Slow-release hydration heat inhibitor as well as preparation method and application thereof

Abstract

The invention relates to a slow-release hydration heat inhibitor as well as a preparation method and application thereof. The slow-release hydration heat inhibitor comprises starch, an organic acid derivative and a polymer, the weight ratio of the starch to the organic acid derivative to the polymer is (8.9-30): (1.3-4.0): 1. The technical problem to be solved is how to provide the slow-release hydration heat inhibitor which enables a cement-based material to be high in strength, high in hydration heat inhibition efficiency and low in doping amount. The slow-release hydration heat inhibitor has the effects of long-acting slow release and effective inhibition of hydration heat through the synergistic effect of the starch, the organic acid derivative and the polymer. The slow-release hydration heat inhibitor is prepared from the starch, the organic acid derivative and the polymer, and the method is simple, environment-friendly and beneficial to large-scale popularization and application. The slow-release hydration heat inhibitor disclosed by the invention can effectively reduce the hydration heat of cement in the cement hydration process, and the later strength of a cement-based material is not influenced due to the low doping amount.

Description

Technical Field

[0001] The present invention relates to the technical field of cement admixtures, and particularly to a slow-release heat of hydration inhibitor, a preparation method thereof, and an application thereof. Background Art

[0002] Cement releases a large amount of heat during the hydration process. Especially in the structure of large-volume cement-based materials, excessive internal temperature will lead to the accumulation of temperature stress, which will in turn cause volume deformation and structural cracking, seriously affecting the durability and safety of the cement-based material structure.

[0003] At present, the main heat of hydration inhibitors of cement are chemical retarders, phase change materials, mineral admixtures, etc. Chemical retarders, such as phosphates, lignosulfonates, etc., reduce the temperature rise by delaying the rate of cement hydration reaction, but are likely to cause the loss of the later strength of cement-based concrete. Phase change materials, such as paraffin wax, fatty acid esters, etc., absorb the heat of hydration through the latent heat of phase change, but there are problems such as leakage and poor compatibility with cement-based materials, and the inhibitory effect on temperature rise is limited. Mineral admixtures, such as fly ash, slag, etc., reduce the heat of hydration by replacing part of the cement, but when the dosage is relatively high, it will affect the early strength and workability of cement-based concrete. The existing heat of hydration inhibitors have low inhibition efficiency on the heat of hydration of cement-based materials, high dosage, and cause strength loss of cement-based materials. At the same time, the preparation processes of some heat of hydration inhibitors are complex and the cost is relatively high, making it difficult to be popularized and applied on a large scale. Summary of the Invention

[0004] The main purpose of the present invention is to provide a slow-release heat of hydration inhibitor, a preparation method thereof, and an application thereof. The technical problem to be solved is how to provide a slow-release heat of hydration inhibitor that enables cement-based materials to have high strength, high heat of hydration inhibition efficiency, and low dosage. The slow-release heat of hydration inhibitor of the present invention has the effect of long-acting slow release and effectively inhibiting the heat of hydration through the synergistic effect of each component of starch, organic acid derivatives, and polymers. By preparing starch, organic acid derivatives, and polymers into a slow-release heat of hydration inhibitor, the method is simple, the cost is relatively low, and it is environmentally friendly, which is conducive to large-scale popularization and application. The slow-release heat of hydration inhibitor of the present invention can effectively inhibit the rate of cement hydration reaction during the cement hydration process, can effectively regulate the process and heat release of cement hydration reaction, can effectively reduce the heat of cement hydration, and has a low dosage without affecting the later strength of cement-based materials.

[0005] The object of the present invention and the solution to its technical problems are achieved by adopting the following technical solutions. A slow-release heat of hydration inhibitor according to the present invention includes:

[0006] Starch, organic acid derivatives, and polymers;

[0007] The weight ratio of the starch, the organic acid derivative and the polymer is 8.9-30:1.3-4.0:1.

[0008] The object of the present invention and the technical problems to be solved can be further realized by the following technical measures.

[0009] Preferably, for the aforementioned slow-release heat of hydration inhibitor, the starch is selected from one or more of waxy corn starch, cassava starch and wheat starch.

[0010] Preferably, for the aforementioned slow-release heat of hydration inhibitor, the organic acid derivative is selected from one or more of citric acid, maleic anhydride and tartaric acid.

