Cement-based material mixing state intelligent regulation and control auxiliary agent and preparation method and application thereof

Abstract

The invention discloses a cement-based material mixing state intelligent regulation and control auxiliary agent and a preparation method and application thereof. The auxiliary agent is composed of reversible sulfonation modified degradable starch and acrylic resin containing hydroxyl. The method is characterized in that the sulfonated modified starch plays roles in dispersing and suspending cement particles and gravels and improving uniformity and flowability in the cement-based material mixing and injection molding stages, and the sulfonated starch is stimulated to be reversibly reduced into dialdehyde starch in a cement paste alkaline environment in the curing and curing stage; the molecules are mutually crosslinked to form a three-dimensional network structure, so that the effects of dispersing, suspending, adhering and fixing cement particles and gravels are achieved. Therefore, the prepared cement-based material mixing state intelligent regulation and control auxiliary agent has the intelligent effects of presenting different molecular structures and playing different roles in the stirring, injection molding and curing states, the preparation method is unique, the materials are easy to obtain, the application effect is remarkable, and the good application prospect is achieved.

Description

Technical Field

[0001] The present invention relates to an admixture for cement-based materials, and specifically to an intelligent regulation aid for the mixing state of cement-based materials, its preparation method and application. Background Art

[0002] The biggest problem with cement-based materials is that they are prone to cracking, resulting in the strength and durability of cement-based materials falling far short of the theoretical level. The main reason for the cracking of cement-based materials is the uneven distribution of components during the mixing, casting, and curing processes of cement-based materials, leading to an uneven and non-dense structure after curing. The key to solving the cracking problem of cement-based materials lies in the use of admixtures with dispersion and suspension effects to ensure that the cement-based materials are always in a state of uniform component distribution, stable and dense structure during the mixing, casting, and curing processes. The defects such as uneven and non-dense structure of cement-based materials are manifested as bleeding and segregation during the mixing and casting stages, and the settlement of sand and gravel and slurry during the static curing stage, resulting in uneven distribution of sand and gravel in cement-based materials, failure to achieve the expected strength target, cracking, and leakage problems. The key to solving the above problems is to use admixtures with dispersion and suspension effects to make the cement-based materials have good fluidity and the persistence of uniform component distribution, so that the components of the cement-based materials are evenly distributed, the structure after curing is uniform, showing high strength, high volume stability, and high crack resistance effect. Summary of the Invention

[0003] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide an intelligent regulation aid for the mixing state of cement-based materials, its preparation method and application. The unique feature is that the structure of the admixture of the present invention has pH stimulus responsiveness to the external environment, that is, it has an intelligent regulation function. Its role in the dynamic stirring stage of mixing and casting is to sulfonate and modify starch to disperse and suspend cement particles and sand and gravel, and can increase the fluidity of cement-based materials. In the static stage of curing components, the alkaline environment of the cement paste makes the sulfonated modified starch reduce to dialdehyde starch, increasing the interaction between molecules, producing an interweaving and cross-linking effect and forming a three-dimensional network structure, achieving the functions of dispersing, suspending, cohesive and fixing cement particles and sand and gravel in cement-based materials, and forming a uniform and dense structure. Therefore, an intelligent regulation aid for the mixing state of cement-based materials prepared by the method of the present invention has different molecular structures and plays different roles in the stirring motion states such as stirring and casting of cement-based materials and the static states such as curing, and the realization of its function depends on the unique structure of the admixture itself and its intelligent responsiveness to external environmental changes.

[0004] In order to achieve the above purpose, the present invention adopts the following technical solutions to achieve: A preparation method and application of an intelligent regulation aid for the mixing state of cement-based materials, comprising the following steps: Step 1: Preparation of modified starch solution: 1) By mass fraction (the same in the following steps), mix 40 - 50 parts of starch, 2 - 3 parts of sodium hydroxide, and 120 - 130 parts of water. After that, heat the mixture with stirring to 85℃ - 95℃ and keep it for 50 - 60 minutes for gelatinization. Then cool it down to 60 - 70℃, add 0.05 - 0.08 parts of α - amylase, keep the temperature and continue stirring for 30 - 40 minutes, and then cool it down to 25 - 35℃ to obtain a degraded starch solution.

