Soluble solid early-strength polycarboxylate superplasticizer and preparation method thereof

Abstract

The invention discloses a soluble solid early strength polycarboxylate superplasticizer and a preparation method thereof, and belongs to the technical field of concrete admixtures. The soluble solid early strength type polycarboxylate superplasticizer comprises a base material, a mixed material A, a mixed material B, a neutralizer and an anti-caking agent. Through the combined action of the catalytic promoter and the antagonist, the solid polycarboxylate superplasticizer is easy to dissolve, the performance loss of the solid polycarboxylate superplasticizer in the preparation process and when the solid polycarboxylate superplasticizer is directly used in a solid form is reduced, and due to the introduction of the amide monomer, the solid polycarboxylate superplasticizer has a certain early strength effect. Through optimization of adjustment of process parameters, reasonable matching of raw materials and the like, the soluble solid early-strength polycarboxylic acid water reducer does not need to be dissolved in water in advance and can be directly mixed with a dry concrete material for use, so that the stability of the overall performance of concrete is ensured, and the construction efficiency and the product quality are greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of concrete admixtures, and particularly relates to a readily soluble solid early-strength polycarboxylate water reducer and a preparation method thereof. Background Art

[0002] Polycarboxylate superplasticizer is one of the most widely used admixtures in modern concrete. Its main function is to improve the fluidity and workability of concrete, while significantly improving the strength and durability of concrete. Compared with traditional superplasticizers, polycarboxylate superplasticizer has significant advantages, including higher water reduction rate, efficient slump retention performance and diversified molecular design. These advantages make polycarboxylate superplasticizer an indispensable material in concrete formulation.

[0003] At present, the polycarboxylic acid water reducers on the market are mainly products with a solid content of 30%-50% produced by aqueous solution polymerization process. Although liquid polycarboxylic acid products have superior performance, they are inconvenient in storage and transportation, especially when transported over long distances, the transportation cost of liquid products increases significantly, and there is a risk of deterioration. These problems lead to a relatively high application cost of liquid polycarboxylic acid water reducers, limiting their widespread application. In order to reduce transportation costs and promote the widespread application of polycarboxylic acid water reducers, it is particularly important to develop solid polycarboxylic acid products. This solid form is not only convenient for transportation and storage, but also can improve the rheological properties of concrete during use, improve construction efficiency, and give cement-based or gypsum-based materials excellent physical properties. The preparation methods of solid polycarboxylic acid water reducers include vacuum suction method, spray drying method and precipitation method, among which spray drying method is particularly common. However, the spray drying method may have some problems in the preparation process, such as the prepared solid polycarboxylic acid water reducer usually contains 5% of other solvents, and during the high-temperature spray drying process, the water reducer may continue to polymerize or the polyether segment may be deactivated, thereby losing the effective ingredients and reducing the water reduction performance. In addition, the high energy consumption of this process also increases production costs and may lead to agglomeration problems in the products.

[0004] For example, Chinese patent application CN201210344349.8 discloses a method for preparing a composite water reducer for refractory materials, which includes the following steps: 1) Synthesis of polycarboxylic acid: 50-60 parts by weight of polyethylene glycol PEG100, 15-20 parts by weight of methacrylic acid, 5-10 parts by weight of 5% ammonium persulfate solution and 18-25 parts by weight of 10% mercaptoethanol solution are mixed, and polymerization reaction is carried out at 1-2 atmospheres and 60-100°C to obtain a polycarboxylic acid mixed solution; 2) Control of carrier slurry: Alumina powder is used as a carrier and is fully stirred with the obtained polycarboxylic acid mixed solution to control the solid content of the slurry to 50-80% and the viscosity to 100-1000 mPa.S; 3) Spray drying: The adjusted slurry is atomized and dried.