[0011] Preferably, for the aforementioned slow-release heat of hydration inhibitor, the polymer is selected from any one of polyvinyl alcohol, polycarboxylate superplasticizer and polyacrylamide.

[0012] The object of the present invention and the technical problems to be solved are also achieved by the following technical solutions. A preparation method of a slow-release heat of hydration inhibitor according to the present invention includes the following steps:

[0013] S1. Add starch, inorganic acid solution or hydrolase into water and hydrolyze to form a pre-gel solution;

[0014] S2. Mix the organic acid derivative and the pre-gel solution for reaction to obtain a reaction mixture;

[0015] S3. Mix the reaction mixture and the polymer for reaction to obtain a gel solution;

[0016] S4. Shape the gel solution to obtain the slow-release heat of hydration inhibitor.

[0017] The object of the present invention and the technical problems to be solved can be further realized by the following technical measures.

[0018] Preferably, for the aforementioned preparation method, in step S1, the concentration of the inorganic acid solution is 0.08-0.1 mol / L.

[0019] Preferably, for the aforementioned preparation method, in step S1, the temperature of the hydrolysis is 55-90 °C.

[0020] Preferably, for the aforementioned preparation method, in step S2, the temperature of the reaction is 70-90 °C.

[0021] Preferably, for the aforementioned preparation method, in step S4, the shaping method is freeze-drying or hot pressing.

[0022] Preferably, in the aforementioned preparation method, in step S3, after mixing the reaction mixture and the polymer, keep it at 40-45 °C for heat preservation, and then add a crosslinking agent to react to obtain a gel solution; the temperature of the mixing is 80-90 °C.

[0023] Preferably, in the aforementioned preparation method, in step S3, after mixing the reaction mixture and the polymer, carry out the reaction through freeze-thaw cycles to obtain a gel solution; the temperature of the mixing is 80-90 °C.

[0024] The object of the present invention and the technical problems to be solved are still achieved by the following technical solutions. An application of a slow-release heat of hydration inhibitor in cement-based materials proposed according to the present invention, based on the total weight of the cement-based materials, the dosage of the slow-release heat of hydration inhibitor is 0.5-0.7%.

[0025] By means of the above technical solutions, a slow-release heat of hydration inhibitor and its preparation method and application proposed by the present invention have at least the following advantages:

[0026] A slow-release heat of hydration inhibitor proposed by the present invention includes starch, an organic acid derivative and a polymer. The organic acid derivative can combine with calcium ions Ca 2 + in cement, directly participate in the inhibition of the hydration reaction, thereby delaying the hydration reaction rate of cement minerals and reducing the release of the heat of hydration. It is the key active ingredient for inhibiting the cement hydration reaction. At the same time, the organic acid derivative can also adjust the pH value of the cement paste, further inhibiting the progress of the hydration reaction. The organic acid derivative binds to starch, and starch can encapsulate the organic acid derivative, enabling it to be slowly released during the cement hydration process and continuously inhibiting the hydration reaction. The polymer can improve the dispersibility of the slow-release heat of hydration inhibitor in the cement paste, ensure the uniform distribution of the active ingredient organic acid derivative, and can improve the mechanical strength and stability of the slow-release heat of hydration inhibitor, preventing it from decomposing prematurely in the cement paste. At the same time, the polymer can also form a composite structure with starch, optimizing the performance and stability of the slow-release heat of hydration inhibitor and further enhancing the slow-release effect. In addition, the formation of a gel-like structure by starch in the cement paste can increase the viscosity of the slow-release heat of hydration inhibitor, contribute to the uniform dispersion of the slow-release heat of hydration inhibitor in the cement paste, and thus prolong the effect of inhibiting the heat of hydration.

[0027] In a slow-release heat of hydration inhibitor proposed by the present invention, the weight ratio of starch, organic acid derivative and polymer is 8.9-30:1.3-4.0:1, which can ensure the stability and long-term effectiveness of the slow-release heat of hydration inhibitor, ensure that the organic acid derivative can effectively inhibit the hydration reaction, and at the same time avoid the slow development of cement strength caused by excessive use of the organic acid derivative. It can ensure that the polymer can optimize the performance of the slow-release heat of hydration inhibitor, and at the same time avoid the increase in cost caused by excessive use of the polymer, ensuring that the slow-release heat of hydration inhibitor has the characteristics of long-term slow release, effective inhibition of heat of hydration and good dispersibility, while taking into account economy and practicality. Among them, starch, as a slow-release carrier, is derived from natural plants and has degradability, meeting the requirements of green environmental protection. The dosages of the polymer and the organic acid derivative are relatively low, reducing the impact on the environment.