[0005] 2) Use citric acid to adjust the pH value of the degraded starch solution prepared in 1) to 3.0 - 3.5. Add 15 - 18 parts of sodium periodate, and react under stirring at 25 - 35℃ for 4.5 - 5.5 hours to obtain a dialdehyde starch solution. Then add 12 - 15 parts of sodium bisulfite, heat it to 60 - 65℃ and stir for 3 - 5 hours, and then cool it down to 25 - 35℃ to obtain a modified starch solution.

[0006] Step 2: Preparation of polycarboxylic acid solution containing side - hydroxyl groups: 1) Add 40 - 50 parts of vinyl butyl ether polyoxyethylene ether, 1.5 - 2.5 parts of acrylic acid, 5 - 8 parts of hydroxyethyl acrylate, 2 - 3 parts of N,N - dimethyl (methacryloyloxyethyl) aminopropyl sulfobetaine, 0.5 - 0.8 parts of ammonium persulfate, and 0.1 - 0.3 parts of zinc oxide into 50 - 60 parts of water in sequence. Stir to make them fully mixed and dissolved, and adjust the system temperature to 40 - 50℃.

[0007] 2) Drop the mixture of 3.5 - 5.5 parts of acrylic acid, 0.3 - 0.5 parts of ascorbic acid, 0.1 - 0.3 parts of mercaptoethanol and 40 - 50 parts of water into the mixture in 1) within 1.5 - 2.5 hours. After the dropping is completed, keep the temperature at 40 - 50℃ and react for 2 - 3 hours. 3) Cool the product in 2) to 25 - 30℃, and then slowly drop 20 - 25 parts of 40% sodium hydroxide solution by mass fraction. Adjust the pH value to 6 - 7 to obtain a polycarboxylic acid solution containing side - hydroxyl groups.

[0008] Step 3: Mix the modified starch solution prepared in Step 1 with the polycarboxylic acid containing side - hydroxyl groups prepared in Step 2, and stir evenly to obtain an intelligent regulating additive for the mixing state of cement - based materials.

[0009] Furthermore, the starch is one or a mixture of corn starch, potato starch, and cassava starch.

[0010] Furthermore, the enzyme activity of the α - amylase is 20000 u / mg, the applicable temperature range is 40 - 70℃, and the applicable pH range is 6.5 - 7.0.

[0011] Further, the purity of the sodium hydroxide, sodium periodate, citric acid, and sodium bisulfite is greater than 99%.

[0012] Further, the purity of the vinyl butyl ether polyoxyethylene ether, acrylic acid, hydroxyethyl acrylate, N,N-dimethyl(methacryloyloxyethyl)aminopropyl sulfobetaine, ammonium persulfate, zinc oxide, ascorbic acid, mercaptoethanol, and sodium hydroxide is greater than 99%.

[0013] Further, the number-average degree of polymerization of the side-hydroxy polycarboxylic acid in step 2 is 50,000 - 80,000, and the molecular weight dispersion coefficient is 1.3 - 1.5.

[0014] Further, the content of the active ingredient in the solution of the intelligent regulation aid for the mixing state of the cement-based material prepared is 30%, and the pH value is 7.0.

[0015] Further, when the intelligent regulation aid for the mixing state of the cement-based material prepared by the method is 1.5% - 2% of the cement dosage in the cement-based material, it has a uniform dispersion and suspension effect on the cement-based material, and when applied to the cement-based material, it will form a uniform and dense structure, having high strength and high durability.

