High-temperature-resistant early-strength slump-retaining polycarboxylate superplasticizer as well as preparation method and application thereof

Abstract

The invention relates to the field of concrete admixtures, in particular to a high-temperature-resistant early-strength slump-retaining polycarboxylate superplasticizer as well as a preparation method and application thereof. The high-temperature-resistant early-strength slump-retaining polycarboxylate superplasticizer provided by the invention contains unsaturated aryl imide silane which can accelerate the cement hydration acceleration period and shorten the concrete setting time, and cooperates with an imide group to improve the heat resistance of a polymer, and then the heat resistance of the polymer is further improved by virtue of the micro-crosslinking effect of N, N-methylene bisacrylamide, so that the high-temperature-resistant early-strength slump-retaining polycarboxylate superplasticizer is prepared. A huge three-dimensional adsorption structure is formed through high-hydrophilic groups such as phosphate groups and benzene rings in the molecular structure and rigid groups, steric hindrance is increased, the slump retention capacity of concrete is improved, a large number of hydrophilic groups such as carboxyl and hydroxyl can form hydrogen bonds with water molecules, the strength of concrete is enhanced, and the concrete is applied to concrete production and has good application prospects. The premixed concrete has the advantages and technical effects that the premixed concrete still has good fluidity and slump retentivity in a high-temperature environment, the setting time is short, and the early strength is high.

Description

Technical Field

[0001] The invention relates to the field of concrete admixtures, and in particular to a high-temperature resistant, early-strength, collapse-retaining polycarboxylate water-reducing agent and a preparation method and application thereof. Background Art

[0002] Concrete water reducer is one of the most widely used concrete admixtures, which can reduce the amount of water per unit mixing and improve the workability of concrete. The slump of concrete is an important indicator for measuring the workability of concrete, including fluidity, cohesion and water retention, and is mainly used to evaluate the plasticization and pumpability of concrete.

[0003] Ready-mixed concrete is widely used in modern engineering projects. The production companies of ready-mixed concrete are often far away from the construction sites, especially when construction is carried out in hot weather. In addition, the pumping time of concrete is long during the construction of large-volume concrete, extra-long concrete structures and super-high-rise buildings. This puts high requirements on the length of time that concrete fluidity can be maintained. That is, the concrete is required to still have a certain slump after a long period of transportation to meet the requirements of on-site pumping construction.

[0004] At the same time, in order to save costs, ready-mixed concrete companies often use sand and gravel materials with high mud and powder content, which requires the use of a large amount of slump-retaining polycarboxylate water-reducing agent to maintain a good slump of concrete, so as to slow down the loss of concrete fluidity during the long construction waiting period. However, the large-scale use of slump-retaining agent, its retarding effect, can easily lead to problems such as long setting time and insufficient early strength of ready-mixed concrete, which will reduce the performance of concrete, prolong the setting time, and reduce construction safety.

[0005] Based on the increased requirements for concrete construction performance in the above-mentioned modern projects, technical personnel in this field have conducted research and exploration on this technical dilemma. For example, a high-temperature resistant, viscosity-reducing, and early-strengthening dispersant disclosed in the patent document with publication number CN117417542B, specifically a high-temperature resistant hyperbranched sulfonate, can improve the thermal stability of concrete, avoid agglomeration between concrete particles, and has uniform dispersion and high stability.

[0006] However, the above-mentioned patents do not solve the problems of poor fluidity and rapid slump loss of ready-mixed concrete during construction in high-temperature environments, while the large-scale use of slump-retaining agents leads to a long setting time and insufficient strength of the concrete. How to make ready-mixed concrete have the advantages of good fluidity, slump retention, short setting time and high early strength in a high-temperature environment is still a problem difficult for technical personnel in this field to solve. Summary of the invention

[0007] In order to solve the technical problem of how to make the ready-mixed concrete have the advantages of good fluidity, slump retention, short setting time and high early strength under high temperature environment mentioned in the above background technology, one embodiment of the present invention provides a high temperature resistant early strength slump retention type polycarboxylate water reducer, including: unsaturated polyether macromonomer, bistrimethylsilyl vinyl phosphate, oxidant, A liquid, B liquid; The A liquid is prepared by mixing a reducing agent and a chain transfer agent in a weight ratio of 0.15-1.5:1-5; The liquid B is prepared by mixing acrylic acid, N,N-methylenebisacrylamide, and a high temperature resistant silane coupling agent in a weight ratio of 10-15:1-5:1-5; The N,N-methylenebisacrylamide forms a micro-crosslinking structure with the unsaturated polyether macromonomer, bistrimethylsilyl vinyl phosphate and acrylic acid.