[0005] Therefore, it is urgent to develop a solid water reducing agent to solve the problems of single function, poor solubility and unsatisfactory comprehensive performance of the products after being mixed with concrete dry materials in existing commercially available solid polycarboxylate water reducing agents. Summary of the invention

[0006] The main technical problem solved by the present invention is to provide a readily soluble solid early-strength polycarboxylate water reducer and a preparation method thereof. The readily soluble solid early-strength polycarboxylate water reducer has the characteristics of strong adaptability to concrete raw materials and easy dissolution in water, and also has a certain early strength effect. In addition, after the water reducer is mixed with the concrete dry material, it can be injected into water for use without pre-dissolving in water.

[0007] In order to achieve the above technical objectives, the technical solution adopted by the present invention is: A readily soluble solid early-strength polycarboxylate water-reducing agent is prepared by comprising the following raw materials in parts by weight: 1019-1276 parts of a base material, 160-185 parts of a mixed material A, 0-25 parts of a mixed material B, 20-24 parts of a neutralizer, and 8-14 parts of an anti-caking agent.

[0008] Furthermore, the base material includes polyether monomer, catalyst, initiator, chain transfer agent A, and water, and the mass ratio thereof is (960-1200): (6-12): (7-9): (0-21): (33-55).

[0009] Furthermore, the polyether monomer is isopentanol polyoxyethylene ether with a molecular weight of 3000-4000; the initiator is one or more of azobisisobutyronitrile, tert-butyl hydroperoxide, and dimethyl azobisisobutyrate; the chain transfer agent A is sodium hypophosphite; and the catalyst aid is sodium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate and sorbitol, with a mass ratio of 1:2.

[0010] Furthermore, the mixed material A includes acrylic acid, amide, chain transfer agent B, and water in a mass ratio of (102-115): (35-58): (0-5): (0-26), and is used after being mixed evenly.

[0011] Furthermore, the amide is one or more of acrylamide, 2-methyl-2-acrylamidopropanesulfonic acid, and blocked amide phosphonate; and the chain transfer agent B is one or more of mercaptopropionic acid, thioglycolic acid, and mercaptoethanol.

[0012] Furthermore, the mixed material B includes a reducing agent and water in a mass ratio of 1:4, which are used after being mixed evenly.

[0013] Furthermore, the reducing agent is one or both of bleaching powder and E51.

[0014] Among them, E51 is a reducing agent, and its specific chemical name is sodium dioctyl sulfosuccinate.

[0015] Furthermore, the neutralizing agent is a 30% by mass sodium hydroxide solution; the anti-caking agent is a 1% by mass ammonium ferric citrate solution and sodium hydroxymethyl starch, and the mass ratio of the two is 1:1.

[0016] A method for preparing a readily soluble solid early-strength polycarboxylate water-reducing agent comprises the following preparation steps: The polyether monomer and water in the base material are heated by microwave until the reaction temperature reaches 70±2°C, stirred to dissolve, and then the catalyst and chain transfer agent A are added and stirred evenly, and the initiator is added step by step. After the initiator is added, the mixed material A and / or the mixed material B are added dropwise, and the reaction temperature is controlled to carry out polymerization reaction. The maximum temperature of the process does not exceed 85°C. After the addition is completed, it is maintained for 1-2 hours. The neutralizer and anti-caking agent are added in turn and mixed evenly. Part of the solvent and part of the unreacted monomer are evaporated under negative pressure at a temperature of 70±2°C, and the water content of the system is controlled to be ≤3%, and the solid content is ≥97%. Finally, the hot solution is cooled and crushed into a solid product with a particle size of less than 3mm to obtain the final product water reducer.

[0017] Furthermore, the microwave heating frequency is 2.45 GHz; after adding the neutralizer, the pH value of the system is ≥7; and the dropwise addition time of the mixed material A and / or material B is controlled within 3 hours.

[0018] The present invention provides a readily soluble solid early-strength polycarboxylate water-reducing agent and a preparation method thereof, wherein a high-solid polycarboxylate water-reducing agent mother liquor is synthesized by a microwave polymerization process, and then subjected to negative pressure evaporation and low-temperature crushing to obtain a solid product. The specific steps are as follows: a functional monomer is introduced into a base material solution in a dropwise manner, and copolymerized under the dual action of a catalytic aid and an initiator to generate a high-solid polycarboxylate water-reducing agent mother liquor, and then subjected to negative pressure evaporation and low-temperature crushing to prepare a final product with a suitable particle size.

