Efficient concrete water reducing agent and preparation method thereof

Abstract

The invention relates to the technical field of concrete water reducing agents, in particular to an efficient concrete water reducing agent and a preparation method thereof.The efficient concrete water reducing agent is prepared from, by weight, 6-10 parts of slow-release filler, 6-8 parts of water reducing auxiliaries and 0.8-1 part of preservative; according to the present invention, the naphthalene sulfonate formaldehyde condensate is loaded, such that the water reducing agent has a certain slow release performance, such that the problem of large slump loss of the existing naphthalene water reducing agent is solved, and the efficient concrete water reducing agent is combined with the water reducing auxiliary agent so as to provide the good performance in the high temperature environment, and the influence of the naphthalene sulfonate formaldehyde condensate on the development of the early strength of the concrete is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete water reducers, and particularly relates to a high-efficiency concrete water reducer and a preparation method thereof. Background Art

[0002] With the development of society, traditional concrete has been gradually replaced by high-performance concrete, and concrete water reducers play an extremely important role in this process. They can effectively reduce the water-cement ratio in concrete. However, the commonly used naphthalene-based water reducer, namely naphthalene sulfonate formaldehyde condensate, often has a large slump loss problem in high-temperature environments. To improve the slump loss problem, a retarder is usually added to the concrete. However, the addition of the retarder will affect the early strength development of the concrete, resulting in its performance not meeting the market demand. Summary of the Invention

[0003] The purpose of the present invention is to provide a high-efficiency concrete water reducer and a preparation method thereof. By loading naphthalene sulfonate formaldehyde condensate, the water reducer has a certain slow-release performance, thus solving the problem of large slump loss of the existing naphthalene-based water reducer. At the same time, by combining with a water-reducing aid, the high-efficiency concrete water reducer still has good performance in high-temperature environments and reduces the impact of naphthalene sulfonate formaldehyde condensate on the early strength development of concrete.

[0004] The purpose of the present invention can be achieved through the following technical solutions: A preparation method of a high-efficiency concrete water reducer, which includes the following steps: Weigh the following raw materials in parts by weight: 6 - 10 parts of slow-release filler, 6 - 8 parts of water-reducing aid, and 0.8 - 1 part of preservative. Mix the slow-release filler, water-reducing aid, and preservative to obtain a high-efficiency concrete water reducer.

[0005] The preservative is Mingjiang Chemical concrete preservative.

[0006] The water-reducing aid is prepared through the following steps:

[0007] Step A1: Mix tartaric acid and glycidyl methacrylate, stir and add triphenylphosphine and p-hydroxyanisole at a stirring rate of 140 - 160 rpm and a temperature of 98 - 100 °C, react for 6 - 8 h, then cool down to 52 - 55 °C and add pyrophosphoric acid, and continue to react for 24 h to obtain Intermediate 1.

[0008] The dosage ratio of tartaric acid, glycidyl methacrylate, triphenylphosphine, p-hydroxyanisole, and pyrophosphoric acid is 0.11 - 0.12 mol: 0.24 - 0.25 mol: 0.23 - 0.25 g: 0.11 - 0.13 g: 0.46 - 0.48 mol.

[0009] During the reaction process, under the condition of using triphenylphosphine and p-methoxyphenol as catalysts, the carboxyl group in tartaric acid first reacts with the epoxy group in glycidyl methacrylate, introducing a double bond and forming a new hydroxyl group at the same time. Then pyrophosphoric acid is added to react with the hydroxyl group to form a phosphate ester structure, and intermediate 1 is obtained.

[0010] Step A2: Mix guar gum and tetrahydrofuran, stir and add potassium hydroxide under the conditions of a stirring rate of 160 - 180 rpm and a temperature of 40 - 42 °C, react for 12 - 14 h, then add carbon disulfide and continue to react for 2 - 3 h, and then add methyl 2-bromoisobutyrate and continue to react for 22 - 24 h to obtain modified guar gum.

[0011] The dosage ratio of guar gum, potassium hydroxide, carbon disulfide and methyl 2-bromoisobutyrate is 4.3 - 4.5 g : 0.08 - 0.082 mol : 0.085 - 0.09 mol : 0.082 - 0.085 mol.

[0012] During the reaction process, under the action of potassium hydroxide, the hydroxyl group in guar gum forms a potassium salt structure, which then reacts with carbon disulfide to form a potassium xanthate structure, and then reacts with methyl 2-bromoisobutyrate to obtain modified guar gum.

