Water reducing agent suitable for calcined clay composite cement as well as preparation method and application of water reducing agent

Abstract

The invention relates to a water reducing agent suitable for calcined clay composite cement and a preparation method and application thereof.The preparation method of the water reducing agent comprises the following steps that isopentenyl polyglycol ether and an oxidizing agent are added into deionized water, heated and stirred until the isopentenyl polyglycol ether and the oxidizing agent are dissolved, and a solution a is obtained; dissolving a carboxylic acid monomer with double bonds, a hydroxy carboxylic acid monomer and a catalyst in deionized water for esterification reaction to obtain a solution b; adding a chain transfer agent and a reducing agent into deionized water, and stirring until the materials are dissolved to obtain a solution c; under the heating and stirring conditions, the solution b and the solution c are dropwise added into the solution a at the same time, then heat preservation treatment is conducted, and after the pH is adjusted, the water reducing agent suitable for the calcined clay composite cement is obtained. Compared with the prior art, the water reducing agent prepared by the invention is simple in process, green and environment-friendly, has excellent performance in a calcined clay composite cement system, and can promote the later strength development while improving the initial working performance and fluidity retention ability.

Description

Technical Field

[0001] The present invention relates to the technical field of building materials, and in particular to a water reducing agent suitable for calcined clay composite cement, and a preparation method and application thereof. Background Art

[0002] my country is a major cement producer and consumer, accounting for over 50% of the world's total cement production. Cement production generates significant CO2 emissions. In 2022, my country's cement industry emitted approximately 1.2 billion tons of carbon, accounting for approximately 10% of the nation's total carbon emissions. Therefore, low-carbon emissions reduction in the cement industry is imperative. Given the unavoidable carbon emissions from raw material decomposition and the near-saturation of cement plant energy utilization, traditional process optimization for Portland cement has reached a bottleneck in carbon reduction. Developing new low-carbon cementitious materials has become an essential path to achieving carbon reduction in the cement industry. In this context, replacing 30%-50% of cement clinker with calcined clay can reduce system carbon emissions by over 30% without compromising subsequent mechanical properties. However, calcined clay composite cements exhibit poor performance in practical applications. Conventional water-reducing agents in calcined clay composite cement systems often require high dosages (4 to 5 times that of ordinary Portland cement) and exhibit poor fluidity loss over time, severely hindering their engineering applications. Therefore, the development of a water-reducing agent suitable for calcined clay composite cement is not only a core technical challenge to break through the performance ceiling of low-carbon cementitious materials, but also a strategic need to promote the green upgrade of 100 million tons of industrial production capacity and accelerate the carbon peak process in the construction field. It has great practical significance for the global response to climate change.

[0003] Chinese patent CN116217830 A discloses a water reducer for calcined kaolin-cement system and its preparation method and application. Compared with traditional water reducers, the introduction of more reactive VPEG macromonomers enables the water reducer synthesis process to be carried out at room temperature, shortening industrial production time and reducing costs. However, the patent does not address the pain point of large drop in the time of calcined clay composite cement system. Chinese patent CN118420843 A discloses a preparation method for calcined clay limestone cement (LC3) water reducer. The patent introduces vinyl acetate and 2-acrylamide-2-methylpropene sulfonic acid into the traditional comb-type water reducer, causing it to continuously hydrolyze carboxyl functional groups in the cement pore solution to obtain continuous adsorption capacity, which improves the water reducer's retention capacity in the LC3 system. However, the patent reduces the initial adsorption capacity of the water reducer, resulting in low initial fluidity, and its time-dependent fluidity still needs to be improved. Summary of the Invention

[0004] The purpose of the present invention is to provide a water reducer suitable for calcined clay composite cement and its preparation method and application, wherein the water reducer can improve the initial fluidity while greatly reducing the fluidity loss of cement paste over time.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] One of the objects of the present invention is to provide a method for preparing a water reducing agent suitable for calcined clay composite cement, comprising the following steps:

[0007] S1: Add isopentenyl polyethylene glycol ether (TPEG) and an oxidant to deionized water, heat and stir until dissolved, and obtain solution a;

[0008] S2: dissolving a carboxylic acid monomer with a double bond, a hydroxycarboxylic acid monomer, and a catalyst in deionized water for esterification to obtain a solution b;

[0009] S3: adding the chain transfer agent and the reducing agent to deionized water and stirring until dissolved to obtain solution c;

[0010] S4: under heating and stirring conditions, the solution b obtained in step S2 and the solution c obtained in step S3 are simultaneously added dropwise to the solution a obtained in step S1, followed by heat preservation treatment and pH adjustment to obtain the water reducing agent suitable for calcined clay composite cement.