[0028] A preparation method of a slow-release heat of hydration inhibitor proposed by the present invention is to prepare a slow-release heat of hydration inhibitor from starch, organic acid derivative and polymer. First, starch, inorganic acid solution or hydrolase is added to water and hydrolyzed to form a pre-gel solution under stirring. Partial hydrolysis of the starch chain can be achieved through acidic catalysis or enzymatic catalysis conditions, generating a pre-gel solution containing low molecular weight dextrin or glucose units. Secondly, the organic acid derivative and the pre-gel solution are mixed and reacted to form a reaction mixture solution with starch-organic acid covalent bonds, and the carboxylic acid groups of the organic acid derivative are condensed with the starch hydroxyl groups. Thirdly, the polymer and the reaction mixture solution are stirred and mixed to form a gel solution with a cross-linked network structure. Finally, a slow-release heat of hydration inhibitor with stable performance is obtained through shaping. The preparation method is simple, has low cost and is environmentally friendly, which is conducive to large-scale popularization and application.

[0029] The application of a slow-release heat of hydration inhibitor proposed by the present invention in cement-based materials. During the cement hydration process, the organic acid derivative reacts with cement minerals to delay the hydration rate and reduce the release of heat of hydration. Starch encapsulates the organic acid derivative, enabling it to be slowly released during the cement hydration process and continuously inhibiting the hydration reaction. The polymer improves the dispersibility and enhances the structural stability to ensure the uniformity and persistence of the slow-release process. Through the slow-release and dispersing effects of starch and polymer, it is ensured that the organic acid derivative is evenly distributed in the cement paste, avoiding too fast or too slow local reactions. Through the synergistic effect of the three, the slow-release heat of hydration inhibitor of the present invention can effectively reduce the heat of hydration of cement, is applicable to large-volume cement-based material projects, and can effectively prevent cracks in large-volume cement-based materials caused by temperature stress. In particular, based on the total weight of the cement-based material, the dosage of the slow-release heat of hydration inhibitor is low, only 0.5-0.7% of the total weight of the cement-based material, reducing the peak heat release of the cement-based material by more than 40%.

[0030] The above description is only an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and implement it in accordance with the content of the specification, the following describes the preferred embodiments of the present invention in detail as follows. Detailed implementation manners

[0031] To further elaborate on the technical means and effects adopted by the present invention to achieve the intended invention purpose, the following, in combination with preferred embodiments, details the specific implementation manners, structures, features and effects of a slow-release heat of hydration inhibitor and its preparation method and application proposed according to the present invention as follows.

[0032] In the first aspect of the present invention, a slow-release heat of hydration inhibitor is proposed, which includes starch, organic acid derivatives and polymers. The starch is selected from one or more of waxy corn starch, cassava starch and wheat starch. The starch is derived from natural plants and has biodegradability and environmental friendliness. As a slow-release carrier, the starch can encapsulate active ingredients such as organic acid derivatives and slowly release them during the cement hydration process. Moreover, a gel-like structure formed in the cement paste can increase the viscosity of the slow-release heat of hydration inhibitor, which helps the slow-release heat of hydration inhibitor to be evenly dispersed in the cement paste, thereby prolonging the effect of inhibiting the heat of hydration. The organic acid derivatives are selected from one or more of citric acid, maleic anhydride and tartaric acid, and can combine with calcium ions Ca 2 + in the cement, directly participate in the inhibition of the hydration reaction, delay the hydration reaction rate of cement minerals, and thus reduce the release of the heat of hydration. The organic acid derivatives can also adjust the pH value of the cement paste, further affecting the progress of the hydration reaction. By combining with starch, the organic acid derivatives can be slowly released and continuously inhibit the hydration reaction, which is the key active ingredient for inhibiting the cement hydration reaction. The polymer is selected from any one of polyvinyl alcohol, polycarboxylate superplasticizer and polyacrylamide, which can improve the dispersibility of the slow-release heat of hydration inhibitor in the cement paste, ensure the uniform distribution of the active ingredient (organic acid derivative), can improve the mechanical strength and stability of the slow-release heat of hydration inhibitor, prevent it from decomposing prematurely in the cement paste, and can further form a composite structure with starch, optimize the performance and stability of the slow-release heat of hydration inhibitor, and further enhance the slow-release effect of the slow-release heat of hydration inhibitor.

