Special polycarboxylate superplasticizer for lithium slag and preparation method of special polycarboxylate superplasticizer

Abstract

The invention discloses a special polycarboxylate superplasticizer for lithium slag and a preparation method of the special polycarboxylate superplasticizer, and belongs to the technical field of concrete admixtures. The special polycarboxylate superplasticizer for the lithium slag has a structure as shown in a formula I; the preparation method comprises the following steps: dissolving unsaturated carboxylic acid acyl chloride and 3-[N, N-bis (ethoxyl) amino]-2-hydroxy propanesulfonic acid in an organic solvent, and carrying out acylation reaction under the action of a catalyst to obtain an unsaturated amide intermediate; carrying out esterification reaction on a betaine monomer and the unsaturated amide intermediate under the action of a dehydrating agent to obtain an unsaturated modified functional monomer; an unsaturated carboxylic acid monomer or an ester monomer, an unsaturated polyether macromonomer and an unsaturated modified functional monomer are subjected to a polymerization reaction in an initiation system, and the unsaturated polyether macromonomer is obtained. The special polycarboxylic acid water reducer for the lithium slag can improve the dispersion and anti-mud effects on a lithium slag cementing material, so that the hardening strength and durability of lithium slag concrete are improved, and the cracking risk of the lithium slag concrete is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of concrete admixtures, and particularly relates to a polycarboxylic acid water reducer special for lithium slag and a preparation method thereof. Background Art

[0002] With the release and implementation of the national "dual carbon" strategy, my country has entered a critical period of focusing on carbon reduction, promoting the synergy of pollution reduction and carbon reduction, and promoting the comprehensive green transformation of the economy and society. The "dual carbon" vision is being fully integrated into all aspects of social and economic development. The cement concrete industry is a major carbon emitter. To this end, reducing the clinker coefficient and building a green low-carbon cementitious material system are the key technical paths for concrete to reduce carbon emissions. In terms of low-carbon cementitious material systems, foreign research focuses on LC3 low-carbon cement and low-cement-high slag content cementitious material systems. Due to differences in material properties, preparation processes and application scenarios, the technology cannot be well integrated into the Chinese market; in China, a large amount of solid waste such as steel slag, lithium slag, and iron tailings slag is generated every year. If not utilized, it will lead to waste of resources and environmental pollution. Solid wastes such as steel slag, lithium slag, and iron tailings slag contain minerals similar to cement clinker, have certain cementitious properties or volcanic ash activity, and can obtain higher mechanical properties after appropriate excitation treatment. They are introduced into concrete to replace part of the powder and play a thickening role, thereby improving the fluidity, cohesion and water retention of concrete. Compared with traditional cementitious materials, the solid waste-based cementitious material system achieves the goals of low carbon and reduced energy consumption, and has more economic advantages.

[0003] However, lithium slag materials are fine-grained, porous, low in early activity, unstable in source, complex in composition, contain a certain amount of tailings powder and soil, and have high content of CaO, MgO, amorphous Al-O and Si-O. These components will adsorb or form stable complexes with the carboxyl or sulfonic acid groups in the polycarboxylic acid water reducer molecules, making it impossible for the water reducer to adsorb to the surface of the cementitious material to play a role, resulting in lithium slag concrete prone to problems such as high admixture dosage, high air content, fast slump loss, high viscosity and poor working performance. The existing special admixtures for solid waste-based gel materials have problems such as complex formula, difficult reaction control, low grafting efficiency, high reaction temperature, high hazard and high price of raw materials, which limit their application.

[0004] Therefore, it is necessary to develop a new type of environmentally friendly polycarboxylic acid water reducer specifically for lithium slag. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the present invention provides a polycarboxylic acid water-reducing agent special for lithium slag and a preparation method thereof. The polycarboxylic acid water-reducing agent has high water solubility, good compatibility with admixtures, good dispersion and anti-mud effects on lithium slag cementitious materials, can reduce the cracking risk of lithium slag concrete and the sensitivity of admixtures, and improve the hardening strength and durability of lithium slag concrete.