[0011] Preferably, in step S1, in solution a, the ratio of the isopentenyl polyethylene glycol ether, the oxidant, and deionized water, calculated by mass, is (15-25): (0.5-1.5): (25-35).

[0012] Preferably, in step S1, the molecular weight of the isopentenyl polyethylene glycol ether is 400-8000.

[0013] Preferably, in step S1, the oxidant includes one or more of hydrogen peroxide, ammonium peroxide or potassium persulfate.

[0014] Preferably, in step S1, the heating refers to water bath heating at a temperature of 30-90°C.

[0015] Further preferably, in step S1, the temperature of the water bath heating is 40°C.

[0016] Further preferably, in step S1, the stirring speed is 100 rpm-1000 rpm, and the stirring time is 5 min-1 h.

[0017] Preferably, in step S2, in solution b, the carboxylic acid monomer with a double bond, the hydroxycarboxylic acid monomer, the catalyst and the deionized water are in a ratio of (1-20): (1-20): (1-2): (10-20) by mass.

[0018] Preferably, in step S2, the carboxylic acid monomer with a double bond includes an unsaturated acid, including one or more of acrylic acid, methacrylic acid, maleic anhydride, and itaconic acid.

[0019] Preferably, in step S2, the hydroxycarboxylic acid monomer includes one or more of citric acid, tartaric acid, gluconic acid or their corresponding salts.

[0020] Further preferably, in step S2, the hydroxycarboxylic acid monomer includes one or more of citric acid and its corresponding salts, tartaric acid and its corresponding salts, gluconic acid and its corresponding salts.

[0021] Preferably, in step S2, the catalyst includes one or more of p-toluenesulfonic acid and hydroquinone.

[0022] Preferably, in step S2, the esterification reaction temperature is 50-95° C., and the reaction time is 1.0-3.5 h.

[0023] Further preferably, in step S2, the esterification reaction is carried out at a temperature of 90° C. and for 2 hours.

[0024] Preferably, in step S3, in solution c, the chain transfer agent, reducing agent and deionized water are in a ratio of (0.01-0.5): (0.1-0.4): (5-15) by mass.

[0025] Preferably, in step S3, the chain transfer agent includes one or both of mercaptopropionic acid and thioglycolic acid.

[0026] Preferably, in step S3, the reducing agent includes one or more of vitamin C, sodium sulfite and sodium thiosulfate.

[0027] Preferably, in step S3, the stirring speed is 200 to 800 rpm, and the stirring time is 1 to 3 hours.

[0028] Preferably, in step S4, the ratio of solution a, solution b, and solution c, calculated by mass, is (35-65): (25-60): (5-16).

[0029] Preferably, in step S4, the heating and stirring temperature is 30-90° C., the stirring speed is 500-700 rpm, and the time is 1.0-3.5 h.

[0030] Further preferably, in step S4, the heating and stirring temperature is 70° C., the stirring speed is 600 rpm, and the time is 2 h.

[0031] Preferably, in step S4, the solution b and solution c are added dropwise to the solution a within 1.5-2.5 hours.

[0032] Further preferably, in step S4, the solution b and solution c are added dropwise to the solution a within 2 hours.

[0033] Preferably, in step S4, the insulation temperature is 30-90° C. and the insulation time is 20-90 min.

[0034] Further preferably, in step S4, the insulation temperature is 70° C. and the insulation time is 30 minutes.

[0035] Preferably, in step S4, the adjusted pH is 5-7.

[0036] More preferably, in step S4, sodium hydroxide is used to adjust the pH to 5-7.

[0037] Preferably, the method for preparing the water reducer suitable for calcined clay composite cement comprises the following steps:

[0038] Step 1: add isopentenyl polyethylene glycol ether (TPEG) and an oxidant into deionized water and stir in a water bath at 40° C. until dissolved to obtain solution a.