[0016] Compared with the prior art, the present invention has the following technical effects: After this aid is added to the cement-based material, it is in a linear structure during the mixing and casting stages, mainly playing the role of externally dispersing and suspending cement particles and sand and gravel to increase the fluidity of the cement-based material. During the curing and solidification stages, the linear molecules of the modified starch and the linear molecules of the copolymer of acrylic acid and hydroxyethyl propionate crosslink in an alkaline environment to form a three-dimensional network structure, which has the effects of dispersing, suspending, cohesively aggregating, and fixing the cement particles and sand and gravel in the cement-based material and forming a uniform and dense structure.

[0017] The molecular structure of this aid has an environmental pH stimulation effect. The linear sulfonated modified starch will release sulfonic acid groups to generate aldehyde groups in the alkaline environment of the cement-based material, and then can undergo aldol condensation with the side-hydroxy groups in the copolymer of acrylic acid and hydroxyethyl acrylate to form a three-dimensional intertwined network structure. The aid of the present invention will change its molecular structure according to the alkaline environment, and can change from a linear molecule to a three-dimensional network structure, achieving the effects of dispersing, suspending, cohesively aggregating, and fixing the cement particles and sand and gravel in the cement-based material.

[0018] The intelligent regulation aid for the mixing state of the cement-based material prepared by the method of the present invention has different molecular structures and plays different roles respectively in the stirring and casting motion states such as stirring and casting of the cement-based material and in the static states such as curing and solidification. The realization of its function depends on the unique structure of the added agent itself and its intelligent responsiveness to external environmental changes. Description of the Drawings

[0019] Figure 1 Schematic diagram of the chemical structure in the preparation process of an intelligent regulation aid for the mixing state of cement-based materials disclosed by the present invention; among them, (a) is a schematic diagram of the chemical reaction process for preparing modified starch; (b) is a schematic diagram of the chemical reaction process in the preparation process of polycarboxylic acid with side hydroxyl groups. Specific embodiments

[0020] The following further elaborates and explains the specific content of the present invention in conjunction with examples.

[0021] The starch selected in Examples 1 to 5 is one or a mixture of corn starch, potato starch, and cassava starch.

[0022] The starch selected in Examples 1 to 5 is one or a mixture of corn starch, potato starch, and cassava starch.

[0023] The enzyme activity of α-amylase selected in Examples 1 to 5 is 20000 u / mg, the applicable temperature range is 40 - 70 °C, and the applicable pH range is 6.0 - 7.0.

[0024] The purity of sodium hydroxide, sodium periodate, citric acid, and sodium bisulfite selected in Examples 1 to 5 is greater than 99%.

[0025] The acrylic resin with side hydroxyl groups prepared by the above method selected in Examples 1 to 5 is an aqueous solution, with an active ingredient content of 30%, a pH value of 6.5 - 7.5, a number average molecular weight of 50,000 - 80,000, and a molecular weight dispersion coefficient of 1.3.

[0026] The starch selected in Examples 1 to 5 is one or a mixture of corn starch, potato starch, and cassava starch.

[0027] The enzyme activity of α-amylase selected in Examples 1 to 5 is 20000 u / mg, the applicable temperature range is 40 - 70 °C, and the applicable pH range is 6.0 - 7.0.

[0028] The purity of sodium hydroxide, sodium periodate, citric acid, and sodium bisulfite selected in Examples 1 to 5 is greater than 99%.

[0029] The purity of vinyl butyl ether polyoxyethylene ether, acrylic acid, hydroxyethyl acrylate, N,N-dimethyl(methacryloyloxyethyl)aminopropylsulfonic acid inner salt, ammonium persulfate, zinc oxide, ascorbic acid, mercaptoethanol, and sodium hydroxide selected in Examples 1 to 5 is greater than 99%.

[0030] The number average degree of polymerization of the polycarboxylic acid with side hydroxyl groups selected in Examples 1 to 5 is 50,000 - 80,000, and the molecular weight dispersion coefficient is 1.3 - 1.5.