[0006] The technical solution adopted to solve the technical problem is to provide a polycarboxylate water reducer for lithium slag, which has a structure as shown in Formula I: ; Where: A is an unsaturated carboxylic acid monomer or an ester monomer; R is C n H 2n , n is an integer of 0 to 6; p is an integer of 0 to 4; R1 is H or C x H 2x+1 , x is an integer of 1 to 4; R2 is CH2, C2H4 or O-(CH2)4; R3 is H or CH3; a, b and c are all integers of 1 to 100, and m is an integer of 5 to 30.

[0007] Preferably, a, b, c and m are all degrees of polymerization.

[0008] Preferably, A is acrylic acid, methacrylic acid, sodium acrylate, sodium methallyl sulfonate, maleic acid, maleic anhydride, fumaric acid, itaconic acid, methyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, butyl acrylate, dibutyl maleate, dimethyl itaconate, diethyl itaconate, dipropyl itaconate, monobutyl itaconate or dibutyl itaconate; R is C n H 2n , n is an integer from 0 to 2; p is 0 or 2; R1 is H or C3H7.

[0009] More preferably, A is acrylic acid, methacrylic acid, maleic anhydride or itaconic acid.

[0010] More preferably, the specific structural formula of the polycarboxylate water reducer for lithium slag is as follows: .

[0011] The present invention also provides a method for preparing the above-mentioned polycarboxylate water-reducing agent for lithium slag, comprising the following steps: (1) dissolving unsaturated carboxylic acid chloride and 3-[N,N-di(hydroxyethyl)amino]-2-hydroxypropanesulfonic acid in an organic solvent, and carrying out an acylation reaction under the action of a catalyst to obtain an unsaturated amide intermediate; (2) subjecting the betaine monomer and the unsaturated amide intermediate to an esterification reaction under the action of a dehydrating agent to obtain an unsaturated modified functional monomer; (3) subjecting unsaturated carboxylic acid monomers or ester monomers, unsaturated polyether macromonomers, and unsaturated modified functional monomers to polymerization reaction under an initiating system to obtain the product.

[0012] The beneficial effects of the above technical solution of the present invention are as follows: the synthesis path of the polycarboxylate water reducer for lithium slag of the present invention is as follows: S1. Acylation reaction: unsaturated carboxylic acid chloride With 3-[N,N-di(hydroxyethyl)amino]-2-hydroxypropanesulfonic acid Acylation reaction is carried out to generate an unsaturated amide intermediate with 3 hydroxyl groups and 1 sulfonic acid group. The reaction mechanism is as follows: , Wherein, R0 and R are alkanes with 0 to 6 C atoms, and when 0 is taken, it is a H atom (take an integer); S2. Esterification reaction: betaine monomers Esterification reaction is carried out with the above intermediate to generate an unsaturated modified functional monomer with two betaine groups. The chemical reaction mechanism is as follows: , wherein p is an integer from 1 to 4; R1 is H or C x H 2x+1 , x is an integer from 0 to 4; S3, polymerization reaction: unsaturated carboxylic acid or ester monomers, unsaturated polyether macromonomers, and modified functional monomers undergo polymerization reaction to generate polycarboxylic acid water reducer for lithium slag. The chemical reaction mechanism is as follows: , wherein the unsaturated carboxylic acid or ester monomer is taken as acrylic acid; R and R1 are shown in S1 and S2; R2 is CH2, CH2CH2 or O-(CH2)4; R3 is H or CH3; a, b, c and m represent the degree of polymerization.

[0013] Preferably, in step (1), the unsaturated carboxylic acid chloride is but-3-enoyl chloride, pentenoyl chloride or isobutylenoyl chloride; the catalyst is triethylamine and / or ammonium chloride; the organic solvent is at least one of tetrahydrofuran, methanol, acetonitrile, ethyl acetate, ether and petroleum ether; the molar ratio of the unsaturated carboxylic acid chloride, 3-[N,N-di(hydroxyethyl)amino]-2-hydroxypropanesulfonate, the catalyst and the organic solvent is 1:(0.5~0.7):(2~3):(0.5~5); the acylation reaction temperature is room temperature and the reaction time is 12~15 h.

[0014] Preferably, in step (2), the dehydrating agent is methanesulfonic acid and / or p-toluenesulfonic acid; the betaine monomer is betaine, propyl betaine or butyl betaine; the molar ratio of the unsaturated amide intermediate, the betaine monomer and the dehydrating agent is 1:(2.5-3):(5-6.5); the esterification reaction temperature is 80-100°C, and the reaction time is 6-9 h.