[0013]

[0014] Step A3: Mix acrylic acid, isopentenol polyoxyethylene ether, modified guar gum, azobisisobutyronitrile and dimethyl sulfoxide, and react for 22 - 24 h under the conditions of nitrogen protection, a stirring rate of 150 - 180 rpm and a temperature of 70 - 72 °C to obtain a water-reducing agent.

[0015] The dosage ratio of acrylic acid, isopentenol polyoxyethylene ether, modified guar gum and azobisisobutyronitrile is 0.012 - 0.015 mol : 2.3 - 2.5 g : 4.5 - 4.8 g : 0.12 - 0.15 g.

[0016] The isopentenol polyoxyethylene ether is Kemic TPEG-2400.

[0017] During the reaction process, under the action of the initiator azobisisobutyronitrile, using modified guar gum as a macromolecular chain transfer agent, through the method of reversible addition-fragmentation chain transfer polymerization, modified guar gum polymerizes with acrylic acid and isopentenol polyoxyethylene ether to form a water-reducing agent with a multi-branched block side chain structure with modified guar gum as the main body.

[0018] The sustained-release filler is prepared through the following steps:

[0019] Step B1: Mix cobalt nitrate hexahydrate, iron nitrate nonahydrate, magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, sodium carbonate and deionized water. Under the conditions of a stirring rate of 120 - 140 rpm and room temperature, stir and add sodium hydroxide solution to maintain the pH value of the system at 10. Heat up to 145 - 150 °C and crystallize for 12 - 14 h. Filter, wash and dry to obtain precursor 1. Mix precursor 1 and formamide. Under nitrogen protection and a stirring rate of 400 - 450 rpm at room temperature, stir for 8 - 10 h, centrifuge, and take the upper layer system to obtain a hydrotalcite exfoliation system;

[0020] The mass fraction of the sodium hydroxide solution is 15%. The dosage ratio of cobalt nitrate hexahydrate, iron nitrate nonahydrate, magnesium nitrate hexahydrate, aluminum nitrate nonahydrate and sodium carbonate is 0.02 - 0.022 mol : 0.01 - 0.11 mol : 0.02 - 0.022 mol : 0.01 - 0.011 mol : 12 - 13 g; The dosage ratio of precursor 1 and formamide is 2.4 - 2.5 g : 40 - 45 mL;

[0021] During the reaction process, through the coprecipitation method, using cobalt nitrate hexahydrate, iron nitrate nonahydrate, magnesium nitrate hexahydrate and aluminum nitrate nonahydrate as cobalt, iron, magnesium and aluminum sources respectively, precursor 1 with a hydrotalcite-like structure was prepared. Then, through the formamide delamination method, precursor 1 was delaminated to obtain a hydrotalcite exfoliation system;

[0022] Step B2: Mix hollow mesoporous silica, naphthalene sulfonate formaldehyde condensate and deionized water. Under the conditions of a stirring rate of 120 - 140 rpm and a temperature of 95 - 100 °C, stir for 12 h to obtain precursor 2. Add precursor 2 to the hydrotalcite exfoliation system. Under nitrogen protection and a stirring rate of 90 - 120 rpm at room temperature, react for 30 - 40 min, filter, wash and dry to obtain a slow-release filler;

[0023] The dosage ratio of hollow mesoporous silica, naphthalene sulfonate formaldehyde condensate and deionized water is 1.5 - 1.6 g : 2.2 - 2.3 g : 80 - 85 mL; The dosage ratio of precursor 2 and the hydrotalcite exfoliation system is 0.1 - 0.12 g : 15 - 20 mL;

[0024] The hollow mesoporous silica is Jike JK - 04 - 009;

[0025] The naphthalene sulfonate formaldehyde condensate is Wanshan brand FDN - A;

[0026] During the reaction process, naphthalene sulfonate formaldehyde condensate is first loaded into hollow mesoporous silica to obtain precursor 2. Since the hydrotalcite nanosheets obtained after the exfoliation of precursor 1 are positively charged, they can undergo electrostatic interaction with precursor 2 that becomes negatively charged after loading naphthalene sulfonate formaldehyde condensate. Thus, through the layer-by-layer self-assembly technique, the hydrotalcite nanosheets are wrapped around precursor 2 to obtain a sustained-release filler;

