud content (more than 1.5%) and stably adsorbed on the surface of cement particles to form a layer of water film. The water film has good thermal stability and can prevent the problem of water easily accelerating the penetration of water into cement in a high temperature (>35°C) environment, thereby delaying the hydration rate of cement in a high temperature environment, and effectively improving the slow-setting effect of the slow-setting polycarboxylate water-reducing agent for a concrete mixture with a fine aggregate mud content greater than 1.5% in a high temperature environment.

[0021] (2) In the present application, the unsaturated polyether monomer is preferably a composition of a first unsaturated polyether monomer and a second unsaturated polyether monomer in a specific ratio, wherein R2 in the first unsaturated polyether monomer is a phenyl group, and R2 in the second unsaturated polyether monomer is a phenylalanine alkyl ester group, which is beneficial to further improve the mud resistance of the slow-setting polycarboxylic acid water-reducing agent and further prolong the initial setting time of concrete with a high fine aggregate mud content in a high temperature environment.

[0022] (3) In the present application, liquid A and liquid E are prepared separately, and part of liquid C and liquid D are first added to liquid A to obtain liquid F after reaction, and then liquid B, the remaining liquid C and the remaining liquid D are added to liquid F to continue the reaction, and finally liquid E is added to react to obtain a slow-setting polycarboxylate water-reducing agent. Among them, the use of this method to prepare a slow-setting polycarboxylate water-reducing agent is conducive to further improving the slow-setting effect of the slow-setting polycarboxylate water-reducing agent on concrete mixtures with a fine aggregate mud content greater than 1.5% in a high temperature environment. DETAILED DESCRIPTION

[0023] The present application is further described below in conjunction with specific experiments. Example

[0024] [Example 1] A slow-setting polycarboxylate water-reducing agent is prepared from the following raw materials: Unsaturated polyether monomer: 45 g; In this embodiment, the unsaturated polyether monomer adopts the first unsaturated polyether monomer, and the structural formula of the first unsaturated polyether monomer is CH2=CHCH2O(CH2CH2O) 18 C6H5; Quaternary ammonium salt cationic monomer: 20 g; in this embodiment, the quaternary ammonium salt cationic monomer is specifically methacryloyloxyethyl dimethylbenzyl ammonium chloride; Unsaturated sulfonic acid or unsaturated sulfonate monomer: 10 g; in this embodiment, the unsaturated sulfonic acid or unsaturated sulfonate monomer is 2-acrylamido-2-methylpropanesulfonic acid; Unsaturated phosphate monomer: 5.5 g; in this embodiment, the unsaturated phosphate monomer is acrylic acid phosphate; Unsaturated hydroxy fatty acid ester monomer: 6.2 g; in this embodiment, the unsaturated hydroxy fatty acid ester monomer is hydroxyethyl acrylate; acrylic acid: 100 g; Chain transfer agent: 1 g; in this embodiment, the chain transfer agent is thioglycolic acid; Oxidant: 1.5 g; in this embodiment, the oxidant is ammonium persulfate; Reducing agent: 0.75 g; in this embodiment, the reducing agent is sodium sulfite; Water: 500g.

[0025] In this embodiment, the preparation method of the slow-setting polycarboxylate water-reducing agent comprises the following steps: Add unsaturated acrylic acid, quaternary ammonium salt cationic monomer, unsaturated sulfonic acid or unsaturated sulfonate monomer to water with a total weight of 25% of the water formula, stir evenly, and obtain liquid A; Add unsaturated polyether monomer, unsaturated phosphate monomer and unsaturated hydroxy fatty acid ester monomer to water with a total weight of 25% of the water formula, stir evenly to obtain liquid B; Add the oxidant to water in an amount of 10% by weight of the total weight of the water formula to obtain liquid C; Add the reducing agent to water in an amount of 10% by weight of the total water formula to obtain liquid D; Add the chain transfer agent to the remaining amount of water to obtain liquid E; Liquid B, liquid C and liquid D were added dropwise to liquid A at the same time, and the adding time was controlled within 300 min. Then liquid E was added and stirred for reaction for 1.5 h to obtain a slow-setting polycarboxylic acid water-reducing agent.