[0039] Step 2: Add a carboxylic acid monomer with a double bond, a hydroxycarboxylic acid monomer, and a catalyst into deionized water and stir until dissolved. Heat to 90°C and perform an esterification reaction for two hours to obtain solution b. Add a chain transfer agent and a reducing agent into deionized water and stir until dissolved to obtain solution c.

[0040] Step 3: Raise the temperature to 70° C., add the solution b and solution c to the solution a simultaneously while stirring continuously. After keeping the temperature for half an hour, adjust the pH to 5-7 with sodium hydroxide to obtain a water reducer suitable for calcined clay composite cement.

[0041] Preferably, taking acrylic acid (carboxylic acid monomer with double bonds) and citric acid (hydroxycarboxylic acid monomer) monomers as examples, the synthetic route of the preparation method of the water reducer suitable for calcined clay composite cement is as follows:

[0042] The second object of the present invention is to provide a water reducing agent suitable for calcined clay composite cement prepared according to the preparation method.

[0043] The third object of the present invention is to provide an application of the water reducer suitable for calcined clay composite cement in calcined clay composite cement slurry, comprising the following steps: stirring and mixing the water reducer and water, and then adding the mixture to the calcined clay composite cement and stirring evenly.

[0044] Preferably, the calcined clay composite cement comprises calcined clay and cement, and the ratio of the water reducer, water, calcined clay and cement is (0.1-0.3): (40-50): (10-50): (50-90) by mass.

[0045] The fourth object of the present invention is to provide an application of the water reducer suitable for calcined clay composite cement in calcined clay composite cement concrete, comprising the following steps: stirring and mixing the water reducer and water, and then adding the water reducer to coarse aggregate, fine aggregate and calcined clay composite cement and stirring evenly.

[0046] Preferably, the calcined clay composite cement comprises calcined clay and cement, and the ratio of the water reducer, water, coarse aggregate, fine aggregate, calcined clay and cement is (0.1-0.3): (40-50): (200-300): (300-400): (10-50): (50-90) by mass.

[0047] This invention introduces one or more hydroxycarboxylic acids into a conventional comb-type water reducer through an esterification reaction. In the alkaline cement pore solution, the water reducer continuously hydrolyzes to produce hydroxycarboxylic acids with a retarding effect, inhibiting the pozzolanic reaction between calcined clay and cement, thereby improving the water reducer's retention capacity in the calcined clay-cement composite system.

[0048] Furthermore, existing technologies (such as CN118420843 A) primarily employ ester side chain modification strategies: by introducing ester functional groups to moderately reduce the initial adsorption capacity of water reducers, the ester groups are gradually hydrolyzed in the alkaline environment of the cement paste to generate carboxylic acid groups. Although this technical solution can partially maintain fluidity, its technical effect comes at the expense of the material's initial fluidity. The present invention, on the other hand, introduces components with retarding properties (hydroxycarboxylic acids) through polymerization. These components can be hydrolyzed and precipitated under alkaline conditions. The precipitated components can effectively inhibit the cement hydration reaction process while maintaining initial fluidity, thereby improving the time-retention capacity.

[0049] In the calcined clay composite cement system, the polycarboxylate ether water reducer of the present invention releases hydroxycarboxylic acid monomers through hydrolysis in the alkaline environment of the cement pore solution, and has a dual inhibitory effect on the hydration of the system: on the one hand, the hydroxycarboxylic acid directly delays the early hydration reaction of cement minerals (such as C3A and C3S), reducing the rapid generation of ettringite and CSH gel; on the other hand, it inhibits the pozzolanic reaction of the active aluminum-silicon components in the calcined clay with Ca(OH)2 through adsorption, reducing the premature formation of secondary CSH. This simultaneous inhibition of hydration and pozzolanic reactions significantly reduces the total amount and specific surface area of hydration products in the system, thereby alleviating the rapid adsorption and consumption of PCE molecules by highly active components. Because the PCE dispersion efficiency is maintained more persistently in the slurry, the dispersion stability of the cement particles is enhanced, and ultimately the time-dependent loss of fluidity of the calcined clay composite cement system is effectively reduced.