[0015] Preferably, the initiation system comprises an oxidant, a reducing agent and a chain transfer agent; the unsaturated polyether macromonomer is methyl allyl polyoxyethylene ether, isopentanol polyoxyethylene ether, 4-hydroxybutyl vinyl polyoxyethylene ether or ethylene glycol monovinyl polyoxyethylene ether with a molecular weight of 2000-3200; step (3) comprises the following steps: dissolving an unsaturated carboxylic acid monomer or an ester monomer and an unsaturated modified functional monomer in water to obtain a first mixed solution; then mixing the reducing agent with water to obtain a second mixed solution; dissolving the unsaturated polyether macromonomer in water and adding an oxidant, then dripping the first mixed solution and the second mixed solution in sequence at room temperature for 40-90 min and 50-120 min, and keeping the temperature for 30-70 min, cooling to room temperature, and then diluting with water to a solid content of 35-45%, thereby obtaining the product.

[0016] Preferably, the molar ratio of the unsaturated carboxylic acid monomer or ester monomer, the unsaturated polyether macromonomer and the unsaturated modified functional monomer is 1:(2.5-5):(0.2-0.5).

[0017] Preferably, the oxidant is ammonium persulfate, sodium persulfate, potassium persulfate or hydrogen peroxide; the reducing agent is E51 reducing agent, L-ascorbic acid, isoascorbic acid, ferrous sulfate, sodium methylthiosulfate, sodium sulfite or sodium bisulfite; the chain transfer agent is thioglycolic acid, mercaptopropionic acid, mercaptoethanol or mercaptoethylamine; the molar ratio of the unsaturated carboxylic acid monomer or ester monomer, the oxidant, the reducing agent and the chain transfer agent is 1:(0.1~0.2):(0.005~0.015):(0.015~0.05).

[0018] The present invention has the following beneficial effects: (1) The polycarboxylic acid water reducer for lithium slag of the present invention introduces a modified functional monomer into the molecular structure through reactions such as acylation, esterification and polymerization, and has two betaine groups as side branches, and the main branch has a hydroxyl group and a sulfonic acid group, and has high hydrophilicity; after the water reducer molecule is hydrolyzed, the main structure retains the alcohol hydroxyl group, sulfonic acid group and quaternary ammonium salt component, further improving the dispersion effect and anti-mud effect of lithium slag cementitious materials, optimizing the bubble structure and pores in concrete, reducing the dosage sensitivity and material sensitivity of the admixture, and saving production costs; (2) The hydrolyzable group of the polycarboxylate water-reducing agent for lithium slag of the present invention also contains a quaternary ammonium salt component, which can not only be preferentially adsorbed on the surface of tailings powder and soil, effectively reducing the adsorption of polycarboxylate water-reducing agent molecules, but also the N element containing lone pair electrons can chelate CaO and MgO in steel slag, lithium slag and iron slag powder to form Ca 2+ and Mg 2+ , slowing down the hydration rate and reducing the risk of cracking of lithium slag concrete; (3) The carboxyl group at the end of the betaine monomer structure in the hydrolyzed group of the polycarboxylic acid water-reducing agent for lithium slag of the present invention can form a stable complex with the amorphous Al-O and Si-O of lithium slag, which is more conducive to the SiO2 and Al2O3 in the lithium slag powder to participate in the secondary hydration reaction to generate hydrated calcium silicate gel, thereby improving the hardening strength and durability of lithium slag concrete. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a graph showing the hydration temperature rise results of lithium slag cement paste after adding the water reducing agent of Examples 1 to 3 and Comparative Example 1. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with embodiment.It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention, that is, the embodiments described are only part of the embodiments of the present invention, rather than all embodiments.If the specific conditions are not indicated in the embodiments, they are carried out according to the conditions recommended by the normal conditions or the manufacturers.If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be obtained by commercial purchase.

[0021] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0022] The features and performance of the present invention are further described in detail below in conjunction with embodiments.

[0023] Example 1 A polycarboxylic acid water reducer specially used for lithium slag has a structure as shown in Formula II: .