[0008] On the basis of the above embodiment, further, the composition ratio is as follows according to weight parts: Unsaturated polyether macromonomer 250~300 parts 5~10 parts of bis(trimethylsilyl) vinyl phosphate 2~4 parts of oxidant Reducing agent 0.5~1.5 parts Chain transfer agent 1~5 parts Acrylic acid 10~15 parts 1~5 parts of N,N-methylenebisacrylamide 1~5 parts of high temperature resistant silane coupling agent.

[0009] On the basis of the above embodiment, further, the unsaturated polyether macromonomer includes at least one of ethoxy vinyl polyethylene glycol ether and isopentenyl polyethylene glycol ether, and the molecular weight is 3000-5000 Da.

[0010] On the basis of the above embodiment, further, the oxidant includes at least one of peracetic acid, hydrogen peroxide, and ammonium persulfate.

[0011] On the basis of the above embodiment, further, the reducing agent includes at least one of L-ascorbic acid-2-phosphate sodium salt and 5,6-isopropyl-L-ascorbic acid.

[0012] On the basis of the above embodiment, further, the chain transfer agent includes at least one of 6-mercapto-1-hexanol, β-mercaptoethanol, and 2,3-dimercapto-1-propanol.

[0013] On the basis of the above embodiment, further, the high temperature resistant silane coupling agent is specifically an unsaturated aryl imide silane.

[0014] On the basis of the above embodiment, the high temperature resistant silane coupling agent is further prepared according to the following steps: S100, weigh potassium phthalimide and dimethylvinylchlorosilane in a molar ratio of 0.8:1.2~2; S101. Add the potassium salt of phthalic acid imide weighed in S100 into a container, and then add 30-60 mL of N,N-dimethylformamide; S102, oil bath heating at 120~140℃; S103, after all the potassium phthalimide salt in the container is dissolved, slowly drip dimethylvinyl chlorosilane, the dripping time is 1-2 hours; S104, after the dropwise addition is completed, heat to reflux for 24-30 h; S105, filter and remove the white precipitate, and take the filtrate; S106. Distill the filtrate in S105 under reduced pressure to remove N,N-dimethylformamide and excess dimethylvinylchlorosilane, and the resulting reddish brown transparent liquid is the unsaturated aryl imide silane.

[0015] The present invention also provides a method for preparing a high temperature resistant, early strength and collapse-retaining polycarboxylate water-reducing agent as described above, comprising the following steps: S200, dissolving the unsaturated polyether macromonomer and the bistrimethylsilyl vinyl phosphate in deionized water at 10-20° C. and mixing and stirring uniformly; S201, adding the oxidant, stirring evenly, to obtain a mixed solution with a mass fraction of 60-70%; S202, dripping the A solution into the mixed solution at a uniform speed, the dripping time being 50 to 60 min; S203, after the A solution has been added for 5 min, the B solution is added at a uniform speed for 70 to 80 min; S204, after the addition is completed, keep warm for 30-60 min; S205, after the heat preservation reaction is completed, sodium hydroxide solution is added dropwise to adjust the pH to 5-7, so as to obtain the high temperature resistant, early strength and collapse retaining polycarboxylate water reducer.

[0016] The present invention also provides a high temperature resistant, early strength and collapse retaining polycarboxylate water reducer as described in any one of the above items and its preparation method and use in concrete production.

[0017] The present invention has the following beneficial effects: The high-temperature resistant, early-strength, collapse-retaining polycarboxylate water-reducing agent provided by the present invention contains unsaturated aromatic imide silane. On the basis of retaining the coupling effect of the silane coupling agent on heterogeneous materials and the crack expansion effect of the flexible deformation layer organization, the presence of the aromatic group and the imide synergistically improves the heat resistance of the polymer, that is, in addition to the advantages of inhibiting the looseness of the initial hydration period, accelerating the cement hydration acceleration period and thus improving the early strength of the concrete, it also has the advantage of good heat resistance, thus solving the problems of long concrete setting time and insufficient strength in a complex high-temperature environment.

[0018] The high temperature resistant, early strength and collapse-retaining polycarboxylate water-reducing agent provided by the present invention further comprises a large number of polyether macromonomers with unsaturated double bonds, acrylic acid, silane phosphate and other components in the system, and the specially added N,N-methylenebisacrylamide can rely on the unsaturated double bonds to produce micro-crosslinking effects, so that the polymer has a micro-crosslinking structure, and utilizes intermolecular chemical bonds to hinder the movement of molecular chains, thereby further improving the heat resistance of the polymer.