[0031] The content of the active ingredient in the solution of the intelligent control aid for the mixing state of the cement-based material prepared in Examples 1 to 5 is 30%, and the pH value is 7.0.

[0032] Example 1 Step 1: Preparation of the modified starch solution: 1) By mass fraction (the same in the following steps), mix 40 parts of starch, 2 parts of sodium hydroxide, and 120 parts of water, heat to 85 °C with stirring for 50 minutes for gelatinization, cool to 60 °C, add 0.05 part of α-amylase, keep warm and continue stirring for 30 minutes, then cool to 25 °C to obtain a degraded starch solution.

[0033] 2) Adjust the pH value of the degraded starch solution prepared in 1) to 3.0 with citric acid, add 15 parts of sodium periodate, react at 25 °C with stirring for 4.5 hours to obtain a dialdehyde starch solution, then add 12 parts of sodium bisulfite, heat to 60 °C and stir for 3 hours, and cool to 25 °C to obtain a modified starch solution.

[0034] Step 2: Preparation of the solution containing side-hydroxy polycarboxylic acid: 1) Add 40 parts of vinyl butyl ether polyoxyethylene ether, 1.5 parts of acrylic acid, 5 parts of hydroxyethyl acrylate, 2 parts of N,N-dimethyl(methacryloyloxyethyl)aminopropyl sulfonate inner salt, 0.5 part of ammonium persulfate, and 0.1 part of zinc oxide to 50 parts of water in sequence, stir to make them fully mixed and dissolved, and adjust the system temperature to 40 °C.

[0035] 2) Drop the mixture of 3.5 parts of acrylic acid, 0.3 part of ascorbic acid, 0.1 part of mercaptoethanol and 40 parts of water into the mixture in 1), the dropping time is 1.5 hours, and keep warm and react at 40 °C for 2 hours after the dropping ends; 3) Cool the product in 2) to 25 °C, and then slowly drop 20 parts of a 40% sodium hydroxide solution by mass fraction, adjust the pH value to 6.0 to obtain a solution containing side-hydroxy polycarboxylic acid.

[0036] Step 3: Mix the modified starch solution prepared in Step 1 with the side-hydroxy polycarboxylate sodium prepared in Step 2, stir evenly to obtain an intelligent control aid for the mixing state of the cement-based material, with a content of 30% and a pH value of 7.0. When it is 1.5% of the cement dosage in the cement-based material, it has a uniform dispersion and suspension effect on the cement-based material. When applied to the cement-based material, it will form a uniform and dense structure, with high strength and high durability.

[0037] Example 2 Step 1: Preparation of the modified starch solution: 1) By mass fraction (the same in the following steps), mix 42 parts of starch, 2.2 parts of sodium hydroxide, and 122 parts of water, heat it to 88 °C with stirring for 53 minutes for gelatinization, cool it down to 62 °C, add 0.07 part of α - amylase, keep it warm and continue stirring for 32 minutes, then cool it down to 27 °C to obtain a degraded starch solution.

[0038] 2) Adjust the pH value of the degraded starch solution prepared in 1) to 3.3 with citric acid, add 16 parts of sodium periodate, react with stirring at 27 °C for 4.6 hours to obtain a dialdehyde starch solution, then add 14 parts of sodium bisulfite, heat it to 63 °C and stir for 3.2 hours, and cool it down to 27 °C to obtain a modified starch solution.

[0039] Step 2: Preparation of the solution containing polycarboxylic acid with side - hydroxyl groups: 1) Add 42 parts of vinyl butyl ether polyoxyethylene ether, 1.7 parts of acrylic acid, 5.2 parts of hydroxyethyl acrylate, 2.4 parts of N,N - dimethyl (methacryloyloxyethyl) aminopropyl sulfobetaine, 0.6 part of ammonium persulfate, and 0.2 part of zinc oxide into 52 parts of water in sequence, stir to make them fully mixed and dissolved, and adjust the system temperature to 42 °C.