[0033] In the slow-release heat of hydration inhibitor proposed by the present invention, by controlling the weight ratio of starch, organic acid derivative and polymer within the range of 8.9-30:1.3-4.0:1, the stability and long-term effectiveness of the slow-release heat of hydration inhibitor can be ensured. It can ensure that the organic acid derivative effectively inhibits the hydration reaction, while avoiding the slow development of cement strength caused by excessive use. It can ensure that the polymer optimizes the performance of the slow-release heat of hydration inhibitor, while avoiding the increase in cost caused by excessive use. It ensures that the slow-release heat of hydration inhibitor has the characteristics of long-term slow release, effective inhibition of the heat of hydration and good dispersibility, while taking into account economy and practicality. Among them, the starch is derived from natural plants and has degradability, meeting the requirements of green environmental protection. The usage amounts of the polymer and the organic acid derivative are relatively low, reducing the impact on the environment.

[0034] The second aspect of the present invention proposes a preparation method of a slow-release heat of hydration inhibitor, which includes the following steps:

[0035] First, add starch, inorganic acid solution or hydrolase into water, and hydrolyze it under stirring to form a pre-gel solution. Through acidic catalysis or enzymatic catalysis conditions, partial hydrolysis of the starch chain can occur, generating a pre-gel solution containing low molecular weight dextrin or glucose units. Secondly, mix the organic acid derivative and the pre-gel solution, and react to form a reaction mixture solution with starch-organic acid covalent bonds. The carboxylic acid group of the organic acid derivative undergoes condensation with the starch hydroxyl group. Thirdly, stir and mix the polymer and the reaction mixture solution, and react to form a gel solution with a cross-linked network structure. Finally, obtain a slow-release heat of hydration inhibitor with stable performance through shaping. The preparation method is simple, has low cost, is environmentally friendly, and is conducive to large-scale popularization and application.

[0036] According to an embodiment of the present invention, add starch, inorganic acid solution or hydrolase into water, and hydrolyze it under stirring to form a pre-gel solution, generating a pre-gel solution containing low molecular weight dextrin or glucose units. Through catalysis by an inorganic acid solution with a concentration of 0.08-0.1 mol / L or enzymatic catalysis, it can further effectively promote the partial hydrolysis of the starch chain at 55-90 °C to form a pre-gel solution. Mix the organic acid derivative and the starch pre-gel solution, and react to form a reaction mixture solution with starch-organic acid covalent bonds. At 70-90 °C, it can further effectively promote the condensation of the carboxylic acid group of the organic acid derivative with the starch hydroxyl group, while maintaining the fluidity of the reaction mixture solution. Stir and mix the polymer and the reaction mixture solution, and react to form a gel solution with a cross-linked network structure. Mixing at 80-90 °C can further improve the diffusion ability of the polymer chain. Finally, obtain a slow-release heat of hydration inhibitor with stable performance through shaping. Further, a slow-release heat of hydration inhibitor with more stable performance can be obtained through freeze-drying or hot pressing shaping.

[0037] According to the present invention, the crosslinking agent can be selected by those skilled in the art according to needs, and the present invention does not make special limitations. For example, it can be glutaraldehyde or a redox initiation system.

[0038] According to the present invention, the inorganic acid solution can be selected by those skilled in the art according to needs. For example, it can be a hydrochloric acid solution with a concentration of 0.1 mol / L, a sulfuric acid solution with a concentration of 0.08 mol / L, etc.

[0039] According to the present invention, when mixing the organic acid derivative and the starch pre-gel solution, N,N-dimethylpropanolamine can also be used as a solvent to enhance the compatibility between the organic acid derivative and the starch pre-gel solution.

[0040] According to the present invention, after stirring and mixing the polymer and the reaction mixture solution at 80-90 °C, keeping it at 40-45 °C for 10-30 min provides the optimal reaction temperature for the subsequent addition of the crosslinking agent, and then adding the crosslinking agent to react to obtain a gel solution.