[0026] [Example 2] A slow-setting polycarboxylate water-reducing agent, which is different from [Example 1] in that the raw material composition and proportion are different. In this embodiment, the raw material composition and proportion of the slow-setting polycarboxylate water-reducing agent are as follows: Unsaturated polyether monomer: 55 g; In this embodiment, the unsaturated polyether monomer adopts the second unsaturated polyether monomer, and the structural formula of the second unsaturated polyether monomer is CH2=CHCH2O(CH2CH2O) 18 C6H4CH2NHCOOCH3; Quaternary ammonium salt cationic monomer: 15 g; in this embodiment, the quaternary ammonium salt cationic monomer is specifically methacryloyloxyethyl trimethyl ammonium chloride; Unsaturated sulfonic acid or unsaturated sulfonate monomer: 15 g; in this embodiment, the unsaturated sulfonic acid or unsaturated sulfonate monomer is sodium 2-acrylamido-2-methylpropane sulfonate; Unsaturated phosphate monomer: 7.5 g; in this embodiment, the unsaturated phosphate monomer is methacrylic acid phosphate; Unsaturated hydroxy fatty acid ester monomer: 4.8 g; in this embodiment, the unsaturated hydroxy fatty acid ester monomer is hydroxyethyl methacrylate; Acrylic acid: 120g; Chain transfer agent: 2 g; in this embodiment, the chain transfer agent is mercaptopropionic acid; Oxidant: 2g; in this embodiment, the oxidant is sodium persulfate; Reducing agent: 1g; in this embodiment, the reducing agent is sodium bisulfite; Water: 500g.

[0027] [Example 3] A slow-setting polycarboxylic acid water-reducing agent, which is different from [Example 1] in that the unsaturated polyether monomer is different. In this embodiment, the unsaturated polyether monomer adopts a second unsaturated polyether monomer, and the structural formula of the second unsaturated polyether monomer is CH2=CHCH2O(CH2CH2O) 18 C6H4CH2NHCOOCH3.

[0028] [Example 4] A slow-setting polycarboxylic acid water-reducing agent, which is different from [Example 1] in that the unsaturated polyether monomer is different. In this embodiment, the unsaturated polyether monomer includes a first unsaturated polyether monomer and a second unsaturated polyether monomer, and the structural formula of the first unsaturated polyether monomer is CH2=CHCH2O(CH2CH2O) 18 C6H5, the structural formula of the second unsaturated polyether monomer is CH2=CHCH2O(CH2CH2O) 18 C6H4CH2NHCOOCH3, the weight ratio of the first unsaturated polyether monomer to the second unsaturated polyether monomer is 1:1.

[0029] [Example 5] A slow-setting polycarboxylic acid water-reducing agent, which is different from [Example 1] in that the unsaturated polyether monomer is different. In this embodiment, the unsaturated polyether monomer includes a first unsaturated polyether monomer and a second unsaturated polyether monomer, and the structural formula of the first unsaturated polyether monomer is CH2=CHCH2O(CH2CH2O) 18 C6H5, the structural formula of the second unsaturated polyether monomer is CH2=CHCH2O(CH2CH2O) 18 C6H4CH2NHCOOCH3, the weight ratio of the first unsaturated polyether monomer to the second unsaturated polyether monomer is 3:1.

[0030] [Example 6] A slow-setting polycarboxylic acid water-reducing agent, which is different from [Example 1] in that the unsaturated polyether monomer is different. In this embodiment, the unsaturated polyether monomer includes a first unsaturated polyether monomer and a second unsaturated polyether monomer, and the structural formula of the first unsaturated polyether monomer is CH2=CHCH2O(CH2CH2O) 18 C6H5, the structural formula of the second unsaturated polyether monomer is CH2=CHCH2O(CH2CH2O) 18 C6H4CH2NHCOOCH3, the weight ratio of the first unsaturated polyether monomer to the second unsaturated polyether monomer is 1:3.

[0031] [Example 7] A slow-setting polycarboxylic acid water-reducing agent, which differs from [Example 4] in that the value of n in the first unsaturated polyether monomer and the second unsaturated polyether monomer is different. In this embodiment, the structural formula of the first unsaturated polyether monomer is CH2=CHCH2O(CH2CH2O) 25 C6H5, the structural formula of the second unsaturated polyether monomer is CH2=CHCH2O(CH2CH2O) 25 C6H4CH2NHCOOCH3.

[0032] [Example 8] A slow-setting polycarboxylate water-reducing agent, which is different from [Example 4] in that the quaternary ammonium salt cationic monomer is different. In this embodiment, the quaternary ammonium salt cationic monomer is a composition of methacryloyloxyethyl trimethyl ammonium chloride and methacryloyloxyethyl dimethyl benzyl ammonium chloride, and the weight ratio of methacryloyloxyethyl trimethyl ammonium chloride to methacryloyloxyethyl dimethyl benzyl ammonium chloride is 1:4.

