A concrete anti-flocculating agent, its preparation method and use

Abstract

The present application provides a concrete anti-flocculating agent, its preparation method and application. The raw materials include: 5-10 parts of nano-titanium dioxide polymer solution, 20-30 parts of peroxide, 1-5 parts of retarding component, and 60-95 parts of solvent. The anti-flocculating agent uses anionic polyacrylamide in the nano-titanium dioxide polymer to adsorb, under light irradiation, the nano-TiO2 reacts with water, oxygen in air, peroxide and other substances to generate free radicals with extremely strong oxidation capacity near the anionic polyacrylamide, so as to rapidly degrade the polyacrylamide in the concrete. On the other hand, the appropriate retarding material is added to complex with the metal ions such as Al 3+ , Fe 3+ generated by the flocculating agent polymeric metal chloride, to prevent the rapid hydration of cement and improve the fluidity and plasticity of concrete. The anti-flocculating agent used in concrete can overcome the problems of large viscosity and rapid loss over time of the concrete with flocculating agent.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of concrete building materials, in particular to a concrete anti-flocculating agent and a preparation method and application thereof. BACKGROUND

[0002] In recent years, with the rapid development of economy, the use of concrete has increased dramatically, leading to overexploitation and consumption of natural sand, causing adverse effects on the environment. Therefore, the exploitation of natural sand is restricted, and machine-made sand with high mud and powder content is gradually widely used. In order to quickly remove mud and stone powder in machine-made sand, adding a flocculating agent during the washing process has become an effective means. The most commonly used flocculating agent is anionic polyacrylamide and polyaluminum chloride, which is inexpensive.

[0003] However, the amount of flocculating agent added is generally controlled by hand, which can easily result in excessive flocculating agent remaining in the washed machine-made sand, causing an increase in concrete viscosity, a decrease in fluidity, and an acceleration of slump loss, which seriously affects the performance of concrete construction. Generally, increasing the dosage of water reducing agent is used to solve the problem of reduced concrete fluidity, but this increases the production cost of concrete, and on the other hand, since the flocculating agent such as polyacrylamide has a very strong thickening and water retention effect, even if the dosage of water reducing agent is increased, the free water will be locked by the flocculating agent in the subsequent action, and the problem of high viscosity and fast loss of concrete has not been solved.

[0004] Currently, the technical route of the concrete anti-flocculating agent in the prior art has the following ways:

[0005] Chinese patent CN113773441A (application number: 202110910111.6) published on December 10, 2021 discloses an anti-flocculating agent and a preparation method and application thereof. The anti-flocculating agent with a molecular weight of 400-1500 is obtained by free radical polymerization reaction of cationic monomer dimethyldiallylammonium chloride and other one or more monomers under the action of an initiator. In the presence of a flocculating agent, the incorporation of this anti-flocculating agent can effectively reduce the fluidity loss of cement mortar mixture. The anti-flocculating agent component of this patent introduces chloride ions, which have a strong erosive ability on steel bars in concrete, reducing the chemical erosion resistance, wear resistance, and strength of concrete, affecting the durability of concrete, and thus leading to a decrease in the quality of concrete.

[0006] CN115959848A (application number 202310253083.4) published on April 14, 2023 discloses a concrete anti-flocculating agent and its preparation method. The anti-flocculating agent is obtained by compounding high-valence cationic inorganic polymer with oxidizing agent. The high-valence cationic inorganic polymer can electro-neutralize the anionic polyacrylamide flocculating agent, weaken the electrostatic adsorption of polyacrylamide, and reduce the molecular entanglement of polyacrylamide. The oxidizing agent can oxidize polyacrylamide to cause the high molecular chain to crack. The oxidizing agent component of the anti-flocculating agent in this patent contains potassium ferrate, potassium permanganate, and potassium dichromate. Potassium permanganate is a deep purple color, which affects the appearance of concrete. Potassium dichromate is a toxic and carcinogenic strong oxidizing agent, which is classified as a first-class carcinogen by the International Cancer Research Agency, and has an impact on the environment and personal safety.

[0007] Since the flocculating agent is used in the sand washing process for a short time, there are relatively few methods to solve the influence of flocculating agent residues in machine-made sand on the performance of concrete mixtures, and there are certain drawbacks. Therefore, in the face of the high flocculating agent residues in machine-made sand, it is particularly urgent to develop a method that can effectively resist flocculating agents and has less impact on the environment. SUMMARY

[0008] The purpose of the present application is to provide a concrete anti-flocculating agent and its preparation method. The raw materials include a nano-titanium dioxide polymer solution, a peroxide, a retarding component, and a solvent. By compounding the above raw materials, the polyacrylamide in the concrete is rapidly degraded, and there is no adverse effect on the concrete itself and the environment. At the same time, it can prevent rapid cement hydration, improve the fluidity and plasticity of concrete, and to some extent solve the adverse effects of polymeric metal chloride-containing concrete fluidity loss.

[0009] Another purpose of the present application is to provide an application of a concrete anti-flocculating agent for concrete to improve the workability of concrete prepared with flocculating agent-containing machine-made sand.

