A concrete glue reducing agent and preparation method thereof

Abstract

The present application discloses a concrete adhesive reducer and a preparation method thereof, which comprises the following raw materials in parts by weight: 30-50 parts of hydrophobically modified carboxymethyl hydroxyethyl cellulose; 0.05-0.1 parts of a dispersant; 0.05-0.1 parts of a penetrant; the hydrophobically modified carboxymethyl hydroxyethyl cellulose having a carboxymethyl cellulose substitution degree of 0.3-0.6 and a hydroxyethyl substitution degree of 1-1.5; the hydrophobically modified carboxymethyl hydroxyethyl cellulose being obtained by hydrophobically modifying a small molecule carboxymethyl hydroxyethyl cellulose; and the small molecule carboxymethyl hydroxyethyl cellulose having a molecular weight of 2000-30000. The concrete adhesive reducer obtained in the present application has a good adhesive reduction rate, can effectively reduce the amount of concrete raw materials used, and can improve the fluidity and compressive strength of concrete.

Description

Technical Field

[0001] The present application relates to the field of adhesive reducers, and in particular to a concrete adhesive reducer and a preparation method thereof. Background Art

[0002] Concrete is widely used in society's development. As human needs increase, higher requirements are placed on concrete properties, leading to the emergence of concrete admixtures. The most common type of admixture is water reducer. Water reducers can absorb cement particles through the hydrophobicity of one end, while the hydrophilic group at the other end faces outward. The like charge of the hydrophilic group creates steric hindrance and electrostatic repulsion between the adsorbed cement particles, destroying the floccules produced during hydration and releasing some of the water that cannot react with the cementitious material, thereby reducing the amount of water required.

[0003] However, water reducers have limitations in destroying flocculent structures. Since commonly used water reducers are composed of macromolecular polymers, they can only adsorb larger cement particles and destroy them through electrostatic repulsion. For some smaller cement particle aggregates, the macromolecular water reducer will adsorb the entire aggregate and cannot destroy its flocculent structure, resulting in a large number of cement particles still unable to be effectively hydrated, which is not conducive to improving the strength and other properties of concrete.

[0004] To address the problem of small cement particle aggregates, existing technologies offer concrete adhesive reducers. Unlike water reducers, adhesive reducers can break down small aggregates, allowing cement particles to fully participate in the hydration reaction and reducing the amount of cement required for cementitious materials. However, current adhesive reducers typically use polymeric polyol compounds, which do not generate strong electrostatic repulsion after adsorbing cement particles. This inadequately destroys small cement particle aggregates, resulting in a relatively low adhesive reduction rate. Summary of the Invention

[0005] In order to solve the problem that the adhesive reducing agent has insufficient adhesive reducing ability for small-volume cement particle aggregates generated during the hydration process, the present application provides a novel concrete adhesive reducing agent and a preparation method thereof.

[0006] In the first aspect, the present application proposes a concrete adhesive reducer, comprising the following raw materials in parts by weight:

[0007] 30-50 parts of hydrophobically modified carboxymethyl hydroxyethyl cellulose;

[0008] Dispersant 0.05-0.1 part;

[0009] Penetrant 0.05-0.1 parts;

[0010] The hydrophobically modified carboxymethyl hydroxyethyl cellulose has a carboxymethyl cellulose substitution degree of 0.5-0.8 and a hydroxyethyl substitution degree of 1-1.5. The hydrophobically modified carboxymethyl hydroxyethyl cellulose is obtained by hydrophobically modifying small molecule carboxymethyl hydroxyethyl cellulose. The molecular weight of the small molecule carboxymethyl hydroxyethyl cellulose is 2000-30000.

[0011] More preferably, the dispersant is at least one of polymaleic anhydride, phosphonopolyacrylic acid and sodium dodecylbenzenesulfonate; and the penetrant is at least one of polyethylene glycol monooleate and methyl silicate.

[0012] Similar to water reducers, gel reducers need to possess amphiphilic properties. During cement hydration, the hydrophobic groups in the gel reducer are directed away from water and adsorbed onto the cement particles, while the hydrophilic groups face outward, acting as steric hindrances while also ionizing in the water. The adsorbed cement particles thus acquire the same electrical properties, generating electrostatic repulsion between the particles and destroying small cement aggregates. However, the gel reducers currently used are mostly made from raw materials such as polymeric polyols, most of whose hydrophilic groups are hydroxyl groups. However, hydroxyl groups are largely incapable of ionization in water, requiring the cationic polymers within the gel reducer to ionize in water to generate electrostatic repulsion, which, however, can only partially destroy small cement aggregates. The present application adopts hydrophobically modified carboxymethyl hydroxyethyl cellulose as the raw material of the gel reducer. Carboxymethyl hydroxyethyl cellulose has very rich carboxyl and hydroxyl groups. The carboxyl groups can be easily ionized in water, so that a stronger electrostatic repulsion is generated between cement particles, thereby causing more effective destruction of cement particle aggregates, allowing cement particles to participate more fully in hydration, reducing the use of cementitious materials, and improving the fluidity and compressive strength of concrete. In addition, carboxymethyl hydroxyethyl cellulose also contains rich hydroxyl groups, which can effectively promote the compatibility of the gel reducer and concrete.

[0013] However, carboxymethyl hydroxyethyl cellulose does not have hydrophobic groups and cannot be adsorbed on cement particles by the hydrophobic groups' repelling water. Therefore, the present invention hydrophobically modifies carboxymethyl hydroxyethyl cellulose, giving it amphiphilic properties and producing a gel-reducing effect.