[0033] [Example 9] A slow-setting polycarboxylate water-reducing agent, which is different from [Example 4] in that the quaternary ammonium salt cationic monomer is different. In this embodiment, the quaternary ammonium salt cationic monomer is a composition of dimethyl diallyl ammonium chloride and methacryloyloxyethyl dimethyl benzyl ammonium chloride, and the weight ratio of dimethyl diallyl ammonium chloride to methacryloyloxyethyl dimethyl benzyl ammonium chloride is 1:4.

[0034] [Example 10] A slow-setting polycarboxylate water-reducing agent, which is different from [Example 4] in that the quaternary ammonium salt cationic monomer is different. In this embodiment, the quaternary ammonium salt cationic monomer is a composition of methacryloyloxyethyl trimethyl ammonium chloride and dimethyl diallyl ammonium chloride, and the weight ratio of methacryloyloxyethyl trimethyl ammonium chloride to dimethyl diallyl ammonium chloride is 1:4.

[0035] [Example 11] A slow-setting polycarboxylate water-reducing agent, which is different from [Example 8] in that the preparation method of the slow-setting polycarboxylate water-reducing agent is different.

[0036] In this embodiment, the preparation method of the slow-setting polycarboxylate water-reducing agent is as follows: Add acrylic acid, quaternary ammonium salt cationic monomer, unsaturated sulfonic acid or unsaturated sulfonate monomer to water with a total weight of 25% of the water formula, stir evenly, and obtain liquid A; Add unsaturated polyether monomer, unsaturated phosphate monomer and unsaturated hydroxy fatty acid ester monomer to water with a total weight of 25% of the water formula, stir evenly to obtain liquid B; Add the oxidant to water in an amount of 10% by weight of the total weight of the water formula to obtain liquid C; Add the reducing agent to water in an amount of 10% by weight of the total water formula to obtain liquid D; Add the chain transfer agent to the remaining amount of water to obtain liquid E; Add part of liquid C and liquid D dropwise to liquid A, the amount of liquid C and liquid D added is 40% of their total weight, the drop speed ratio of liquid C and liquid D is 2:1, and the drop time is controlled at 120 min to obtain liquid F; Liquid B, the remaining liquid C and the remaining liquid D were simultaneously added dropwise to liquid F, the adding time was controlled within 150 min, and then liquid E was added, and the reaction was stirred for 1.5 h to obtain a slow-setting polycarboxylate water-reducing agent.

[0037] Comparative Example [Comparative Example 1] A slow-setting polycarboxylic acid water-reducing agent, which differs from [Example 1] in that the distribution ratios of the components are different.

[0038] In this comparative example, the slow-setting polycarboxylate water-reducing agent is prepared from the following raw materials: Unsaturated polyether monomer: 25 g; In this embodiment, the unsaturated polyether monomer adopts the first unsaturated polyether monomer, and the structural formula of the first unsaturated polyether monomer is CH2=CHCH2O(CH2CH2O) 18 C6H5; Quaternary ammonium salt cationic monomer: 30 g; in this embodiment, the quaternary ammonium salt cationic monomer is specifically methacryloyloxyethyl dimethylbenzyl ammonium chloride; Unsaturated sulfonic acid or unsaturated sulfonate monomer: 20 g; in this embodiment, the unsaturated sulfonic acid or unsaturated sulfonate monomer is 2-acrylamido-2-methylpropanesulfonic acid; Unsaturated phosphate monomer: 2.5 g; in this embodiment, the unsaturated phosphate monomer is acrylic acid phosphate; Unsaturated hydroxy fatty acid ester monomer: 9.2 g; in this embodiment, the unsaturated hydroxy fatty acid ester monomer is hydroxyethyl acrylate; acrylic acid: 100 g; Chain transfer agent: 1 g; in this embodiment, the chain transfer agent is thioglycolic acid; Oxidant: 1.5 g; in this embodiment, the oxidant is ammonium persulfate; Reducing agent: 0.75 g; in this embodiment, the reducing agent is sodium sulfite; Water: 500g.

[0039] Performance testing The mix ratio of the benchmark concrete C30 is shown in Table 1. The cement used is Huaxin Cement PO42.5, the fineness modulus of the sand used is 2.6-2.9, and the mud content is 2.15%; the gravel used is a secondary mix, of which 5mm-10mm accounts for about 40% and 10mm-20mm accounts for about 60%.