[0040] 2) Drop the mixture of 3.6 parts of acrylic acid, 0.35 part of ascorbic acid, 0.15 part of mercaptoethanol and 43 parts of water into the mixture in 1) over 1.6 hours, and keep it warm and react at 42 °C for 2.2 hours after dropping; 3) Cool the product in 2) to 27 °C, then slowly drop 22 parts of 40% sodium hydroxide solution by mass fraction, and adjust the pH value to 6.5 to obtain the solution containing polycarboxylic acid with side - hydroxyl groups.

[0041] Step 3: Mix the modified starch solution prepared in Step 1 with the polycarboxylate with side - hydroxyl groups prepared in Step 2, stir evenly to obtain an intelligent regulating additive for the mixing state of cement - based materials, with a content of 30% and a pH value of 7.0. When it is 1.6% of the cement dosage in the cement - based material, it has a uniform dispersion and suspension effect on the cement - based material, and when applied to the cement - based material, it will form a uniform and dense structure, with high strength and high durability.

[0042] Example 3 Step 1: Preparation of the modified starch solution: 1) By mass fraction (the same in the following steps), mix 45 parts of starch, 2.5 parts of sodium hydroxide, and 125 parts of water, heat it to 90 °C with stirring for 55 minutes for gelatinization, cool it down to 65 °C, add 0.07 part of α - amylase, keep it warm and continue stirring for 35 minutes, then cool it down to 30 °C to obtain a degraded starch solution.

[0043] 2) Adjust the pH value of the degraded starch solution prepared in 1) to 3.3 with citric acid, add 17 parts of sodium periodate, react for 5.0 hours under stirring at 30 °C to obtain a dialdehyde starch solution, then add 14 parts of sodium bisulfite, heat to 63 °C and stir for 4 hours, and cool to 32 °C to obtain a modified starch solution.

[0044] Step 2: Preparation of the solution containing polycarboxylic acid with side hydroxyl groups: 1) Add 43 parts of vinyl butyl ether polyoxyethylene ether, 2.0 parts of acrylic acid, 6 parts of hydroxyethyl acrylate, 2.6 parts of N,N-dimethyl(methacryloyloxyethyl)aminopropyl sulfobetaine, 0.7 part of ammonium persulfate, and 0.2 part of zinc oxide to 58 parts of water in sequence, stir to fully mix and dissolve them, and adjust the system temperature to 46 °C.

[0045] 2) Dropwise add a mixture of 4.0 parts of acrylic acid, 0.4 part of ascorbic acid, 0.2 part of mercaptoethanol and 43 parts of water to the mixture in 1) over 2.0 hours, and keep the temperature at 46 °C for 2.5 hours after the addition; 3) Cool the product in 2) to 28 °C, then slowly dropwise add 23 parts of a 40% sodium hydroxide solution by mass, and adjust the pH value to 6.5 to obtain a solution containing polycarboxylic acid with side hydroxyl groups.

[0046] Step 3: Mix the modified starch solution prepared in Step 1 with the solution containing polycarboxylic acid with side hydroxyl groups prepared in Step 2, stir evenly to obtain an intelligent regulating aid for the mixing state of cement-based materials, with a content of 30% and a pH value of 7.0. When it is 1.7% of the cement dosage in the cement-based material, it has a uniform dispersion and suspension effect on the cement-based material, and applying it to the cement-based material will form a uniform and dense structure with high strength and high durability.

[0047] Example 4 Step 1: Preparation of the modified starch solution: 1) (The same in the following steps) Mix 48 parts of starch, 2.8 parts of sodium hydroxide, and 128 parts of water by mass, heat to 93 °C under stirring for 58 minutes for gelatinization, cool to 68 °C, add 0.07 part of α-amylase, keep the temperature and continue stirring for 38 minutes, and cool to 32 °C to obtain a degraded starch solution.