[0014] At the same time, an important factor that distinguishes a gel reducer from a water reducer is that a water reducer breaks up the large-volume cement flocculent structure, releasing water in the middle that cannot participate in the reaction. Therefore, a water reducer uses a large molecular raw material to produce a better destructive effect; while a gel reducer breaks up the small-volume aggregates of cement particles, allowing the cement particles to fully participate in the reaction. Large molecules cannot destroy and disperse the aggregates of small-volume particles, so a gel reducer requires a small-molecule raw material. This application depolymerizes carboxymethyl hydroxyethyl cellulose to reduce its molecular weight to between 2000 and 30,000, which can better destroy small-volume cement particle aggregates, increase the number and proportion of cement particles participating in the reaction, reduce the amount of cementitious materials used, and improve the fluidity and compressive strength of concrete.

[0015] Preferably, the raw materials for the depolymerization step include carboxymethyl hydroxyethyl cellulose, a diluent and a protonic acid aqueous solution in a mass ratio of (1-2): (3-7): (0.05-1); the protonic acid aqueous solution is at least one of hydrochloric acid and sulfuric acid aqueous solutions.

[0016] By adopting the above technical solution, the molecular weight of the macromolecular carboxymethyl hydroxyethyl cellulose can be reduced, and its ability to destroy small-volume cement particle aggregates can be increased. The present application uses acid to catalyze the hydrolysis and depolymerization of carboxymethyl hydroxyethyl cellulose in a diluent. Under the catalysis of the acid, the carboxymethyl hydroxyethyl cellulose will be hydrolyzed in the diluent to produce small-molecule carboxymethyl hydroxyethyl cellulose.

[0017] On the other hand, the higher the molecular weight of carboxymethyl hydroxyethyl cellulose, the longer its molecular chain, the greater the frictional resistance between molecules, the more likely it is to become disordered, and the greater its viscosity. When the viscosity of the gel reducer increases, it inhibits the fluidity of the concrete and hinders the full reaction between the gel reducer and the concrete. Depolymerizing carboxymethyl hydroxyethyl cellulose to reduce its molecular weight not only improves its permeability and increases its ability to destroy small cement particle aggregates, but also reduces its viscosity, fully dispersing it to exert its gel reducer effect, and enhancing the fluidity and compressive strength of the concrete.

[0018] Preferably, the diluent is an alcohol solvent, and the alcohol solvent is at least one of ethanol, n-propanol, n-butanol, and methylcyclohexanol.

[0019] During the depolymerization process of carboxymethyl hydroxyethyl cellulose, the resulting depolymerized carboxymethyl hydroxyethyl cellulose is prone to severe yellowing, which indicates that some of its groups have been oxidized, affecting the properties of the carboxymethyl hydroxyethyl cellulose. The present application uses alcohols as diluents to not only effectively disperse the carboxymethyl hydroxyethyl cellulose and promote the depolymerization reaction, but also effectively protect the carboxymethyl hydroxyethyl cellulose from oxidation during the depolymerization process, thereby increasing the gel reduction rate of the gel reducer.

[0020] Preferably, the preparation operation of the small molecule carboxymethyl hydroxyethyl cellulose is as follows: dispersing carboxymethyl hydroxyethyl cellulose in a diluent, adding a protonic acid aqueous solution under stirring, and heating to 70-80°C, reacting for 2-6 hours, adjusting the pH value to 7-8 after reacting for 2-6 hours, and then adding a non-polar organic solvent until solids no longer precipitate, filtering and drying to obtain the small molecule carboxymethyl hydroxyethyl cellulose.

[0021] More preferably, the non-polar organic solvent is at least one of hexane and toluene.

[0022] More preferably, the preparation process of the small molecule carboxymethyl hydroxyethyl cellulose is carried out under the protection of an inert gas.

[0023] Preferably, the raw materials of the hydrophobically modified carboxymethyl hydroxyethyl cellulose include the following raw materials in parts by weight:

[0024] 6-10 parts of low molecule carboxymethyl hydroxyethyl cellulose;

[0025] 6-15 parts of hexamethyldisilazane;

[0026] ε-caprolactone 6-15;

[0027] Isopropyl alcohol / hydrochloric acid mixture 60-100;

[0028] 0.1-0.5 parts of acidic catalyst;

[0029] 50-200 parts water;

[0030] The hexamethyldisilazane reacts with water under an acidic catalyst to generate trimethylalkoxysilane, which undergoes a condensation reaction with a small molecule carboxymethyl hydroxyethyl cellulose to generate trimethylsilyl carboxymethyl hydroxyethyl cellulose; the ε-caprolactone is ring-opening polymerized and grafted onto the trimethylsilyl carboxymethyl hydroxyethyl cellulose to obtain polycaprolactone-grafted carboxymethyl hydroxyethyl cellulose; the polycaprolactone-water-grafted carboxymethyl hydroxyethyl cellulose reacts with an isopropyl alcohol / hydrochloric acid mixture to elute the trimethylsilyl hydroxyl group to obtain a hydrophobically modified carboxymethyl hydroxyethyl cellulose.

[0031] Preferably, the preparation method of the hydrophobically modified carboxymethyl hydroxyethyl cellulose comprises the following steps:

[0032] Protection: Dissolve depolymerized carboxymethyl hydroxyethyl cellulose in N,N-dimethylformamide, stir evenly, heat to 95-120°C, then dropwise add hexamethyldisilazane, water and acidic catalyst, react for 7-9 hours, and filter to obtain a crude product;

[0033] Purification: Disperse the crude product in ketone solution, filter, add distilled water, filter and dry to obtain trimethylsilyl carboxymethyl hydroxyethyl cellulose;

[0034] Grafting: Mix trimethylsilyl carboxymethyl hydroxyethyl cellulose and xylene, heat to 70-90°C, stir and react for 1-2 hours, then add ε-caprolactone and catalyst, heat to 110-130°C and react for 12-16 hours to obtain trimethylsilyl carboxymethyl hydroxyethyl cellulose polycaprolactone grafted product;

[0035] Deprotection: add trimethylsilyl carboxymethyl hydroxyethyl cellulose polycaprolactone grafted product to a mixed solution of isopropyl alcohol and hydrochloric acid, stir evenly, heat to 70-80°C and react for 20-30 minutes, filter and dry to obtain hydrophobically modified carboxymethyl hydroxyethyl cellulose.