[0010] The specific technical solutions of the present application are as follows:

[0011] A concrete anti-flocculating agent, comprising the following raw materials by mass:

[0012] The nano-titanium dioxide polymer solution is 5-10 parts, the peroxide is 20-30 parts, the retarding component is 1-5 parts, and the solvent is 60-95 parts.

[0013] The peroxide is selected from hydrogen peroxide, ammonium persulfate, or potassium persulfate;

[0014] The retarding component is selected from white sugar, sodium gluconate, sodium citrate, potassium sodium tartrate, sodium dihydrogen phosphate, tetrasodium diphosphate, or sodium hexametaphosphate.

[0015] The solvent is selected from water.

[0016] The nano-titania-containing polymer solution has the following structure:

[0017]

[0018] In the structure, ● is nano-titania with a particle size of 50-100 nm;

[0019] In the structure, a is in the range of 4-9, b is in the range of 3-7, and c is in the range of 1-2; a, b and c are positive integers; the number average molecular weight of the nano-titania-containing polymer is in the range of 1800-4000;

[0020] The preparation of the nano-titania-containing polymer solution comprises the following steps:

[0021] a. Mixing acryloyloxyethyl dimethyl benzyl ammonium chloride, a solvent and azobisisobutyronitrile, stirring and heating to 50-70℃ to form a bottom solution; preparing an A solution by mixing an acrylate and a silane coupling agent with a solvent, preparing a B solution by mixing 3-mercaptopropionic acid with a solvent, simultaneously adding the A solution and the B solution dropwise, and then keeping constant speed for dropping, and then keeping constant temperature, drying, and obtaining a solid polymer dispersant;

[0022] b. Dissolving tetrabutyl titanate in anhydrous ethanol, adding an aqueous metal salt solution and the solid polymer dispersant under magnetic stirring, heating and stirring to obtain a transparent sol, adding an HNO3 solution, and finally heating and stirring under a sealed condition to obtain the nano-titania-containing polymer solution.

[0023] In the bottom solution of step a, the mass ratio of acryloyloxyethyl dimethyl benzyl ammonium chloride, the solvent and azobisisobutyronitrile is 80-150:300:0.3-0.5;

[0024] In the A solution of step a, the mass ratio of the acrylate, the silane coupling agent and the solvent is 10-40:20-50:30;

[0025] In step a, the acrylate is selected from hydroxyethyl acrylate, hydroxypropyl acrylate or hydroxybutyl acrylate;

[0026] In step a, the silane coupling agent is [3-(methacryloyloxy)propyl]trimethoxysilane, vinyltrimethoxysilane or vinyltris(β-methoxyethoxy)silane.

[0027] In the B solution of step a, the mass ratio of the 3-mercaptopropionic acid and the solvent is 0.3-0.9:30;

[0028] In step a, A solution and B solution are added simultaneously, A solution is added for 1 h 30 min, and B solution is added for 2 h;

[0029] In step a, the mass ratio of acryloyloxyethyl dimethyl benzyl ammonium chloride, acrylate and 3-mercaptopropionic acid is 80-150:10-40:0.3-0.9.

[0030] In step a, the incubation is at 50-70℃ for 1 h.

[0031] In step a, the number average molecular weight of the prepared solid polymer dispersant is 1000-3000.

[0032] In step a, the solvent in the bottom liquid, the solvent of A solution and B solution are all tetrahydrofuran (THF).

[0033] Preferably, the preparation method of step a is specifically as follows:

[0034] a. 80-150 parts of acryloyloxyethyl dimethyl benzyl ammonium chloride, 300 parts of tetrahydrofuran (THF) and 0.3-0.5 parts of azobisisobutyronitrile (AIBN) are added into a four-necked flask, stirring is started and heating is performed to 50-70℃, then 10-40 parts of acrylate and 20-50 parts of silane coupling agent are configured into A solution with 30 parts of THF, 0.3-0.9 parts of 3-mercaptopropionic acid (3-MPA) is configured into B solution with 30 parts of THF, A solution and B solution are added at a constant speed within 2 h, then incubation is performed for 1 h, after incubation, the polymer solution is placed in a vacuum drying oven and dried at 50℃ for 72 h, to obtain a solid polymer dispersant, and the number average molecular weight of the polymer is 1000-3000.

[0035] In step b, the mass ratio of tetrabutyl titanate, anhydrous ethanol, aqueous metal salt solution, solid polymer dispersant and HNO3 solution is 3-5:100:30:1-2:70.

[0036] In step b, the aqueous metal salt solution is selected from the aqueous solution of potassium dicyanogolden acid, europium nitrate or copper nitrate.

[0037] In step b, the concentration of the aqueous metal salt solution is 0.01 mol / L.

[0038] In step b, the heating and stirring refers to magnetic stirring at 60-80℃ for 45 min.

[0039] In step b, the concentration of the HNO3 solution is 0.4 mol / L HNO3 solution.

[0040] In step b, the heating and stirring reaction is magnetic stirring at 70℃ for 4 h.

[0041] Preferably, the preparation method of step b is specifically as follows:

[0042] Take 3-5 parts of tetrabutyl titanate and dissolve in 100 parts of anhydrous ethanol, under magnetic stirring, add 30 parts of 0.01 mol / L metal salt aqueous solution and 1-2 parts of the prepared solid polymer, under magnetic stirring at 60-80 DEG C for 45 min, then add 70 parts of 0.4 mol / L HNO3 solution, finally under sealed condition, magnetic stirring at 70 DEG C for 4 h, to obtain a nano-titanium dioxide-containing polymer solution.