[0027] Advantages of the present invention: The present invention discloses a high-performance concrete water reducer and its preparation method. By loading naphthalene sulfonate formaldehyde condensate, the water reducer has certain sustained-release performance, thus solving the problem of large slump loss of existing naphthalene-based water reducers. At the same time, by combining with a water-reducing auxiliary agent, the high-performance concrete water reducer still has good performance in a high-temperature environment and reduces the influence of naphthalene sulfonate formaldehyde condensate on the early strength development of concrete; after loading naphthalene sulfonate formaldehyde condensate into hollow mesoporous silica and then wrapping it with hydrotalcite nanosheets through electrostatic interaction, during the setting process of concrete, due to the characteristics of concrete itself, the environmental pH value changes, which causes the wrapped hydrotalcite nanosheets to detach, enabling the internal naphthalene sulfonate formaldehyde condensate to be slowly released. While the wrapping of hydrotalcite nanosheets when not in use ensures its stability during storage. At the same time, since the detached hydrotalcite nanosheets themselves contain cobalt, iron, magnesium, and aluminum elements, they can also promote the hydration process. And since the water-reducing auxiliary agent itself is mainly composed of guar gum and forms a structure with multiple branched block side chains through reversible addition-fragmentation chain transfer polymerization, and it contains a large number of phosphate ester groups. These groups can effectively cooperate with the detached hydrotalcite nanosheets in an alkaline environment, thus ensuring the early strength development of concrete, reducing the influence of naphthalene sulfonate formaldehyde condensate on the early strength development of concrete. At the same time, its own multi-branched block side chain structure can ensure that the water reducer still maintains good performance in a high-temperature environment. Specific embodiments

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0029] Example 1 A preparation method of a high-performance concrete water reducer, which includes the following steps: Weigh the following raw materials in parts by weight: 6 parts of sustained-release filler, 8 parts of water-reducing auxiliary agent, and 0.8 part of preservative. Mix the sustained-release filler, water-reducing auxiliary agent, and preservative to obtain a high-performance concrete water reducer;

[0030] The preservative is Mingjiang Chemical concrete preservative;

[0031] The water-reducing aid is prepared through the following steps:

[0032] Step A1: Mix tartaric acid and glycidyl methacrylate, and under the conditions of a stirring rate of 140 rpm and a temperature of 98 °C, stir and add triphenylphosphine and p-hydroxyanisole, react for 6 h, then cool down to 52 °C and add pyrophosphoric acid, and continue to react for 24 h to obtain Intermediate 1;

[0033] The dosage ratio of tartaric acid, glycidyl methacrylate, triphenylphosphine, p-hydroxyanisole and pyrophosphoric acid is 0.11 mol: 0.24 mol: 0.23 g: 0.11 g: 0.46 mol;

[0034] Step A2: Mix guar gum and tetrahydrofuran, and under the conditions of a stirring rate of 160 rpm and a temperature of 40 °C, stir and add potassium hydroxide, react for 12 h, then add carbon disulfide, continue to react for 2 h, and then add methyl 2-bromoisobutyrate, and continue to react for 22 h to obtain modified guar gum;

[0035] The dosage ratio of guar gum, potassium hydroxide, carbon disulfide and methyl 2-bromoisobutyrate is 4.3 g: 0.08 mol: 0.085 mol: 0.082 mol;

[0036] Step A3: Mix acrylic acid, isopentenol polyoxyethylene ether, modified guar gum, azobisisobutyronitrile and dimethyl sulfoxide, and under nitrogen protection, a stirring rate of 150 rpm and a temperature of 70 °C, react for 22 h to obtain the water-reducing aid;

[0037] The dosage ratio of acrylic acid, isopentenol polyoxyethylene ether, modified guar gum and azobisisobutyronitrile is 0.012 mol: 2.3 g: 4.5 g: 0.12 g;

[0038] The isopentenol polyoxyethylene ether is Kemic TPEG-2400;

[0039] The sustained-release filler is prepared through the following steps:

[0040] Step B1: Mix cobalt nitrate hexahydrate, iron nitrate nonahydrate, magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, sodium carbonate and deionized water, and under the conditions of a stirring rate of 140 rpm and room temperature, stir and add sodium hydroxide solution to keep the pH value of the system at 10, heat up to 150 °C, crystallize for 14 h, filter, wash, dry to obtain Precursor 1, mix Precursor 1 and formamide, and under nitrogen protection, a stirring rate of 450 rpm and room temperature conditions, stir for 10 h, centrifuge, and take the upper layer system to obtain the hydrotalcite exfoliation system;