[0019] The high-temperature resistant, early-strength, slump-retaining polycarboxylate water-reducing agent provided by the present invention contains highly hydrophilic groups and rigid groups such as phosphate groups and benzene rings in its molecular structure, can form a huge three-dimensional adsorption structure, produce a strong steric hindrance, improve the dispersibility and mud resistance of the water-reducing agent, and can significantly improve the slump retention ability of the concrete when added to concrete, solve the problem of poor fluidity of premixed concrete during construction in high temperature weather, and reduce the problems of large resistance, pipe blockage and long construction time during concrete pumping caused by excessive slump loss of premixed concrete.

[0020] The high-temperature resistant, early-strength, collapse-retaining polycarboxylate water-reducing agent provided by the present invention also contains a large number of hydrophilic groups such as carboxylic acid groups and hydroxyl groups in its molecular structure, which can combine with water molecules to form hydrogen bonds, thereby inhibiting the escape of water molecules into the air, reducing the evaporation of water, reducing the generation of shrinkage cracks inside the concrete, enhancing the degree of hydration of cement particles in the concrete, and strengthening the strength of the concrete.

[0021] The present invention also provides a high temperature resistant early strength slump retaining polycarboxylic acid water reducer and its preparation method for use in concrete production, which comprehensively solves the problems of poor fluidity and rapid slump loss of ready-mixed concrete in a high temperature environment, while the large amount of slump retaining agent leads to a long setting time and insufficient strength of the concrete.

[0022] Other features and beneficial effects of the present invention will be described in the following description, and some of the technical features and beneficial effects can be obviously derived from the description or understood by implementing the present invention. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments; the technical features designed in the different implementation modes of the present invention described below can be combined with each other as long as they do not conflict with each other; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0024] Example 1 Embodiment 1 of the present invention provides a high temperature resistant early strength and collapse retaining polycarboxylate water reducer, which is prepared by the following steps: Preparation of unsaturated aryl imide silane Weigh phthalic acid imide potassium salt and dimethylvinyl chlorosilane in a molar ratio of 0.8:1.2; Add the weighed potassium phthalimide salt into a three-necked flask equipped with a stirring device, a reflux condenser and a constant pressure dropping funnel, and then add 40 mL of N,N-dimethylformamide; The three-necked flask is heated in an oil bath at a temperature of 120° C. After the potassium phthalimide salt in the three-necked flask is completely dissolved, dimethylvinylchlorosilane is slowly added dropwise using a peristaltic pump for 1 h; After the addition was completed, the mixture was heated to reflux for 24 h; Filter to remove the white precipitate and take the filtrate; The filtrate is distilled under reduced pressure to remove N,N-dimethylformamide and excess dimethylvinylchlorosilane, and the resulting reddish brown transparent liquid is the unsaturated aryl imide silane.

[0025] Preparation of Solution A 0.5 parts of L-ascorbic acid-2-phosphate sodium salt and 1 part of β-mercaptoethanol were dissolved in deionized water and mixed and stirred evenly to prepare a liquid A with a mass fraction of 6.5%.

[0026] Preparation of Solution B 10 parts of acrylic acid, 3 parts of N,N-methylenebisacrylamide and 3 parts of unsaturated aryl imide silane were dissolved in deionized water and mixed and stirred evenly to prepare a liquid B with a mass fraction of 16%.

[0027] Preparation of high temperature resistant early strength and collapse-retaining polycarboxylate water reducer At 15°C, 250 parts of isopentenyl polyethylene glycol ether and 5 parts of bistrimethylsilyl vinyl phosphate were dissolved in deionized water and mixed and stirred evenly; Then add 3 parts of hydrogen peroxide and stir evenly to obtain a mixed solution with a mass fraction of 62%; The A solution was dripped into the mixed solution at a uniform speed for 50 min; After the A solution has been added for 5 min, the B solution is then added at a uniform speed for 70 min. After the addition was completed, the temperature was kept at room temperature for 30 min; After the heat preservation reaction is completed, a sodium hydroxide solution with a mass fraction of 30% is added dropwise to adjust the pH to 5.2 to obtain the high temperature resistant, early strength and collapse retaining polycarboxylate water reducer.

[0028] Example 2 Embodiment 2 of the present invention provides a high temperature resistant early strength and collapse retaining polycarboxylate water reducer, which is prepared by the following steps: Preparation of unsaturated aryl imide silane Weigh phthalic acid imide potassium salt and dimethylvinyl chlorosilane in a molar ratio of 0.8:1.4; Add the weighed potassium phthalimide salt into a three-necked flask equipped with a stirring device, a reflux condenser and a constant pressure dropping funnel, and then add 50 mL of N,N-dimethylformamide; The three-necked flask is heated in an oil bath at a temperature of 130° C. After the potassium phthalimide salt in the three-necked flask is completely dissolved, dimethylvinylchlorosilane is slowly added dropwise using a peristaltic pump for 1.5 h; After the addition was completed, the mixture was heated to reflux for 30 h; Filter to remove the white precipitate and take the filtrate; The filtrate is distilled under reduced pressure to remove N,N-dimethylformamide and excess dimethylvinylchlorosilane, and the resulting reddish brown transparent liquid is the unsaturated aryl imide silane.