[0043] The anti-flocculating agent provided by the application contains nano-titanium dioxide-containing polymer, and the nano-titanium dioxide-containing polymer structure has cationic groups, which can quickly complex with anionic polyacrylamide, prevent the anionic polyacrylamide anionic groups from being connected together with two or more positively charged cement particles through a 'bridging' mode, and thus prevent flocculation from forming; the nano-titanium dioxide-containing polymer prepared by the method of the application has a benzene ring in the structure, which has large steric hindrance and is adsorbed in the anionic polyacrylamide, preventing the anionic polyacrylamide from forming a coiled and twisted conformation and reducing the coating of the cement particles and the water reducing agent, which also reduces the flocculation and avoids the rapid loss of the fluidity of the concrete; and the nano-titanium dioxide-containing polymer contains silane-bonded grafted nano TiO2, after the polymer adsorbs the anionic polyacrylamide, under light conditions, a hydroxyl radical (HO·) with extremely strong oxidizing capacity is generated near the anionic polyacrylamide, which promotes the rapid degradation of the anionic polyacrylamide. The process is as follows:

[0044] TiO2+hv→h + +e -

[0045] h + +OH - →·OH

[0046] h + +H2O→·OH+H +

[0047] e - +O2→·O2 -

[0048] H2O+·O2 - →HO2·+OH -

[0049] 2HO2·+e - +H2O→H2O2+OH -

[0050] H2O2+e - →·OH+OH -

[0051] (peroxide + e - → free radical)

[0052] ·OH + PAMn → ··· → CO2 + H2O

[0053] ·O2 - + PAMn → ··· → CO2 + H2O

[0054] (free radical + PAMn → ··· → CO2 + H2O).

[0055] In addition, since the surface polarity of nano-TiO2 is very strong, it is in a thermodynamic non-stable state, and is prone to agglomeration to form secondary particles, and cannot be well dispersed, which affects the special performance. In the preparation process of nano-TiO2, the polymer dispersant prepared in step a is added, the silane bond in the structure is organically grafted and modified with the surface hydroxyl group of nano-TiO2, which can effectively control the particle size of nano-TiO2 and has good dispersion effect. In the preparation of the application, metal salts are used as doping modifiers. The metal salt acts as a doping modifier during the growth of the TiO2 crystal, introduces a small amount of metal impurity atoms into the TiO2 crystal lattice, forms a complex energy band structure, improves the photocatalytic performance of the TiO2 powder, and the prepared TiO2 has higher activity and greatly widened light response range, thereby enhancing the utilization rate of light and improving the degradation rate of polyacrylamide in concrete. In addition, with the complexation of the nano-titanium dioxide-containing polymer and polyacrylamide, the polyacrylamide is continuously degraded from macromolecules to small molecules. At this time, the structure after complexation is similar to the structure of a comb-type water reducing agent, and the structure has a hydroxyethyl ester group. Under the alkaline condition of cement, the hydroxyethyl ester group is hydrolyzed to produce carboxylic acid, which plays a role of a water reducing agent in concrete, which also avoids the rapid loss of concrete.

[0056] The application provides a preparation method of a concrete anti-flocculating agent, and specifically comprises the following steps: stirring and uniformly mixing 5-10 parts of a nano-titanium dioxide-containing polymer solution, 20-30 parts of a peroxide, 1-5 parts of a retarding component and 60-95 parts of a solvent according to mass fraction, so as to obtain the anti-flocculating agent.

[0057] The prepared nano-titanium dioxide-containing polymer solution can promote the rapid degradation of anionic polyacrylamide. In addition, the anti-flocculating agent in the raw material contains a peroxide, and under the condition of light, the nano-TiO2 produces a strong reducing e - , and forms an oxidation-reduction reaction with the peroxide to generate a large amount of free radicals, which supplements the slow generation of free radicals under the condition of only nano-TiO2, and synergistically promotes the rapid degradation of polyacrylamide in concrete, and has no adverse effect on concrete itself and the environment. The anti-flocculating agent provided by the application contains a retarding component, and Al 3+, Fe 3+ and other metal ions, prevent rapid hydration of cement, improve the fluidity and plasticity of concrete, and to some extent solve the adverse effects of the loss of fluidity of concrete containing polymeric metal chloride compounds.

[0058] The application provides the application of the concrete anti-flocculating agent to concrete.