[0036] By adopting this technical solution, ε-caprolactone undergoes ring-opening polymerization under the action of a catalyst to form polycaprolactone, which is then grafted onto the hydroxyethyl groups in the depolymerized carboxymethyl hydroxyethyl cellulose, imparting hydrophobic groups to the polycarboxymethyl hydroxyethyl cellulose. As an aliphatic polyester, polycaprolactone exhibits excellent hydrophobicity. These hydrophobic groups effectively adsorb cement particles during concrete hydration, thereby increasing the adhesive reduction rate of the adhesive reducer.

[0037] Since the polarity of carboxymethyl hydroxyethyl cellulose and ε-caprolactone is very different, it is difficult to form a good dissolution and dispersion in a solvent for reaction at the same time; moreover, the grafting of polycaprolactone requires the replacement of hydroxyl and carboxyl groups. Without protection, it is easy to replace too many carboxyl and hydroxyl groups, resulting in insufficient carboxyl and hydroxyl groups in the obtained hydrophobically modified carboxymethyl hydroxyethyl cellulose, affecting the ionization strength and compatibility of the glue reducer in concrete. The present application solves this problem by first trimethyl silylation of carboxymethyl hydroxyethyl cellulose. Hexamethyldisilazane undergoes a condensation reaction with the hydroxyl and carboxyl groups after hydrolysis and reduction, which can protect a large number of hydroxyl and carboxyl groups, leaving only a part of the hydroxyl and carboxyl groups for grafting; and after trimethyl silylation, the hydroxyl and carboxyl groups of the carboxymethyl hydroxyethyl cellulose are protected inside, and the outside is hydrophobic, which can react homogeneously with ε-caprolactone in an organic solvent.

[0038] Then, ε-caprolactone is heated under the action of a catalyst for ring-opening polymerization and grafted onto trimethylsilyl carboxymethyl hydroxyethyl cellulose. Finally, the trimethylsilyl group is removed by using an alcoholysis solution to expose the protected hydroxyl and carboxyl groups to obtain hydrophobically modified carboxymethyl hydroxyethyl cellulose.

[0039] During the reaction, the amount of hexamethyldisilazane added can be adjusted to control the number of protected hydroxyl and carboxyl groups; the length of the grafted side chains can be controlled by adjusting the ratio of ε-caprolactone and depolymerized carboxymethyl hydroxyethyl cellulose. The reaction is highly controllable, which is beneficial for preparing the required hydrophobically modified carboxymethyl hydroxyethyl cellulose, improving the performance of the gel reducer, and increasing its energy-saving and consumption-reducing effects.

[0040] Preferably, the catalyst in the grafting step is stannous octoate, and the added amount is 1-5 wt% of the trimethylsilyl carboxymethyl hydroxyethyl cellulose.

[0041] During the catalytic process, stannous octoate will be dissociated into an electronic form and form an organic complex with stannous octoate, becoming the active center of the catalyst. The stannous octoate in the active center maintains a covalent bond and can form coordination with ε-caprolactone. ε-caprolactone is then inserted into the active center and tightly combined with the covalent bond between the previous chain segments to achieve chain growth. The reaction is efficient with few side reactions, which is beneficial to the grafting of polycaprolactone and the more effective adsorption of the gel reducer on cement particles.

[0042] Preferably, in the protection step, trimethylchlorosilane is added to N,N-dimethylformamide in an amount of 2-5 wt% of the small molecule carboxymethyl hydroxyethyl cellulose.

[0043] Trimethylchlorosilane can efficiently catalyze the trimethylsilylation of carboxymethyl hydroxyethyl cellulose. The reaction activity of trimethylchlorosilane is higher than that of hexamethyldisilazane. It will first react with the hydroxyl group in carboxymethyl hydroxyethyl cellulose to generate hydrogen chloride, and the hydrogen chloride will then react with hexamethyldisilazane to generate trimethylsilylcarboxymethyl hydroxyethyl cellulose and new trimethylchlorosilane and release ammonia, which promotes the trimethylsilylation reaction and more effectively protects the hydroxyl and carboxyl groups. The glue reducer can generate sufficient electrostatic repulsion to destroy small-volume cement particle aggregates during the concrete hydration process, thereby ensuring the glue reduction rate of the glue reducer.

[0044] In a second aspect, the present application provides a method for preparing a concrete glue reducer, which is as follows: dissolving hydrophobically modified carboxymethyl hydroxyethyl cellulose in water, adding a penetrant and a dispersant, and stirring for 30-60 minutes to obtain the concrete glue reducer.

[0045] In summary, this application has the following beneficial effects:

[0046] 1. The present application hydrophobically modifies carboxymethyl hydroxyethyl cellulose and grafts polycaprolactone onto the carboxymethyl hydroxyethyl cellulose, thereby giving the carboxymethyl hydroxyethyl cellulose hydrophobic groups and making it amphiphilic. It can adsorb cement particles through the hydrophobic groups, and at the same time, the hydrophilic groups generate electrostatic repulsion in water, effectively destroying cement particle aggregates, increasing the number of cement particles participating in the reaction, thereby reducing the amount of raw materials used, and at the same time increasing the proportion of cement particles participating in the reaction, thereby improving the fluidity and compressive strength of the concrete.

[0047] 2. This application depolymerizes carboxymethyl hydroxyethyl cellulose through acid and alcohol diluents, thereby reducing the molecular weight of carboxymethyl hydroxyethyl cellulose, improving its adhesion to small-volume objects, increasing its adsorption and destructive effect on small-volume cement particle aggregates, and increasing the gel reduction rate of the gel reducer.