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] (1) The present invention introduces one or more hydroxycarboxylic acids through an esterification reaction to prepare a water reducer suitable for calcined clay composite cement. The water reducer can greatly improve the fluidity loss of cement paste over time while having good initial fluidity.

[0052] (2) The water-reducing agent prepared by the present invention can be hydrolyzed in cement paste to generate hydroxycarboxylic acid with a retarding effect, which can effectively limit the reactivity of calcined clay, thereby improving the time-dependent fluidity loss of cement paste.

[0053] (3) The water reducer prepared by the present invention can significantly improve the initial fluidity of calcined clay composite cement and concrete without affecting the early compressive strength and promoting the later compressive strength, and can improve its time-maintaining ability.

[0054] (4) The water-reducing agent of the present invention can not only reduce the fluidity loss of cement paste over time, but also effectively improve the slump loss of concrete over time: the cement paste prepared by using the water-reducing agent of the present invention has excellent initial fluidity and its 2h fluidity loss rate can be reduced to 2.7%; the concrete prepared by using the water-reducing agent of the present invention has excellent slump initial fluidity and its 2h slump loss rate can be reduced to 7.3%.

[0055] (5) The water-reducing agent prepared by the present invention is green and environmentally friendly, has a simple process, and is low in cost, and is conducive to industrial production. DETAILED DESCRIPTION

[0056] This embodiment is implemented on the premise of the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiment.

[0057] Unless otherwise specified, the reagents, methods, instruments and equipment used in the present invention are conventional reagents, methods, instruments and equipment in the art. Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0058] A method for preparing a water reducer suitable for calcined clay composite cement comprises the following steps:

[0059] S1: adding isopentenyl polyethylene glycol ether and oxidant to deionized water, heating and stirring until dissolved to obtain solution a;

[0060] S2: dissolving a carboxylic acid monomer with a double bond, a hydroxycarboxylic acid monomer, and a catalyst in deionized water for esterification to obtain a solution b;

[0061] S3: adding the chain transfer agent and the reducing agent to deionized water and stirring until dissolved to obtain solution c;

[0062] S4: under heating and stirring conditions, the solution b obtained in step S2 and the solution c obtained in step S3 are simultaneously added dropwise to the solution a obtained in step S1, followed by heat preservation treatment and pH adjustment to obtain the water reducing agent suitable for calcined clay composite cement.

[0063] The present invention is described in detail below with reference to specific embodiments.

[0064] Example 1

[0065] A method for preparing a water reducer suitable for calcined clay composite cement comprises the following steps:

[0066] 19.6 parts by mass of TPEG (molecular weight 2400) and 0.7 parts of ammonium peroxide were added to 30 parts of deionized water and stirred in a water bath at 40° C. until dissolved to obtain solution a.

[0067] Step 2: Add 8.1 parts of acrylic acid, 11.7 parts of citric acid, 0.5 parts of hydroquinone and 0.5 parts of p-toluenesulfonic acid to 15.4 parts of deionized water and stir until dissolved. Heat to 90° C. for esterification reaction for two hours to obtain solution b. Add 0.24 parts of mercaptopropionic acid and 0.2 parts of sodium sulfite to 12.8 parts of deionized water and stir until dissolved to obtain solution c.

[0068] Step 3: Raise the temperature to 70° C., add the solution b and solution c simultaneously to the solution a over 2 hours, stir continuously at 600 rpm, keep warm for half an hour, and adjust the pH to 7 with sodium hydroxide to obtain a water reducer suitable for calcined clay composite cement.

[0069] Example 2

[0070] A method for preparing a water reducer suitable for calcined clay composite cement comprises the following steps:

[0071] 19.6 parts by mass of TPEG (molecular weight 2400) and 0.64 parts of ammonium peroxide were added to 30 parts of deionized water and stirred in a water bath at 40° C. until dissolved to obtain solution a.

[0072] Step 2: Add 8.1 parts of acrylic acid, 14.1 parts of citric acid, 0.6 parts of hydroquinone and 0.4 parts of p-toluenesulfonic acid to 15.8 parts of deionized water and stir until dissolved. Heat to 90° C. for esterification reaction for two hours to obtain solution b. Add 0.22 parts of mercaptopropionic acid and 0.2 parts of sodium sulfite to 13.9 parts of deionized water and stir until dissolved to obtain solution c.