[0059] Compared with the prior art, the anti-flocculating agent has the following advantages: on the one hand, the anionic polyacrylamide in the nano-titanium dioxide polymer is adsorbed, under the irradiation of light, the nano-TiO2 reacts with water, oxygen in air, peroxide and other substances to generate free radicals with extremely strong oxidation capacity near the anionic polyacrylamide, so that the polyacrylamide in the concrete is rapidly degraded; on the other hand, the appropriate retarding substance is added to complex with Al 3+ , Fe 3+ and other metal ions, prevent rapid hydration of cement, improve the fluidity and plasticity of concrete, and to some extent solve the adverse effects of the loss of fluidity of concrete containing polymeric metal chloride compounds. The anti-flocculating agent can be used in concrete to overcome the problems of high viscosity and rapid loss over time of concrete containing flocculants. DETAILED DESCRIPTION

[0060] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described below in connection with the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0061] Embodiment 1

[0062] A concrete anti-flocculating agent is prepared by the following method:

[0063] The embodiment provides a preparation method of an anti-flocculating agent, which comprises the following steps:

[0064] a. 104.2 parts of acryloyloxyethyl dimethyl benzyl ammonium chloride, 300 parts of tetrahydrofuran (THF) and 0.3 parts of azobisisobutyronitrile (AIBN) were added into a four-necked flask, stirring was started and the temperature was raised to 50°C, then 17.4 parts of hydroxyethyl acrylate, 24.8 parts of 3-(methacryloyloxy)propyl] trimethoxysilane and 30 parts of THF were configured into solution A, 0.3 parts of 3-mercaptopropionic acid (3-MPA) and 30 parts of THF were configured into solution B, solution A and solution B were dropped at a constant speed within 2 hours, solution A was dropped for 1 hour and 30 minutes, solution B was dropped for 2 hours, and the temperature was kept for 1 hour, then the polymer solution was placed in a vacuum drying oven, dried at 50°C for 72 hours, and a solid polymer dispersant PC1 was obtained.

[0065] b. 3.4 g of tetrabutyl titanate was accurately measured and dissolved in 100 g of anhydrous ethanol, 30 g of 0.01 mol / L potassium dicyanogoldate solution and 1 g of PC1 were added under magnetic stirring, then the mixture was stirred at 70°C for 45 minutes to obtain a transparent sol, 70 g of 0.4 mol / L HNO3 solution was added, and finally the mixture was stirred at 70°C for 4 hours under sealed conditions to obtain a nano-titanium dioxide-containing polymer solution T-1.

[0066] c. 5 parts of the nano-titanium dioxide-containing polymer solution T-1, 20 parts of 8% mass concentration hydrogen peroxide solution, 3 parts of tetrasodium diphosphate and 72 parts of water were mixed and stirred for 3 minutes, and then added into the mixed concrete according to the mixing amount.

[0067] The structure of the solid polymer dispersant PC1 in Example 1 is as follows, and the molecular weight is 3712,

[0068]

[0069] The structure of the nano-titanium dioxide-containing polymer solution T-1 in Example 1 is as follows, and the molecular weight is 3956,

[0070]

[0071] Example 2

[0072] A concrete anti-flocculating agent is prepared by the following method:

[0073] a. Into a four-necked flask, 89.3 parts of acryloyloxyethyl dimethyl benzyl ammonium chloride, 300 parts of tetrahydrofuran (THF) and 0.5 parts of azobisisobutyronitrile (AIBN) were added, stirring was started and heating was carried out to 60°C, then 23.2 parts of hydroxyethyl acrylate, 24.8 parts of 3-(methacryloyloxy)propyl] trimethoxysilane and 30 parts of THF were configured into an A solution, 0.5 parts of 3-mercaptopropionic acid (3-MPA) and 30 parts of THF were configured into a B solution, the A solution and the B solution were dropped at a constant speed within 2h, the A solution was dropped for 1h30min, the B solution was dropped for 2h, and the polymer solution was kept for 1h, after the keeping, the polymer solution was placed in a vacuum drying oven, and was dried at 50°C for 72h, to obtain a solid polymer dispersant PC2.

[0074] b. 3.4g of tetrabutyl titanate was accurately measured and dissolved in 100g of anhydrous ethanol, under magnetic stirring, 30g of 0.01mol / L potassium dicyanogoldate solution and 1g of PC2 were added, then magnetic stirring was carried out at 70°C for 45min, to obtain a transparent sol, then 70g of 0.4mol / L HNO3 solution was added, finally, under sealed conditions, magnetic stirring was carried out at 70°C for 4h, to obtain a nano-titania-containing polymer solution T-2.

[0075] c. 5 parts of the nano-titania-containing polymer solution T-2, 20 parts of 8% mass concentration hydrogen peroxide solution, 3 parts of tetrasodium diphosphate and 72 parts of water were mixed and stirred for 3min, and were added into the mixed concrete according to the mixing amount.

[0076] The structure of the solid polymer dispersant PC2 in Example 2 is: the molecular weight is 3219.

[0077] The structure of the nano-titania-containing polymer solution T-2 in Example 2 is: the molecular weight is 3651,

[0078]

[0079] Example 3

[0080] A concrete anti-flocculating agent, the preparation method is as follows:

[0081] a. 134 parts of acryloyloxyethyl dimethyl benzyl ammonium chloride, 300 parts of tetrahydrofuran (THF) and 0.4 parts of azobisisobutyronitrile (AIBN) were added into a four-necked flask, and stirring was started and heated to 50°C, then 23.2 parts of hydroxyethyl acrylate, 24.8 parts of 3-(methacryloyloxy)propyl] trimethoxysilane were dissolved in 30 parts of THF to form solution A, 0.9 parts of 3-mercaptopropionic acid (3-MPA) was dissolved in 30 parts of THF to form solution B, solution A and solution B were dropped at a constant speed within 2 hours, solution A was dropped for 1 hour and 30 minutes, solution B was dropped for 2 hours, and the mixture was kept for 1 hour, then the polymer solution was placed in a vacuum drying oven and dried at 50°C for 72 hours to obtain a solid polymer dispersant PC3.