[0048] 3. The present application grafts polycaprolactone onto depolymerized carboxymethyl hydroxyethyl cellulose by trimethyl silanization-protection of hydroxyl groups-grafting-deprotection. This not only reduces the polarity of carboxymethyl hydroxyethyl cellulose under trimethyl silanization and allows it to react homogeneously and stably with ε-caprolactone in an organic solvent, but also controllably protects the hydroxyl and carboxyl groups from being replaced, ensuring that the electrostatic repulsion generated by the gel reducer during concrete hydration can effectively destroy small-volume cement particle aggregates and has good compatibility with concrete. DETAILED DESCRIPTION

[0049] Preparation example of hydrophobically modified cellulose

[0050] Preparation Example 1: A hydrophobically modified carboxymethyl hydroxyethyl cellulose was prepared according to the following method:

[0051] Depolymerization: 200 g of carboxymethyl hydroxyethyl cellulose (number average molecular weight of 100,000, carboxymethyl substitution degree of 0.7, hydroxyethyl substitution degree of 1.2) was dissolved in 600 g of ethanol. 26 g of 37% mass concentration hydrochloric acid was added under stirring, and the temperature was raised to 75°C. After reacting for 4 hours, hexane was added until no solid precipitated. After filtration and drying, low-molecule carboxymethyl hydroxyethyl cellulose (number average molecular weight of 12,000) was obtained.

[0052] Protection: Dissolve 200g of small molecule carboxymethyl hydroxyethyl cellulose in 1500g of N,N-dimethylformamide, stir evenly, heat to 110°C, then dropwise add 300g of hexamethyldisilazane, 300g of water and 7g of phosphoric acid, react for 8 hours, and filter to obtain a crude product.

[0053] Purification: Disperse the crude product in acetone, filter, add distilled water, filter, and dry to obtain trimethylsilyl carboxymethyl hydroxyethyl cellulose.

[0054] Grafting: 200 g of trimethylsilyl carboxymethyl hydroxyethyl cellulose and 2000 g of xylene were mixed, heated to 80°C, stirred and reacted for 1.5 hours, then 250 g of ε-caprolactone and 20 g of stannous octoate were added, and the mixture was heated to 120°C and reacted for 14 hours to obtain trimethylsilyl carboxymethyl hydroxyethyl cellulose polycaprolactone grafted product.

[0055] Deprotection: 200 g of trimethylsilyl carboxymethyl hydroxyethyl cellulose polycaprolactone graft was added to a mixed solution of 1000 g of isopropyl alcohol and 1000 g of 2% mass concentration hydrochloric acid, stirred evenly, heated to 75° C. and reacted for 30 minutes, filtered and dried to obtain hydrophobically modified carboxymethyl hydroxyethyl cellulose.

[0056] Preparation Example 2: A hydrophobically modified carboxymethyl hydroxyethyl cellulose was prepared according to the following method:

[0057] Depolymerization: 200 g of carboxymethyl hydroxyethyl cellulose (number average molecular weight of 100,000, carboxymethyl substitution degree of 0.8, hydroxyethyl substitution degree of 1) was dissolved in 500 g of ethanol. 40 g of 37% mass concentration hydrochloric acid was added under stirring, and the temperature was raised to 75°C. After reacting for 6 hours, hexane was added until no solid precipitated. After filtration and drying, low-molecule carboxymethyl hydroxyethyl cellulose (number average molecular weight of 5000) was obtained.

[0058] Protection: Dissolve 200g of small molecule carboxymethyl hydroxyethyl cellulose in 1500g of N,N-dimethylformamide, stir evenly, heat to 110°C, then dropwise add 400g of hexamethyldisilazane, 300g of water and 12.5g of phosphoric acid, react for 8 hours, and filter to obtain a crude product.

[0059] Purification: Disperse the crude product in acetone, filter, add distilled water, filter, and dry to obtain trimethylsilyl carboxymethyl hydroxyethyl cellulose.

[0060] Grafting: Mix 200g of trimethylsilyl carboxymethyl hydroxyethyl cellulose and 2000g of xylene, heat to 80°C, stir and react for 1.5 hours, then add 300g of ε-caprolactone and 10g of stannous octoate, heat to 120°C and react for 14 hours to obtain trimethylsilyl carboxymethyl hydroxyethyl cellulose polycaprolactone grafted product.

[0061] Deprotection: 200 g of trimethylsilyl carboxymethyl hydroxyethyl cellulose polycaprolactone graft was added to a mixed solution of 1000 g of isopropyl alcohol and 1000 g of 2% mass concentration hydrochloric acid, stirred evenly, heated to 75° C. and reacted for 30 minutes, filtered and dried to obtain hydrophobically modified carboxymethyl hydroxyethyl cellulose.

[0062] Preparation Example 3: A hydrophobically modified carboxymethyl hydroxyethyl cellulose was prepared according to the following method:

[0063] Depolymerization: 200 g of carboxymethyl hydroxyethyl cellulose (number average molecular weight of 100,000, carboxymethyl substitution degree of 0.5, hydroxyethyl substitution degree of 1.5) was dissolved in 700 g of isopropanol. 40 g of 37% mass concentration hydrochloric acid was added under stirring, and the temperature was raised to 75°C. After reacting for 2 hours, hexane was added until no solid precipitated. After filtration and drying, low-molecule carboxymethyl hydroxyethyl cellulose (number average molecular weight of 25,000) was obtained.

[0064] Protection: Dissolve 200g of small molecule carboxymethyl hydroxyethyl cellulose in 1500g of N,N-dimethylformamide, stir evenly, heat to 110°C, then dropwise add 200g of hexamethyldisilazane, 300g of water and 2.5g of phosphoric acid, react for 8 hours, and filter to obtain a crude product.

[0065] Purification: Disperse the crude product in acetone solution, filter, add distilled water, filter and dry to obtain trimethylsilyl carboxymethyl hydroxyethyl cellulose.

[0066] Grafting: Mix 200g of trimethylsilyl carboxymethyl hydroxyethyl cellulose and 2000g of xylene, heat to 80°C, stir and react for 1.5 hours, then add 200g of ε-caprolactone and 10g of stannous octoate, heat to 120°C and react for 14 hours to obtain trimethylsilyl carboxymethyl hydroxyethyl cellulose polycaprolactone grafted product.