[0029] Preparation of Solution A Dissolve 0.5 parts of L-ascorbic acid-2-phosphate sodium salt and 1 part of β-mercaptoethanol in deionized water, mix and stir evenly, and prepare a liquid A with a mass fraction of 6.5%.

[0030] Preparation of Solution B 12 parts of acrylic acid, 3 parts of N,N-methylenebisacrylamide and 3 parts of unsaturated aryl imide silane were dissolved in deionized water and mixed and stirred evenly to prepare a liquid B with a mass fraction of 17.1%.

[0031] Preparation of high temperature resistant early strength and collapse-retaining polycarboxylate water reducer At 15° C., 270 parts of isopentenyl polyethylene glycol ether and 7 parts of bistrimethylsilyl vinyl phosphate were dissolved in deionized water and mixed and stirred uniformly; Then add 3 parts of hydrogen peroxide and stir evenly to obtain a mixed solution with a mass fraction of 63.7%; The A solution was dripped into the mixed solution at a uniform speed for 60 min; After the A solution has been added for 5 min, the B solution is then added at a uniform speed for 70 min. After the addition was completed, the temperature was kept at room temperature for 30 min; After the heat preservation reaction is completed, a sodium hydroxide solution with a mass fraction of 30% is added dropwise to adjust the pH to 5.1 to obtain the high temperature resistant, early strength and collapse retaining polycarboxylate water reducer.

[0032] Example 3 Embodiment 3 of the present invention provides a high temperature resistant, early strength and collapse-retaining polycarboxylate water reducer, which is prepared by the following steps: Preparation of unsaturated aryl imide silane Weigh phthalic acid imide potassium salt and dimethylvinyl chlorosilane in a molar ratio of 0.8:1.6; Add the weighed potassium phthalimide salt into a three-necked flask equipped with a stirring device, a reflux condenser and a constant pressure dropping funnel, and then add 40 mL of N,N-dimethylformamide; The three-necked flask is heated in an oil bath at a temperature of 140° C. After the potassium phthalimide salt in the three-necked flask is completely dissolved, dimethylvinylchlorosilane is slowly added dropwise using a peristaltic pump for 1.5 h; After the addition was completed, the mixture was heated to reflux for 30 h; Filter to remove the white precipitate and take the filtrate; The filtrate is distilled under reduced pressure to remove N,N-dimethylformamide and excess dimethylvinylchlorosilane, and the resulting reddish brown transparent liquid is the unsaturated aryl imide silane.

[0033] Preparation of Solution A 0.8 parts of 5,6-isopropylidene-L-ascorbic acid and 2 parts of 6-mercapto-1-hexanol were dissolved in deionized water and mixed and stirred evenly to prepare a liquid A with a mass fraction of 7.2%.

[0034] Preparation of Solution B 15 parts of acrylic acid, 5 parts of N,N-methylenebisacrylamide and 4 parts of unsaturated aryl imide silane were dissolved in deionized water and mixed and stirred evenly to prepare a liquid B with a mass fraction of 18.5%.

[0035] Preparation of high temperature resistant early strength and collapse-retaining polycarboxylate water reducer At 15° C., 300 parts of isopentenyl polyethylene glycol ether and 10 parts of bistrimethylsilyl vinyl phosphate were dissolved in deionized water and mixed and stirred uniformly; Then add 3 parts of ammonium persulfate and stir evenly to obtain a mixed solution with a mass fraction of 67.3%; The A solution was dripped into the mixed solution at a uniform speed for 60 min; After the A solution has been added for 5 min, the B solution is then added at a uniform speed for 70 min. After the addition was completed, the temperature was kept at room temperature for 30 min; After the heat preservation reaction is completed, a sodium hydroxide solution with a mass fraction of 30% is added dropwise to adjust the pH to 5.5 to obtain the high temperature resistant, early strength and collapse retaining polycarboxylate water reducer.