[0041] The mass fraction of the sodium hydroxide solution is 15%, and the dosage ratio of cobalt nitrate hexahydrate, iron nitrate nonahydrate, magnesium nitrate hexahydrate, aluminum nitrate nonahydrate and sodium carbonate is 0.022 mol: 0.11 mol: 0.022 mol: 0.011 mol: 13 g; the dosage ratio of precursor 1 and formamide is 2.5 g: 45 mL;

[0042] Step B2: Mix hollow mesoporous silica, naphthalene sulfonate formaldehyde condensate and deionized water, and stir at a stirring rate of 140 rpm and a temperature of 100 °C for 12 h to obtain precursor 2. Add precursor 2 to the hydrotalcite exfoliation system, and react under nitrogen protection, at a stirring rate of 120 rpm and a temperature of room temperature for 40 min, filter, wash, and dry to obtain the sustained-release filler;

[0043] The dosage ratio of hollow mesoporous silica, naphthalene sulfonate formaldehyde condensate and deionized water is 1.6 g: 2.3 g: 85 mL; the dosage ratio of precursor 2 and the hydrotalcite exfoliation system is 0.12 g: 20 mL;

[0044] The hollow mesoporous silica is Jike JK-04-009;

[0045] The naphthalene sulfonate formaldehyde condensate is Wanshan brand FDN-A.

[0046] Example 2 A preparation method of a high-efficiency concrete water reducer, which includes the following steps: Weigh the following raw materials in parts by weight: 10 parts of sustained-release filler, 6 parts of water-reducing aid and 1 part of preservative, and mix the sustained-release filler, water-reducing aid and preservative to obtain a high-efficiency concrete water reducer;

[0047] The preservative is Mingjiang Chemical concrete preservative;

[0048] The water-reducing aid is prepared by the following steps:

[0049] Step A1: Mix tartaric acid and glycidyl methacrylate, stir and add triphenylphosphine and p-hydroxyanisole at a stirring rate of 160 rpm and a temperature of 100 °C, react for 8 h, then cool down to 55 °C and add pyrophosphoric acid, and continue to react for 24 h to obtain intermediate 1;

[0050] The dosage ratio of tartaric acid, glycidyl methacrylate, triphenylphosphine, p-hydroxyanisole and pyrophosphoric acid is 0.12 mol: 0.25 mol: 0.25 g: 0.13 g: 0.48 mol;

[0051] Step A2: Mix guar gum and tetrahydrofuran, stir and add potassium hydroxide under the conditions of a stirring rate of 180 rpm and a temperature of 42 °C, react for 14 h, then add carbon disulfide, continue to react for 3 h, and then add methyl 2-bromoisobutyrate, continue to react for 24 h to obtain modified guar gum;

[0052] The dosage ratio of guar gum, potassium hydroxide, carbon disulfide and methyl 2-bromoisobutyrate is 4.5 g: 0.082 mol: 0.09 mol: 0.085 mol;

[0053] Step A3: Mix acrylic acid, isopentenol polyoxyethylene ether, modified guar gum, azobisisobutyronitrile and dimethyl sulfoxide, and react for 24 h under the conditions of nitrogen protection, a stirring rate of 180 rpm and a temperature of 72 °C to obtain a water-reducing agent;

[0054] The dosage ratio of acrylic acid, isopentenol polyoxyethylene ether, modified guar gum and azobisisobutyronitrile is 0.015 mol: 2.5 g: 4.8 g: 0.15 g;

[0055] The isopentenol polyoxyethylene ether is Kemic TPEG-2400;

[0056] The slow-release filler is prepared through the following steps:

[0057] Step B1: Mix cobalt nitrate hexahydrate, iron nitrate nonahydrate, magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, sodium carbonate and deionized water, stir and add sodium hydroxide solution to keep the pH value of the system at 10 under the conditions of a stirring rate of 120 rpm and room temperature, heat up to 145 °C, crystallize for 12 h, filter, wash and dry to obtain precursor 1. Mix precursor 1 and formamide, stir for 8 h under the conditions of nitrogen protection, a stirring rate of 400 rpm and room temperature, centrifuge, and take the upper layer system to obtain a hydrotalcite exfoliation system;