[0019] Traditionally, polycarboxylate water reducers are mostly used in liquid form. However, the solid synthesis process popular in the market often has a significant negative impact on the performance of water reducers. This is because the solidification process may cause performance degradation or inhomogeneity. To overcome this challenge, we have taken a series of optimization measures, including adjusting process parameters, rationally matching raw materials to improve mixing uniformity, and improving the later powder pulverization process to avoid the impact of traditional high temperature environment on powder.

[0020] The catalyst additive added in the present invention is composed of sodium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate and sorbitol. The two are used in combination. On the one hand, sodium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate can interact with the electron cloud in the reactant to reduce the activation energy of the reaction, thereby making the reaction easier to occur; at the same time, the water-soluble properties of sodium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate also enable it to be evenly dispersed in the solution, further improving its catalytic efficiency; on the other hand, the added sorbitol can increase hydrophilicity by reducing surface tension, attracting water molecules to more easily penetrate into solid particles to accelerate the overall wetting process, forming hydrates with water molecules, increasing overall solubility, and quickly dissolving in water. In addition, it can also help improve the fluidity of concrete, and further improve the compatibility, dispersibility and stability of each component of the water reducer, so that the water reducer can be well dispersed in concrete, and a smaller amount of water reducer can be used to achieve the same water reduction effect, thereby reducing costs.

[0021] Secondly, using ammonium ferric citrate solution and sodium hydroxymethyl starch as anti-caking agents, ammonium ferric citrate can accelerate the crystallization process in the product, which helps to improve the dispersion of the product during use and prevent the aggregation of particles, thereby effectively avoiding the bonding problem in the later stage. Ammonium ferric citrate can also promote a more uniform hydration reaction, resulting in a denser microstructure in the early stage and improved early strength. Sodium hydroxymethyl starch promotes rapid water penetration and restores elasticity through its super strong water absorption and expansion ability, promotes particle separation, and allows solid polycarboxylate water reducer to disperse quickly in water. The synergistic effect of the catalyst and antagonist makes the water reducer more water-soluble, the concrete has high early strength, and excellent comprehensive mechanical properties.

[0022] By adding amide compounds, the amide groups participate in the formation of a physical network structure, which increases the cohesion of the cement paste. In addition, it has a strong adsorption effect on the surface of cement particles, which can promote early hydration reactions and help improve early strength.

[0023] In addition, the present invention adopts microwave heating, which improves the heating efficiency compared with the traditional heating method, and more importantly, promotes the movement of polar molecules, significantly increases the collision probability of reactant molecules, thereby making the reaction more complete. At the same time, the relatively suitable molecular polymerization degree improves the dispersibility and performance stability of the water reducer.

[0024] Beneficial Effects The solid water reducer of the present invention adopts microwave heating, and introduces a catalytic aid and an antagonist. On the one hand, the solid polycarboxylate water reducer can be quickly dissolved in water, and the dissolution time is significantly shortened, so that it is more convenient to mix with concrete dry materials, and the compatibility, dispersibility and stability of each component of the water reducer are improved, so that the water reducer can be better dispersed in concrete, and the fluidity of the concrete is improved; on the other hand, the present invention can not only be water-soluble before use, but also can be directly mixed with cement in a solid form for use. When the solid form is directly used, the solid polycarboxylate water reducer of the present invention can be more quickly and evenly dispersed in the entire mixed system after water is added, so that the workability of the concrete is significantly improved, and the early strength of the concrete can be further promoted.