[0036] Example 4 Embodiment 4 of the present invention provides a high temperature resistant early strength and collapse retaining polycarboxylate water reducer, which is prepared by the following steps: Preparation of unsaturated aryl imide silane Weigh phthalic acid imide potassium salt and dimethylvinyl chlorosilane in a molar ratio of 0.8:1.8; Add the weighed potassium phthalimide salt into a three-necked flask equipped with a stirring device, a reflux condenser and a constant pressure dropping funnel, and then add 60 mL of N,N-dimethylformamide; The three-necked flask is heated in an oil bath at a temperature of 135° C. After the potassium phthalimide salt in the three-necked flask is completely dissolved, dimethylvinylchlorosilane is slowly added dropwise using a peristaltic pump for 1.5 h; After the addition was completed, the mixture was heated to reflux for 27 h; Filter to remove the white precipitate and take the filtrate; The filtrate is distilled under reduced pressure to remove N,N-dimethylformamide and excess dimethylvinylchlorosilane, and the resulting reddish brown transparent liquid is the unsaturated aryl imide silane.

[0037] Preparation of Solution A Dissolve 1 part of 5,6-isopropylidene-L-ascorbic acid and 4 parts of 6-mercapto-1-hexanol in deionized water, mix and stir evenly, and prepare a liquid A with a mass fraction of 8.5%.

[0038] Preparation of Solution B 12 parts of acrylic acid, 3.5 parts of N,N-methylenebisacrylamide and 2.5 parts of unsaturated aryl imide silane were dissolved in deionized water and mixed and stirred evenly to prepare a liquid B with a mass fraction of 16.1%.

[0039] Preparation of high temperature resistant early strength and collapse-retaining polycarboxylate water reducer At 20° C., 265 parts of isopentenyl polyethylene glycol ether and 8.5 parts of bistrimethylsilyl vinyl phosphate were dissolved in deionized water and mixed and stirred uniformly; Then add 3 parts of peracetic acid and stir evenly to obtain a mixed solution with a mass fraction of 65.2%; The A solution was dripped into the mixed solution at a uniform speed for 60 min; After the A solution has been added for 5 min, the B solution is then added at a uniform speed for 70 min. After the addition was completed, the temperature was kept at room temperature for 30 min; After the heat preservation reaction is completed, a sodium hydroxide solution with a mass fraction of 30% is added dropwise to adjust the pH to 5.4 to obtain the high temperature resistant, early strength and collapse retaining polycarboxylate water reducer.

[0040] Example 5 Example 5 of the present invention provides a high temperature resistant, early strength and collapse-retaining polycarboxylate water reducer, which is prepared by the following steps: Preparation of unsaturated aryl imide silane Weigh phthalic acid imide potassium salt and dimethylvinyl chlorosilane in a molar ratio of 0.8:2; Add the weighed potassium phthalimide salt into a three-necked flask equipped with a stirring device, a reflux condenser and a constant pressure dropping funnel, and then add 60 mL of N,N-dimethylformamide; The three-necked flask is heated in an oil bath at a temperature of 130° C. After the potassium phthalimide salt in the three-necked flask is completely dissolved, dimethylvinylchlorosilane is slowly added dropwise using a peristaltic pump for 1.5 h; After the addition was completed, the mixture was heated to reflux for 27 h; Filter to remove the white precipitate and take the filtrate; The filtrate is distilled under reduced pressure to remove N,N-dimethylformamide and excess dimethylvinylchlorosilane, and the resulting reddish brown transparent liquid is the unsaturated aryl imide silane.

[0041] Preparation of Solution A 0.5 parts of L-ascorbic acid-2-phosphate sodium salt and 1 part of β-mercaptoethanol were dissolved in deionized water and mixed and stirred evenly to prepare a liquid A with a mass fraction of 6.3%.

[0042] Preparation of Solution B 10 parts of acrylic acid, 1.5 parts of N,N-methylenebisacrylamide and 5 parts of unsaturated aryl imide silane were dissolved in deionized water and mixed and stirred evenly to prepare a liquid B with a mass fraction of 17.4%.

[0043] Preparation of high temperature resistant early strength and collapse-retaining polycarboxylate water reducer At 20° C., 290 parts of isopentenyl polyethylene glycol ether and 5.5 parts of bistrimethylsilyl vinyl phosphate were dissolved in deionized water and mixed and stirred uniformly; Then add 4 parts of hydrogen peroxide and stir evenly to obtain a mixed solution with a mass fraction of 68.3%; The A solution was dripped into the mixed solution at a uniform speed for 60 min; After the A solution has been added for 5 min, the B solution is then added at a uniform speed for 70 min. After the addition was completed, the temperature was kept at room temperature for 30 min; After the heat preservation reaction is completed, a sodium hydroxide solution with a mass fraction of 30% is added dropwise to adjust the pH to 5.7 to obtain the high temperature resistant, early strength and collapse retaining polycarboxylate water reducer.