[0073] Step 3: Raise the temperature to 70° C., add the solution b and solution c simultaneously to the solution a over 2 hours, stir continuously at 600 rpm, keep warm for half an hour, and adjust the pH to 7 with sodium hydroxide to obtain a water reducer suitable for calcined clay composite cement.

[0074] Example 3

[0075] A method for preparing a water reducer suitable for calcined clay composite cement comprises the following steps:

[0076] 19.6 parts by mass of TPEG (molecular weight 2400) and 0.64 parts of ammonium peroxide were added to 30 parts of deionized water and stirred in a water bath at 40° C. until dissolved to obtain solution a.

[0077] Step 2: Add 8.1 parts of acrylic acid, 15.2 parts of citric acid, 0.8 parts of hydroquinone and 0.2 parts of p-toluenesulfonic acid to 15.1 parts of deionized water and stir until dissolved. Heat to 90° C. for esterification reaction for two hours to obtain solution b. Add 0.3 parts of mercaptopropionic acid and 0.3 parts of sodium sulfite to 13.0 parts of deionized water and stir until dissolved to obtain solution c.

[0078] Step 3: Raise the temperature to 70° C., add the solution b and solution c simultaneously to the solution a over 2 hours, stir continuously at 600 rpm, keep warm for half an hour, and adjust the pH to 7 with sodium hydroxide to obtain a water reducer suitable for calcined clay composite cement.

[0079] Example 4

[0080] A method for preparing a water reducer suitable for calcined clay composite cement comprises the following steps:

[0081] 19.6 parts by mass of TPEG (molecular weight 2400) and 0.7 parts of ammonium peroxide were added to 30 parts of deionized water and stirred in a water bath at 40° C. until dissolved to obtain solution a.

[0082] Step 2: Add 8.1 parts of acrylic acid, 11.7 parts of gluconic acid, 0.5 parts of hydroquinone and 0.5 parts of p-toluenesulfonic acid to 15.4 parts of deionized water and stir until dissolved. Heat to 90° C. for esterification reaction for two hours to obtain solution b. Add 0.24 parts of mercaptopropionic acid and 0.2 parts of sodium sulfite to 12.8 parts of deionized water and stir until dissolved to obtain solution c.

[0083] Step 3: Raise the temperature to 70° C., add the solution b and solution c simultaneously to the solution a over 2 hours, stir continuously at 600 rpm, keep warm for half an hour, and adjust the pH to 7 with sodium hydroxide to obtain a water reducer suitable for calcined clay composite cement.

[0084] Example 5

[0085] A method for preparing a water reducer suitable for calcined clay composite cement comprises the following steps:

[0086] 19.6 parts by mass of TPEG (molecular weight 2400) and 0.7 parts of ammonium peroxide were added to 30 parts of deionized water and stirred in a water bath at 40° C. until dissolved to obtain solution a.

[0087] Step 2: Add 8.1 parts of acrylic acid, 6.2 parts of citric acid, 5.5 parts of gluconic acid, 0.5 parts of hydroquinone and 0.5 parts of p-toluenesulfonic acid to 15.4 parts of deionized water and stir until dissolved. Heat to 90° C. for esterification reaction for two hours to obtain solution b. Add 0.24 parts of mercaptopropionic acid and 0.2 parts of sodium sulfite to 12.8 parts of deionized water and stir until dissolved to obtain solution c.

[0088] Step 3: Raise the temperature to 70° C., add the solution b and solution c simultaneously to the solution a over 2 hours, stir continuously at 600 rpm, keep warm for half an hour, and adjust the pH to 7 with sodium hydroxide to obtain a water reducer suitable for calcined clay composite cement.

[0089] Comparative Example 1

[0090] 19.6 parts by mass of TPEG (molecular weight 2400) and 0.7 parts of ammonium peroxide were added to 30 parts of deionized water and stirred in a water bath at 40° C. until dissolved to obtain solution a.

[0091] Step 2: Add 19.8 parts of acrylic acid, 0.5 parts of hydroquinone and 0.5 parts of p-toluenesulfonic acid to 15.4 parts of deionized water and stir until dissolved. Heat to 90° C. for esterification reaction for two hours to obtain solution b. Add 0.24 parts of mercaptopropionic acid and 0.2 parts of sodium sulfite to 12.8 parts of deionized water and stir until dissolved to obtain solution c.