[0067] Deprotection: Add 200g of trimethylsilyl carboxymethyl hydroxyethyl cellulose polycaprolactone graft to a mixed solution of 1000g of isopropyl alcohol and 1000g of 2% mass concentration hydrochloric acid, stir evenly, heat to 75°C and react for 20-30 minutes, filter and dry to obtain hydrophobically modified carboxymethyl hydroxyethyl cellulose.

[0068] Preparation Example 4, a hydrophobically modified carboxymethyl hydroxyethyl cellulose, differs from Preparation Example 1 in that the small molecule carboxymethyl hydroxyethyl cellulose is not trimethyl silylated when grafting polycaprolactone. It is prepared according to the following method:

[0069] Depolymerization: 200 g of carboxymethyl hydroxyethyl cellulose (number average molecular weight of 100,000, carboxymethyl substitution degree of 0.7, hydroxyethyl substitution degree of 1.2) was dissolved in 600 g of ethanol. 26 g of 37% mass concentration hydrochloric acid was added under stirring, and the temperature was raised to 75°C. After reacting for 4 hours, hexane was added until no solid precipitated. After filtration and drying, low-molecule carboxymethyl hydroxyethyl cellulose (number average molecular weight of 12,000) was obtained.

[0070] Grafting: Mix 200g of small molecule carboxymethyl hydroxyethyl cellulose with 2000g of xylene, heat to 80°C, stir and react for 1.5 hours, then add 250g of ε-caprolactone and 20g of stannous octoate, heat to 120°C and react for 14 hours to obtain trimethylsilyl carboxymethyl hydroxyethyl cellulose polycaprolactone grafted product.

[0071] Preparation Example 5, a hydrophobically modified carboxymethyl hydroxyethyl cellulose, differs from Preparation Example 1 in that an equal amount of L-alanine is used instead of stannous octoate in the grafting step.

[0072] Preparation Example 6, a hydrophobically modified carboxymethyl hydroxyethyl cellulose, differs from Preparation Example 1 in that trimethylsilyl chloride is added in the protection step. The specific operation is as follows: 200 g of small molecule carboxymethyl hydroxyethyl cellulose is dissolved in 1500 g of N,N-dimethylformamide, stirred evenly, heated to 110°C, and then 300 g of hexamethyldisilazane, 6 g of trimethylsilyl chloride, 300 g of water and 7 g of phosphoric acid are added dropwise. The reaction is carried out for 8 hours and filtered to obtain a crude product.

[0073] Preparation Example 7, a hydrophobically modified carboxymethyl hydroxyethyl cellulose, differs from Preparation Example 1 in that an equal amount of dimethoxyethane is used instead of ethanol in the depolymerization step.

[0074] Preparation Example 8, a hydrophobically modified carboxymethyl hydroxyethyl cellulose, which differs from Preparation Example 1 in that no depolymerization step is provided, is prepared according to the following steps:

[0075] Protection: Dissolve 200g of carboxymethyl hydroxyethyl cellulose (number average molecular weight 100,000, carboxymethyl substitution degree 0.7, hydroxyethyl substitution degree 1.2) in 1500g of N,N-dimethylformamide, stir evenly, heat to 110°C, then dropwise add 300g of hexamethyldisilazane, 300g of water, and 7g of phosphoric acid. React for 8 hours, and filter to obtain the crude product.

[0076] Purification: Disperse the crude product in acetone, filter, add distilled water, filter, and dry to obtain trimethylsilyl carboxymethyl hydroxyethyl cellulose.

[0077] Grafting: 200 g of trimethylsilyl carboxymethyl hydroxyethyl cellulose and 2000 g of xylene were mixed, heated to 80°C, stirred and reacted for 1.5 hours, then 250 g of ε-caprolactone and 20 g of stannous octoate were added, and the mixture was heated to 120°C and reacted for 14 hours to obtain trimethylsilyl carboxymethyl hydroxyethyl cellulose polycaprolactone grafted product.

[0078] Deprotection: 200 g of trimethylsilyl carboxymethyl hydroxyethyl cellulose polycaprolactone graft was added to a mixed solution of 1000 g of isopropyl alcohol and 1000 g of 2% mass concentration hydrochloric acid, stirred evenly, heated to 75° C. and reacted for 30 minutes, filtered and dried to obtain hydrophobically modified carboxymethyl hydroxyethyl cellulose.

[0079] Preparation Example 9 A hydrophobically modified hydroxyethyl cellulose was prepared as follows:

[0080] Depolymerization: 200 g of hydroxyethyl cellulose (number average molecular weight of 100,000, degree of substitution of hydroxyethyl group of 1.2) was dissolved in 600 g of ethanol. 26 g of 37% mass concentration hydrochloric acid was added under stirring, and the temperature was raised to 75°C. After reacting for 4 hours, hexane was added until no solid precipitated. After filtration and drying, low-molecule hydroxyethyl cellulose (number average molecular weight of 12,000) was obtained.

[0081] Protection: Dissolve 200g of small molecule hydroxyethyl cellulose in 1500g of N,N-dimethylformamide, stir evenly, heat to 110°C, then dropwise add 300g of hexamethyldisilazane, 300g of water and 7g of phosphoric acid, react for 8 hours, and filter to obtain a crude product.

[0082] Purification: Disperse the crude product in acetone, filter, add distilled water, filter, and dry to obtain trimethylsilyl hydroxyethyl cellulose.

[0083] Grafting: 200 g of trimethylsilyl hydroxyethyl cellulose and 2000 g of xylene were mixed, heated to 80°C, stirred and reacted for 1.5 hours, then 250 g of ε-caprolactone and 20 g of stannous octoate were added, and the mixture was heated to 120°C and reacted for 14 hours to obtain trimethylsilyl hydroxyethyl cellulose polycaprolactone grafted product.

