A cement curing agent and its preparation method

Abstract

The invention belongs to the technical field of cement, and specifically relates to a cement curing-free agent and a preparation method thereof, wherein porous silica is taken, the porous silica is subjected to amino modification to obtain modified silica; calcium silicate seed crystals are prepared; then the modified silica and the calcium silicate seed crystals are compounded with polycarboxylate ether to obtain a composite; the composite is subjected to carbon dioxide adsorption and then mixed with an early strength material to obtain a curing-free agent. The cement curing-free agent of the invention can improve the strength of cement, promote hydration, and significantly shorten the curing time.

Description

Technical Field

[0001] The invention belongs to the technical field of cement, and in particular relates to a cement curing-free agent and a preparation method thereof. Background Art

[0002] Semi-rigid base is the main load-bearing layer of asphalt pavement. Among various semi-rigid bases, cement-stabilized gravel is widely used in high-grade highway bases due to its high strength, high rigidity, good stability, and strong ability to diffuse stress. However, while cement-stabilized gravel base is widely used, some problems have gradually been exposed. For example, cement-stabilized gravel base is relatively brittle and sensitive to changes in temperature and humidity. During construction and use, shrinkage cracks are prone to occur when temperature or humidity changes alternately. Cracks in cement-stabilized gravel base develop upward, causing reflective cracks in the asphalt surface layer. Water on the road surface penetrates into the base structure through the reflective cracks, exacerbating the damage to the roadbed structure, seriously reducing the road quality of the asphalt pavement, and shortening the service life of the road.

[0003] At the same time, the maintenance time and curing method of cement-stabilized gravel base in road construction and maintenance seriously restrict the progress of the construction period. The strength of cement-stabilized gravel base needs a long enough time to form. During this period, traffic needs to be blocked. If the load disturbs its overall structure, the mechanical properties of cement-stabilized gravel will be greatly affected. This requires that the cement-stabilized gravel base must be cured for a certain period of time after compaction to reach a certain strength before the surface layer can be paved. The current transportation industry standard "Technical Specifications for Highway Pavement Base Construction" (JTG / T F20-2015) stipulates that the curing period of inorganic binder stabilized materials shall not be less than 7 days, and the curing period should be extended to 2 days before the construction of the upper structure begins. At the same time, appropriate curing methods should be selected according to the actual situation of the project, such as: watering curing, geotextile covering curing, straw mat covering curing, etc. The above-mentioned external curing method has the disadvantages of large curing area and difficult curing, and it is difficult for external water to enter the interior of the cement-stabilized gravel base, and the curing effect is poor, which is difficult to meet the current requirements for rapid construction of highway projects. Summary of the invention

[0004] In order to solve the problems of difficult curing and long curing period in the prior art, the present invention mainly provides a method for preparing a curing agent-free cement that can rapidly solidify cement and rapidly improve strength. The specific scheme is as follows:

[0005] A method for preparing a cement curing-free agent, characterized in that porous silica is taken and subjected to amino modification to obtain modified silica; calcium silicate seed crystals are prepared; the modified silica and the calcium silicate seed crystals are then compounded with polycarboxylate ether to obtain a composite; the composite is subjected to carbon dioxide adsorption and then mixed with an early strength material to obtain a curing-free agent.

[0006] Furthermore, the mass ratio of the modified silica to the calcium silicate seed is 1:1-3; the mass ratio of the modified silica to the polycarboxylate ether is 1:1.2-2; the early strength material is a metal salt and triethanolamine; the mass ratio of the composite to the metal salt and triethanolamine is 1:0.2-2:0.02-0.06.

[0007] Furthermore, the metal salt is one or more of sodium sulfate, aluminum sulfate, sodium aluminate, calcium chloride, calcium formate, and lithium carbonate.

[0008] Furthermore, the preparation of the complex comprises the following steps:

[0009] a. Fully disperse porous silica in ethanol, and use ammonia water to adjust the pH of the system to 9-11; add 3-aminopropyltriethoxysilane, and stir the reaction at 50-70° C. for 9-12 hours; after the reaction, collect the precipitate by centrifugation, wash the precipitate with ethanol, and fully dry it to obtain modified silica;

[0010] b. Dissolve calcium nitrate in water to prepare a calcium nitrate solution, add cyclodextrin to the calcium nitrate solution, and then use sodium hydroxide to adjust the pH of the solution to 11-12 to obtain a precursor solution; take sodium silicate to prepare a sodium silicate solution; adjust the temperature of the precursor solution and the sodium silicate solution to 50-70° C., and then slowly drop the sodium silicate solution into the precursor solution, after the dropwise addition is completed, stir at high speed to evenly mix, and keep the temperature and stand; after the end, wash with water and ethanol and dry to obtain calcium silicate seed crystals;

[0011] c. Dispersing modified silicon dioxide and calcium silicate seed crystals in water to obtain a dispersed mixed liquid; dispersing polycarboxylate ether in water to obtain a polycarboxylate ether dispersion, dropping the polycarboxylate ether dispersion into the mixed dispersion, fully dispersing at 40-60° C. and standing for 10-20 hours; then separating and collecting the precipitate, fully washing the precipitate and drying it to obtain a composite.

[0012] Furthermore, the mass ratio of 3-aminopropyltriethoxysilane to porous silica in step a is 1:1.5-4; the mass ratio of calcium nitrate to sodium silicate in step b is 1:1.1-1.5; and the mass ratio of calcium nitrate to cyclodextrin in step b is 1:1.5-3.

[0013] Furthermore, in step b, the mixture is stirred at a high speed for 0.5 to 1 hour, and then kept warm and allowed to stand for 0.5 to 2 days.

[0014] Furthermore, the slow dripping speed in step b is 0.1-0.3 mL / s; and the high-speed stirring speed is 800-1500 rpm.

[0015] Furthermore, the composite is placed in a carbon dioxide atmosphere with a flow rate of 0.5 to 5 L / min, adsorbed at 40 to 60°C for 0.5 to 1 hour, and after naturally cooling to room temperature, the adsorbed composite is taken out and mixed with an early strength material, moistened with alcohol, and ground at a speed of 1 to 5 r / s to constant weight to obtain a health-free agent.

[0016] Furthermore, the preparation of the porous silica includes the following steps: taking hexadecyltrimethylammonium bromide and placing it in 40-60% v / v ethanol, adjusting the pH to 11-12 with ammonia water to obtain a hexadecyltrimethylammonium bromide solution; adding tetraethoxysilane to the hexadecyltrimethylammonium bromide solution, stirring and reacting for 10-12 hours, separating and collecting the precipitate, washing it thoroughly with ethanol and drying it, and then calcining it at 500-600°C for 3-8 hours to obtain porous silica; the mass ratio of the hexadecyltrimethylammonium bromide to tetraethoxysilane is 1:1.2-1.8.