[0058] The mass fraction of the sodium hydroxide solution is 15%, and the dosage ratio of cobalt nitrate hexahydrate, iron nitrate nonahydrate, magnesium nitrate hexahydrate, aluminum nitrate nonahydrate and sodium carbonate is 0.02 mol: 0.01 mol: 0.02 mol: 0.01 mol: 12 g; the dosage ratio of precursor 1 and formamide is 2.4 g: 40 mL;

[0059] Step B2: Mix hollow mesoporous silica, naphthalene sulfonate formaldehyde condensate and deionized water, stir for 12 h under the conditions of a stirring rate of 120 rpm and a temperature of 95 °C to obtain precursor 2. Add precursor 2 to the hydrotalcite exfoliation system, react for 30 min under the conditions of nitrogen protection, a stirring rate of 90 rpm and room temperature, filter, wash and dry to obtain the slow-release filler;

[0060] The dosage ratio of hollow mesoporous silica, naphthalene sulfonate formaldehyde condensate and deionized water is 1.5 g: 2.2 g: 80 mL; the dosage ratio of precursor 2 and hydrotalcite exfoliation system is 0.1 g: 150 mL;

[0061] The hollow mesoporous silica is Jike JK-04-009;

[0062] The naphthalene sulfonate formaldehyde condensate is Wanshan brand FDN-A.

[0063] Example 3 A preparation method of a high-efficiency concrete water reducer, which comprises the following steps: Weigh the following raw materials in parts by weight: 10 parts of slow-release filler, 8 parts of water-reducing auxiliary and 1 part of preservative, and mix the slow-release filler, water-reducing auxiliary and preservative to obtain a high-efficiency concrete water reducer;

[0064] The preservative is Mingjiang Chemical concrete preservative;

[0065] The water-reducing auxiliary is prepared by the following steps:

[0066] Step A1: Mix tartaric acid and glycidyl methacrylate, stir and add triphenylphosphine and p-hydroxyanisole at a stirring rate of 160 rpm and a temperature of 100 °C, react for 8 h, then cool down to 55 °C and add pyrophosphoric acid, and continue to react for 24 h to obtain intermediate 1;

[0067] The dosage ratio of tartaric acid, glycidyl methacrylate, triphenylphosphine, p-hydroxyanisole and pyrophosphoric acid is 0.12 mol: 0.25 mol: 0.25 g: 0.13 g: 0.48 mol;

[0068] Step A2: Mix guar gum and tetrahydrofuran, stir and add potassium hydroxide at a stirring rate of 180 rpm and a temperature of 42 °C, react for 14 h, then add carbon disulfide, continue to react for 3 h, and then add methyl 2-bromoisobutyrate, and continue to react for 24 h to obtain modified guar gum;

[0069] The dosage ratio of guar gum, potassium hydroxide, carbon disulfide and methyl 2-bromoisobutyrate is 4.5 g: 0.082 mol: 0.09 mol: 0.085 mol;

[0070] Step A3: Mix acrylic acid, isopentenol polyoxyethylene ether, modified guar gum, azobisisobutyronitrile and dimethyl sulfoxide, and react for 24 h under nitrogen protection, at a stirring rate of 180 rpm and a temperature of 70 - 72 °C to obtain the water-reducing auxiliary;

[0071] The dosage ratio of acrylic acid, isopentenol polyoxyethylene ether, modified guar gum and azobisisobutyronitrile is 0.015 mol: 2.5 g: 4.8 g: 0.15 g;

[0072] The isopentenyl alcohol polyoxyethylene ether is Kemike TPEG-2400;

[0073] The sustained-release filler is prepared through the following steps:

[0074] Step B1: Mix cobalt nitrate hexahydrate, iron nitrate nonahydrate, magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, sodium carbonate and deionized water. Under the conditions of a stirring rate of 140 rpm and room temperature, stir and add sodium hydroxide solution to keep the pH value of the system at 10. Heat up to 150 °C, crystallize for 14 h, filter, wash, and dry to obtain precursor 1. Mix precursor 1 and formamide. Under the protection of nitrogen and at a stirring rate of 450 rpm and room temperature, stir for 10 h, centrifuge, and take the upper layer system to obtain the hydrotalcite exfoliation system;

[0075] The mass fraction of the sodium hydroxide solution is 15%. The dosage ratio of cobalt nitrate hexahydrate, iron nitrate nonahydrate, magnesium nitrate hexahydrate, aluminum nitrate nonahydrate and sodium carbonate is 0.022 mol: 0.11 mol: 0.022 mol: 0.011 mol: 13 g; the dosage ratio of precursor 1 and formamide is 2.5 g: 45 mL;