[0084] Deprotection: 200 g of trimethylsilyl hydroxyethyl cellulose polycaprolactone grafted product was added to a mixed solution of 1000 g of isopropyl alcohol and 1000 g of 2% mass concentration hydrochloric acid, stirred evenly, heated to 75° C. and reacted for 30 minutes, filtered and dried to obtain hydrophobically modified hydroxyethyl cellulose.

[0085] Preparation Example 10: A hydrophobically modified carboxymethyl cellulose was prepared as follows:

[0086] Depolymerization: 200 g of carboxymethyl cellulose (number average molecular weight of 100,000, degree of carboxymethyl substitution of 0.7) was dissolved in 600 g of ethanol. 26 g of 37% mass concentration hydrochloric acid was added under stirring, and the temperature was raised to 75°C. After reacting for 4 hours, hexane was added until no solid precipitated. After filtration and drying, low-molecule carboxymethyl cellulose (number average molecular weight of 12,000) was obtained.

[0087] Protection: Dissolve 200g of small molecule carboxymethyl cellulose in 1500g of N,N-dimethylformamide, stir evenly, heat to 110°C, then add 300g of hexamethyldisilazane, 300g of water and 7g of phosphoric acid dropwise, react for 8 hours, and filter to obtain a crude product.

[0088] Purification: Disperse the crude product in acetone, filter, add distilled water, filter, and dry to obtain trimethylsilyl carboxymethyl cellulose.

[0089] Grafting: 200 g of trimethylsilyl carboxymethyl cellulose and 2000 g of xylene were mixed, heated to 80°C, stirred and reacted for 1.5 hours, then 250 g of ε-caprolactone and 20 g of stannous octoate were added, and the mixture was heated to 120°C and reacted for 14 hours to obtain trimethylsilyl carboxymethyl cellulose polycaprolactone grafted product.

[0090] Deprotection: 200 g of trimethylsilyl carboxymethyl cellulose polycaprolactone graft was added to a mixed solution of 1000 g of isopropyl alcohol and 1000 g of 2% mass concentration hydrochloric acid, stirred evenly, heated to 75° C. and reacted for 30 minutes, filtered and dried to obtain hydrophobically modified carboxymethyl cellulose.

[0091] Preparation Example 11, a hydrophobically modified carboxymethyl hydroxyethyl cellulose, differs from Preparation Example 1 in that the degree of substitution of carboxymethyl groups and the degree of substitution of hydroxyethyl groups in the depolymerization step are 0.3 and 0.7, respectively.

[0092] Example

[0093] Example 1, a concrete adhesive reducer, is prepared according to the following method:

[0094] 200 g of the hydrophobically modified carboxymethyl hydroxyethyl cellulose prepared in Preparation Example 1 was dissolved in 3000 g of water, 0.35 g of sodium dodecylbenzenesulfonate and 0.35 g of polyethylene glycol monooleate (A-103) were added, and the mixture was stirred for 40 minutes to obtain a concrete adhesive reducer.

[0095] Example 2, a concrete adhesive reducer, is prepared according to the following method:

[0096] 250 g of the hydrophobically modified carboxymethyl hydroxyethyl cellulose prepared in Preparation Example 2 was dissolved in 3000 g of water, 0.25 g of sodium dodecylbenzenesulfonate and 0.25 g of polyethylene glycol monooleate (A-103) were added, and the mixture was stirred for 60 minutes to obtain a concrete adhesive reducer.

[0097] Example 3, a concrete adhesive reducer, is prepared according to the following method:

[0098] 150 g of the hydrophobically modified carboxymethyl hydroxyethyl cellulose prepared in Preparation Example 3 was dissolved in 3000 g of water, 0.4 g of sodium dodecylbenzenesulfonate and 0.4 g of polyethylene glycol monooleate (A-103) were added, and the mixture was stirred for 30 minutes to obtain a concrete adhesive reducer.

[0099] Example 4 is a concrete adhesive reducer. The difference from Example 1 is that an equal amount of the hydrophobically modified carboxymethyl hydroxyethyl cellulose prepared in Preparation Example 4 is used instead of the hydrophobically modified carboxymethyl hydroxyethyl cellulose prepared in Preparation Example 1.

[0100] Example 5, a concrete adhesive reducer, differs from Example 1 in that an equal amount of the hydrophobically modified carboxymethyl hydroxyethyl cellulose prepared in Preparation Example 5 is used instead of the hydrophobically modified carboxymethyl hydroxyethyl cellulose prepared in Preparation Example 1.

[0101] Example 6, a concrete adhesive reducer, differs from Example 1 in that an equal amount of the hydrophobically modified carboxymethyl hydroxyethyl cellulose prepared in Preparation Example 6 is used instead of the hydrophobically modified carboxymethyl hydroxyethyl cellulose prepared in Preparation Example 1.

[0102] Example 7, a concrete adhesive reducer, differs from Example 1 in that an equal amount of the hydrophobically modified carboxymethyl hydroxyethyl cellulose prepared in Preparation Example 7 is used instead of the hydrophobically modified carboxymethyl hydroxyethyl cellulose prepared in Preparation Example 1.

[0103] Comparative Example

[0104] Comparative Example 1 is a concrete adhesive reducer, which differs from Example 1 in that an equal amount of the hydrophobically modified carboxymethyl hydroxyethyl cellulose prepared in Preparation Example 8 is used instead of the hydrophobically modified carboxymethyl hydroxyethyl cellulose prepared in Preparation Example 1.

[0105] Comparative Example 2, a concrete adhesive reducer, was prepared according to the following method:

[0106] Depolymerization: 200 g of carboxymethyl hydroxyethyl cellulose (number average molecular weight of 100,000, carboxymethyl substitution degree of 0.7, hydroxyethyl substitution degree of 1.2) was dissolved in 600 g of ethanol. 26 g of 37% mass concentration hydrochloric acid was added under stirring, and the temperature was raised to 75°C. After reacting for 4 hours, hexane was added until no solid precipitated. After filtration and drying, low-molecule carboxymethyl hydroxyethyl cellulose (number average molecular weight of 12,000) was obtained.