[0017] A cement curing-free agent prepared by the above method.

[0018] By adopting the above scheme, the method of the present invention has the following advantages:

[0019] 1. The cement curing agent of the present invention can quickly improve the strength of cement, increase the number of condensation nuclei and the dispersion between condensation nuclei during the hydration process of cement, promote hydration, and can increase the solubility of carbon dioxide in cement, significantly shortening the curing time.

[0020] 2. The curing agent of the present invention comprises silicon dioxide and calcium silicate crystal seeds, which have different morphologies and sizes and are fully dispersed in the pore solution of cement, providing multi-scale condensation nuclei for the formation of gel, promoting the gel to grow uniformly and quickly in the pore solution, ensuring the strength of cement while shortening the hydration cycle.

[0021] 3. The curing-free agent of the present invention utilizes porous silica to absorb carbon dioxide, has a large contact area with substances in cement, and continuously reacts with silicon phase minerals, calcium silicate gel and other substances during the cement gelation process. The carbonization efficiency is high and long-lasting, thereby improving cement strength and shortening curing time.

[0022] 4. The present invention modifies silicon dioxide by amino modification so that the surface of silicon dioxide has a large number of amino groups, making it more compatible with carbon dioxide and easier to capture carbon dioxide. The silicon dioxide and seed crystals can be simultaneously compounded with polycarboxylate ether to control the distance between the silicon dioxide and the seed crystals.

[0023] 5. The silicon dioxide and the seed crystals of the present invention are maintained at a certain dispersion under the action of the polycarboxylate ether, so as to avoid the silicon dioxide and the seed crystals being too close and self-agglomeration, so that the raw materials in the health agent are fully dispersed in the cement, thereby making the hydration promotion effect more uniform.

[0024] 6. The present invention adds cyclodextrin during the seed crystal growth process, so that the seed crystal tends to grow radially, providing more channels for water ion diffusion and transmission, increasing the contact area with the hydration product, reducing the lateral accumulation of the hydration product aggregation on the particle surface, and improving the strength and strengthening speed of the cement.

[0025] 7. The preparation method of the present invention is simple, does not require high temperature treatment, and the raw materials are cheap and easily available, the production cost is low, and it is conducive to industrial promotion and production. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Embodiment 1:

[0028] (1) 3 g of hexadecyltrimethylammonium bromide was placed in 50% v / v ethanol, and the pH was adjusted to 12 with aqueous ammonia to obtain a hexadecyltrimethylammonium bromide solution; 5 g of tetraethoxysilane was added to the hexadecyltrimethylammonium bromide solution, and the mixture was stirred for 11 h. After the precipitate was separated and collected, it was fully washed with ethanol and dried, and then calcined at 600° C. for 5 h to obtain porous silica;

[0029] (2) 1.5 g of porous silica was fully dispersed in ethanol, and the pH of the system was adjusted to 10 with aqueous ammonia; 1 g of 3-aminopropyltriethoxysilane was added, and the reaction was stirred at 60° C. for 10 h; after the reaction, the precipitate was collected by centrifugation, and the precipitate was fully washed with ethanol and fully dried to obtain modified silica;

[0030] (3) 1.6 g of calcium nitrate was dissolved in water to prepare a calcium nitrate solution, 2.4 g of cyclodextrin was added to the calcium nitrate solution, and then the pH of the solution was adjusted to 11 using sodium hydroxide to obtain a precursor solution; 1.3 g of sodium silicate was taken to prepare a sodium silicate solution; the temperature of the precursor solution and the sodium silicate solution was adjusted to 60° C., and then the sodium silicate solution was slowly added dropwise to the precursor solution at a rate of 0.1 mL / s. After the addition was completed, the solution was stirred at a high speed of 800 rpm for 0.5 h, and then kept warm and allowed to stand for 1 day; after completion, the solution was fully washed with water and ethanol and dried to obtain calcium silicate seed crystals;

[0031] (4) dispersing 2 g of modified silicon dioxide and 2 g of calcium silicate seed crystals in water to obtain a dispersed mixed liquid; dispersing 2.4 g of polycarboxylate ether in water to obtain a polycarboxylate ether dispersion, adding the polycarboxylate ether dispersion dropwise to the mixed dispersion, fully dispersing at 50° C. and standing for 14 h; then separating and collecting the precipitate, fully washing the precipitate and drying it to obtain a composite;

[0032] (5) Place 2 g of the complex in a carbon dioxide atmosphere at a flow rate of 1 L / min, adsorb at 50°C for 0.5 to 1 h, and after naturally cooling to room temperature, take out the adsorbed complex and mix it with 0.4 g of aluminum sulfate, 0.2 g of calcium formate, 1.4 g of lithium carbonate and 0.1 g of triethanolamine, add alcohol to moisten it, and grind it at a speed of 1 r / s to constant weight to obtain a health-free agent.

[0033] Embodiment 2:

[0034] (1) 3 g of hexadecyltrimethylammonium bromide was placed in 50% v / v ethanol, and the pH was adjusted to 12 with aqueous ammonia to obtain a hexadecyltrimethylammonium bromide solution; 5 g of tetraethoxysilane was added to the hexadecyltrimethylammonium bromide solution, and the mixture was stirred for 11 h. After the precipitate was separated and collected, it was fully washed with ethanol and dried, and then calcined at 600° C. for 8 h to obtain porous silica;

[0035] (2) 1.5 g of porous silica was fully dispersed in ethanol, and the pH of the system was adjusted to 10 with aqueous ammonia; 1 g of 3-aminopropyltriethoxysilane was added, and the reaction was stirred at 60° C. for 10 h; after the reaction, the precipitate was collected by centrifugation, and the precipitate was fully washed with ethanol and fully dried to obtain modified silica;

[0036] (3) 1.6 g of calcium nitrate was dissolved in water to prepare a calcium nitrate solution, 2.4 g of cyclodextrin was added to the calcium nitrate solution, and then the pH of the solution was adjusted to 11 using sodium hydroxide to obtain a precursor solution; 1.3 g of sodium silicate was taken to prepare a sodium silicate solution; the temperature of the precursor solution and the sodium silicate solution was adjusted to 60° C., and then the sodium silicate solution was slowly added dropwise to the precursor solution at a rate of 0.1 mL / s. After the addition was completed, the solution was stirred at a high speed of 800 rpm for 0.5 h, and then kept warm and allowed to stand for 1 day; after completion, the solution was fully washed with water and ethanol and dried to obtain calcium silicate seed crystals;

[0037] (4) dispersing 2 g of modified silicon dioxide and 2 g of calcium silicate seed crystals in water to obtain a dispersed mixed liquid; dispersing 2.4 g of polycarboxylate ether in water to obtain a polycarboxylate ether dispersion, adding the polycarboxylate ether dispersion dropwise to the mixed dispersion, fully dispersing at 50° C. and standing for 14 h; then separating and collecting the precipitate, fully washing the precipitate and drying it to obtain a composite;

[0038] (5) Place 2 g of the complex in a carbon dioxide atmosphere at a flow rate of 1 L / min, adsorb at 50°C for 0.5 to 1 h, and after naturally cooling to room temperature, take out the adsorbed complex and mix it with 0.4 g of aluminum sulfate, 0.2 g of calcium formate, 1.4 g of lithium carbonate and 0.1 g of triethanolamine, add alcohol to moisten it, and grind it at a speed of 1 r / s to constant weight to obtain a health-free agent.