[0024] This embodiment also provides a method for preparing the above-mentioned polycarboxylate water-reducing agent for lithium slag, comprising the following steps: (1) 1 mol of 3-[N,N-di(hydroxyethyl)amino]-2-hydroxypropanesulfonic acid was taken and dissolved, and poured into a reaction flask with a stirrer. Then, 1.5 mol of but-3-enoyl chloride and 3.2 mol of triethylamine were dissolved in 1 mol of ether and mixed in a reaction flask with a stirrer to carry out acylation reaction at room temperature for 13 h. After the reaction was completed, filtration, neutralization with saturated sodium carbonate solution, drying, filtration and distillation to remove ether were carried out in sequence to obtain an unsaturated amide intermediate with 3 hydroxyl groups and 1 sulfonic acid group; (2) 1 mol of unsaturated amide intermediate, 2.5 mol of betaine and 5 mol of methanesulfonic acid were added to a reactor with a water separator, and the esterification reaction was carried out at 85° C. for 8 h. After the reaction was completed, the mixture was cooled to room temperature, and then neutralized with sodium hydroxide, extracted with tetrahydrofuran, filtered and distilled to obtain an unsaturated modified functional monomer; (3) 1 mol acrylic acid, 0.4 mol unsaturated modified functional monomer and 0.018 mol mercaptoethanol were mixed and then water was added to obtain a first mixed solution; 0.005 mol E51 reducing agent was mixed with water to obtain a second mixed solution; 3 mol 4-hydroxybutyl vinyl polyoxyethylene ether with a molecular weight of 3000 was dissolved in water and placed in a reactor with a thermometer and a stirrer, 0.14 mol hydrogen peroxide was added to the reactor, and then the first mixed solution and the second mixed solution were added dropwise respectively. The first mixed solution was added dropwise for 45 min at room temperature, and the second mixed solution was added dropwise for 55 min. After completion, the mixture was kept warm for 70 min, cooled to room temperature, and diluted with water to a solid content of 40%, thereby obtaining a polycarboxylic acid water reducer for lithium slag.

[0025] Example 2 A polycarboxylate water reducer specially used for lithium slag has a structure as shown in Formula III: .

[0026] This embodiment also provides a method for preparing the above-mentioned polycarboxylate water-reducing agent for lithium slag, comprising the following steps: (1) 1 mol of 3-[N,N-di(hydroxyethyl)amino]-2-hydroxypropanesulfonic acid was taken and dissolved, and poured into a reaction flask with a stirrer. Then, 1.7 mol of pentenoyl chloride and 4 mol of triethylamine were dissolved in 2.5 mol of tetrahydrofuran and mixed in a reaction flask with a stirrer to carry out acylation reaction at room temperature for 14 h. After the reaction was completed, filtration, neutralization with saturated sodium carbonate solution, drying, filtration and distillation to remove ether were carried out in sequence to obtain an unsaturated amide intermediate with 3 hydroxyl groups and 1 sulfonic acid group; (2) 1 mol of unsaturated amide intermediate, 3 mol of propyl betaine and 6.5 mol of p-toluenesulfonic acid were added to a reactor with a water separator, and the esterification reaction was carried out at 100° C. for 6 h. After the reaction was completed, the mixture was cooled to room temperature, and then neutralized with sodium hydroxide, extracted with tetrahydrofuran, filtered and distilled to obtain an unsaturated modified functional monomer; (3) 1 mol itaconic acid, 0.2 mol unsaturated modified functional monomer and 0.025 mol thioglycolic acid were mixed and then water was added to obtain a first mixed solution; 0.008 mol L-ascorbic acid was mixed with water to obtain a second mixed solution; 3 mol isopentyl polyoxyethylene ether with a molecular weight of 2400 was dissolved in water and placed in a reactor equipped with a thermometer and a stirrer, 0.2 mol potassium persulfate was added to the reactor, and then the first mixed solution and the second mixed solution were added dropwise respectively. The first mixed solution was added dropwise for 70 min at room temperature, and the second mixed solution was added dropwise for 85 min. After completion, the mixture was kept warm for 60 min, cooled to room temperature, and diluted with water to a solid content of 40%, thereby obtaining a polycarboxylic acid water reducer for lithium slag.

[0027] Example 3 A polycarboxylate water reducer specially used for lithium slag has a structure as shown in Formula IV: .