[0025] Through these optimizations, the water solubility of solid polycarboxylate water reducer is greatly improved, the performance loss of solid polycarboxylate water reducer in the preparation process and when it is directly used in solid form is reduced, and a certain early strength effect is achieved. Finally, the improved solid polycarboxylate water reducer does not need to be dissolved in water in advance and can be directly mixed with concrete dry materials, which not only ensures the stability of the overall performance of concrete, but also greatly improves construction efficiency and product quality. DETAILED DESCRIPTION

[0026] The technical solution of the present invention is further described below in conjunction with specific embodiments, but is not limited thereto.

[0027] Example 1 A readily soluble solid early-strength polycarboxylate water-reducing agent comprises the following raw materials in parts by weight: 1081 parts of a base material, 160 parts of a mixed material A, 25 parts of a mixed material B, 20 parts of a neutralizer, and 12 parts of an anti-caking agent.

[0028] The base material includes 1000 parts of isopentanol polyoxyethylene ether, 9 parts of catalyst auxiliary, 7 parts of azobisisobutyronitrile, 21 parts of sodium hypophosphite, and 44 parts of water; the A material includes 102 parts of acrylic acid and 58 parts of acrylamido-2-methylpropane sulfonic acid; the B material includes 5 parts of bleaching powder and 20 parts of water; the neutralizer is a sodium hydroxide solution with a mass fraction of 30%; the anti-caking agent is 6 parts of ammonium ferric citrate solution with a mass fraction of 1% and 6 parts of sodium hydroxymethyl starch; the catalyst auxiliary includes 3 parts of sodium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate and 6 parts of sorbitol.

[0029] A method for preparing a readily soluble solid early-strength polycarboxylate water-reducing agent comprises the following preparation steps: The polyether monomer and water in the base material are heated by microwave until the reaction temperature reaches 70±2℃, the microwave frequency is 2.45GHz, stirred and dissolved, then the catalyst and chain transfer agent A sodium hypophosphite are added and stirred evenly, and the initiator is added step by step, and then the mixed material A and mixed material B are added dropwise, and the mixed material A and material B are added dropwise at the same time, and the addition is controlled within 3 hours. Then the system temperature is controlled to carry out polymerization reaction, and the highest temperature of the process does not exceed 85℃. After the addition is completed, it is maintained for 1h, and the neutralizer and anti-caking agent are added in sequence and mixed evenly. The pH value of the system is ≥7, and part of the solvent and part of the unreacted monomer are evaporated under negative pressure at a temperature of 70±2℃, and the water content of the system is controlled to be ≤3%. Finally, the hot solution is cooled and crushed into a solid product with a particle size of less than 3mm, and the final product water reducer is obtained.

[0030] Example 2 A readily soluble solid early-strength polycarboxylate water-reducing agent comprises the following raw materials in parts by weight: 1019 parts of a base material, 175 parts of a mixed material A, 24 parts of a neutralizer, and 8 parts of an anti-caking agent.

[0031] The base material includes 960 parts of isopentanol polyoxyethylene ether, 6 parts of catalyst aid, 8 parts of tert-butyl hydroperoxide, and 45 parts of water; the A material includes 110 parts of acrylic acid, 35 parts of acrylamide, 4 parts of mercaptopropionic acid, and 26 parts of water; the neutralizer is a 30% by mass sodium hydroxide solution; the anti-caking agent is 4 parts of a 1% by mass ammonium ferric citrate solution and 4 parts of sodium hydroxymethyl starch; the catalyst aid includes 2 parts of sodium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate and 4 parts of sorbitol.

[0032] A method for preparing a readily soluble solid early-strength polycarboxylate water-reducing agent comprises the following preparation steps: The polyether monomer and water in the base material are heated by microwave until the reaction temperature reaches 70±2℃, the microwave frequency is 2.45GHz, stirred and dissolved, then the catalyst is added and stirred evenly, and the initiator is added step by step, and then the mixed material A is added dropwise, and the mixed material A is controlled to be added dropwise within 3 hours. The system temperature is controlled to carry out polymerization reaction, and the highest temperature of the process does not exceed 85℃. After the addition is completed, it is maintained for 1.5h, and the neutralizer and anti-caking agent are added in sequence and mixed evenly. The pH value of the system is ≥7, and part of the solvent and part of the unreacted monomer are evaporated under negative pressure at a temperature of 70±2℃, and the water content of the system is controlled to be ≤3%. Finally, the hot solution is cooled and crushed into a solid product with a particle size of less than 3mm, and the final product water reducer is obtained.