[0039] Embodiment 3:

[0040] (1) 3 g of hexadecyltrimethylammonium bromide was placed in 50% v / v ethanol, and the pH was adjusted to 12 with aqueous ammonia to obtain a hexadecyltrimethylammonium bromide solution; 5 g of tetraethoxysilane was added to the hexadecyltrimethylammonium bromide solution, and the mixture was stirred for 11 h. After the precipitate was separated and collected, it was fully washed with ethanol and dried, and then calcined at 600° C. for 5 h to obtain porous silica;

[0041] (2) 4 g of porous silica was fully dispersed in ethanol, and the pH of the system was adjusted to 10 with aqueous ammonia; 1 g of 3-aminopropyltriethoxysilane was added, and the reaction was stirred at 60° C. for 10 h; after the reaction, the precipitate was collected by centrifugation, and the precipitate was fully washed with ethanol and fully dried to obtain modified silica;

[0042] (3) 1.6 g of calcium nitrate was dissolved in water to prepare a calcium nitrate solution, 2.4 g of cyclodextrin was added to the calcium nitrate solution, and then the pH of the solution was adjusted to 11 using sodium hydroxide to obtain a precursor solution; 1.3 g of sodium silicate was taken to prepare a sodium silicate solution; the temperature of the precursor solution and the sodium silicate solution was adjusted to 60° C., and then the sodium silicate solution was slowly added dropwise to the precursor solution at a rate of 0.1 mL / s. After the addition was completed, the solution was stirred at a high speed of 800 rpm for 0.5 h, and then kept warm and allowed to stand for 1 day; after completion, the solution was fully washed with water and ethanol and dried to obtain calcium silicate seed crystals;

[0043] (4) dispersing 2 g of modified silicon dioxide and 2 g of calcium silicate seed crystals in water to obtain a dispersed mixed liquid; dispersing 2.4 g of polycarboxylate ether in water to obtain a polycarboxylate ether dispersion, adding the polycarboxylate ether dispersion dropwise to the mixed dispersion, fully dispersing at 50° C. and standing for 14 h; then separating and collecting the precipitate, fully washing the precipitate and drying it to obtain a composite;

[0044] (5) Place 2 g of the complex in a carbon dioxide atmosphere at a flow rate of 1 L / min, adsorb at 50°C for 0.5 to 1 h, and after naturally cooling to room temperature, take out the adsorbed complex and mix it with 0.4 g of aluminum sulfate, 0.2 g of calcium formate, 1.4 g of lithium carbonate and 0.1 g of triethanolamine, add alcohol to moisten it, and grind it at a speed of 1 r / s to constant weight to obtain a health-free agent.

[0045] Embodiment 4:

[0046] (1) 3 g of hexadecyltrimethylammonium bromide was placed in 50% v / v ethanol, and the pH was adjusted to 12 with aqueous ammonia to obtain a hexadecyltrimethylammonium bromide solution; 5 g of tetraethoxysilane was added to the hexadecyltrimethylammonium bromide solution, and the mixture was stirred for 11 h. After the precipitate was separated and collected, it was fully washed with ethanol and dried, and then calcined at 600° C. for 5 h to obtain porous silica;

[0047] (2) 1.5 g of porous silica was fully dispersed in ethanol, and the pH of the system was adjusted to 10 with aqueous ammonia; 1 g of 3-aminopropyltriethoxysilane was added, and the reaction was stirred at 60° C. for 10 h; after the reaction, the precipitate was collected by centrifugation, and the precipitate was fully washed with ethanol and fully dried to obtain modified silica;

[0048] (3) 1.6 g of calcium nitrate was dissolved in water to prepare a calcium nitrate solution, 4.8 g of cyclodextrin was added to the calcium nitrate solution, and then the pH of the solution was adjusted to 11 using sodium hydroxide to obtain a precursor solution; 1.3 g of sodium silicate was taken to prepare a sodium silicate solution; the temperature of the precursor solution and the sodium silicate solution was adjusted to 60° C., and then the sodium silicate solution was slowly added dropwise to the precursor solution at a rate of 0.1 mL / s. After the addition was completed, the solution was stirred at a high speed of 800 rpm for 0.5 h, and then kept warm and allowed to stand for 1 day; after completion, the solution was fully washed with water and ethanol and dried to obtain calcium silicate seed crystals;

[0049] (4) dispersing 2 g of modified silicon dioxide and 2 g of calcium silicate seed crystals in water to obtain a dispersed mixed liquid; dispersing 2.4 g of polycarboxylate ether in water to obtain a polycarboxylate ether dispersion, adding the polycarboxylate ether dispersion dropwise to the mixed dispersion, fully dispersing at 50° C. and standing for 14 h; then separating and collecting the precipitate, fully washing the precipitate and drying it to obtain a composite;

[0050] (5) Place 2 g of the complex in a carbon dioxide atmosphere at a flow rate of 1 L / min, adsorb at 50°C for 0.5 to 1 h, and after naturally cooling to room temperature, take out the adsorbed complex and mix it with 0.4 g of aluminum sulfate, 0.2 g of calcium formate, 1.4 g of lithium carbonate and 0.1 g of triethanolamine, add alcohol to moisten it, and grind it at a speed of 1 r / s to constant weight to obtain a health-free agent.