[0048] 2) Adjust the pH value of the degraded starch solution prepared in 1) to 3.4 with citric acid, add 17 parts of sodium periodate, react for 5.2 hours under stirring at 31 °C to obtain a dialdehyde starch solution, then add 14 parts of sodium bisulfite, heat to 64 °C and stir for 4 hours, and cool to 30 °C to obtain a modified starch solution.

[0049] Step 2: Preparation of the solution containing polycarboxylic acid with side hydroxyl groups: 1) Add 48 parts of vinyl butyl ether polyoxyethylene ether, 2.2 parts of acrylic acid, 7 parts of hydroxyethyl acrylate, 2.8 parts of N,N-dimethyl(methacryloyloxyethyl)aminopropylsulfonic acid inner salt, 0.7 part of ammonium persulfate, and 0.25 part of zinc oxide to 58 parts of water in sequence, stir to make them fully mixed and dissolved, and adjust the system temperature to 48 °C.

[0050] 2) Dropwise add a mixture of 5.0 parts of acrylic acid, 0.4 part of ascorbic acid, 0.2 part of mercaptoethanol and 45 parts of water into the mixture in 1), the dropping time is 2.0 hours, and keep the temperature at 48 °C for 2.5 hours after the dropping ends; 3) Cool the product in 2) to 28 °C, and then slowly dropwise add 23 parts of 40% sodium hydroxide solution by mass, adjust the pH value to 7.0, and obtain a solution containing polycarboxylic acid with side hydroxyl groups.

[0051] Step 3: Mix the modified starch solution prepared in Step 1 with the polycarboxylate sodium with side hydroxyl groups prepared in Step 2, stir evenly, and obtain an intelligent control aid for the mixing state of cement-based materials, with a content of 30% and a pH value of 7.0. When it is 1.8% of the cement dosage in the cement-based material, it has a uniform dispersion and suspension effect on the cement-based material. When applied to the cement-based material, it will form a uniform and dense structure, with high strength and high durability.

[0052] Example 5 Step 1: Preparation of modified starch solution: 1) By mass fraction (the same in the following steps), mix 50 parts of starch, 3 parts of sodium hydroxide, and 130 parts of water, heat to 95 °C under stirring and keep it for 60 minutes for gelatinization, cool to 70 °C, add 0.08 part of α-amylase, keep the temperature and continue to stir for 40 minutes, and then cool to 35 °C to obtain a degraded starch solution.

[0053] 2) Adjust the pH value of the degraded starch solution prepared in 1) to 3.5 with citric acid, add 18 parts of sodium periodate, react under stirring at 35 °C for 5.5 hours to obtain a dialdehyde starch solution, then add 15 parts of sodium bisulfite, heat to 65 °C and stir for 5 hours, and cool to 35 °C to obtain a modified starch solution.

[0054] Step 2: Preparation of polycarboxylic acid solution with side hydroxyl groups: 1) Add 50 parts of vinyl butyl ether polyoxyethylene ether, 2.5 parts of acrylic acid, 8 parts of hydroxyethyl acrylate, 3 parts of N,N-dimethyl(methacryloyloxyethyl)aminopropylsulfonic acid inner salt, 0.8 part of ammonium persulfate, and 0.3 part of zinc oxide to 60 parts of water in sequence, stir to make them fully mixed and dissolved, and adjust the system temperature to 50 °C.

[0055] 2) A mixture of 5.5 parts of acrylic acid, 0.5 part of ascorbic acid, 0.3 part of mercaptoethanol and 50 parts of water was added dropwise to the mixture in 1) over a period of 2.5 hours. After the addition was complete, the reaction mixture was kept at 50 °C for 3 hours for reaction. 3) The product of 2) was cooled to 30 °C, and then 25 parts of a 40% sodium hydroxide solution by mass was slowly added dropwise while adjusting the pH value to 7.0 to obtain a solution containing polycarboxylic acid with side hydroxyl groups.