[0082] b. 3.4 parts of tetrabutyl titanate was accurately measured and dissolved in 100 parts of anhydrous ethanol, 30 parts of 0.01 mol / L potassium dicyanogoldate solution and 1.5 parts of PC3 were added under magnetic stirring, then the mixture was stirred at 70°C for 45 minutes to obtain a transparent sol, 70 parts of 0.4 mol / L HNO3 solution was added, and finally the mixture was stirred at 70°C for 4 hours under sealed conditions to obtain a nano-titanium dioxide-containing polymer solution T-3.

[0083] c. 5 parts of the nano-titanium dioxide-containing polymer solution T-3, 20 parts of 8% mass concentration hydrogen peroxide solution, 3 parts of tetrasodium diphosphate and 72 parts of water were mixed and stirred for 3 minutes, and then added into the concrete according to the mixing amount.

[0084] The structure of the solid polymer dispersant PC3 in Example 3 is as follows: the molecular weight is 2532,

[0085]

[0086] The structure of the nano-titanium dioxide-containing polymer solution T-3 in Example 3 is as follows: the molecular weight is 2807,

[0087]

[0088] Comparative Example 1

[0089] A method for preparing an anti-flocculating agent, comprising the following steps:

[0090] a. 134 parts of acryloyloxyethyl dimethyl benzyl ammonium chloride, 300 parts of tetrahydrofuran (THF) and 0.4 parts of azobisisobutyronitrile (AIBN) were added into a four-necked flask, and stirring was started and heated to 50°C, then 23.2 parts of hydroxyethyl acrylate, 24.8 parts of 3-(methacryloyloxy)propyl] trimethoxysilane were dissolved in 30 parts of THF to form solution A, 0.9 parts of 3-mercaptopropionic acid (3-MPA) was dissolved in 30 parts of THF to form solution B, solution A and solution B were dropped at a constant speed within 2 hours, solution A was dropped for 1 hour and 30 minutes, solution B was dropped for 2 hours, and the mixture was kept for 1 hour, then the polymer solution was placed in a vacuum drying oven and dried at 50°C for 72 hours to obtain a solid polymer dispersant PC3. 300 parts of tetrahydrofuran (THF) and 0.4 parts of azobisisobutyronitrile (AIBN) were introduced into a four-necked flask, open stirring and heating to 50°C, then 23.2 parts of hydroxyethyl acrylate, 24.8 parts of 3-(methacryloyloxy)propyl] trimethoxysilane and 30 parts of THF are configured into A solution, 0.3 parts of 3-mercaptopropionic acid (3-MPA) and 30 parts of THF are configured into B solution, A solution and B solution are constantly dropped within 2h, A solution is dropped for 1h30min, B solution is dropped for 2h, and incubated for 1h, after incubation, the polymer solution is placed in a vacuum drying oven, dried at 50°C for 72h, and a solid polymer dispersant PC4 is obtained.

[0091] b. Accurately take 3.4g of tetrabutyl titanate and dissolve it in 100g of anhydrous ethanol, under magnetic stirring, add 30g of 0.01mol / L potassium dicyanogoldate solution and 1g of PC4, then magnetically stir at 70°C for 45min, add 70ml of 0.4mol / L HNO3 solution after obtaining a transparent sol, and finally magnetically stir at 70°C for 4h under sealed conditions to obtain a nano-titanium dioxide-containing polymer solution T-4.

[0092] c. 5 parts of the nano-titanium dioxide-containing polymer solution T-4, 3 parts of tetrasodium diphosphate and 92 parts of water Mix for 3min, and add to the mixed concrete according to the mixing amount.

[0093] The structure of the solid polymer dispersant PC4 in Comparative Example 1 has a molecular weight of 2523.

[0094]

[0095] The structure of the nano-titanium dioxide-containing polymer solution T-4 in Comparative Example 1 has a molecular weight of 2756,

[0096]

[0097] Comparative Example 2

[0098] A method for preparing an anti-flocculating agent, comprising the following steps:

[0099] a. 104.2 parts of acryloyloxyethyl dimethyl benzyl ammonium chloride, 300 parts of tetrahydrofuran (THF) and 0.4 parts of azobisisobutyronitrile (AIBN) are added to a four-necked flask, open stirring and heating to 50°C, then 17.4 parts of hydroxyethyl acrylate and 30 parts of THF were prepared as solution A , 0.9 parts of 3-mercaptopropionic acid (3-MPA) and 30 parts of THF are configured into B solution, A solution and B solution are constantly dropped within 2h, A solution is dropped for 1h30min, B solution is dropped for 2h, and incubated for 1h, after incubation, the polymer solution is placed in a vacuum drying oven, dried at 50°C for 72h, and a solid polymer dispersant PC5 is obtained.