[0051] Embodiment 5:

[0052] (1) 3 g of hexadecyltrimethylammonium bromide was placed in 50% v / v ethanol, and the pH was adjusted to 12 with aqueous ammonia to obtain a hexadecyltrimethylammonium bromide solution; 5 g of tetraethoxysilane was added to the hexadecyltrimethylammonium bromide solution, and the mixture was stirred for 11 h. After the precipitate was separated and collected, it was fully washed with ethanol and dried, and then calcined at 600° C. for 5 h to obtain porous silica;

[0053] (2) 1.5 g of porous silica was fully dispersed in ethanol, and the pH of the system was adjusted to 10 with aqueous ammonia; 1 g of 3-aminopropyltriethoxysilane was added, and the reaction was stirred at 60° C. for 10 h; after the reaction, the precipitate was collected by centrifugation, and the precipitate was fully washed with ethanol and fully dried to obtain modified silica;

[0054] (3) 1.6 g of calcium nitrate was dissolved in water to prepare a calcium nitrate solution, 2.4 g of cyclodextrin was added to the calcium nitrate solution, and then the pH of the solution was adjusted to 11 using sodium hydroxide to obtain a precursor solution; 1.3 g of sodium silicate was taken to prepare a sodium silicate solution; the temperature of the precursor solution and the sodium silicate solution was adjusted to 60° C., and then the sodium silicate solution was slowly added dropwise to the precursor solution at a rate of 0.3 mL / s. After the addition was completed, the solution was stirred at a high speed of 800 rpm for 0.5 h, and then kept warm and allowed to stand for 1 day; after completion, the solution was fully washed with water and ethanol and dried to obtain calcium silicate seed crystals;

[0055] (4) dispersing 2 g of modified silicon dioxide and 2 g of calcium silicate seed crystals in water to obtain a dispersed mixed liquid; dispersing 2.4 g of polycarboxylate ether in water to obtain a polycarboxylate ether dispersion, adding the polycarboxylate ether dispersion dropwise to the mixed dispersion, fully dispersing at 50° C. and standing for 14 h; then separating and collecting the precipitate, fully washing the precipitate and drying it to obtain a composite;

[0056] (5) Place 2 g of the complex in a carbon dioxide atmosphere at a flow rate of 1 L / min, adsorb at 50°C for 0.5 to 1 h, and after naturally cooling to room temperature, take out the adsorbed complex and mix it with 0.4 g of aluminum sulfate, 0.2 g of calcium formate, 1.4 g of lithium carbonate and 0.1 g of triethanolamine, add alcohol to moisten it, and grind it at a speed of 1 r / s to constant weight to obtain a health-free agent.

[0057] Embodiment 6:

[0058] (1) 3 g of hexadecyltrimethylammonium bromide was placed in 50% v / v ethanol, and the pH was adjusted to 12 with aqueous ammonia to obtain a hexadecyltrimethylammonium bromide solution; 5 g of tetraethoxysilane was added to the hexadecyltrimethylammonium bromide solution, and the mixture was stirred for 11 h. After the precipitate was separated and collected, it was fully washed with ethanol and dried, and then calcined at 600° C. for 5 h to obtain porous silica;

[0059] (2) 1.5 g of porous silica was fully dispersed in ethanol, and the pH of the system was adjusted to 10 with aqueous ammonia; 1 g of 3-aminopropyltriethoxysilane was added, and the reaction was stirred at 60° C. for 10 h; after the reaction, the precipitate was collected by centrifugation, and the precipitate was fully washed with ethanol and fully dried to obtain modified silica;

[0060] (3) 1.6 g of calcium nitrate was dissolved in water to prepare a calcium nitrate solution, 2.4 g of cyclodextrin was added to the calcium nitrate solution, and then the pH of the solution was adjusted to 11 using sodium hydroxide to obtain a precursor solution; 1.3 g of sodium silicate was taken to prepare a sodium silicate solution; the temperature of the precursor solution and the sodium silicate solution was adjusted to 60° C., and then the sodium silicate solution was slowly added dropwise to the precursor solution at a rate of 0.1 mL / s. After the addition was completed, the solution was stirred at a high speed of 1500 rpm for 0.5 h, and then kept warm and allowed to stand for 1 day; after completion, the solution was fully washed with water and ethanol and dried to obtain calcium silicate seed crystals;

[0061] (4) dispersing 2 g of modified silicon dioxide and 2 g of calcium silicate seed crystals in water to obtain a dispersed mixed liquid; dispersing 2.4 g of polycarboxylate ether in water to obtain a polycarboxylate ether dispersion, adding the polycarboxylate ether dispersion dropwise to the mixed dispersion, fully dispersing at 50° C. and standing for 14 h; then separating and collecting the precipitate, fully washing the precipitate and drying it to obtain a composite;

[0062] (5) Place 2 g of the complex in a carbon dioxide atmosphere at a flow rate of 1 L / min, adsorb at 50°C for 0.5 to 1 h, and after naturally cooling to room temperature, take out the adsorbed complex and mix it with 0.4 g of aluminum sulfate, 0.2 g of calcium formate, 1.4 g of lithium carbonate and 0.1 g of triethanolamine, add alcohol to moisten it, and grind it at a speed of 1 r / s to constant weight to obtain a health-free agent.

[0063] Embodiment 7:

[0064] (1) 3 g of hexadecyltrimethylammonium bromide was placed in 50% v / v ethanol, and the pH was adjusted to 12 with aqueous ammonia to obtain a hexadecyltrimethylammonium bromide solution; 5 g of tetraethoxysilane was added to the hexadecyltrimethylammonium bromide solution, and the mixture was stirred for 11 h. After the precipitate was separated and collected, it was fully washed with ethanol and dried, and then calcined at 600° C. for 5 h to obtain porous silica;

[0065] (2) 1.5 g of porous silica was fully dispersed in ethanol, and the pH of the system was adjusted to 10 with aqueous ammonia; 1 g of 3-aminopropyltriethoxysilane was added, and the reaction was stirred at 60° C. for 10 h; after the reaction, the precipitate was collected by centrifugation, and the precipitate was fully washed with ethanol and fully dried to obtain modified silica;

[0066] (3) 1.6 g of calcium nitrate was dissolved in water to prepare a calcium nitrate solution, 2.4 g of cyclodextrin was added to the calcium nitrate solution, and then the pH of the solution was adjusted to 11 using sodium hydroxide to obtain a precursor solution; 1.3 g of sodium silicate was taken to prepare a sodium silicate solution; the temperature of the precursor solution and the sodium silicate solution was adjusted to 60° C., and then the sodium silicate solution was slowly added dropwise to the precursor solution at a rate of 0.1 mL / s. After the addition was completed, the solution was stirred at a high speed of 800 rpm for 0.5 h, and then kept warm and allowed to stand for 2 days; after completion, the solution was fully washed with water and ethanol and dried to obtain calcium silicate seed crystals;

[0067] (4) dispersing 2 g of modified silicon dioxide and 2 g of calcium silicate seed crystals in water to obtain a dispersed mixed liquid; dispersing 2.4 g of polycarboxylate ether in water to obtain a polycarboxylate ether dispersion, adding the polycarboxylate ether dispersion dropwise to the mixed dispersion, fully dispersing at 50° C. and standing for 14 h; then separating and collecting the precipitate, fully washing the precipitate and drying it to obtain a composite;

[0068] (5) Place 2 g of the complex in a carbon dioxide atmosphere at a flow rate of 1 L / min, adsorb at 50°C for 0.5 to 1 h, and after naturally cooling to room temperature, take out the adsorbed complex and mix it with 0.4 g of aluminum sulfate, 0.2 g of calcium formate, 1.4 g of lithium carbonate and 0.1 g of triethanolamine, add alcohol to moisten it, and grind it at a speed of 1 r / s to constant weight to obtain a health-free agent.