[0056] Step 3: The modified starch solution prepared in Step 1 was mixed with the polycarboxylate sodium with side hydroxyl groups prepared in Step 2 and stirred evenly to obtain an intelligent regulating aid for the mixing state of cement-based materials, with a content of 30% and a pH value of 7.0. When used at 2.0% of the cement dosage in the cement-based material, it has a uniform dispersion and suspension effect on the cement-based material. When applied to the cement-based material, it will form a uniform and dense structure with high strength and high durability.

[0057] An intelligent regulating aid for the mixing state of cement-based materials prepared in Examples 1 to 5 is used for cement-based composites such as cement mortar and concrete, and for cement-based materials such as buildings, roads, bridges, culverts, hydropower dams, and high-rise buildings.

[0058] To facilitate the comparison of the performance of the samples prepared in different examples, the intelligent regulating aids for the mixing state of cement-based materials prepared in Examples 1 to 5 were used in C40 concrete. Concrete samples were prepared according to the mass ratio of cement: manufactured sand: manufactured gravel: water: solid polycarboxylate superplasticizer of 446:687:1122:165:0.90. The performance of the prepared concrete samples was tested in accordance with GB / T8076 - 2023 "Test Methods for the Homogeneity of Concrete Admixtures", GB / T50080 - 2016 "Standard Test Methods for Properties of Ordinary Concrete Mixtures", GB / T50107 - 2019 "Standard for Evaluation of Concrete Strength Inspection", and GB / T50082 - 2023 "Standard Test Methods for Long-Term Performance and Durability of Ordinary Concrete". The results are shown in Table 1: Table 1 Application Performance of the Aids Prepared in Examples 1 to 5 As can be seen from Table 1, a kind of intelligent control additive for the mixing state of cement-based materials and application specimens prepared in Examples 1 to 5 have excellent mechanical properties and durability, specifically manifested as follows: 1) It has good fluidity, the initial setting time and final setting time are increased compared with the comparative samples, and the compressive strength and flexural strength at 7 days and 28 days are respectively greatly improved compared with the control samples, indicating that this additive has a water retention and good dispersion effect, enabling the cement-based materials to have sufficient hydration time and form a structure with higher strength; the compressive strength at 28 days reaches 46.43 - 53.83 MPa. 2) The results of the 28-day freeze-thaw experiment and impermeability test show that this plugging material has good durability, indicating good frost resistance and being more durable; 3) The carbonation depth is 0.1 - 0.2 mm, having good durability; 4) The results of the 28-day volume dry shrinkage show no shrinkage phenomenon, indicating good volume stability; 5) The results of the 28-day dry shrinkage test show that this additive has a good anti-shrinkage and micro-expansion effect. The intelligent control additive for the mixing state of cement-based materials prepared in Examples 1 to 5 has excellent working performance, strength, volume stability and durability, and is suitable for making different types of cement-based composites.