[0076] Step B2: Mix hollow mesoporous silica, naphthalene sulfonate formaldehyde condensate and deionized water. Under the conditions of a stirring rate of 140 rpm and a temperature of 100 °C, stir for 12 h to obtain precursor 2. Add precursor 2 to the hydrotalcite exfoliation system. Under the protection of nitrogen and at a stirring rate of 120 rpm and room temperature, react for 40 min, filter, wash, and dry to obtain the sustained-release filler;

[0077] The dosage ratio of hollow mesoporous silica, naphthalene sulfonate formaldehyde condensate and deionized water is 1.6 g: 2.3 g: 85 mL; the dosage ratio of precursor 2 and the hydrotalcite exfoliation system is 0.12 g: 20 mL;

[0078] The hollow mesoporous silica is Jike JK-04-009;

[0079] The naphthalene sulfonate formaldehyde condensate is Wanshan brand FDN-A.

[0080] Comparative Example 1 Compared with Example 3, in this comparative example, the sustained-release filler in the preparation process of the high-efficiency concrete water reducer in Example 3 is replaced with Wanshan brand FDN-A naphthalene sulfonate formaldehyde condensate and Jike JK-04-009 hollow mesoporous silica. The weight ratio of naphthalene sulfonate formaldehyde condensate and hollow mesoporous silica is 1.6 g: 2.3 g, and other steps are the same.

[0081] Comparative Example 2 Compared with Example 3, this comparative example replaces the water-reducing adjuvant in the preparation process of the high-efficiency concrete water reducer in Example 3 with Bofei BF-01 polycarboxylate water reducer, and the other steps are the same.

[0082] Take the high-efficiency concrete water reducer prepared in Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2, refer to GB / T17671-1999, mix 1350g of standard sand, 80g of fly ash and 450g of cement, stir and add water and a total mass fraction of 0.8% of high-efficiency concrete water reducer, and adjust the amount of water so that the fluidity of the cement mortar is 180±5mm, pour it into a 40×40×160mm mold, demold it after 24h, and cure it at a curing temperature of 20°C. Test its compressive strength at 1d, 7d and 28d, raise the curing temperature to 40°C, measure its compressive strength at 28d, and calculate its performance retention rate, refer to GB / T 8077-2012, after removing the high-efficiency concrete water reducing agent, record the amount of water used to adjust the water volume so that the cement mortar fluidity is 180±5mm, so as to calculate its water reduction rate, mix 250g water, 1350g standard sand, 80g fly ash, 450g cement and 15g high-efficiency concrete water reducing agent, refer to GB 8077-1997, measure the cement paste fluidity, and calculate its fluidity after 30 minutes, so as to calculate its retention rate, so as to evaluate the slow release and slump reduction effect, and its test results are as follows: Table 1 Test results table:

[0083]

[0084]

[0085] It can be seen from the test results in the table shown that when Example 1, Example 2 and Example 3 are compared with Comparative Example 1 and Comparative Example 2, Comparative Example 1 replaces the slow-release filler in the preparation process of the high-efficiency concrete water reducer in Example 3 with naphthalenesulfonate formaldehyde condensate and hollow mesoporous silica. Due to the lack of slow-release structure and hydrotalcite-like crystals, its performance is reduced. Comparative Example 2 replaces the water-reducing additive in the preparation process of the high-efficiency concrete water reducer in Example 3 with a polycarboxylate water reducer. Due to the lack of a multi-branched block side chain structure and a phosphate group, its performance is reduced.

[0086] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0087] The above content is only an example and illustration of the concept of the present invention. Those skilled in the art of this technology can make various modifications, supplements, or use similar methods to substitute for the specific embodiments described. As long as they do not deviate from the concept of the invention, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing a high-efficiency concrete water reducing agent, characterized in that: The method comprises the following steps: weighing the following raw materials by weight: 6-10 parts of slow-release filler, 6-8 parts of water-reducing aid and 0.8-1 part of preservative, mixing the slow-release filler, the water-reducing aid and the preservative to prepare a high-efficiency concrete water-reducing agent.