[0107] Stirring: Dissolve 200 g of small molecule hydroxyethyl fiber in 3000 g of water, add 0.35 g of sodium dodecylbenzene sulfonate and 0.35 g of polyethylene glycol monooleate (A-103), and stir for 40 minutes to obtain a concrete glue reducer.

[0108] Comparative Example 3, a concrete adhesive reducer, is different from Example 1 in that an equal amount of the hydrophobically modified hydroxyethyl cellulose prepared in Preparation Example 9 is used instead of the hydrophobically modified carboxymethyl hydroxyethyl cellulose prepared in Preparation Example 1.

[0109] Comparative Example 4, a concrete adhesive reducer, is different from Example 1 in that an equal amount of the hydrophobically modified carboxymethyl cellulose prepared in Preparation Example 10 is used instead of the hydrophobically modified carboxymethyl hydroxyethyl cellulose prepared in Preparation Example 1.

[0110] Comparative Example 5, a concrete adhesive reducer, differs from Example 1 in that an equal amount of the hydrophobically modified carboxymethyl hydroxyethyl cellulose prepared in Preparation Example 11 is used instead of the hydrophobically modified carboxymethyl hydroxyethyl cellulose prepared in Preparation Example 1.

[0111] Comparative Example 6, a concrete adhesive reducer, was prepared according to the following method:

[0112] Preparation of polymer polyol: 60g butylethanolamine, 120g ethylene glycol diglycidyl ether, and 10g methacryloylpropyltrimethylammonium chloride were added to a reactor, stirred evenly, heated to 30°C, and 5g diethanolamine and 5g triisopropanolamine were added. After half an hour, the polymer polyol was filtered to obtain the polymer polyol.

[0113] Stirring: dissolve 200g of polymer polyol in 3000g of water, add 0.35g of sodium dodecylbenzene sulfonate and 0.35g of polyethylene glycol monooleate, and stir for 30-60 minutes to obtain a concrete glue reducer.

[0114] Performance testing

[0115] Sample preparation: The concrete mix ratio meets the following requirements:

[0116] Cement consumption: 385kg / m 3 , model is PO42.5; river sand 765kg / m 3， Average particle size 1mm; crushed stone 750kg / m 3 , average particle size 10mm; water 154kg / m 3 .

[0117] Test 1: Glue reduction rate test Test method: The glue reduction rate of the glue reducer was tested in the sample according to the method in JC / T 2469-2018 "Concrete Glue Reducer". The test results are shown in Table 1.

[0118] Test 2: Test on the impact of concrete fluidity Test method: every 1m 3 The sample was mixed with 0.2 kg of the concrete adhesive prepared in the examples or comparative examples, and the fluidity was tested according to GB / T50080-2012 "Test methods for properties of ordinary concrete mixtures" and characterized by slump. The test results are shown in Table 1.

[0119] Test 3: Test on the impact of concrete compressive strength Test method: Every 1m 3 The sample was added with 0.2 kg of the concrete adhesive prepared in the embodiment or comparative example. After 28 years, the compressive strength was tested according to GB / T 50081-2019 "Standard for Test Methods for Physical and Mechanical Properties of Concrete". The test results are shown in Table 1.

[0120] Table 1. Test on the performance of adhesive reducing agent

[0121]

[0122]

[0123] Analysis of test results:

[0124] 1. Combining Examples 1-7 and Comparative Examples 1-5 with Table 1, it can be seen that the hydrophobic modification of carboxymethyl hydroxyethyl cellulose in this application increases the gel reduction rate of the gel reducer and enhances its effect on improving the slump and compressive strength of concrete. This may be because the hydrophobic groups grafted onto the carboxymethyl hydroxyethyl cellulose impart amphiphilicity. The hydrophobic groups allow the carboxymethyl hydroxyethyl cellulose to be directionally adsorbed onto cement particles in water. The hydrophilic groups then impart a charge of the same electrical property to the cement particles, generating electrostatic repulsion between the cement particles, breaking up the flocculent structure of the cement and allowing more cement particles to participate in the hydration reaction. This increases the gel reduction rate of the gel reducer and reduces the amount of raw materials used. Furthermore, the proportion of cement particles participating in the hydration reaction is increased, which also improves the fluidity and compressive strength of the concrete.

[0125] 2. Combining Examples 1-4 and Table 1, it can be seen that the present application effectively improves the performance of the glue reducing agent by first performing trimethyl silanization protection on the carboxymethyl hydroxyethyl cellulose when grafting it with polycaprolactone. The reason for this may be that after trimethyl silanization, the trimethyl cinnamic group can encapsulate most of the carboxyl and hydroxyl groups on the carboxymethyl hydroxyethyl cellulose, protecting both, so that the polycaprolactone can only replace a small part of the carboxyl and hydroxyl groups. After deprotection, the hydrophobically modified carboxymethyl hydroxyethyl cellulose still has enough carboxyl groups to ionize during the hydration process to generate electrostatic repulsion, thereby improving the glue reduction rate of the glue reducing agent. At the same time, the encapsulation of the carboxyl and hydroxyl groups also greatly reduces the polarity of the carboxymethyl hydroxyethyl cellulose, allowing it to react homogeneously with caprolactone while being dispersed in an organic solvent.

[0126] 3. Combining Examples 1-3, Example 7, and Comparative Example 1 with Table 1, it can be seen that the present application effectively improves the performance of the glue reducer by depolymerizing hydroxyethyl cellulose and using alcohol solvents such as ethanol as diluents during the depolymerization process. This may be because the glue reducer needs to destroy small-volume cement particle aggregates rather than large-scale cement flocculent structures, so the glue reducer requires a low-molecular-weight raw material. Depolymerizing carboxymethyl hydroxyethyl cellulose can effectively reduce its molecular weight, which can more effectively destroy small-volume cement particle aggregates and improve the performance of the glue reducer. Using alcohol solvents such as ethanol as diluents during the depolymerization process can protect the carboxymethyl hydroxyethyl cellulose from oxidation and improve the glue reduction rate of the glue reducer.