[0028] This embodiment also provides a method for preparing the above-mentioned polycarboxylate water-reducing agent for lithium slag, comprising the following steps: (1) 1 mol of 3-[N,N-di(hydroxyethyl)amino]-2-hydroxypropanesulfonic acid was taken and dissolved, and poured into a reaction flask with a stirrer. Then, 1.8 mol of acryloyl chloride and 3.6 mol of ammonium chloride were dissolved in 5 mol of petroleum ether and mixed in a reaction flask with a stirrer to carry out acylation reaction at room temperature for 13 h. After the reaction was completed, filtration, neutralization with saturated sodium carbonate solution, drying, filtration and distillation were carried out to remove ether to obtain an unsaturated amide intermediate with 3 hydroxyl groups and 1 sulfonic acid group; (2) 1 mol of unsaturated amide intermediate, 2.5 mol of butyl betaine, 4.5 mol of methanesulfonic acid and 1 mol of p-toluenesulfonic acid were added to a reactor equipped with a water separator, and an esterification reaction was carried out at 90° C. for 6.5 h. After the reaction was completed, the mixture was cooled to room temperature, and then neutralized with sodium hydroxide, extracted with tetrahydrofuran, filtered and distilled to obtain an unsaturated modified functional monomer; (3) 1 mol maleic anhydride, 0.4 mol unsaturated modified functional monomer and 0.030 mol mercaptoethylamine were mixed and then water was added to obtain a first mixed solution; 0.010 mol isoascorbic acid was mixed with water to obtain a second mixed solution; 3.8 mol ethylene glycol monovinyl polyoxyethylene ether with a molecular weight of 2600 was dissolved in water and placed in a reactor equipped with a thermometer and a stirrer, 0.2 mol ammonium persulfate was added to the reactor, and then the first mixed solution and the second mixed solution were added dropwise respectively. The first mixed solution was added dropwise for 50 min at room temperature, and the second mixed solution was added dropwise for 60 min. After completion, the mixture was kept warm for 40 min, cooled to room temperature, and diluted with water to a solid content of 40%, thereby obtaining a polycarboxylic acid water reducer for lithium slag.

[0029] Example 4 A polycarboxylate water reducer for lithium slag, having a structure as shown in Formula V: .

[0030] This embodiment also provides a method for preparing the above-mentioned polycarboxylate water-reducing agent for lithium slag, comprising the following steps: (1) 1 mol of 3-[N,N-di(hydroxyethyl)amino]-2-hydroxypropanesulfonic acid is taken and dissolved, and poured into a reaction flask with a stirrer. Then, 1.5 mol of methacryloyl chloride, 3 mol of ammonium chloride and 1.2 mol of triethylamine are dissolved in 4 mol of methanol and mixed in a reaction flask with a stirrer to carry out acylation reaction at room temperature for 15 hours. After the reaction is completed, filtration, neutralization with saturated sodium carbonate solution, drying, filtration and distillation are carried out to remove ether to obtain an unsaturated amide intermediate with 3 hydroxyl groups and 1 sulfonic acid group. (2) 1 mol of unsaturated amide intermediate, 3 mol of propyl betaine, 5 mol of methanesulfonic acid and 1 mol of p-toluenesulfonic acid were added to a reactor equipped with a water separator, and an esterification reaction was carried out at 80° C. for 9 h. After the reaction was completed, the mixture was cooled to room temperature, and then neutralized with sodium hydroxide, extracted with tetrahydrofuran, filtered and distilled to obtain an unsaturated modified functional monomer; (3) 1 mol of methacrylic acid, 0.4 mol of unsaturated modified functional monomer and 0.030 mol of mercaptoethylamine were mixed and then water was added to obtain a first mixed solution; 0.012 mol of E51 reducing agent, 0.0001 mol of ferrous sulfate and water were mixed to obtain a second mixed solution; 4.5 mol of methyl allyl polyoxyethylene ether with a molecular weight of 2200 was dissolved in water and placed in a reactor with a thermometer and a stirrer, 0.15 mol of hydrogen peroxide was added to the reactor, and then the first mixed solution and the second mixed solution were added dropwise respectively. The first mixed solution was added dropwise for 90 min at room temperature, and the second mixed solution was added dropwise for 120 min. After completion, the mixture was kept warm for 60 min, cooled to room temperature, and diluted with water to a solid content of 40%, thereby obtaining a polycarboxylic acid water reducer for lithium slag.