2. The method for preparing a high-efficiency concrete water reducing agent according to claim 1, characterized in that: The water reducing agent is prepared by the following steps: Step A1: tartaric acid and glycidyl methacrylate are mixed, and triphenylphosphine and p-hydroxyanisole are added under stirring at a rate of 140-160 rpm and a temperature of 98-100° C., and the mixture is reacted for 6-8 hours, and then the temperature is lowered to 52-55° C. and pyrophosphoric acid is added, and the reaction is continued for 24 hours to obtain intermediate 1; Step A2: guar gum and tetrahydrofuran are mixed, stirred at a stirring rate of 160-180 rpm and a temperature of 40-42° C., potassium hydroxide is added, and the mixture is reacted for 12-14 hours, carbon disulfide is added, and the reaction is continued for 2-3 hours, and methyl 2-bromoisobutyrate is added, and the reaction is continued for 22-24 hours to obtain modified guar gum; Step A3: acrylic acid, isopentanol polyoxyethylene ether, modified guar gum, azobisisobutyronitrile and dimethyl sulfoxide are mixed, and reacted for 22-24 hours under nitrogen protection, a stirring rate of 150-180 rpm, and a temperature of 70-72° C. to obtain a water reducing agent.

3. The method for preparing a high-efficiency concrete water reducing agent according to claim 2, characterized in that: In step A1, the ratio of tartaric acid, glycidyl methacrylate, triphenylphosphine, p-hydroxyanisole and pyrophosphoric acid is 0.11-0.12 mol: 0.24-0.25 mol: 0.23-0.25 g: 0.11-0.13 g: 0.46-0.48 mol.

4. The method for preparing a high-efficiency concrete water reducing agent according to claim 2, characterized in that: In step A2, the usage ratio of guar gum, potassium hydroxide, carbon disulfide and methyl 2-bromoisobutyrate is 4.3-4.5 g: 0.08-0.082 mol: 0.085-0.09 mol: 0.082-0.085 mol.

5. The method for preparing a high-efficiency concrete water reducing agent according to claim 2, characterized in that: In step A3, the usage ratio of acrylic acid, prenol polyoxyethylene ether, modified guar gum and azobisisobutyronitrile is 0.012-0.015 mol: 2.3-2.5 g: 4.5-4.8 g: 0.12-0.15 g.

6. The method for preparing a high-efficiency concrete water reducing agent according to claim 1, characterized in that: The sustained-release filler is prepared by the following steps: Step B1: Cobalt nitrate hexahydrate, iron nitrate nonahydrate, magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, sodium carbonate and deionized water are mixed, stirred at a stirring rate of 120-140 rpm and room temperature, and sodium hydroxide solution is added to keep the pH value of the system at 10, the temperature is raised to 145-150° C., crystallized for 12-14 hours, filtered, washed, and dried to obtain precursor 1, and precursor 1 is mixed with formamide, stirred at a stirring rate of 400-450 rpm and room temperature under nitrogen protection for 8-10 hours, centrifuged, and the upper layer system is taken to obtain a hydrotalcite exfoliation system; Step B2: Mix hollow mesoporous silica, naphthalenesulfonate formaldehyde condensate and deionized water, stir for 12 hours at a stirring rate of 120-140 rpm and a temperature of 95-100°C to obtain precursor 2, add precursor 2 to the hydrotalcite exfoliation system, react for 30-40 minutes under nitrogen protection, stirring rate of 90-120 rpm, and room temperature, filter, wash, and dry to obtain a sustained-release filler.

7. The method for preparing a high-efficiency concrete water reducing agent according to claim 6, characterized in that: In step B1: the mass fraction of the sodium hydroxide solution is 15%, the amount ratio of cobalt nitrate hexahydrate, iron nitrate nonahydrate, magnesium nitrate hexahydrate, aluminum nitrate nonahydrate and sodium carbonate is 0.02-0.022 mol: 0.01-0.11 mol: 0.02-0.022 mol: 0.01-0.011 mol: 12-13 g; the amount ratio of precursor 1 and formamide is 2.4-2.5 g: 40-45 mL.

8. The method for preparing a high-efficiency concrete water reducing agent according to claim 6, characterized in that: In step B2, the ratio of hollow mesoporous silica, naphthalenesulfonate formaldehyde condensate and deionized water is 1.5-1.6 g: 2.2-2.3 g: 80-85 mL; the ratio of precursor 2 and hydrotalcite exfoliation system is 0.1-0.12 g: 15-20 mL.

9. A high-efficiency concrete water reducing agent, characterized in that: Prepared according to any one of claims 1 to 8.

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