[0069] Embodiment 8:

[0070] (1) 3 g of hexadecyltrimethylammonium bromide was placed in 50% v / v ethanol, and the pH was adjusted to 12 with aqueous ammonia to obtain a hexadecyltrimethylammonium bromide solution; 5 g of tetraethoxysilane was added to the hexadecyltrimethylammonium bromide solution, and the mixture was stirred for 11 h. After the precipitate was separated and collected, it was fully washed with ethanol and dried, and then calcined at 600° C. for 5 h to obtain porous silica;

[0071] (2) 1.5 g of porous silica was fully dispersed in ethanol, and the pH of the system was adjusted to 10 with aqueous ammonia; 1 g of 3-aminopropyltriethoxysilane was added, and the reaction was stirred at 60° C. for 10 h; after the reaction, the precipitate was collected by centrifugation, and the precipitate was fully washed with ethanol and fully dried to obtain modified silica;

[0072] (3) 1.6 g of calcium nitrate was dissolved in water to prepare a calcium nitrate solution, 2.4 g of cyclodextrin was added to the calcium nitrate solution, and then the pH of the solution was adjusted to 11 using sodium hydroxide to obtain a precursor solution; 1.3 g of sodium silicate was taken to prepare a sodium silicate solution; the temperature of the precursor solution and the sodium silicate solution was adjusted to 60° C., and then the sodium silicate solution was slowly added dropwise to the precursor solution at a rate of 0.1 mL / s. After the addition was completed, the solution was stirred at a high speed of 800 rpm for 0.5 h, and then kept warm and allowed to stand for 1 day; after completion, the solution was fully washed with water and ethanol and dried to obtain calcium silicate seed crystals;

[0073] (4) dispersing 2 g of modified silicon dioxide and 6 g of calcium silicate seed crystals in water to obtain a dispersed mixed liquid; dispersing 2.4 g of polycarboxylate ether in water to obtain a polycarboxylate ether dispersion, adding the polycarboxylate ether dispersion dropwise to the mixed dispersion, fully dispersing at 50° C. and standing for 14 h; then separating and collecting the precipitate, fully washing the precipitate and drying it to obtain a composite;

[0074] (5) Place 2 g of the complex in a carbon dioxide atmosphere at a flow rate of 1 L / min, adsorb at 50°C for 0.5 to 1 h, and after naturally cooling to room temperature, take out the adsorbed complex and mix it with 0.4 g of aluminum sulfate, 0.2 g of calcium formate, 1.4 g of lithium carbonate and 0.1 g of triethanolamine, add alcohol to moisten it, and grind it at a speed of 1 r / s to constant weight to obtain a health-free agent.

[0075] Embodiment 9:

[0076] (1) 3 g of hexadecyltrimethylammonium bromide was placed in 50% v / v ethanol, and the pH was adjusted to 12 with aqueous ammonia to obtain a hexadecyltrimethylammonium bromide solution; 5 g of tetraethoxysilane was added to the hexadecyltrimethylammonium bromide solution, and the mixture was stirred for 11 h. After the precipitate was separated and collected, it was fully washed with ethanol and dried, and then calcined at 600° C. for 5 h to obtain porous silica;

[0077] (2) 1.5 g of porous silica was fully dispersed in ethanol, and the pH of the system was adjusted to 10 with aqueous ammonia; 1 g of 3-aminopropyltriethoxysilane was added, and the reaction was stirred at 60° C. for 10 h; after the reaction, the precipitate was collected by centrifugation, and the precipitate was fully washed with ethanol and fully dried to obtain modified silica;

[0078] (3) 1.6 g of calcium nitrate was dissolved in water to prepare a calcium nitrate solution, 2.4 g of cyclodextrin was added to the calcium nitrate solution, and then the pH of the solution was adjusted to 11 using sodium hydroxide to obtain a precursor solution; 1.3 g of sodium silicate was taken to prepare a sodium silicate solution; the temperature of the precursor solution and the sodium silicate solution was adjusted to 60° C., and then the sodium silicate solution was slowly added dropwise to the precursor solution at a rate of 0.1 mL / s. After the addition was completed, the solution was stirred at a high speed of 800 rpm for 0.5 h, and then kept warm and allowed to stand for 1 day; after completion, the solution was fully washed with water and ethanol and dried to obtain calcium silicate seed crystals;

[0079] (4) dispersing 2 g of modified silicon dioxide and 2 g of calcium silicate seed crystals in water to obtain a dispersed mixed liquid; dispersing 4 g of polycarboxylate ether in water to obtain a polycarboxylate ether dispersion, adding the polycarboxylate ether dispersion dropwise to the mixed dispersion, fully dispersing at 50° C. and standing for 14 h; then separating and collecting the precipitate, fully washing the precipitate and drying it to obtain a composite;

[0080] (5) Place 2 g of the complex in a carbon dioxide atmosphere at a flow rate of 1 L / min, adsorb at 50°C for 0.5 to 1 h, and after naturally cooling to room temperature, take out the adsorbed complex and mix it with 0.4 g of aluminum sulfate, 0.2 g of calcium formate, 1.4 g of lithium carbonate and 0.1 g of triethanolamine, add alcohol to moisten it, and grind it at a speed of 1 r / s to constant weight to obtain a health-free agent.

[0081] Embodiment 10:

[0082] (1) 3 g of hexadecyltrimethylammonium bromide was placed in 50% v / v ethanol, and the pH was adjusted to 12 with aqueous ammonia to obtain a hexadecyltrimethylammonium bromide solution; 5 g of tetraethoxysilane was added to the hexadecyltrimethylammonium bromide solution, and the mixture was stirred for 11 h. After the precipitate was separated and collected, it was fully washed with ethanol and dried, and then calcined at 600° C. for 5 h to obtain porous silica;

[0083] (2) 1.5 g of porous silica was fully dispersed in ethanol, and the pH of the system was adjusted to 10 with aqueous ammonia; 1 g of 3-aminopropyltriethoxysilane was added, and the reaction was stirred at 60° C. for 10 h; after the reaction, the precipitate was collected by centrifugation, and the precipitate was fully washed with ethanol and fully dried to obtain modified silica;