[0044] Comparative Example 1 Comparative Example 1 is a commercially available high temperature resistant and super collapse-resistant polycarboxylate water reducer, and the specific product information is BASF RHEOPLUS412, and its components include organic polymers such as sulfonated melamine, polyethylene glycol and polycarboxylate ether.

[0045] Comparative Example 2 Comparative Example 2 is a commercially available high early strength polycarboxylate water reducer, the specific product information of which is Sika 20HE-20, and its components include: modified polymers and organic polymers such as polycarboxylate ethers.

[0046] Comparative Example 3 Comparative Example 3 is a commercially available high temperature resistant collapse-preserving polycarboxylate water reducer, and the specific product information is SXH-P2 from Xinjiang Shengxinhe Chemical Technology Co., Ltd., and its components include organic polymers such as sugar calcium, phosphate and polycarboxylate ether.

[0047] Comparative Example 4 Comparative Example 4 is a commercially available early-strength and collapse-retaining polycarboxylate water-reducing agent, and the specific product information is BASF RHEOPLUS 329 (W1), and its components include: modified polymers and organic polymers such as polycarboxylate ethers.

[0048] Comparative Example 5 The difference from the high temperature resistant early strength and collapse-retaining polycarboxylic acid water-reducing agent provided in Example 1 is that it does not involve the preparation and addition of unsaturated aromatic imide silane, does not add N,N-methylenebisacrylamide, and replaces the silane phosphate bistrimethyl silylated vinyl phosphate with an unsaturated phosphoric acid monomer prepared from itaconic acid, 1-aminopropyl phosphoric acid and the inhibitor hydroquinone, and the other raw materials, preparation steps, reaction conditions and test methods are consistent with those in Example 1. That is, this comparative example provides a polycarboxylic acid water-reducing agent that does not contain silicon, imide and aromatic groups in its molecular structure, and its specific preparation steps are as follows: Preparation of unsaturated phosphoric acid monomer Itaconic acid, 1-aminopropylphosphoric acid and hydroquinone were weighed in a molar ratio of 1:1.5:0.003; Add the weighed itaconic acid, 1-aminopropylphosphoric acid and hydroquinone into a flask with a stirring device; The reaction was carried out at 115 °C with nitrogen blowing for 8 h; After the reaction is completed, the mixture is cooled to room temperature to obtain an unsaturated phosphoric acid monomer.

[0049] Preparation of Solution A 0.5 parts of L-ascorbic acid-2-phosphate sodium salt and 1 part of β-mercaptoethanol were dissolved in deionized water and mixed and stirred evenly to prepare a liquid A with a mass fraction of 6.5%.

[0050] Preparation of Solution B Dissolve 10 parts of acrylic acid in deionized water and stir evenly to prepare a liquid B with a mass fraction of 16%.

[0051] Preparation of polycarboxylate water reducer At 15° C., 250 parts of isopentyl polyethylene glycol ether and 5 parts of unsaturated phosphoric acid monomer were dissolved in deionized water and mixed and stirred evenly; Then add 3 parts of hydrogen peroxide and stir evenly to obtain a mixed solution with a mass fraction of 62%; The A solution was dripped into the mixed solution at a uniform speed for 50 min; After the A solution has been added for 5 min, the B solution is then added at a uniform speed for 70 min. After the addition was completed, the temperature was kept at room temperature for 30 min; After the heat preservation reaction is completed, a sodium hydroxide solution with a mass fraction of 30% is added dropwise to adjust the pH to 5.2 to obtain the polycarboxylate water reducer.

[0052] Comparative Example 6 The difference from the high temperature resistant early strength and collapse-retaining polycarboxylate water-reducing agent provided in Example 1 is that the unsaturated aryl imide silane is replaced by 2-maleimidoacetic acid, and the silane phosphate bistrimethyl silylated vinyl phosphate is replaced by an unsaturated phosphoric acid monomer prepared from butenoic acid, 2-hydroxyphosphonoacetic acid, a catalyst p-toluenesulfonic acid and an inhibitor p-hydroxyanisole, and other raw materials, preparation steps, reaction conditions and test methods are consistent with those in Example 1. That is, this comparative example provides a polycarboxylate water-reducing agent that does not contain silicon and aromatic groups in its molecular structure, and its specific preparation steps are as follows: Preparation of unsaturated phosphoric acid monomer Weigh crotonic acid, 2-hydroxyphosphonoacetic acid, p-toluenesulfonic acid and p-hydroxyanisole in a molar ratio of 1:0.8:0.04:0.007; Add the weighed crotonic acid, 2-hydroxyphosphonoacetic acid, p-toluenesulfonic acid and p-hydroxyanisole into a three-necked flask equipped with a stirring device, a reflux condenser and a constant pressure dropping funnel; The reaction was stirred at 110 °C for 3.5 h, and water was removed during the reaction; After the reaction is completed, the mixture is cooled to room temperature to obtain an unsaturated phosphoric acid monomer.