[0127] 4. Combining Examples 1-3 and Comparative Examples 1-4 with Table 1, it can be seen that the present application improves the performance of the gel reducer by using carboxymethyl hydroxyethyl cellulose with a carboxymethyl degree of substitution of 0.5-0.8 and a hydroxyethyl degree of substitution of 1-1.5. This may be because the carboxyl groups provided by the carboxymethyl groups can ionize in water, providing electrostatic repulsion to destroy small-particle cement aggregates, while the abundant hydroxyl groups provided by the hydroxyethyl groups can improve the compatibility of the gel reducer with concrete, increase the efficiency of the gel reducer's adsorption on small-particle cement aggregates, and enhance the gel reducing effect of the gel reducer.

[0128] 5. Combining Examples 1-3 and 5-6 with Table 1, it can be seen that the present application effectively improves the performance of the gel reducer by using stannous octoate as a catalyst and adding trimethylchlorosilane during the trimethyl silanization process. This may be because stannous octoate can serve as an activation center, more effectively catalyzing the formation and grafting of polycaprolactone, while trimethylchlorosilane can accelerate the trimethyl silanization process and complete the reaction. The resulting hydrophobically modified carboxymethyl hydroxyethyl cellulose can effectively adsorb cement particles while also effectively generating electrostatic repulsion to destroy small-volume cement aggregates. This allows the gel reducer to reduce the amount of raw materials used.

[0129] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A concrete adhesive reducer, characterized in that: The invention comprises the following raw materials in parts by weight: 30-50 parts of hydrophobically modified carboxymethyl hydroxyethyl cellulose; Dispersant 0.05-0.1 part; Penetrant 0.05-0.1 parts; The hydrophobically modified carboxymethyl hydroxyethyl cellulose has a carboxymethyl substitution degree of 0.5-0.8 and a hydroxyethyl substitution degree of 1-1.5; the hydrophobically modified carboxymethyl hydroxyethyl cellulose is prepared by hydrophobically modifying small molecule carboxymethyl hydroxyethyl cellulose through the following steps: Protection: Dissolve small molecule carboxymethyl hydroxyethyl cellulose in N,N-dimethylformamide, stir evenly, heat to 95-120°C, then dropwise add hexamethyldisilazane, water and acidic catalyst, react for 7-9 hours, and filter to obtain a crude product; Purification: Disperse the crude product in acetone solution, filter, add distilled water, filter and dry to obtain trimethylsilyl carboxymethyl hydroxyethyl cellulose; Grafting: Mix trimethylsilyl carboxymethyl hydroxyethyl cellulose and xylene, heat to 70-90°C, stir and react for 1-2 hours, then add ε-caprolactone and catalyst, heat to 110-130°C and react for 12-16 hours to obtain trimethylsilyl carboxymethyl hydroxyethyl cellulose polycaprolactone grafted product; Deprotection: add trimethylsilyl carboxymethyl hydroxyethyl cellulose polycaprolactone grafted product to a mixed solution of isopropyl alcohol and hydrochloric acid, stir evenly, heat to 70-80°C and react for 20-30 minutes, filter and dry to obtain hydrophobically modified carboxymethyl hydroxyethyl cellulose; The molecular weight of the small molecule carboxymethyl hydroxyethyl cellulose is 2000-30000. The preparation process of the small molecule carboxymethyl hydroxyethyl cellulose is as follows: dissolving the carboxymethyl hydroxyethyl cellulose in a diluent, adding a protonic acid aqueous solution under stirring, heating the solution to 70-80° C., reacting for 2-6 hours, adjusting the pH value to 7-8, adding a non-polar solvent until no solid precipitates, filtering and drying the solution to obtain the small molecule carboxymethyl hydroxyethyl cellulose.

2. A concrete adhesive reducer according to claim 1, characterized in that: The raw materials for preparing the small molecule carboxymethyl hydroxyethyl cellulose include carboxymethyl hydroxyethyl cellulose, a diluent and a protonic acid aqueous solution in a mass ratio of (1-2): (3-7): (0.05-1); the protonic acid aqueous solution is at least one of a hydrochloric acid aqueous solution and a sulfuric acid aqueous solution.

3. A concrete adhesive reducer according to claim 2, characterized in that: The diluent is an alcohol solvent, and the alcohol solvent is at least one of ethanol, n-propanol, n-butanol, and methylcyclohexanol.

4. A concrete adhesive reducer according to claim 1, characterized in that: The preparation process of the small molecule carboxymethyl hydroxyethyl cellulose is carried out under the protection of an inert gas.

5. A concrete adhesive reducer according to claim 1, characterized in that: The raw materials of the hydrophobically modified carboxymethyl hydroxyethyl cellulose include the following raw materials in parts by weight: 6-10 parts of low molecule carboxymethyl hydroxyethyl cellulose; 6-15 parts of hexamethyldisilazane; 6-15 parts of ε-caprolactone; 60-100 parts of isopropyl alcohol / hydrochloric acid mixture; 0.1-0.5 parts of acidic catalyst; 50-200 parts of water.

6. A concrete adhesive reducer according to claim 1, characterized in that: The catalyst in the grafting step is stannous octoate, and the addition amount is 1-5wt% of trimethylsilyl carboxymethyl hydroxyethyl cellulose.

7. A concrete adhesive reducer according to claim 1, characterized in that: In the protection step, trimethylchlorosilane is added to N,N-dimethylformamide in an amount of 2-5 wt% of the small molecule carboxymethyl hydroxyethyl cellulose.

8. The method for preparing a concrete adhesive reducer according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: dissolving hydrophobically modified carboxymethyl hydroxyethyl cellulose in water, adding a penetrant and a dispersant, and stirring for 30-60 minutes to obtain a concrete glue reducing agent.

Images