[0092] Step 3: Raise the temperature to 70° C., add the solution b and solution c simultaneously to the solution a over 2 hours, stir continuously at 600 rpm, keep warm for half an hour, and adjust the pH to 7 with sodium hydroxide to obtain a water reducer suitable for calcined clay composite cement.

[0093] Comparative Example 2

[0094] 19.6 parts by mass of TPEG (molecular weight 2400) and 0.7 parts of ammonium peroxide were added to 30 parts of deionized water and stirred in a water bath at 40° C. until dissolved to obtain solution a.

[0095] Step 2: Add 8.1 parts of acrylic acid, 0.5 parts of hydroquinone and 0.5 parts of p-toluenesulfonic acid to 15.4 parts of deionized water and stir until dissolved. Heat to 90° C. for esterification reaction for two hours to obtain solution b. Add 0.24 parts of mercaptopropionic acid and 0.2 parts of sodium sulfite to 12.8 parts of deionized water and stir until dissolved to obtain solution c.

[0096] Step 3: Raise the temperature to 70° C., add the solution b and solution c simultaneously to the solution a over 2 hours, stir continuously at 600 rpm, keep warm for half an hour, and adjust the pH to 7 with sodium hydroxide to obtain a water reducer suitable for calcined clay composite cement.

[0097] Comparative Example 3

[0098] A commercial high-efficiency concrete water reducer purchased by a building materials company.

[0099] Comparative Example 4

[0100] A commercial slump-preventing concrete water-reducing agent purchased by a building materials company.

[0101] Performance testing

[0102] Detection method

[0103] (1) Cement paste fluidity test: Refer to the standard GB / T 8077-2000 "Test method for homogeneity of concrete admixtures" and test the fluidity of the sample after 5 minutes, 60 minutes and 120 minutes.

[0104] (2) Cement mortar compressive strength test: Refer to the standard GB / T 17671-2021 "Test method for strength of cement mortar", and test the average compressive strength of the sample after 3d, 7d and 28d.

[0105] (3) Concrete slump test: Refer to the standard GB / T 50080-2016 "Standard for test methods of performance of ordinary concrete mixtures" and test the slump of the sample after 5 minutes, 60 minutes and 120 minutes.

[0106] (4) Concrete compressive strength test: Refer to the standard GB / T 50081-2019 "Standard for test methods of physical and mechanical properties of concrete" to test the average compressive strength of the sample after 28 days.

[0107] The mix ratio designs of cement paste and concrete are shown in Table 1. The performance evaluation results of the embodiment and comparative example on the fluidity and compressive strength of cement paste and concrete are shown in Table 2 and Table 3, respectively.

[0108] Table 1 Cement paste and concrete mix design

[0109] Raw materials / mass Cement paste concrete water reducer 0.2 0.2 water 45 45 calcined clay 30 30 cement 70 70 medium sand 300 Pebbles 400

[0110] Table 2 Cement paste performance evaluation results

[0111]

[0112]

[0113] Table 3 Concrete performance evaluation results

[0114]

[0115] The results show that compared to the water reducers in Comparative Examples 1-4, the water reducers in Examples 1-5 of the present invention exhibit significant advantages in both initial performance and fluidity retention, as well as improved compressive strength in later stages, in calcined clay composite cement or concrete. Furthermore, compared to the water reducers in Comparative Examples 1-2, the water reducer in Example 1 of the present invention, which incorporates a hydroxycarboxylic acid, exhibits even superior fluidity retention. Therefore, the water reducer of the present invention is highly compatible with calcined clay composite cement systems, which is conducive to further promoting the development and application of low-carbon cementitious materials.

[0116] In summary, the present invention introduces one or more hydroxycarboxylic acids to prepare a water reducer suitable for calcined clay composite cement. The water reducer can improve the fluidity loss of cement paste over time, and while not affecting the early strength and maintaining the fluidity, it can also promote the later strength development, which is conducive to industrial production.