[0053] Preparation of Solution A 0.5 parts of L-ascorbic acid-2-phosphate sodium salt and 1 part of β-mercaptoethanol were dissolved in deionized water and mixed and stirred evenly to prepare a liquid A with a mass fraction of 6.5%.

[0054] Preparation of Solution B 10 parts of acrylic acid and 3 parts of 2-maleimidoacetic acid were dissolved in deionized water and mixed and stirred evenly to prepare a liquid B with a mass fraction of 16%.

[0055] Preparation of polycarboxylate water reducer At 15° C., 250 parts of isopentyl polyethylene glycol ether and 5 parts of unsaturated phosphoric acid monomer were dissolved in deionized water and mixed and stirred evenly; Then add 3 parts of hydrogen peroxide and stir evenly to obtain a mixed solution with a mass fraction of 62%; The A solution was dripped into the mixed solution at a uniform speed for 50 min; After the A solution has been added for 5 min, the B solution is then added at a uniform speed for 70 min. After the addition was completed, the temperature was kept at room temperature for 30 min; After the heat preservation reaction is completed, a sodium hydroxide solution with a mass fraction of 30% is added dropwise to adjust the pH to 5.2 to obtain the polycarboxylate water reducer.

[0056] Test example The high temperature resistant, early strength and slump-retaining polycarboxylate water-reducers provided in Examples 1 to 5 of the present invention, the commercially available slump-retaining polycarboxylate water-reducers of different types provided in Comparative Examples 1 to 4, and the polycarboxylate water-reducers prepared in Comparative Examples 5 and 6 with reference to the prior art were solidified to have the same solid content, compounded with a retarder, mixed into concrete, and the same dosage performance tests were performed in different temperature environments for comparison.

[0057] Among them, the concrete mixing environment temperature is 40℃ and 50℃; the concrete mix ratio is shown in Table 1; the admixture compounding scheme is shown in Table 2.

[0058] Table 1 Concrete mix ratio (kg / m 3 )

[0059] Table 2 Additive compounding scheme (g)

[0060] According to GB / T 8076-2008 Concrete Admixtures, the concrete mixtures to which the water reducers described in Examples 1 to 5 of the present invention and Comparative Examples 1 to 4 were added were tested for performance under the same conditions; wherein, the solid content was 2.2 to 2.5%. According to GB / T50081-2002 Standard Test Methods for Mechanical Properties of Ordinary Concrete, the concrete mixtures to which the water reducers described in Examples 1 to 5 of the present invention and Comparative Examples 1 to 4 were added were tested for mechanical properties; wherein, the concrete 1 d and 3 d compressive strength were specifically tested. The concrete test results are shown in Table 3.

[0061] Table 3 Concrete test results

[0062] In this test example, under the conditions of a certain concrete mix ratio and consistent solid content and dosage of the water reducing agent, the changes in concrete expansion and 1 d and 3 d compressive strength of concrete mixtures to which the water reducing agents described in Examples 1 to 5 of the present invention and Comparative Examples 1 to 6 are added are compared.

[0063] Among them, the concrete mixture mixed with the commercially available slump-retaining polycarboxylate water-reducing agent described in comparative examples 1 to 6 or the polycarboxylate water-reducing agent prepared with reference to the prior art has a large expansion loss at different ambient temperatures, and its expansion loss degree is significantly higher than the expansion loss degree of the concrete mixture mixed with the water-reducing agent described in Examples 1 to 5 of the present invention. Further, the 1 d and 3 d compressive strengths of the concrete mixtures respectively mixed with the water-reducing agents described in Examples 1 to 5 of the present invention and Comparative Examples 1 to 6 are tested. It can be seen from the data in Table 3 that the concrete mixture mixed with the water-reducing agent described in Examples 1 to 5 of the present invention has a significant early strength effect, can accelerate the cement hydration rate in a short time, and improve the early strength of concrete. The above test results fully illustrate that the high-temperature resistant early-strength slump-retaining polycarboxylate water-reducing agent provided by the present invention can maintain good fluidity and slump retention in a high temperature environment in a solid dosage range of 2.2% to 2.5%, and can significantly accelerate the cement hydration rate, shorten the setting time, and improve the early strength of the concrete mixture.