[0084] (3) 1.6 g of calcium nitrate was dissolved in water to prepare a calcium nitrate solution, 2.4 g of cyclodextrin was added to the calcium nitrate solution, and then the pH of the solution was adjusted to 11 using sodium hydroxide to obtain a precursor solution; 1.3 g of sodium silicate was taken to prepare a sodium silicate solution; the temperature of the precursor solution and the sodium silicate solution was adjusted to 60° C., and then the sodium silicate solution was slowly added dropwise to the precursor solution at a rate of 0.1 mL / s. After the addition was completed, the solution was stirred at a high speed of 800 rpm for 0.5 h, and then kept warm and allowed to stand for 1 day; after completion, the solution was fully washed with water and ethanol and dried to obtain calcium silicate seed crystals;

[0085] (4) dispersing 2 g of modified silicon dioxide and 2 g of calcium silicate seed crystals in water to obtain a dispersed mixed liquid; dispersing 2.4 g of polycarboxylate ether in water to obtain a polycarboxylate ether dispersion, adding the polycarboxylate ether dispersion dropwise to the mixed dispersion, fully dispersing at 50° C. and standing for 14 h; then separating and collecting the precipitate, fully washing the precipitate and drying it to obtain a composite;

[0086] (5) Place 5 g of the complex in a carbon dioxide atmosphere at a flow rate of 1 L / min, adsorb at 50°C for 0.5 to 1 h, and after naturally cooling to room temperature, take out the adsorbed complex and mix it with 0.4 g of aluminum sulfate, 0.2 g of calcium formate, 1.4 g of lithium carbonate and 0.1 g of triethanolamine, add alcohol to moisten it, and grind it at a speed of 1 r / s to constant weight to obtain a health-free agent.

[0087] Embodiment 11:

[0088] (1) 3 g of hexadecyltrimethylammonium bromide was placed in 50% v / v ethanol, and the pH was adjusted to 12 with aqueous ammonia to obtain a hexadecyltrimethylammonium bromide solution; 5 g of tetraethoxysilane was added to the hexadecyltrimethylammonium bromide solution, and the mixture was stirred for 11 h. After the precipitate was separated and collected, it was fully washed with ethanol and dried, and then calcined at 600° C. for 5 h to obtain porous silica;

[0089] (2) 1.5 g of porous silica was fully dispersed in ethanol, and the pH of the system was adjusted to 10 with aqueous ammonia; 1 g of 3-aminopropyltriethoxysilane was added, and the reaction was stirred at 60° C. for 10 h; after the reaction, the precipitate was collected by centrifugation, and the precipitate was fully washed with ethanol and fully dried to obtain modified silica;

[0090] (3) 1.6 g of calcium nitrate was dissolved in water to prepare a calcium nitrate solution, 2.4 g of cyclodextrin was added to the calcium nitrate solution, and then the pH of the solution was adjusted to 11 using sodium hydroxide to obtain a precursor solution; 1.3 g of sodium silicate was taken to prepare a sodium silicate solution; the temperature of the precursor solution and the sodium silicate solution was adjusted to 60° C., and then the sodium silicate solution was slowly added dropwise to the precursor solution at a rate of 0.1 mL / s. After the addition was completed, the solution was stirred at a high speed of 800 rpm for 0.5 h, and then kept warm and allowed to stand for 1 day; after completion, the solution was fully washed with water and ethanol and dried to obtain calcium silicate seed crystals;

[0091] (4) dispersing 2 g of modified silicon dioxide and 2 g of calcium silicate seed crystals in water to obtain a dispersed mixed liquid; dispersing 2.4 g of polycarboxylate ether in water to obtain a polycarboxylate ether dispersion, adding the polycarboxylate ether dispersion dropwise to the mixed dispersion, fully dispersing at 50° C. and standing for 14 h; then separating and collecting the precipitate, fully washing the precipitate and drying it to obtain a composite;

[0092] (5) Place 2 g of the complex in a carbon dioxide atmosphere at a flow rate of 5 L / min, adsorb at 50°C for 0.5 to 1 h, and after naturally cooling to room temperature, take out the adsorbed complex and mix it with 0.4 g of aluminum sulfate, 0.2 g of calcium formate, 1.4 g of lithium carbonate and 0.1 g of triethanolamine, add alcohol to moisten it, and grind it at a speed of 1 r / s to constant weight to obtain a health-free agent.

[0093] Embodiment 12:

[0094] (1) 3 g of hexadecyltrimethylammonium bromide was placed in 50% v / v ethanol, and the pH was adjusted to 12 with aqueous ammonia to obtain a hexadecyltrimethylammonium bromide solution; 5 g of tetraethoxysilane was added to the hexadecyltrimethylammonium bromide solution, and the mixture was stirred for 11 h. After the precipitate was separated and collected, it was fully washed with ethanol and dried, and then calcined at 600° C. for 5 h to obtain porous silica;

[0095] (2) 1.5 g of porous silica was fully dispersed in ethanol, and the pH of the system was adjusted to 10 with aqueous ammonia; 1 g of 3-aminopropyltriethoxysilane was added, and the reaction was stirred at 60° C. for 10 h; after the reaction, the precipitate was collected by centrifugation, and the precipitate was fully washed with ethanol and fully dried to obtain modified silica;

[0096] (3) 1.6 g of calcium nitrate was dissolved in water to prepare a calcium nitrate solution, 2.4 g of cyclodextrin was added to the calcium nitrate solution, and then the pH of the solution was adjusted to 11 using sodium hydroxide to obtain a precursor solution; 1.3 g of sodium silicate was taken to prepare a sodium silicate solution; the temperature of the precursor solution and the sodium silicate solution was adjusted to 60° C., and then the sodium silicate solution was slowly added dropwise to the precursor solution at a rate of 0.1 mL / s. After the addition was completed, the solution was stirred at a high speed of 800 rpm for 0.5 h, and then kept warm and allowed to stand for 1 day; after completion, the solution was fully washed with water and ethanol and dried to obtain calcium silicate seed crystals;

[0097] (4) dispersing 2 g of modified silicon dioxide and 2 g of calcium silicate seed crystals in water to obtain a dispersed mixed liquid; dispersing 2.4 g of polycarboxylate ether in water to obtain a polycarboxylate ether dispersion, adding the polycarboxylate ether dispersion dropwise to the mixed dispersion, fully dispersing at 50° C. and standing for 14 h; then separating and collecting the precipitate, fully washing the precipitate and drying it to obtain a composite;

[0098] (5) Place 2 g of the complex in a carbon dioxide atmosphere at a flow rate of 1 L / min, adsorb at 40°C for 0.5 to 1 h, and after naturally cooling to room temperature, take out the adsorbed complex and mix it with 0.4 g of aluminum sulfate, 0.2 g of calcium formate, 1.4 g of lithium carbonate and 0.1 g of triethanolamine, add alcohol to moisten it, and grind it at a speed of 1 r / s to constant weight to obtain a health-free agent.