[0100] b. Accurately take 3.4 g of tetrabutyl titanate and dissolve it in 100 g of anhydrous ethanol, under magnetic stirring, add 30 g of 0.01 mol / L potassium dicyanogolden acid solution and 1 g of PC5, then under magnetic stirring at 70°C for 45 min, add 70 g of 0.4 mol / L HNO3 solution after obtaining a transparent sol, and finally under sealed conditions, under magnetic stirring at 70°C for 4 h, to obtain a nano-titanium dioxide-containing polymer solution T-5.

[0101] c. Mix 5 parts of the nano-titanium dioxide-containing polymer solution T-5, 20 parts of 8% concentration hydrogen peroxide, 3 parts of tetrasodium diphosphate, and 72 parts of water for 3 min, and add them into the mixed concrete according to the mixing amount.

[0102] The structure of the solid polymer dispersant PC4 in Comparative Example 2 has a molecular weight of 2963,

[0103]

[0104] The structure of the nano-titanium dioxide-containing polymer solution T-5 in Comparative Example 2 has a molecular weight of 2963,

[0105]

[0106] Comparative Example 3

[0107] A preparation method of an anti-flocculating agent, comprising the following steps:

[0108] a. Add 134 parts of acryloyloxyethyl dimethyl benzyl ammonium chloride, 300 parts of tetrahydrofuran (THF), and 0.4 parts of azobisisobutyronitrile (AIBN) into a four-necked flask, start stirring, and heat to 50°C, then 24.8 parts of 3-(methacryloyloxy)propyl]trimethoxysilane and 8 parts of the solid polymer dispersant PC3 and 30 parts of THF to prepare A solution, and 0.9 parts of 3-mercaptopropionic acid (3-MPA) and 30 parts of THF to prepare B solution, drop the A solution at a constant speed within 1 h and 30 min, drop the B solution at a constant speed within 2 h, and keep the temperature for 1 h, then place the polymer solution in a vacuum drying box and dry at 50°C for 72 h to obtain the solid polymer dispersant PC6.

[0109] b. Accurately take 3.4 g of tetrabutyl titanate and dissolve it in 100 g of anhydrous ethanol, under magnetic stirring, add 30 g of 0.01 mol / L potassium dicyanogolden acid solution and 1 g of PC6, then under magnetic stirring at 70°C for 45 min, add 70 g of 0.4 mol / L HNO3 solution after obtaining a transparent sol, and finally under sealed conditions, under magnetic stirring at 70°C for 4 h, to obtain a nano-titanium dioxide-containing polymer solution T-6.

[0110] c. Mix 5 parts of nano-titanium dioxide polymer solution T-6, 20 parts of 8% hydrogen peroxide, 3 parts of tetrasodium diphosphate and 72 parts of water for 3 minutes, and add to the mixed concrete according to the dosage.

[0111] The solid polymer dispersant PC6 in Comparative Example 3 has a molecular weight of 2964.

[0112]

[0113] Comparative Example 3 contained a T-6 structure of a polymer solution containing nano-titanium dioxide, with a molecular weight of 3321.

[0114]

[0115] Comparative Example 4

[0116] A method for preparing an anti-flocculating agent includes the following steps:

[0117] a. Add 134 parts of acryloyloxyethyl dimethyl benzyl ammonium chloride, 300 parts of tetrahydrofuran (THF), and 0.4 parts of azobisisobutyronitrile (AIBN) to a four-necked flask, turn on the stirrer and heat to 50°C. Then, prepare solution A by mixing 23.2 parts of hydroxyethyl acrylate, 24.8 parts of 3-(methacryloyloxy)propyltrimethoxysilane with 30 parts of THF, and prepare solution B by mixing 0.9 parts of 3-mercaptopropionic acid (3-MPA) with 30 parts of THF. Add solutions A and B at a constant rate over 2 hours. Add solution A for 1 hour and 30 minutes and solution B for 2 hours, and keep warm for 1 hour. After keeping warm, place the polymer solution in a vacuum drying oven and dry at 50°C for 72 hours to obtain solid polymer dispersant PC3.

[0118] b. 3 parts of tetrasodium diphosphate and 92 parts of water Mix 20 parts of 8% hydrogen peroxide, 3 parts of tetrasodium diphosphate and 72 parts of water for 3 minutes, and then add them to the concrete according to the dosage.

[0119] The structure of the solid polymer dispersant PC3 in Comparative Example 4 is as follows:

[0120]

[0121] Comparative Example 5

[0122] A method for preparing an anti-flocculating agent includes the following steps:

[0123] a. 134 parts of acryloyloxyethyl dimethyl benzyl ammonium chloride, 300 parts of tetrahydrofuran (THF) and 0.4 parts of azobisisobutyronitrile (AIBN) were added into a four-necked flask, and stirred and heated to 50°C, then 23.2 parts of hydroxyethyl acrylate, 24.8 parts of 3-(methacryloyloxy)propyl] trimethoxysilane were dissolved in 30 parts of THF to form solution A, 0.9 parts of 3-mercaptopropionic acid (3-MPA) was dissolved in 30 parts of THF to form solution B, and the solutions A and B were dropped at a constant speed within 2 hours, the dropping time of solution A was 1 hour and 30 minutes, and the dropping time of solution B was 2 hours, and the mixture was incubated for 1 hour, then the polymer solution was placed in a vacuum drying oven and dried at 50°C for 72 hours to obtain a solid polymer dispersant PC3.