[0031] Example 5 A polycarboxylate water reducer specially used for lithium slag has a structure as shown in Formula III: .

[0032] This embodiment also provides a preparation method of the above-mentioned polycarboxylic acid water-reducing agent for lithium slag, which is different from the preparation method of Example 2 in that the molecular weight of the isopentenyl polyoxyethylene ether used in the polymerization reaction in step (3) of this embodiment is 3200, and the other conditions and parameters are the same as those in Example 2.

[0033] Example 6 A polycarboxylate water reducer specially used for lithium slag has a structure as shown in Formula IV: .

[0034] This embodiment also provides a preparation method of the above-mentioned polycarboxylic acid water-reducing agent for lithium slag, which is different from the preparation method in Example 3 in that the molecular weight of ethylene glycol monovinyl polyoxyethylene ether used in the polymerization reaction in step (3) of this embodiment is 2000, and the other conditions and parameters are the same as those in Example 3.

[0035] Comparative Example 1 A polycarboxylate water reducer for lithium slag, having a structure as shown in formula VI: .

[0036] This comparative example also provides a method for preparing the above-mentioned polycarboxylic acid water-reducing agent for lithium slag, which differs from the preparation method of Example 2 in that: step (1) and step (2) in Example 2 are cancelled, and no unsaturated modified functional monomer is added in step (3), the amount of itaconic acid is changed from 1 mol to 1.2 mol, the types of oxidant, chain transfer agent, and reducing agent and their molar ratio to itaconic acid remain unchanged, and their amounts are changed accordingly according to the amount of itaconic acid, and the other conditions and parameters are the same as those in Example 2.

[0037] Comparative Example 2 Commercially available conventional polycarboxylic acid water reducer 1, ZJC-1 (solid content 10%, sourced from China Construction Western Construction New Materials Technology Co., Ltd.).

[0038] Comparative Example 3 Commercially available conventional polycarboxylate water reducer 2, ZJC-2 (solid content 10%, sourced from China Construction Western Construction New Materials Technology Co., Ltd.).

[0039] Experimental example (1) Using the reference cement P·O 42.5, the water reducers in Examples 1 to 6 of the present invention and Comparative Examples 1 to 3 (prepared into 10% concentration of water) were tested for cement mortar. Lithium slag powder replaced 30% of the cement, and montmorillonite and kaolin continued to replace 1% and 3% of the cement. The fluidity and mechanical strength of the lithium slag mortar were tested. The test mix ratios and test results are shown in Tables 1 and 2, respectively.

[0040] Table 1 Lithium slag powder cement mortar mix ratio (kg / m 3 )

[0041] Table 2 Test table of fluidity and mechanical strength of cement mortar containing lithium slag powder

[0042] (2) The polycarboxylate water reducer for lithium slag prepared in Examples 1 to 6 of the present invention and Comparative Example 1 and the water reducer prepared in Comparative Examples 2 to 3 were applied to C30 and C60 concrete using the same admixture formula (only the water reducer samples in the embodiments and comparative examples were replaced in equal amounts, and the other components and proportions remained unchanged), and the time-dependent fluidity and mechanical strength of the concrete were tested. Among them, the cement was Esheng cement P·O 42.5, and the fineness modulus of machine-made sand was 2.6; the crushed stone was a continuously graded crushed stone with a particle size of 5 to 20 mm, and the fly ash was Class I fly ash. The test method was based on GB / T50080-2016 "Standard Test Method for Performance of Ordinary Concrete Mixtures", GB / T50080-2016 "Standard Specification for Air Content of Concrete" and GB / T50081-2002 "Standard Test Method for Mechanical Properties of Ordinary Concrete", and the test results are shown in Table 4.