[0064] In addition, those skilled in the art should understand that, although there are many problems in the prior art, each embodiment or technical solution of the present invention can be improved in only one or several aspects, without having to solve all the technical problems listed in the prior art or background technology at the same time. Those skilled in the art should understand that the content not mentioned in a claim should not be used as a limitation on the claim.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high temperature resistant, early strength and collapse-retaining polycarboxylate water reducer, characterized in that: include: Unsaturated polyether macromonomer, bistrimethylsilyl vinyl phosphate, oxidant, liquid A, liquid B; The A liquid is prepared by mixing a reducing agent and a chain transfer agent in a weight ratio of 0.15-1.5:1-5; The liquid B is prepared by mixing acrylic acid, N,N-methylenebisacrylamide, and a high temperature resistant silane coupling agent in a weight ratio of 10-15:1-5:1-5; The N,N-methylenebisacrylamide forms a micro-crosslinking structure with the unsaturated polyether macromonomer, bistrimethylsilyl vinyl phosphate and acrylic acid.

2. The high temperature resistant, early strength and collapse-retaining polycarboxylate water reducer according to claim 1, characterized in that: The composition ratio is as follows: Unsaturated polyether macromonomer 250~300 parts 5~10 parts of bis(trimethylsilyl) vinyl phosphate 2~4 parts of oxidant Reducing agent 0.5~1.5 parts Chain transfer agent 1~5 parts Acrylic acid 10~15 parts 1~5 parts of N,N-methylenebisacrylamide 1~5 parts of high temperature resistant silane coupling agent.

3. The high temperature resistant, early strength and collapse-retaining polycarboxylate water reducer according to claim 1, characterized in that: The unsaturated polyether macromonomer includes at least one of ethoxy vinyl polyethylene glycol ether and isopentenyl polyethylene glycol ether, and has a molecular weight of 3000-5000 Da.

4. The high temperature resistant, early strength and collapse-retaining polycarboxylate water reducer according to claim 1, characterized in that: The oxidant includes at least one of peracetic acid, hydrogen peroxide, and ammonium persulfate.

5. The high temperature resistant, early strength and collapse-retaining polycarboxylate water reducer according to claim 1, characterized in that: The reducing agent includes at least one of L-ascorbic acid-2-phosphate sodium salt and 5,6-isopropylidene-L-ascorbic acid.

6. The high temperature resistant, early strength and collapse-retaining polycarboxylate water reducer according to claim 1, characterized in that: The chain transfer agent includes at least one of 6-mercapto-1-hexanol, β-mercaptoethanol, and 2,3-dimercapto-1-propanol.

7. The high temperature resistant, early strength and collapse-retaining polycarboxylate water reducer according to claim 1, characterized in that: The high temperature resistant silane coupling agent is specifically an unsaturated aryl imide silane.

8. The high temperature resistant, early strength and collapse-retaining polycarboxylate water reducer according to claim 7, characterized in that: The high temperature resistant silane coupling agent is prepared specifically according to the following steps: S100, weigh potassium phthalimide and dimethylvinylchlorosilane in a molar ratio of 0.8:1.2~2; S101. Add the potassium salt of phthalic acid imide weighed in S100 into a container, and then add 30-60 mL of N,N-dimethylformamide; S102, oil bath heating at 120~140℃; S103, after all the potassium phthalimide salt in the container is dissolved, slowly drip dimethylvinyl chlorosilane, the dripping time is 1-2 hours; S104, after the dropwise addition is completed, heat to reflux for 24-30 h; S105, filter and remove the white precipitate, and take the filtrate; S106. Distill the filtrate in S105 under reduced pressure to remove N,N-dimethylformamide and excess dimethylvinylchlorosilane, and the resulting reddish brown transparent liquid is the unsaturated aryl imide silane.

9. A method for preparing a high temperature resistant, early strength and collapse-retaining polycarboxylate water reducer according to any one of claims 1 to 8, characterized in that: The following steps are involved: S200, dissolving the unsaturated polyether macromonomer and the bistrimethylsilyl vinyl phosphate in deionized water at 10-20° C. and mixing and stirring uniformly; S201, adding the oxidant, stirring evenly, to obtain a mixed solution with a mass fraction of 60-70%; S202, dripping the A solution into the mixed solution at a uniform speed, the dripping time being 50 to 60 min; S203, after the A solution has been added for 3 to 10 minutes, the B solution is added at a uniform speed for 70 to 80 minutes; S204, after the addition is completed, keep warm for 30-60 min; S205, after the heat preservation reaction is completed, sodium hydroxide solution is added dropwise to adjust the pH to 5-7, so as to obtain the high temperature resistant, early strength and collapse retaining polycarboxylate water reducer.

10. Use of the high temperature resistant, early strength and collapse retaining polycarboxylate water reducer as claimed in any one of claims 1 to 9 and the preparation method thereof in concrete production.

Images