[0124] b. 3.4 g of tetrabutyl titanate was accurately measured and dissolved in 100 g of anhydrous ethanol, 30 g of 0.01 mol / L potassium dicyanogoldate solution and 1.5 g of PC3 were added under magnetic stirring, and then the mixture was stirred at 70°C for 45 minutes to obtain a transparent sol, 70 g of 0.4 mol / L HNO3 solution was added, and finally the mixture was stirred at 70°C for 4 hours under sealed conditions to obtain a nano-titania-containing polymer solution T-3.

[0125] c. 5 parts of the nano-titania-containing polymer solution T-3, 20 parts of 8% strength hydrogen peroxide and 75 parts of The mixture was stirred for 3 minutes, 5 parts of water was added and stirred for 3 minutes, and then the mixture was added to the concrete according to the mixing amount.

[0126] The nano-titania-containing polymer solution T-3 in Comparative Example 5 had the same structure as that in Example 3.

[0127] Comparative Example 6

[0128] A method for preparing an anti-flocculating agent, comprising the following steps:

[0129] a. 134 parts of acryloyloxyethyl dimethyl benzyl ammonium chloride, 300 parts of tetrahydrofuran (THF) and 0.4 parts of azobisisobutyronitrile (AIBN) were added into a four-necked flask, and stirred and heated to 50°C, then 23.2 parts of hydroxyethyl acrylate, 24.8 parts of 3-(methacryloyloxy)propyl] trimethoxysilane were dissolved in 30 parts of THF to form solution A, 0.9 parts of 3-mercaptopropionic acid (3-MPA) was dissolved in 30 parts of THF to form solution B, and the solutions A and B were dropped at a constant speed within 2 hours, the dropping time of solution A was 1 hour and 30 minutes, and the dropping time of solution B was 2 hours, and the mixture was incubated for 1 hour, then the polymer solution was placed in a vacuum drying oven and dried at 50°C for 72 hours to obtain a solid polymer dispersant PC3.

[0130] b. Accurately weigh 3.4 g of tetrabutyl titanate into 100 g of anhydrous ethanol, under magnetic stirring, add 30 g of 0.01 mol / L potassium dicyanogoldate solution and 1.5 g of PC3, then under magnetic stirring at 70°C for 45 min, add 70 g of 0.4 mol / L HNO3 solution, and finally under sealed condition, magnetic stirring at 70°C for 4 h to obtain a nano-titania-containing polymer solution T-3.

[0131] c. Mix 5 parts of the nano-titania-containing polymer solution T-3, ​ water for 3 min, and add into the mixed concrete according to the mixing amount.

[0132] The nano-titania-containing polymer solution T-3 in Comparative Example 6 has the same structure as that in Example 3.

[0133] The anti-flocculating agents prepared in Examples 1-3 and Comparative Examples 1-6 are respectively added into the flocculating agent-containing concrete and stirred for 2 min, and the concrete expansion degree, slump, expansion degree and slump loss over time are measured according to GB 8076-2008 "Concrete Admixtures". The concrete mixing ratio is shown in Table 1. The cement used for preparing the concrete is P·O42.5 Baima Cement; the fly ash is I-grade fly ash; the fine sand has a fineness modulus of about 1.4; the machine-made sand has a fineness modulus of about 3.1; the gravel has a particle size of 10-25 mm and a general gradation with more medium stone needle flake. The anti-flocculating agent prepared in each example and comparative example has a mixing amount of 0.2% of the cementitious material mass. The concrete test results are shown in Table 2, and the blank group is the concrete without adding the anti-flocculating agent.

[0134] Table 1 Concrete reference mixing ratio (kg / m 3 )

[0135]

[0136]

[0137] Table 2 Concrete working performance

[0138]

[0139] The main difference between Examples 1, 2 and 3 is the different proportions of acryloyloxyethyl dimethyl benzyl ammonium chloride, hydroxyethyl acrylate and 3-(methacryloyloxy) propyl trimethoxysilane used in the anti-flocculating agent component. The results all show good anti-flocculating effect, and the effect of Example 3 is the best, the proportion is the best, the initial and over-time expansion degrees of the concrete are the largest, and the fluidity of the concrete is the best.

[0140] The main difference between Comparative Examples 1, 2, 3 and Example 3 is that the polymer dispersant preparation process is respectively missing acryloyloxyethyl dimethyl benzyl ammonium chloride, 3-(methacryloyloxy) propyl] trimethoxysilane and hydroxyethyl acrylate, and it is found that the absence of these components cannot achieve the anti-flocculating effect of Example 3;

[0141] The absence of acryloyloxyethyl dimethyl benzyl ammonium chloride in the polymer dispersant preparation process reduces the adsorption capacity of the anionic polyacrylamide, making it difficult to prevent the adsorption of cement particles by the anionic polyacrylamide, and reducing the contact probability between the anti-flocculating agent and the anionic polyacrylamide, thereby reducing the anti-flocculating effect;

[0142] The absence of 3-(methacryloyloxy) propyl] trimethoxysilane in the polymer dispersant preparation process makes it difficult for nano-titanium dioxide to be grafted into the polymer structure, and the dispersion of nano-titanium dioxide is difficult to solve, thereby reducing the photocatalytic degradation effect of the anti-flocculating agent;

[0143] The absence of hydroxyethyl acrylate in the polymer dispersant preparation process does not produce carboxylic acid through subsequent hydrolysis, and cannot achieve the effect of increasing the slump retaining agent, thereby reducing the effect of reducing the concrete loss over time.