[0041] According to the present invention, after stirring and mixing the reaction mixture and the polymer at 80-90 °C, the reaction is carried out through freeze-thaw cycles to obtain a gel solution.

[0042] According to the present invention, before the gel solution is shaped, if necessary, post-modification treatment can be carried out on the gel solution, micro-regulation is carried out by the sol-gel method, and finally it is shaped by freeze-drying or hot pressing.

[0043] It should be noted that the conditions for freeze-drying in the present invention can be selected by those skilled in the art according to needs. For example, they can be: pre-freezing: maintaining at -60 °C for 4-6 h; first drying: from -35 °C to -25 °C, vacuum degree 10-30 Pa, 24-36 h, second drying: 25 °C - 30 °C, vacuum degree 5-15 Pa, 8-12 h. Thus, the porosity of the slow-release heat of hydration inhibitor prepared by freeze-drying reaches more than 92%, and the specific surface area is not less than 17.3 m 2 / g, having the effect of effectively inhibiting the heat of hydration.

[0044] It should be noted that the conditions for hot pressing in the present invention can be selected by those skilled in the art according to needs. For example, they can be: preheating: maintaining at 60 °C for 30 min; pressing: 10-15 MPa, 1-2 h; cooling: naturally cooling to room temperature. Thus, the structural density of the slow-release heat of hydration inhibitor prepared by hot pressing is increased by more than 30%, and the compressive strength is increased by more than 25%, having the effects of effectively inhibiting the heat of hydration and high strength.

[0045] A preparation method of a slow-release heat of hydration inhibitor proposed by the present invention prepares a slow-release heat of hydration inhibitor by using starch, an organic acid derivative, and a polymer. This slow-release heat of hydration inhibitor can effectively inhibit the rate of cement hydration reaction during the cement hydration process, can effectively regulate the process and heat release of cement hydration reaction, and can effectively reduce the heat of hydration of cement. This slow-release heat of hydration inhibitor has the characteristics of long-term slow release, effective inhibition of heat of hydration, and good dispersibility, and takes into account economy and practicability at the same time.

[0046] The third aspect of the present invention proposes an application of a slow-release heat of hydration inhibitor in cement-based materials. Based on the total weight of the cement-based materials, the dosage of the slow-release heat of hydration inhibitor is 0.5-0.7%.

[0047] Applying the slow-release heat of hydration inhibitor prepared by the present invention in cement-based materials, the starch in the slow-release heat of hydration inhibitor interacts with the surface of cement particles through its molecular chain, adsorbs and inhibits the dissolution of tricalcium silicate, delays the cement hydration reaction, and reduces the early hydration heat release peak. The organic acid derivative in the slow-release heat of hydration inhibitor delays the formation of ettringite, inhibits the nucleation of calcium silicate hydrate, interferes with the nucleation and growth of hydration products, and slows down the rate of cement hydration reaction. The polymer in the slow-release heat of hydration inhibitor reacts with the cement hydration products through the functional groups on its molecular chain during cement hydration, further regulating the process and heat release of cement hydration reaction. At the same time, the three components of the slow-release heat of hydration inhibitor can interact with each other. Starch can wrap the organic acid derivative, making it slowly release during the cement hydration process, continuously inhibiting the hydration reaction, and reducing the heat of hydration release. Starch and polymer ensure the uniform distribution of the organic acid derivative in the cement paste through slow release and dispersion effects, avoiding too fast or too slow local reactions.

[0048] Therefore, when applying the slow-release heat of hydration inhibitor prepared by the present invention in cement-based materials, based on the total weight of the cement-based materials, the dosage of the slow-release heat of hydration inhibitor is 0.5-0.7%, and the peak value of the heat of hydration of the cement-based materials is reduced by more than 40%.

[0049] The present invention will be further described below in conjunction with specific embodiments, but it should not be understood as a limitation to the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art to the present invention based on the above content of the present invention still fall within the protection scope of the present invention.

[0050] Unless otherwise specified, the materials, reagents, etc. involved below are all commercially available products well-known to those skilled in the art; unless otherwise specified, the methods are all well-known methods in the art. Unless otherwise defined, the technical terms or scientific terms used should have the ordinary meaning understood by those of ordinary skill in the art to which the present invention belongs.