[0033] Example 3 A readily soluble solid early-strength polycarboxylate water-reducing agent comprises the following raw materials in parts by weight: 1276 parts of a base material, 185 parts of a mixed material A, 22 parts of a neutralizer, and 14 parts of an anti-caking agent.

[0034] The base material includes 1200 parts of isopentanol polyoxyethylene ether, 12 parts of catalyst auxiliary, 9 parts of dimethyl azobisisobutyrate, and 55 parts of water; the A material includes 115 parts of acrylic acid, 50 parts of blocked amide phosphonate, 5 parts of mercaptoethanol, and 15 parts of water; the neutralizer is a 30% by mass sodium hydroxide solution; the anti-caking agent is 7 parts of a 1% by mass ammonium ferric citrate solution and 7 parts of sodium hydroxymethyl starch; the catalyst auxiliary includes 4 parts of sodium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate and 8 parts of sorbitol.

[0035] A method for preparing a readily soluble solid early-strength polycarboxylate water-reducing agent comprises the following preparation steps: The polyether monomer and water in the base material are heated by microwave until the reaction temperature reaches 70±2℃, the microwave frequency is 2.45GHz, stirred and dissolved, then the catalyst is added and stirred evenly, and the initiator is added step by step, and then the mixed material A is added dropwise, and the mixed material A is added dropwise within 2 hours. The system temperature is controlled to carry out polymerization reaction, and the highest temperature of the process does not exceed 85℃. After the addition is completed, it is maintained for 2h, and the neutralizer and anti-caking agent are added in sequence and mixed evenly. The pH value of the system is ≥7, and part of the solvent and part of the unreacted monomer are evaporated under negative pressure at a temperature of 70±2℃, and the water content of the system is controlled to be ≤3%. Finally, the hot solution is cooled and crushed into a solid product with a particle size of less than 3mm, and the final product water reducer is obtained.

[0036] Example 4 A readily soluble solid early-strength polycarboxylate water-reducing agent comprises the following raw materials in parts by weight: 1110 parts of a base material, 170 parts of a mixed material A, 10 parts of a mixed material B, 22 parts of a neutralizer, and 11 parts of an anti-caking agent.

[0037] The base material includes 1060 parts of isopentanol polyoxyethylene ether, 9 parts of catalyst aid, 8 parts of tert-butyl hydroperoxide, and 33 parts of water; the A material includes 110 parts of acrylic acid, 35 parts of blocked amide phosphonate, 4 parts of thioglycolic acid, and 21 parts of water; the B material includes 2 parts of E51 and 8 parts of water; the neutralizer is a 30% by mass sodium hydroxide solution; the anti-caking agent is 5.5 parts of a 1% by mass ammonium ferric citrate solution and 5.5 parts of sodium hydroxymethyl starch; the catalyst aid includes 3 parts of sodium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate and 6 parts of sorbitol.

[0038] A method for preparing a readily soluble solid early-strength polycarboxylate water-reducing agent comprises the following preparation steps: The polyether monomer and water in the base material are heated by microwave until the reaction temperature reaches 70±2℃, the microwave frequency is 2.45GHz, stirred and dissolved, then the catalyst is added and stirred evenly, and the initiator is added step by step, and then the mixed material A and mixed material B are added dropwise, and the mixed material A and material B are added dropwise at the same time, and the addition is controlled to be completed within 2 hours. The system temperature is controlled to carry out polymerization reaction, and the highest temperature of the process does not exceed 85℃. After the addition is completed, it is maintained for 1.5h, and the neutralizer and anti-caking agent are added in sequence and mixed evenly. The pH value of the system is ≥7, and part of the solvent and part of the unreacted monomer are evaporated under negative pressure at a temperature of 70±2℃, and the water content of the system is controlled to be ≤3%. Finally, the hot solution is cooled and crushed into a solid product with a particle size of less than 3mm, and the final product water reducer is obtained.