[0144] The main difference between Comparative Examples 4, 5, 6 and Example 3 is that the anti-flocculating agent respectively lacks nano-titanium dioxide, peroxide and retarding components, and it is found that the absence of these components cannot achieve the anti-flocculating effect of Example 3;

[0145] The absence of nano-titanium dioxide in the anti-flocculating agent means that there is no photocatalytic generation of free radicals to decompose the anionic polyacrylamide, thereby making it difficult to reduce the initial and over-time loss of concrete;

[0146] The absence of peroxide in the anti-flocculating agent relies only on the generation of free radicals by nano-titanium dioxide under light conditions, and the decomposition of anionic polyacrylamide is relatively slow, and the over-time loss of concrete is still relatively fast;

[0147] The absence of retarding components in the anti-flocculating agent makes the cement hydration rate too fast, and still has an adverse effect on the fluidity and plasticity of concrete.

[0148] Through the test results of Comparative Examples 1-3, Comparative Examples 1-6 and the blank group, the concrete anti-flocculating agent of the present application can effectively reduce the viscosity of concrete, accelerate the fluidity of concrete, reduce the over-time loss of concrete, improve the compressive strength of concrete, and improve the workability of concrete.

[0149] The above underlined part does not meet the requirements of the present application.

[0150] The above description of the embodiments is made for the purpose of enabling a person of ordinary skill in the art to understand and use the application. It is obvious that those skilled in the art can easily make various modifications to the embodiments and apply the general principles described herein to other embodiments without creative labor. Therefore, the present application is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art without departing from the scope of the present application should be within the scope of protection of the present application.

Claims

1. A concrete deflocculant, characterized by, The concrete anti-flocculating agent comprises the following raw materials in parts by mass: 5-10 parts of a nano-titanium dioxide-containing polymer solution, 20-30 parts of a peroxide, 1-5 parts of a retarding component, and 60-95 parts of a solvent; The nano-titanium dioxide-containing polymer in the nano-titanium dioxide-containing polymer solution has the following structural formula: ； In the structural formula, The nano-titanium dioxide has a particle size of 50-100 nm. In the structural formula, a is in the range of 4-9, b is in the range of 3-7, and c is in the range of 1-2; a, b, and c are positive integers; The preparation of the nano-titanium dioxide-containing polymer solution comprises the following steps: a. Mixing acryloyloxyethyl dimethyl benzyl ammonium chloride, a solvent, and azobisisobutyronitrile, stirring, and heating to 50-70°C to obtain a bottom liquid; preparing an A solution by mixing an acrylate, a silane coupling agent, and a solvent, preparing a B solution by mixing 3-mercaptopropionic acid and a solvent, dropping the A solution and the B solution at a constant speed within 2 hours, then keeping warm, and drying to obtain a solid polymer dispersant; b. Dissolving tetrabutyl titanate in anhydrous ethanol, adding an aqueous metal salt solution and the solid polymer dispersant under magnetic stirring, heating and stirring to obtain a transparent sol, then adding an HNO3 solution, and finally heating and stirring under a sealed condition to obtain the nano-titanium dioxide-containing polymer solution.

2. The concrete deflocculant according to claim 1, characterized in that, In the bottom liquid in step a, the mass ratio of acryloyloxyethyl dimethyl benzyl ammonium chloride, the solvent, and azobisisobutyronitrile is 80-150:300:0.3-0.

5.

3. The concrete deflocculant according to claim 1 or 2, characterized in that, In the A solution in step a, the mass ratio of the acrylate, the silane coupling agent, and the solvent is 10-40:20-50:

30.

4. The concrete deflocculant according to claim 2, characterized in that, In the B solution in step a, the mass ratio of the 3-mercaptopropionic acid and the solvent is 0.3-0.9:

30.

5. The concrete deflocculant of claim 1, wherein In step b, the mass ratio of tetrabutyl titanate, anhydrous ethanol, the aqueous metal salt solution, the solid polymer dispersant, and the HNO3 solution is 3-5:100:30:1-2:

70.

6. The concrete de-flocculant of claim 1, wherein In step b, the aqueous metal salt solution is selected from an aqueous solution of potassium dicyanogoldate, europium nitrate, or copper nitrate.

7. The concrete deflocculant of claim 1, wherein In step b, the heating and stirring refers to magnetic stirring at 60-80°C for 45 minutes; and the heating and stirring reaction refers to magnetic stirring at 70°C for 4 hours.

8. A method of preparing the concrete deflocculant according to any one of claims 1 to 7, characterized in that, The preparation method is as follows: mixing 5-10 parts of the nano-titanium dioxide-containing polymer solution, 20-30 parts of the peroxide, 1-5 parts of the retarding component, and 60-95 parts of the solvent, and stirring to obtain the concrete anti-flocculating agent.

9. Use of a concrete deflocculant according to any one of claims 1 to 7, characterized in that The concrete anti-flocculating agent is used for concrete.

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