[0051] Examples

[0052] Examples 1-7 are used to illustrate the reduction of the peak value of the heat of hydration of cement paste with the addition of the slow-release heat of hydration inhibitor of the present invention and the 28-day compressive strength of cement mortar specimens.

[0053] The reduction amplitude of the peak value of the maximum heat release rate during hydration is used as the criterion for judging the performance of the slow-release heat of hydration inhibitor of the present invention. The greater the reduction amplitude of the heat release rate peak under the same conditions, the better the inhibitory performance of the slow-release heat of hydration inhibitor on cement hydration. The test method is carried out in accordance with Chapter 6, Isothermal Conduction Calorimetry, of GB / T 12959-2024 "Test Method for Heat of Hydration of Cement".

[0054] In the examples of the present invention, 42.5 ordinary Portland cement is used. The mix ratio of the cement mortar specimens used in the test, the production method, and the test method for compressive strength are carried out in accordance with GB / T50081-2002 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete".

[0055] Example 1

[0056] Add 100 g of waxy corn starch to 1000 mL of water, stir at 55 °C and slowly add 0.1 mol / L hydrochloric acid solution, and carry out hydrolysis reaction for 1 h. The starch is partially hydrolyzed to form a pre-gel solution. Add 15 g of citric acid to the pre-gel solution, react at 90 °C for 2 h to obtain a reaction mixture. After the reaction is completed, then add 5 g of polycarboxylate superplasticizer, stir and mix at 90 °C for 1 h, then cool down to 45 °C, and then add an appropriate amount of glutaraldehyde and react for 1 h. Freeze-dry the gel solution to obtain a heat of hydration inhibitor.

[0057] Add the prepared inhibitor to the cement at an admixture amount of 0.6% and test according to the test method. The results show that the peak value of the maximum heat release rate during hydration is reduced by 66.0%, and the 28-day compressive strength reaches 53.1 MPa.

[0058] Example 2

[0059] Add 120 g of tapioca starch to 1200 mL of water, stir at 90 °C and slowly add 0.08 mol / L sulfuric acid solution, and carry out hydrolysis reaction for 1.5 h. The starch is partially hydrolyzed to form a pre-gel solution. Add 20 g of maleic anhydride to the pre-gel solution, react at 70 °C for 2.5 h to obtain a reaction mixture. After the reaction is completed, then add 8 g of polyacrylamide, stir and mix at 80 °C for 1.5 h, then cool down to 40 °C, and then add a redox initiation system and react for 1.5 h. Shape the gel solution by hot pressing to obtain a heat of hydration inhibitor.

[0060] The inhibitor was added to cement at a dosage of 0.7% and tested according to the test method. The results showed that the peak value of the maximum heat release rate of hydration decreased by 68.6%, and the compressive strength at 28 days reached 51.5 MPa.

[0061] Example 3

[0062] 80 g of wheat starch was added to 800 mL of water, stirred at 80 °C and an enzyme catalyst was added, and the hydrolysis reaction was carried out for 50 min. The wheat starch was partially hydrolyzed to form a pre-gel solution. 12 g of tartaric acid was added to the pre-gel solution, and the reaction was carried out at 85 °C for 1.5 h to obtain a reaction mixture. After the reaction was completed, 6 g of polyvinyl alcohol was then added, and the mixture was stirred and mixed at 88 °C for 1 h, cross-linked by freeze-thaw cycles, and finally the gel solution was post-modified, microscopically regulated by the sol-gel method, and finally freeze-dried to obtain a hydration heat inhibitor.

[0063] The inhibitor was added to cement at a dosage of 0.5%, and the test showed that the peak value of the maximum heat release rate of hydration decreased by 46.1%, and the compressive strength at 28 days reached 55.8 MPa.

[0064] Example 4

[0065] 150 g of waxy corn starch was added to 1500 mL of deionized water, stirred at 85 °C and a 0.1 mol / L hydrochloric acid solution was slowly added dropwise, and the hydrolysis reaction was carried out for 1 h. The waxy corn starch was partially hydrolyzed to form a pre-gel solution. 18 g of tartaric acid was added to the pre-gel solution, and the reaction was carried out at 85 °C for 2 h. After the reaction was completed, 7 g of polyvinyl alcohol was then added, and the mixture was stirred and mixed at 90 °C for 1 h. Subsequently, the temperature was lowered to 50 °C, and an appropriate amount of glutaraldehyde was added and reacted for 1 h. The gel solution was freeze-dried to obtain a hydration heat inhibitor.