[0040] Table 1 Initial setting time difference test: The slow-setting polycarboxylate water-reducing agent in each embodiment and comparative example was added to the above-mentioned reference concrete C30 at a cement dosage of 0.5% (solidified), and concrete mixtures 1-12 were prepared respectively. Then, the concrete mixtures were placed in an environment with a temperature of 45° C. and a humidity of 85%, and the initial setting time of each concrete mixture was tested with reference to the determination of the initial setting time in Section 11 of the setting time test of GB / T 50080-2016, and compared with the initial setting time of the reference concrete in Table 1, and the difference between the initial setting time of the concrete mixtures 1-12 and the reference concrete was recorded. The larger the difference, the better the retarding effect of the slow-setting polycarboxylate water-reducing agent.

[0041] Table 2 The difference between Comparative Example 1 and Example 1 is that the ratio of the components of the slow-setting polycarboxylate water-reducing agent in Comparative Example 1 is different from that in Example 1. Combined with the data in Table 2, it can be seen that the slow-setting polycarboxylate water-reducing agent in Example 1 has a much better slow-setting effect on the concrete mixture with a fine aggregate mud content greater than 1.5% in a high temperature environment than that of Comparative Document 1, indicating that the ratio between the raw material components affects the slow-setting effect of the slow-setting polycarboxylate water-reducing agent.

[0042] The difference between Examples 3-6 and Example 1 is that the unsaturated polyether monomers are different. Among them, the unsaturated polyether monomers in Examples 4-6 are a combination of a first unsaturated polyether monomer and a second unsaturated polyether monomer, and in Example 4, the weight ratio of the first unsaturated polyether monomer to the second unsaturated polyether monomer is 1:1, in Example 5, the weight ratio of the first unsaturated polyether monomer to the second unsaturated polyether monomer is 3:1, and in Example 6, the weight ratio of the first unsaturated polyether monomer to the second unsaturated polyether monomer is 1:3. Combined with the data in Table 2, it can be seen that the unsaturated polyether monomer uses a combination of the first unsaturated polyether monomer and the second unsaturated polyether monomer in a weight ratio of 1: (1-1.5), which is conducive to further improving the retarding effect of the retarding polycarboxylic acid water-reducing agent for concrete mixtures with a fine aggregate mud content greater than 1.5% in a high temperature environment.

[0043] The difference between Example 7 and Example 4 is that in Example 4, the value of n in the first unsaturated polyether monomer and the second unsaturated polyether monomer is within 15-20, and in Example 7, the value of n in the first unsaturated polyether monomer and the second unsaturated polyether monomer is greater than 20. Combined with the data in Table 2, it can be seen that the value of n in the unsaturated polyether monomer is within 15-20, which is conducive to further improving the retarding effect of the retarding polycarboxylic acid water-reducing agent for concrete mixtures with a fine aggregate mud content greater than 1.5% in a high temperature environment.

[0044] The difference between Examples 8-10 and Example 4 is that the quaternary ammonium salt cationic monomers are different. Among them, in Example 8, the quaternary ammonium salt cationic monomer adopts a composition of methacryloyloxyethyl trimethyl ammonium chloride and methacryloyloxyethyl dimethyl benzyl ammonium chloride in a weight ratio of 1:4, in Example 9, the quaternary ammonium salt cationic monomer adopts a composition of dimethyl diallyl ammonium chloride and methacryloyloxyethyl dimethyl benzyl ammonium chloride in a weight ratio of 1:4, and in Example 10, the quaternary ammonium salt cationic monomer adopts a composition of methacryloyloxyethyl trimethyl ammonium chloride and dimethyl diallyl ammonium chloride in a weight ratio of 1:4. Combined with the data in Table 1, it can be seen that the quaternary ammonium salt cationic monomer adopts a composition of methacryloyloxyethyl trimethyl ammonium chloride and methacryloyloxyethyl dimethyl benzyl ammonium chloride in a weight ratio of 1: (3-4), which is conducive to further improving the retarding effect of the retarding polycarboxylate water reducer for concrete mixtures with a fine aggregate mud content greater than 1.5% in a high temperature environment.

[0045] The difference between Example 11 and Example 8 is that the preparation method of the slow-setting polycarboxylate water-reducing agent in Example 11 is different from that in Example 8. In Example 11, liquid A and liquid E are prepared separately, and then part of liquid C and liquid D are added to liquid A to obtain liquid F after reaction, and then liquid B, the remaining liquid C and the remaining liquid D are added to liquid F to continue the reaction, and finally liquid E is added to react to obtain the slow-setting polycarboxylate water-reducing agent. Combined with the data in Table 2, it can be seen that the slow-setting polycarboxylate water-reducing agent prepared by the method in Example 11 is conducive to further improving the slow-setting effect of the slow-setting polycarboxylate water-reducing agent on concrete mixtures with a fine aggregate mud content greater than 1.5% in a high temperature environment.