[0043] Table 3 Mix ratio of C30 and C60 concrete containing lithium slag (kg / m 3 )

[0044] Table 4 C30 and C60 concrete test table at room temperature

[0045] From the data in Table 2 and Table 4, it can be seen that the fluidity of the cement mortar containing lithium slag powder in Examples 1 to 6 is better than that in Comparative Examples 1 to 3. Under the same dosage, the mortar has good fluidity and the compressive strength is 1.5 to 6 MPa higher than that of the comparative examples. This shows that the modified functional monomer introduced into the structure of the polycarboxylate water-reducing agent for lithium slag of the present invention can improve the dispersibility and compressive strength of the lithium slag cement mortar. After adding a certain proportion of montmorillonite and kaolin, the dosage of the admixture is increased. When the dosage of each group remains the same, the fluidity of the mortar of Examples 1 to 6 is still better than that of the comparative example, and the compressive strength of the mortar is also improved to varying degrees. This is because after the prepared polycarboxylate water-reducing agent for lithium slag molecules are hydrolyzed, the main structure retains the alcohol hydroxyl group, sulfonic acid group and quaternary ammonium salt components, which further improves the dispersion effect and anti-mud effect on lithium slag concrete. Similarly, the fluidity and compressive strength data of C30 and C60 lithium slag concrete also show that, at the same dosage, the fluidity of Examples 1 to 6 is better, the loss is smaller, and the 28d compressive strength is also higher than that of the comparative example. From the comprehensive experimental results, the polycarboxylate water-reducing agent for lithium slag prepared by the present invention has better anti-mud, collapse protection and lithium slag powder dispersion effects than ordinary polycarboxylate water-reducing agents, and improves the sensitivity of the admixture to a certain extent.

[0046] (3) The water reducing agent samples prepared in Examples 1 to 3 and Comparative Example 1 were selected to prepare a 10% concentration of water agent for the hydration temperature rise test of lithium slag cement slurry. The test formula is shown in Table 5. The test results are shown in Table 5. Figure 1 .

[0047] Table 5 Hydration heat test mix ratio of cement paste containing lithium slag powder (g)

[0048] from Figure 1 It can be seen that compared with Comparative Example 1, after adding the lithium slag special polycarboxylate water reducer prepared in Examples 1 to 3, the hydration temperature rise of lithium slag cement paste is delayed, and the temperature peak is also reduced. In combination with the data in Table 2 and Table 3, it can be shown that the lithium slag special polycarboxylate water reducer described in the present invention, after introducing the modified functional monomer in the molecular structure by reactions such as acylation, esterification and polymerization, the water reducer molecule has high hydrophilicity, and the alcohol hydroxyl group, sulfonic acid group and quaternary ammonium salt group produced by hydrolysis further improve the dispersion effect and anti-mud effect of lithium slag concrete. At the same time, the N element containing lone pair electrons in the hydrolyzed quaternary ammonium salt group forms a chelate with CaO and MgO in the lithium slag powder, delaying the hydration temperature rise time of lithium slag concrete, slowing down the hydration rate and temperature peak, thereby reducing the risk of concrete cracking. In addition, the carboxyl group at the end of the betaine structure can form a stable complex with amorphous Al-O and Si-O in solid waste, which is more conducive to the participation of SiO2 and Al2O3 in lithium slag powder in secondary hydration reaction to generate hydrated calcium silicate gel, thereby improving the later strength of concrete in the lithium slag cementitious material system.

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A polycarboxylate water reducer for lithium slag, characterized in that: The polycarboxylate water reducer for lithium slag has a structure as shown in Formula I: ； Where: A is an unsaturated carboxylic acid monomer or an ester monomer; R is C n H 2n , n is an integer of 0 to 6; p is an integer of 0 to 4; R1 is H or C x H 2x+1 , x is an integer of 1 to 4; R2 is CH2, C2H4 or O-(CH2)4; R3 is H or CH3; a, b and c are all integers of 1 to 100, and m is an integer of 5 to 30.

2. The polycarboxylate water reducer for lithium slag according to claim 1, characterized in that: A is acrylic acid, methacrylic acid, sodium acrylate, sodium methallyl sulfonate, maleic acid, maleic anhydride, fumaric acid, itaconic acid, methyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, butyl acrylate, dibutyl maleate, dimethyl itaconate, diethyl itaconate, dipropyl itaconate, monobutyl itaconate or dibutyl itaconate; R is C n H 2n , n is an integer from 0 to 2; p is 0 or 2; R1 is H or C3H7.