[0066] The prepared inhibitor was added to cement at a dosage of 0.6% and tested according to the test method. The results showed that the peak value of the maximum heat release rate of hydration decreased by 55.2%, and the compressive strength at 28 days reached 54.2 MPa.

[0067] Example 5

[0068] 130 g of cassava starch was added to 1300 mL of deionized water, stirred at 90 °C and a 0.08 mol / L sulfuric acid solution was slowly added dropwise, and the hydrolysis reaction was carried out for 1.5 h. The cassava starch was partially hydrolyzed to form a pre-gel solution. 16 g of citric acid was added to the pre-gel solution, and the reaction was carried out at 80 °C for 2 h. After the reaction was completed, 9 g of polyacrylamide was then added, and the mixture was stirred and mixed at 85 °C for 1.5 h. Subsequently, the temperature was lowered to 40 °C, and a redox initiation system was added and reacted for 1.5 h. The gel solution was freeze-dried to obtain a hydration heat inhibitor.

[0069] The inhibitor was added to cement at a dosage of 0.7%, and the test results showed that the peak value of the maximum exothermic rate of hydration decreased by 62.7%, and the 28-day compressive strength reached 53.1 MPa.

[0070] Example 6

[0071] 110 g of wheat starch was added to 1100 mL of deionized water, stirred at 90 °C and an enzyme catalyst was added, and the hydrolysis reaction was carried out for 50 min. The starch was partially hydrolyzed to form a pre-gel solution. 14 g of maleic anhydride was added to the pre-gel solution, and the reaction was carried out at 88 °C for 1.5 h. After the reaction was completed, 6 g of polycarboxylate superplasticizer was then added, and the mixture was stirred and mixed at 88 °C for 1 h. Subsequently, the temperature was lowered to 45 °C, and an appropriate amount of glutaraldehyde was added and reacted for 1 h. The gel solution was post-modified, microscopically regulated by the sol-gel method, and finally freeze-dried to obtain a hydration heat inhibitor.

[0072] The inhibitor was added to cement at a dosage of 0.6%, and the test showed that the peak value of the maximum exothermic rate of hydration decreased by 65.0%, and the 28-day compressive strength reached 54.7 MPa.

[0073] Example 7

[0074] 140 g of waxy corn starch was added to 1400 mL of deionized water, stirred at 90 °C and a 0.08 mol / L hydrochloric acid solution was slowly added dropwise, and the hydrolysis reaction was carried out for 1 h. The starch was partially hydrolyzed to form a pre-gel solution. 8 g of citric acid and 8 g of tartaric acid were added to the pre-gel solution, and the reaction was carried out at 85 °C for 2 h. After the reaction was completed, 8 g of polyvinyl alcohol was then added, and the mixture was stirred and mixed at 90 °C for 1 h. Crosslinking was carried out by freeze-thaw cycles. The gel solution was post-modified, microscopically regulated by the sol-gel method, and finally freeze-dried to obtain a hydration heat inhibitor. The pH of the slurry was 4.2, and the release rate of organic acids was controlled by starch slow release to avoid sudden pH drop from damaging the setting process.

[0075] The prepared inhibitor was added to cement at a dosage of 0.5% and tested according to the test method. The results showed that the peak value of the maximum exothermic rate of hydration decreased by 52.3%, and the 28-day compressive strength reached 51.5 MPa.

[0076] Blank example

[0077] The blank example was the reference group, and the slow-release hydration heat inhibitor of the present invention was not added.

[0078] Comparative example 1

[0079] 100 g of waxy corn starch was added to 1000 mL of water, stirred at 55 °C and a 0.1 mol / L hydrochloric acid solution was slowly added dropwise, and the hydrolysis reaction was carried out for 1 h to form a pre-gel solution. The pre-gel solution was cooled to 45 °C. It was freeze-dried and shaped to obtain an inhibitor.

[0080] The prepared inhibitor was added to cement at a dosage of 0.6%, and tested according to the test method. The results showed that the peak value of the maximum exothermic rate of hydration decreased by 40.2%, and the 28-day compressive strength reached 48.4 MPa.