[0099] Embodiment 13:

[0100] (1) 3 g of hexadecyltrimethylammonium bromide was placed in 50% v / v ethanol, and the pH was adjusted to 12 with aqueous ammonia to obtain a hexadecyltrimethylammonium bromide solution; 5 g of tetraethoxysilane was added to the hexadecyltrimethylammonium bromide solution, and the mixture was stirred for 11 h. After the precipitate was separated and collected, it was fully washed with ethanol and dried, and then calcined at 600° C. for 5 h to obtain porous silica;

[0101] (2) 1.5 g of porous silica was fully dispersed in ethanol, and the pH of the system was adjusted to 10 with aqueous ammonia; 1 g of 3-aminopropyltriethoxysilane was added, and the reaction was stirred at 60° C. for 10 h; after the reaction, the precipitate was collected by centrifugation, and the precipitate was fully washed with ethanol and fully dried to obtain modified silica;

[0102] (3) 1.6 g of calcium nitrate was dissolved in water to prepare a calcium nitrate solution, 2.4 g of cyclodextrin was added to the calcium nitrate solution, and then the pH of the solution was adjusted to 11 using sodium hydroxide to obtain a precursor solution; 1.3 g of sodium silicate was taken to prepare a sodium silicate solution; the temperature of the precursor solution and the sodium silicate solution was adjusted to 60° C., and then the sodium silicate solution was slowly added dropwise to the precursor solution at a rate of 0.1 mL / s. After the addition was completed, the solution was stirred at a high speed of 800 rpm for 0.5 h, and then kept warm and allowed to stand for 1 day; after completion, the solution was fully washed with water and ethanol and dried to obtain calcium silicate seed crystals;

[0103] (4) dispersing 2 g of modified silicon dioxide and 2 g of calcium silicate seed crystals in water to obtain a dispersed mixed liquid; dispersing 2.4 g of polycarboxylate ether in water to obtain a polycarboxylate ether dispersion, adding the polycarboxylate ether dispersion dropwise to the mixed dispersion, fully dispersing at 50° C. and standing for 14 h; then separating and collecting the precipitate, fully washing the precipitate and drying it to obtain a composite;

[0104] (5) Place 2 g of the complex in a carbon dioxide atmosphere at a flow rate of 1 L / min, adsorb at 60°C for 0.5 to 1 h, and after naturally cooling to room temperature, take out the adsorbed complex and mix it with 0.4 g of aluminum sulfate, 0.2 g of calcium formate, 1.4 g of lithium carbonate and 0.1 g of triethanolamine, add alcohol to moisten it, and grind it at a speed of 1 r / s to constant weight to obtain a health-free agent.

[0105] Embodiment 14:

[0106] (1) 3 g of hexadecyltrimethylammonium bromide was placed in 50% v / v ethanol, and the pH was adjusted to 12 with aqueous ammonia to obtain a hexadecyltrimethylammonium bromide solution; 5 g of tetraethoxysilane was added to the hexadecyltrimethylammonium bromide solution, and the mixture was stirred for 11 h. After the precipitate was separated and collected, it was fully washed with ethanol and dried, and then calcined at 600° C. for 5 h to obtain porous silica;

[0107] (2) 1.5 g of porous silica was fully dispersed in ethanol, and the pH of the system was adjusted to 10 with aqueous ammonia; 1 g of 3-aminopropyltriethoxysilane was added, and the reaction was stirred at 60° C. for 10 h; after the reaction, the precipitate was collected by centrifugation, and the precipitate was fully washed with ethanol and fully dried to obtain modified silica;

[0108] (3) 1.6 g of calcium nitrate was dissolved in water to prepare a calcium nitrate solution, 2.4 g of cyclodextrin was added to the calcium nitrate solution, and then the pH of the solution was adjusted to 11 using sodium hydroxide to obtain a precursor solution; 1.3 g of sodium silicate was taken to prepare a sodium silicate solution; the temperature of the precursor solution and the sodium silicate solution was adjusted to 60° C., and then the sodium silicate solution was slowly added dropwise to the precursor solution at a rate of 0.1 mL / s. After the addition was completed, the solution was stirred at a high speed of 800 rpm for 0.5 h, and then kept warm and allowed to stand for 1 day; after completion, the solution was fully washed with water and ethanol and dried to obtain calcium silicate seed crystals;

[0109] (4) dispersing 2 g of modified silicon dioxide and 2 g of calcium silicate seed crystals in water to obtain a dispersed mixed liquid; dispersing 2.4 g of polycarboxylate ether in water to obtain a polycarboxylate ether dispersion, adding the polycarboxylate ether dispersion dropwise to the mixed dispersion, fully dispersing at 50° C. and standing for 14 h; then separating and collecting the precipitate, fully washing the precipitate and drying it to obtain a composite;

[0110] (5) Place 2 g of the complex in a carbon dioxide atmosphere at a flow rate of 1 L / min, adsorb at 50°C for 0.5 to 1 h, and after naturally cooling to room temperature, take out the adsorbed complex and mix it with 0.4 g of aluminum sulfate, 0.2 g of calcium formate, 1.4 g of lithium carbonate and 0.1 g of triethanolamine, add alcohol to moisten it, and grind it at a speed of 5 r / s to constant weight to obtain a health-free agent.

[0111] Example sample test:

[0112] Weigh the PI 42.5 cement raw material and then place it in a mixer, stir at a speed of 140r / min for 2min until it is evenly mixed, disperse the curing agent of each embodiment in water, and then stir it with cement at a dosage of 2%, and continue stirring at the same speed for 4min; finally, mold the mixed cement slurry to make a 4cm×4cm×4cm cube; cover the surface of the molded specimen with plastic wrap, and demould it after curing for 12h. After the specimen is demoulded, standard curing is performed to the specified age, and the compressive strength of the specimens cured for 1d and 28d is tested, and the compressive strength growth rate from 1d to 28d is calculated, and the specimen without curing agent is used as a control. The results are shown in Table 1:

[0113] Table 1:

[0114]

[0115] According to GB / T 5008-2016 "Standard for Test Methods for Performance of Ordinary Concrete Mixtures", the fluidity, initial setting time and final setting time of the mixed cement were tested. The results are shown in Table 2 below:

[0116] Table 2:

[0117]

[0118]