[0039] Comparative Example 1 A readily soluble solid early-strength polycarboxylate water-reducing agent comprises the following raw materials in parts by weight: 1072 parts of a base material, 160 parts of a mixed material A, 25 parts of a mixed material B, 20 parts of a neutralizer, and 12 parts of an anti-caking agent.

[0040] The base material includes 1000 parts of isopentanol polyoxyethylene ether, 7 parts of azobisisobutyronitrile, 21 parts of sodium hypophosphite, and 44 parts of water; the A material includes 102 parts of acrylic acid and 58 parts of acrylamide-2-methylpropane sulfonic acid; the B material includes 5 parts of bleaching powder and 20 parts of water; the neutralizer is a sodium hydroxide solution with a mass fraction of 30%; the anti-caking agent is 6 parts of ammonium ferric citrate solution with a mass fraction of 1% and 6 parts of sodium hydroxymethyl starch.

[0041] In this comparative example, except that no catalyst aid is added, the other raw materials and preparation method are the same as those in Example 1.

[0042] Comparative Example 2 A readily soluble solid early-strength polycarboxylate water-reducing agent comprises the following raw materials in parts by weight: 1081 parts of a base material, 160 parts of a mixed material A, 25 parts of a mixed material B, 20 parts of a neutralizer, and 12 parts of an anti-caking agent.

[0043] The base material includes 1000 parts of isopentanol polyoxyethylene ether, 9 parts of catalyst auxiliary agent, 7 parts of azobisisobutyronitrile, 21 parts of sodium hypophosphite, and 44 parts of water; the A material includes 102 parts of acrylic acid and 58 parts of acrylamide-2-methylpropane sulfonic acid; the B material includes 5 parts of bleaching powder and 20 parts of water; the neutralizer is a sodium hydroxide solution with a mass fraction of 30%; the anti-caking agent is an ammonium ferric citrate solution with a mass fraction of 1%; the catalyst auxiliary agent includes 3 parts of sodium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate and 6 parts of sorbitol.

[0044] In this comparative example, except that only 1% by mass of ammonium ferric citrate solution was used as the antagonist, the other raw materials and preparation method were the same as those in Example 1.

[0045] Comparative Example 3 A readily soluble solid early-strength polycarboxylate water-reducing agent comprises the following raw materials in parts by weight: 1081 parts of a base material, 160 parts of a mixed material A, 25 parts of a mixed material B, 20 parts of a neutralizer, and 12 parts of an anti-caking agent.

[0046] The base material includes 1000 parts of isopentanol polyoxyethylene ether, 9 parts of catalyst auxiliary, 7 parts of azobisisobutyronitrile, 21 parts of sodium hypophosphite, and 44 parts of water; the A material includes 102 parts of acrylic acid and 58 parts of acrylamido-2-methylpropane sulfonic acid; the B material includes 5 parts of bleaching powder and 20 parts of water; the neutralizer is a sodium hydroxide solution with a mass fraction of 30%; the anti-caking agent is sodium hydroxymethyl starch; the catalyst auxiliary includes 3 parts of sodium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate and 6 parts of sorbitol.

[0047] In this comparative example, except that only sodium hydroxymethyl starch was used as the antagonist, the other raw materials and preparation methods were the same as those in Example 1.

[0048] Comparative Example 4 A readily soluble solid early-strength polycarboxylate water-reducing agent comprises the following raw materials in parts by weight: 1081 parts of a base material, 160 parts of a mixed material A, 25 parts of a mixed material B, 20 parts of a neutralizer, and 12 parts of an anti-caking agent.