[0081] Comparative Example 2

[0082] 15 g of citric acid was dissolved in 1000 mL of water to directly obtain a mixed solution. The temperature was lowered to 45 °C. It was freeze-dried and shaped to obtain an inhibitor.

[0083] The prepared inhibitor was added to cement at a dosage of 0.6%, and tested according to the test method. The results showed that the peak value of the maximum exothermic rate of hydration decreased by 33.5%, and the 28-day compressive strength reached 50.5 MPa.

[0084] Comparative Example 3

[0085] 5 g of polycarboxylate superplasticizer was added to 1000 mL of water and stirred and mixed for 1 h. It was freeze-dried and shaped to obtain an inhibitor.

[0086] The prepared inhibitor was added to cement at a dosage of 0.6%, and tested according to the test method. The results showed that the peak value of the maximum exothermic rate of hydration decreased by 43.2%, and the 28-day compressive strength reached 47.3 MPa.

[0087] Table 1 shows the test data of the comparative examples and the examples

[0088]

[0089] From the data of the above examples and comparative examples, it can be seen that when the slow-release heat of hydration inhibitor of the present invention is applied in cement-based materials, based on the total weight of the cement-based materials, the dosage of the slow-release heat of hydration inhibitor is 0.5-0.7%, the peak value of the heat of hydration of the cement-based materials is reduced by more than 40%, and its 28-day compressive strength increases normally, meeting the engineering requirements and conforming to relevant standards.

[0090] Therefore, the slow-release heat of hydration inhibitor of the present invention has a high efficiency in inhibiting the heat of hydration of cement-based materials, a low dosage, and does not affect the later strength of cement-based materials. At the same time, the preparation process of the slow-release heat of hydration inhibitor of the present invention is simple, the cost is low, it is environmentally friendly, and has the potential for large-scale popularization and application.

[0091] The technical features in the claims and / or the specification of the present invention can be combined, and the combination method is not limited to the combination obtained through the citation relationship in the claims. The technical solutions obtained by combining the claims and / or technical features are also within the protection scope of the present invention.

[0092] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A slow-release hydration heat inhibitor, characterized in that: It includes: starch, organic acid derivatives and polymers; The weight ratio of the starch, the organic acid derivative and the polymer is 8.9-30:1.3-4.0:

1.

2. The inhibitor according to claim 1, characterized in that The starch is selected from one or more of waxy corn starch, tapioca starch and wheat starch.

3. The inhibitor according to claim 1, characterized in that The organic acid derivative is selected from one or more of citric acid, maleic anhydride and tartaric acid.

4. The inhibitor according to claim 1, characterized in that The polymer is selected from any one of polyvinyl alcohol, polycarboxylic acid superplasticizer and polyacrylamide.

5. A method for preparing a slow-release hydration heat inhibitor, characterized in that: It includes the following steps: S1. Adding starch, inorganic acid solution or hydrolase into water to hydrolyze to form a pre-gel solution; S2. mixing the organic acid derivative and the pre-gel solution to react to obtain a reaction mixture; S3. The reaction mixture and the polymer are mixed and reacted to obtain a gel solution; S4. shaping the gel solution to obtain a slow-release hydration heat inhibitor.

6. The preparation method according to claim 5, characterized in that: In step S1, the concentration of the inorganic acid solution is 0.08-0.1 mol / L; the temperature of the hydrolysis is 55-90°C.

7. The preparation method according to claim 5, characterized in that: In step S2, the reaction temperature is 70-90°C; In step S4, the shaping method is freeze drying or hot pressing.

8. The preparation method according to claim 5, characterized in that: In step S3, the reaction mixture and the polymer are mixed and kept warm at 40-45°C, and then a cross-linking agent is added to react to obtain a gel solution; the mixing temperature is 80-90°C.

9. The preparation method according to claim 5, characterized in that: In step S3, the reaction mixture and the polymer are mixed and reacted through a freeze-thaw cycle to obtain a gel solution; the mixing temperature is 80-90°C.

10. Application of a slow-release hydration heat inhibitor in cement-based materials, characterized in that: Based on the total weight of the cement-based material, the slow-release hydration heat inhibitor is added in an amount of 0.5-0.7%.

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