[0119] As can be seen from Table 1 and Table 2, the compressive strength of the cement samples prepared in each embodiment is close to the strength of the curing for 28 days after curing for 1 day, and the setting time is short, indicating that the cement curing agent of the present invention can significantly shorten the curing time of cement. Compared with Example 1, when preparing porous carbon dioxide, the initial setting time and final setting time of Example 2 are shorter, indicating that the calcination time is longer and more conducive to the adsorption of carbon dioxide. The silica in Example 3 is more, the content of aminosilane is reduced, and the setting time of the sample is longer. It can be seen that the amino modification of carbon dioxide is conducive to shortening the setting time of cement and increasing the strength. The fluidity of Example 4 is significantly reduced, but the setting time is significantly reduced, and the strength is also increased, indicating that cyclodextrin is conducive to the growth of calcium silicate seeds. The setting time of the sample of Example 5 increases, and the strength is also reduced, indicating that in the process of preparing calcium silicate seeds, a faster feeding speed will be unfavorable for the growth of seeds. The fluidity of Example 6 increases, the setting time decreases, but the strength decreases slightly, indicating that a faster stirring speed is beneficial to improving the function of the curing agent to promote setting, but a faster stirring speed is not conducive to the radial growth of the seed crystals. The fluidity of Example 7 is significantly reduced, the setting speed is fast, and the strength is also increased, indicating that a longer growth time of the seed crystals is beneficial to the accelerated setting and early strength of the curing agent of the present invention. Compared with Example 1, the setting speed and strength of Example 8 are both reduced, while the setting speed and strength of Example 9 are increased, indicating that a single increase in the amount of seed crystals is not conducive to improving the performance of the curing agent, and more polycarboxylic acid ethers are beneficial to the full connection of silicon dioxide and calcium silicate seed crystals, improving the accelerated setting and early strength capabilities of the curing agent.

[0120] In Example 10, more complexes are added to the curing agent-free formula compared to Example 1, and the setting time is reduced and the setting strength is increased, but it does not match the increase in the content of the complexes, and the fluidity is significantly reduced, indicating that the complexes and the remaining metal salts and triethanolamine need to work together to shorten the curing time of cement. Increasing the amount of the complexes alone will affect the construction performance of cement. The cement of Example 11 has a fast setting speed, and the growth rate of compressive strength also increases, indicating that the greater the flow rate of carbon dioxide, the more conducive it is to its adsorption, the more conducive it is to shorten the curing time of cement and the long-term growth of strength. The adsorption temperature of Example 12 is lower, and the adsorption temperature of Example 13 is higher, but the setting speed and strength of both are lower than that of Example 1. It may be that the lower temperature is not conducive to the adsorption of carbon dioxide, and the higher temperature may affect the properties of the adsorption matrix. The grinding speed of Example 14 is faster, the fluidity of cement is increased, but the setting speed and strength are reduced. It may be that the excessively fast grinding speed easily destroys the structure of the complex, affecting the performance of the curing agent-free.

[0121] For those skilled in the art, various other corresponding changes and deformations can be made according to the technical solutions and concepts described above, and all of these changes and deformations should fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a cement curing agent, characterized in that: Take porous silica, perform amino modification on the porous silica to obtain modified silica; prepare calcium silicate seed crystals; then compound the modified silica and calcium silicate seed crystals with polycarboxylate ether to obtain a composite; adsorb carbon dioxide on the composite and mix it with an early strength material to obtain a health-free agent; the preparation of the composite includes the following steps: a. Disperse the porous silica in ethanol and adjust the pH of the system to 9-11 with ammonia water; add 3-aminopropyltriethoxysilane and stir the reaction at 50-70°C for 9-12 hours; collect the precipitate by centrifugation, wash the precipitate with ethanol, and dry it to obtain modified silica; b. Calcium nitrate is dissolved in water to prepare a calcium nitrate solution, cyclodextrin is added to the calcium nitrate solution, and then the pH of the solution is adjusted to 11-12 using sodium hydroxide to obtain a precursor solution; sodium silicate is taken to prepare a sodium silicate solution; the temperature of the precursor solution and the sodium silicate solution is adjusted to 50-70° C., and then the sodium silicate solution is slowly added dropwise to the precursor solution, and after the addition is completed, the solution is stirred at a high speed and then kept warm and allowed to stand; after the addition is completed, the solution is fully washed with water and ethanol and dried to obtain calcium silicate seed crystals; c. Dispersing modified silicon dioxide and calcium silicate seed crystals in water to obtain a dispersed mixed liquid; dispersing polycarboxylate ether in water to obtain a polycarboxylate ether dispersion, dropping the polycarboxylate ether dispersion into the mixed dispersion, fully dispersing at 40-60° C. and standing for 10-20 hours; then separating and collecting the precipitate, fully washing the precipitate and drying it to obtain a composite.

2. The method for preparing the cement curing agent according to claim 1, characterized in that: The mass ratio of the modified silica to the calcium silicate seed is 1:1-3; the mass ratio of the modified silica to the polycarboxylate ether is 1:1.2-2; the early strength material is a metal salt and triethanolamine; the mass ratio of the composite to the metal salt and triethanolamine is 1:0.2-2:0.02-0.

06.

3. The method for preparing the cement curing agent according to claim 2, characterized in that: The metal salt is one or more of sodium sulfate, aluminum sulfate, sodium aluminate, calcium chloride, calcium formate, and lithium carbonate.

4. The method for preparing the cement curing agent according to claim 1, characterized in that: The mass ratio of 3-aminopropyltriethoxysilane to porous silica in step a is 1:1.5-4; the mass ratio of calcium nitrate to sodium silicate in step b is 1:1.1-1.5; the mass ratio of calcium nitrate to cyclodextrin in step b is 1:1.5-3.

5. The method for preparing the cement curing agent according to claim 1, characterized in that: In step b, the mixture is stirred at high speed for 0.5 to 1 hour, and then kept warm and allowed to stand for 0.5 to 2 days.

6. The method for preparing the cement curing agent according to claim 1, characterized in that: The speed of the slow dripping in step b is 0.1-0.3 mL / s; the speed of the high-speed stirring is 800-1500 rpm.

7. The method for preparing the cement curing agent according to claim 1, characterized in that: The composite is placed in a carbon dioxide atmosphere with a flow rate of 0.5~5L / min, adsorbed at 40~60℃ for 0.5~1h, and after naturally dropping to room temperature, the adsorbed composite is taken out and mixed with the early strength material, moistened with alcohol, and ground at a speed of 1~5r / s to constant weight to obtain a health-free agent.

8. The method for preparing the cement curing agent according to claim 1, characterized in that: The preparation of the porous silica comprises the following steps: Hexadecyltrimethylammonium bromide is placed in 40-60% v / v ethanol, and the pH is adjusted to 11-12 with ammonia water to obtain a hexadecyltrimethylammonium bromide solution; tetraethoxysilane is added to the hexadecyltrimethylammonium bromide solution, and the mixture is stirred for reaction for 10-12 hours. After the precipitate is separated and collected, it is fully washed with ethanol and dried, and then calcined at 500-600° C. for 3-8 hours to obtain porous silica; the mass ratio of the hexadecyltrimethylammonium bromide to the tetraethoxysilane is 1:1.2-1.

8.

9. A cement curing agent prepared by the method according to any one of claims 1 to 8.

Images