[0049] The base material includes 1000 parts of isopentanol polyoxyethylene ether, 9 parts of catalyst auxiliary, 7 parts of azobisisobutyronitrile, 21 parts of sodium hypophosphite, and 44 parts of water; the A material includes 102 parts of acrylic acid and 58 parts of acrylamido-2-methylpropane sulfonic acid; the B material includes 5 parts of bleaching powder and 20 parts of water; the neutralizer is a sodium hydroxide solution with a mass fraction of 30%; the anti-caking agent is 6 parts of ammonium ferric citrate solution with a mass fraction of 1% and 6 parts of sodium hydroxymethyl starch; the catalyst auxiliary includes 3 parts of sodium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate and 6 parts of sorbitol.

[0050] A method for preparing a readily soluble solid early-strength polycarboxylate water-reducing agent comprises the following preparation steps: The polyether monomer and water in the base material are heated in a conventional water bath until the reaction temperature reaches 70±2℃, stirred and dissolved, and then the catalyst is added and stirred evenly, and the initiator is added step by step, and then the mixed material A and mixed material B are added dropwise, and the mixed material A and material B are added dropwise at the same time, and the addition is controlled to be completed within 2 hours. The system temperature is controlled to carry out the polymerization reaction, and the maximum temperature of the process does not exceed 85℃. After the addition is completed, it is maintained for 1.5h, and the neutralizer and anti-caking agent are added in sequence and mixed evenly. The pH value of the system is ≥7, and part of the solvent and part of the unreacted monomer are evaporated under negative pressure at a temperature of 70±2℃. The water content of the system is controlled to be ≤3%. Finally, the hot solution is cooled and crushed into a solid product with a particle size of less than 3mm, and the final product water reducer is obtained.

[0051] In this comparative example, except that microwave heating was not used and conventional water bath heating was used, the other raw materials and preparation method were the same as those in Example 1.

[0052] Performance Testing Zhonglian PO 42.5 cement was used respectively, and the solid water-reducing agent and the water-soluble liquid water-reducing agent added in the experiment were kept consistent in the solid dosage, and the usage amount was 0.18% of the total amount of cementitious materials. The products obtained in Examples 1-4 and Comparative Examples 1-4 were compared with commercially available solid polycarboxylate water-reducing agent products for concrete performance. According to GB / T 8077-2023 "Test Method for Homogeneity of Concrete Admixtures", the fluidity of cement paste was measured, the water-cement ratio was 0.29, and the reference cement was used. The test results are shown in Table 1; according to the test requirements of GB / T 50081-2019 "Standard for Test Methods for Mechanical Properties of Ordinary Concrete", the concrete test blocks were formed, and the strength of the concrete at each age was measured. Each group of experiments was tested 10 times, and the results were averaged. The test results are shown in Table 2.

[0053] Table 1. Water dissolution time and cement slurry fluidity data

[0054] Table 2. Compressive strength data of concrete at different ages

[0055] According to the data analysis of the embodiments, comparative examples and commercially available solid polycarboxylate water-reducers in Tables 1 and 2, the solid polycarboxylate water-reducer prepared in the embodiments has good water solubility. After being introduced into the concrete system, the early strength of the concrete is effectively improved. At the same time, the water-reducer of the present invention can be directly incorporated into concrete in solid form, and after adding water, it can be quickly dissolved in water and dispersed in the concrete system. The present invention adds a catalytic promoter and an antagonist, and is assisted by microwave heating. The three key technical means work together to enable the solid polycarboxylate water-reducer to be quickly dissolved in water, and improve the compatibility, dispersibility and stability of the various components of the water-reducing agent, so that the water-reducing agent can be better dispersed in the concrete slurry, helping to improve the fluidity of the concrete. The three key technical means complement each other, and the effect is weak if one is missing.