[0117] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A method for preparing a water reducing agent suitable for calcined clay composite cement, characterized in that: The following steps are involved: S1: adding isopentenyl polyethylene glycol ether and oxidant to deionized water, heating and stirring until dissolved to obtain solution a; S2: dissolving a carboxylic acid monomer with a double bond, a hydroxycarboxylic acid monomer, and a catalyst in deionized water for esterification to obtain a solution b; S3: adding the chain transfer agent and the reducing agent to deionized water and stirring until dissolved to obtain solution c; S4: under heating and stirring conditions, the solution b obtained in step S2 and the solution c obtained in step S3 are simultaneously added dropwise to the solution a obtained in step S1, followed by heat preservation treatment and pH adjustment to obtain the water reducing agent suitable for calcined clay composite cement.

2. The method for preparing a water reducer suitable for calcined clay composite cement according to claim 1, characterized in that: In step S1, In solution a, the isopentenyl polyethylene glycol ether, the oxidant, and the deionized water are in a ratio of (15-25): (0.5-1.5): (25-35) by mass; The molecular weight of the isopentenyl polyethylene glycol ether is 400-8000; The oxidant includes one or more of hydrogen peroxide, ammonium peroxide or potassium persulfate; The heating refers to water bath heating at a temperature of 30-90°C.

3. The method for preparing a water reducer suitable for calcined clay composite cement according to claim 1, characterized in that: In step S2, In solution b, the carboxylic acid monomer with a double bond, the hydroxycarboxylic acid monomer, the catalyst and deionized water are in a ratio of (1-20): (1-20): (1-2): (10-20) by mass; The carboxylic acid monomer with a double bond includes an unsaturated acid, including one or more of acrylic acid, methacrylic acid, maleic anhydride, and itaconic acid; The hydroxycarboxylic acid monomer includes one or more of citric acid, tartaric acid, gluconic acid or their corresponding salts; The catalyst includes one or more of p-toluenesulfonic acid and hydroquinone.

4. The method for preparing a water reducer suitable for calcined clay composite cement according to claim 1, characterized in that: In step S2, the esterification reaction temperature is 50-95° C., and the reaction time is 1.0-3.5 h.

5. The method for preparing a water reducer suitable for calcined clay composite cement according to claim 1, characterized in that: In step S3, In solution c, the chain transfer agent, reducing agent and deionized water are in a ratio of (0.01-0.5): (0.1-0.4): (5-15) by mass; The chain transfer agent includes one or both of mercaptopropionic acid and thioglycolic acid; The reducing agent includes one or more of vitamin C, sodium sulfite and sodium thiosulfate; The stirring speed is 200 to 800 rpm, and the stirring time is 1 to 3 hours.

6. The method for preparing a water reducer suitable for calcined clay composite cement according to claim 1, characterized in that: In step S4, the ratio of solution a, solution b, and solution c, calculated by mass, is (35-65): (25-60): (5-16).

7. The method for preparing a water reducer suitable for calcined clay composite cement according to claim 1, characterized in that: In step S4, the heating and stirring temperature is 30-90° C., the stirring speed is 500-700 rpm, the time is 1.0-3.5 h, the insulation temperature is 30-90° C., the time is 20-90 min; and the adjusted pH is 5-7.

8. A water reducing agent suitable for calcined clay composite cement, characterized in that: The water reducer suitable for calcined clay composite cement is prepared according to the preparation method of any one of claims 1 to 7.

9. Use of the water reducer suitable for calcined clay composite cement according to claim 8 in calcined clay composite cement slurry, characterized in that: The following steps are involved: The water reducer and water are mixed and added to the calcined clay composite cement and stirred evenly. The calcined clay composite cement comprises calcined clay and cement, and the ratio of the water reducer, water, calcined clay and cement is (0.1-0.3): (40-50): (10-50): (50-90) by mass.

10. Use of the water reducer suitable for calcined clay composite cement according to claim 8 in calcined clay composite cement concrete, characterized in that: The following steps are involved: The water reducer and water are mixed and added to the coarse aggregate, fine aggregate and calcined clay composite cement and stirred evenly. The calcined clay composite cement comprises calcined clay and cement, and the ratio of the water reducer, water, coarse aggregate, fine aggregate, calcined clay and cement is (0.1-0.3): (40-50): (200-300): (300-400): (10-50): (50-90) by mass.

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