Claims

1. A preparation method and application of an intelligent regulation aid for the mixing state of cement-based materials, characterized in that, Its preparation method comprises the following steps: Step 1. Preparation of the modified starch solution: 1) By mass fraction (the same in the following steps), mix 40 - 50 parts of starch, 2 - 3 parts of sodium hydroxide, and 120 - 130 parts of water. Under stirring, heat to 85°C - 95°C and keep for 50 - 60 minutes for gelatinization. Then cool to 60°C - 70°C, add 0.05 - 0.08 parts of α - amylase, keep warm and continue stirring for 30 - 40 minutes, and then cool to 25°C - 35°C to obtain a degraded starch solution; 2) Adjust the pH value of the degraded starch solution prepared in 1) to 3.0 - 3.5 with citric acid, add 15 - 18 parts of sodium periodate, react at 25°C - 35°C under stirring for 4.5 - 5.5 hours to obtain a dialdehyde starch solution. Then add 12 - 15 parts of sodium bisulfite, heat to 60°C - 65°C and stir for 3 - 5 hours, and then cool to 25°C - 35°C to obtain a modified starch solution; Step 2. Preparation of the polycarboxylic acid solution containing side - hydroxyl groups: 1) Add 40 - 50 parts of vinyl butyl ether polyoxyethylene ether, 1.5 - 2.5 parts of acrylic acid, 5 - 8 parts of hydroxyethyl acrylate, 2 - 3 parts of N,N - dimethyl (methacryloyloxyethyl) aminopropyl sulfobetaine, 0.5 - 0.8 parts of ammonium persulfate, and 0.1 - 0.3 parts of zinc oxide into 50 - 60 parts of water in sequence. Stir to make them fully mixed and dissolved, and adjust the system temperature to 40°C - 50°C; 2) Dropwise add the mixture of 3.5 - 5.5 parts of acrylic acid, 0.3 - 0.5 parts of ascorbic acid, 0.1 - 0.3 parts of mercaptoethanol and 40 - 50 parts of water into the mixture in 1) within 1.5 - 2.5 hours. After the dropping is completed, keep warm and react at 40°C - 50°C for 2 - 3 hours; 3) Cool the product in 2) to 25°C - 30°C, and then slowly dropwise add 20 - 25 parts of a 40% sodium hydroxide solution by mass fraction to adjust the pH value to 6.0 - 7.0, thus obtaining the polycarboxylic acid solution containing side - hydroxyl groups; Step 3. Mix the modified starch solution prepared in Step 1 with the polycarboxylic acid containing side - hydroxyl groups prepared in Step 2, and stir evenly to obtain an intelligent regulating aid for the mixing state of cement - based materials.

2. The preparation method of an intelligent regulation aid for the mixing state of a cement-based material according to claim 1, characterized in that, The starch described in Step 1 is one or a mixture of corn starch, potato starch, and cassava starch.

3. The preparation method of an intelligent regulation aid for the mixing state of a cement-based material according to claim 1, characterized in that, The enzyme activity of the α - amylase described in Step 1 is 20000 u / mg, the applicable temperature range is 40°C - 70°C, and the applicable pH range is 6.0 - 7.

0.

4. The preparation method of an intelligent regulation aid for the mixing state of a cement-based material according to claim 1, characterized in that, The purity of the sodium hydroxide, sodium periodate, citric acid, and sodium bisulfite described in Step 1 is greater than 99%.

5. The preparation method of an intelligent regulation aid for the mixing state of a cement-based material according to claim 1, characterized in that, The purity of the vinyl butyl ether polyoxyethylene ether, acrylic acid, hydroxyethyl acrylate, N,N - dimethyl (methacryloyloxyethyl) aminopropyl sulfobetaine, ammonium persulfate, zinc oxide, ascorbic acid, mercaptoethanol, and sodium hydroxide described in Step 2 is greater than 99%.

6. The preparation method of an intelligent control aid for the mixing state of a cement-based material according to claim 1, characterized in that, The number - average degree of polymerization of the polycarboxylic acid containing side - hydroxyl groups described in Step 2 is 50000 - 80000, and the molecular weight distribution coefficient is 1.3 - 1.

5.

7. A preparation method of an intelligent regulation aid for the mixing state of a cement-based material according to claims 1-5, characterized in that, In the solution of the intelligent regulating aid for the mixing state of the prepared cement - based materials, the content of the active ingredient is 30%, and the pH value is 7.

0.

8. An intelligent regulation aid for the mixing state of cement-based materials prepared by the method according to any one of claims 1 to 7.

9. Application of an intelligent regulation aid for cement-based material in mixing state prepared by the preparation method according to any one of claims 1 to 7, characterized in that: It is used at 1.5% to 2% of the cement dosage in the cement-based material, has a uniform dispersion and suspension effect on the cement-based material, forms a uniform and dense structure when applied to the cement-based material, and has high strength and high durability.

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