3. The polycarboxylate water reducer for lithium slag according to claim 2, characterized in that: The A is acrylic acid, methacrylic acid, maleic anhydride or itaconic acid.

4. The polycarboxylate water reducer for lithium slag according to claim 3, characterized in that: The specific structural formula is as follows: 。 5. The method for preparing the polycarboxylate water-reducing agent for lithium slag according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) dissolving an unsaturated carboxylic acid chloride and 3-[N,N-di(hydroxyethyl)amino]-2-hydroxypropanesulfonic acid in an organic solvent, and carrying out an acylation reaction under the action of a catalyst to obtain an unsaturated amide intermediate; (2) subjecting the betaine monomer and the unsaturated amide intermediate to an esterification reaction under the action of a dehydrating agent to obtain an unsaturated modified functional monomer; (3) subjecting unsaturated carboxylic acid monomers or ester monomers, unsaturated polyether macromonomers, and unsaturated modified functional monomers to polymerization reaction under an initiating system to obtain the product.

6. The method for preparing a polycarboxylate water-reducing agent for lithium slag according to claim 5, characterized in that: In the step (1), the unsaturated carboxylic acid chloride is but-3-enoyl chloride, pentenoyl chloride or isobutylenoyl chloride; the catalyst is triethylamine and / or ammonium chloride; the organic solvent is at least one of tetrahydrofuran, methanol, acetonitrile, ethyl acetate, ether and petroleum ether; the molar ratio of the unsaturated carboxylic acid chloride, 3-[N,N-di(hydroxyethyl)amino]-2-hydroxypropanesulfonate, the catalyst and the organic solvent is 1:(0.5-0.7):(2-3):(0.5-5); the acylation reaction temperature is room temperature and the reaction time is 12-15 h.

7. The method for preparing a polycarboxylate water-reducing agent for lithium slag according to claim 5, characterized in that: In the step (2), the dehydrating agent is methanesulfonic acid and / or p-toluenesulfonic acid; the betaine monomer is betaine, propyl betaine or butyl betaine; the molar ratio of the unsaturated amide intermediate, the betaine monomer and the dehydrating agent is 1:(2.5-3):(5-6.5); the esterification reaction temperature is 80-100°C and the reaction time is 6-9 h.

8. The method for preparing a polycarboxylate water-reducing agent for lithium slag according to claim 5, characterized in that: The initiation system comprises an oxidant, a reducing agent and a chain transfer agent; the unsaturated polyether macromonomer is methyl allyl polyoxyethylene ether, isopentanol polyoxyethylene ether, 4-hydroxybutyl vinyl polyoxyethylene ether or ethylene glycol monovinyl polyoxyethylene ether with a molecular weight of 2000-3200; the step (3) comprises the following steps: dissolving an unsaturated carboxylic acid monomer or an ester monomer and an unsaturated modified functional monomer in water to obtain a first mixed solution; then mixing the reducing agent with water to obtain a second mixed solution; dissolving the unsaturated polyether macromonomer in water and adding an oxidant, then dripping the first mixed solution and the second mixed solution in sequence at room temperature for 40-90 min and 50-120 min, keeping the temperature for 30-70 min, cooling to room temperature, and then diluting with water to a solid content of 35-45%, thereby obtaining the product.

9. The method for preparing a polycarboxylate water-reducing agent for lithium slag according to claim 8, characterized in that: The molar ratio of the unsaturated carboxylic acid monomer or ester monomer, the unsaturated polyether macromonomer and the unsaturated modified functional monomer is 1:(2.5-5):(0.2-0.5).

10. The method for preparing a polycarboxylate water-reducing agent for lithium slag according to claim 8, characterized in that: The oxidant is ammonium persulfate, sodium persulfate, potassium persulfate or hydrogen peroxide; the reducing agent is E51 reducing agent, L-ascorbic acid, isoascorbic acid, ferrous sulfate, sodium methylthiosulfate, sodium sulfite or sodium bisulfite; the chain transfer agent is thioglycolic acid, mercaptopropionic acid, mercaptoethanol or mercaptoethylamine; the molar ratio of the unsaturated carboxylic acid monomer or ester monomer, the oxidant, the reducing agent and the chain transfer agent is 1:(0.1-0.2):(0.005-0.015):(0.015-0.05).

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