[0056] The present invention can not only be treated with water before use, but also can be directly mixed with concrete dry materials in solid form. When used directly in solid form, the solid polycarboxylate water reducer of the present invention can be more quickly and evenly dispersed in the entire mixed system after water is added, significantly improving the workability of concrete and effectively reducing the effect of cement on the initial performance of the solid water reducer. From the above data, it can be seen that the solid polycarboxylate water reducer of the present invention exhibits more excellent water-reducing performance in practical applications. By adjusting process parameters, reasonably matching raw materials, etc., the performance loss of the solid polycarboxylate water reducer during the preparation process and when it is directly used in solid form is reduced, and the concrete quality and construction efficiency are significantly improved.

[0057] It should be noted that the above embodiments are only partial embodiments of the preferred methods of implementing the present invention, rather than all embodiments. Obviously, based on the above embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

Claims

1. A readily soluble solid early-strength polycarboxylate water-reducing agent, characterized in that: The invention comprises the following raw materials in parts by weight: 1019-1276 parts of base material, 160-185 parts of mixed material A, 0-25 parts of mixed material B, 20-24 parts of neutralizer and 8-14 parts of anti-caking agent.

2. The readily soluble solid early-strength polycarboxylate water-reducing agent according to claim 1, characterized in that: The base material comprises polyether monomer, catalyst aid, initiator, chain transfer agent A and water, and the mass ratio thereof is (960-1200): (6-12): (7-9): (0-21): (33-55).

3. The readily soluble solid early-strength polycarboxylate water-reducing agent according to claim 2, characterized in that: The polyether monomer is prenol polyoxyethylene ether with a molecular weight of 3000-4000; the initiator is one or more of azobisisobutyronitrile, tert-butyl hydroperoxide, and dimethyl azobisisobutyrate; and the chain transfer agent A is sodium hypophosphite.

4. The readily soluble solid early-strength polycarboxylate water-reducing agent according to claim 2, characterized in that: The catalyst aid is sodium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate and sorbitol, and the mass ratio thereof is 1:

2.

5. The readily soluble solid early-strength polycarboxylate water-reducing agent according to claim 1, characterized in that: The mixed material A includes acrylic acid, amide, chain transfer agent B, and water, and the mass ratio thereof is (102-115): (35-58): (0-5): (0-26); the mixed material B includes a reducing agent and water, and the mass ratio thereof is 1:4; the reducing agent is one or two of bleaching powder and E51; the neutralizing agent is a sodium hydroxide solution with a mass fraction of 30%; the anti-caking agent is an ammonium ferric citrate solution with a mass fraction of 1% and sodium carboxymethyl starch, and the mass ratio thereof is 1:

1.

6. The readily soluble solid early-strength polycarboxylate water-reducing agent according to claim 5, characterized in that: The amide is one or more of acrylamide, 2-methyl-2-acrylamidopropanesulfonic acid, and blocked amide phosphonate; the chain transfer agent B is one or more of mercaptopropionic acid, thioglycolic acid, and mercaptoethanol.

7. A method for preparing the readily soluble solid early-strength polycarboxylate water-reducing agent according to any one of claims 1 to 6, characterized in that: The method comprises the following preparation steps: The polyether monomer and water in the base material are heated by microwave until the reaction temperature reaches 70±2℃, stirred to dissolve, and then the catalyst and / or chain transfer agent A are added and stirred evenly, and the initiator is added step by step. After the initiator is added, the mixed material A and / or mixed material B are added dropwise, and the temperature is controlled to carry out polymerization reaction. The maximum temperature of the process does not exceed 85℃. After the addition is completed, it is maintained for 1-2h. The neutralizer and anti-caking agent are added in sequence and mixed evenly. Part of the solvent and part of the unreacted monomer are evaporated under negative pressure at a temperature of 70±2℃, and the water content of the system is controlled to be ≤3%. Finally, the hot solution is cooled and crushed into a solid product with a particle size of less than 3mm to obtain the final product water reducer.

8. The method for preparing the readily soluble solid early-strength polycarboxylate water-reducing agent according to claim 7, characterized in that: The microwave heating frequency is 2.45 GHz; after adding the neutralizer, the pH value of the system is ≥7; and the dropwise addition time of the mixed material A and / or material B is controlled within 3 hours.

Images