[0046] This specific implementation manner is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the specific implementation manner as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A slow-setting polycarboxylate water-reducing agent, characterized in that: The invention comprises 45-55 parts by weight of an unsaturated polyether monomer, 15-20 parts by weight of a quaternary ammonium salt cationic monomer, 10-15 parts by weight of an unsaturated sulfonic acid or unsaturated sulfonate monomer, 5.5-7.5 parts by weight of an unsaturated phosphate monomer, 4.8-6.2 parts by weight of an unsaturated hydroxy fatty acid ester monomer, 100-120 parts by weight of acrylic acid, 1-2 parts by weight of a chain transfer agent, 1.5-2 parts by weight of an oxidant, 0.75-1 parts by weight of a reducing agent and 500 parts by weight of water, wherein the unsaturated polyether monomer has a general structural formula of R1CH2O(CH2CH2O): n R2, wherein R1 is an alkenyl group, and R2 is any one of a phenyl group and a phenylalanine alkyl ester group.

2. A slow-setting polycarboxylate water-reducing agent according to claim 1, characterized in that: The unsaturated polyether monomer comprises a first unsaturated polyether monomer and a second unsaturated polyether monomer, in which R2 is a phenyl group; in which R2 is a phenylalanine alkyl ester group, the weight ratio of the first unsaturated polyether monomer to the second unsaturated polyether monomer is (1-1.5):

1.

3. A slow-setting polycarboxylate water-reducing agent according to claim 1 or 2, characterized in that: In the unsaturated polyether monomer, the value of n is 15-20.

4. A slow-setting polycarboxylate water-reducing agent according to claim 3, characterized in that: The quaternary ammonium salt cationic monomer is at least one of dimethyldiallylammonium chloride, methacryloyloxyethyltrimethylammonium chloride, and methacryloyloxyethyldimethylbenzylammonium chloride.

5. A slow-setting polycarboxylate water-reducing agent according to claim 4, characterized in that: The quaternary ammonium salt cationic monomer is a composition of methacryloyloxyethyl trimethyl ammonium chloride and methacryloyloxyethyl dimethyl benzyl ammonium chloride, and the weight ratio of the methacryloyloxyethyl trimethyl ammonium chloride to the methacryloyloxyethyl dimethyl benzyl ammonium chloride is 1: (3-4).

6. A slow-setting polycarboxylate water-reducing agent according to claim 1, characterized in that: The unsaturated phosphate monomer is at least one of acrylic acid phosphate and methacrylic acid phosphate.

7. A slow-setting polycarboxylate water-reducing agent according to claim 1, characterized in that: The unsaturated sulfonic acid or unsaturated sulfonate monomer is at least one of 2-acrylamide-2-methylpropane sulfonic acid and sodium 2-acrylamide-2-methylpropane sulfonate.

8. The slow-setting polycarboxylate water-reducing agent according to claim 1, characterized in that: The unsaturated hydroxy fatty acid ester monomer is at least one of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate and hydroxypropyl methacrylate.

9. A slow-setting polycarboxylate water-reducing agent according to claim 1, characterized in that: The chain transfer agent is at least one of thioglycolic acid, mercaptoethanol and mercaptopropionic acid.

10. A method for preparing a slow-setting polycarboxylate water-reducing agent according to any one of claims 1 to 9, characterized in that: The following steps are involved: Add acrylic acid, quaternary ammonium salt cationic monomer, unsaturated sulfonic acid or unsaturated sulfonate monomer to water with a total weight of 20-25% of the water formula, stir evenly, and obtain liquid A; Add unsaturated polyether monomer, unsaturated phosphate monomer and unsaturated hydroxy fatty acid ester monomer to water with a total weight of 20-25% of the water formula, stir evenly to obtain liquid B; Add the oxidant to water in an amount of 10-15% of the total weight of the water formula to obtain liquid C; Add the reducing agent to water in an amount of 10-15% of the total weight of the water formula to obtain liquid D; Add the chain transfer agent to the remaining amount of water to obtain liquid E; Add part of liquid C and liquid D dropwise to liquid A, the amount of liquid C and liquid D added is 40-45% of their respective total weights, the dropwise acceleration ratio of liquid C and liquid D is (1.5-2.5):1, and the dropwise addition time is controlled at 100-120 min to obtain liquid F; Add liquid B, the remaining liquid C and the remaining liquid D to liquid F at the same time, and control the dropping time to 120-150 minutes. Then add liquid E and stir the reaction for 1-2 hours to obtain a slow-setting polycarboxylate water-reducing agent.

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