Multifunctional concrete admixture with air entraining and foam stabilizing functions and preparation method thereof

Abstract

This invention relates to the field of concrete admixture technology, specifically to a multifunctional concrete admixture that combines toughening, air entrainment, and foam stabilization, and its preparation method. The method involves adding an emulsifier to water and heating the mixture to 35–45°C. Then, polymer monomers, an initiator, and an aqueous solution containing a macromolecular thickener and an air entrainer are simultaneously added dropwise, and the mixture is stirred for 0.5–1.5 hours. The temperature is then raised to 60–70°C, and the remaining polymer monomers and initiator are added, with continued stirring for 3–4 hours. The mixture is then cooled to room temperature to obtain the multifunctional concrete admixture. This multifunctional concrete admixture possesses toughening, air entrainment, and foam stabilization properties, improving not only the dispersibility of the admixture in concrete but also its stability, thus ensuring the performance of the concrete.

Description

Technical Field

[0001] This invention relates to the field of concrete admixture technology, and in particular to a multifunctional concrete admixture that combines toughening, air-entraining, and foam-stabilizing properties, and its preparation method. Background Technology

[0002] To address the varying performance requirements of concrete, various admixtures are often introduced for adjustment. For example, polymers can improve the internal cohesion of concrete, enhancing its durability and long-term performance; air-entraining agents can generate numerous microbubbles within the concrete, improving the workability of the concrete mixture and enhancing its impermeability and frost resistance. In practical engineering, especially in cold regions or projects with high requirements for concrete impermeability, concrete performance is often improved through compounding (i.e., simultaneously adding polymers and air-entraining agents). Patent CN202110733570.1 discloses a crack-resistant, seepage-proof, self-healing C35 mass concrete, comprising the following components in parts by weight: 200-290 parts cement, 0-50 parts mineral powder, 30-100 parts fly ash, 0.1-0.3 parts air-entraining agent, 700-850 parts fine aggregate, 1000-1100 parts coarse aggregate, 155-175 parts water, 4-10 parts retarding water-reducing agent, 25-35 parts crack-resistant agent, and 5-10 parts polyacrylate superabsorbent resin. The admixtures in this patent are simply compounded, thus resulting in a slight decrease in compressive strength.

[0003] There are usually several problems with compounding: (1) The polymer is not evenly dispersed and is prone to agglomeration in the concrete, which creates weak points and reduces the performance of the concrete; (2) The air-entraining agent is unstable and the air bubbles are prone to merge and break during the concrete forming and curing process, which has a negative impact on the performance of the concrete; (3) There are many types of polymers and air-entraining agents, which have a great impact on their compatibility, and the compounding effect is unstable, which in turn affects the performance of the concrete.

[0004] Therefore, it is necessary to provide an improved multifunctional concrete admixture that combines toughening, air entrainment, and foam stabilization, as well as its preparation method, to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to provide a multifunctional concrete admixture that combines toughening, air entrainment, and foam stabilization, and its preparation method. By controlling the preparation process, a multifunctional concrete admixture with toughening, air entrainment, and foam stabilization properties can be obtained. This not only improves the dispersibility of the admixture in concrete but also enhances its stability, thus ensuring the performance of the concrete.

[0006] To achieve the above objectives, the present invention provides a method for preparing a multifunctional concrete admixture that combines toughening, air-entraining, and foam-stabilizing properties, comprising:

[0007] Add the emulsifier to water and heat to 35-45°C. Then, simultaneously add the polymer monomer, initiator, and an aqueous solution containing macromolecular thickener and air-entraining agent. Stir and react for 0.5-1.5 hours. Then, raise the temperature to 60-70°C and continue to add the remaining polymer monomer and initiator. Continue stirring and react for 3-4 hours. Cool to room temperature to obtain a multifunctional concrete admixture (emulsion form).

[0008] This invention introduces a macromolecular thickener and air-entraining agent during the emulsion polymerization of polymer monomers, adding the polymer monomers in batches. This ensures that the macromolecular thickener and air-entraining agent are uniformly dispersed in the resulting polymer emulsion, forming a stable, emulsion-like, multifunctional concrete admixture. This admixture possesses multiple functions, including toughening, air entrainment, and foam stabilization. It improves both the dispersibility and stability of the admixture in concrete. When added to concrete, it maximizes the effects of each component, thereby enhancing concrete performance.

[0009] Furthermore, the raw materials of the multifunctional concrete admixture are provided by weight as follows: 100 parts water, 90-110 parts polymer monomer, 1-3 parts initiator, 2-5 parts emulsifier, 2-4 parts macromolecular thickener, and 1-3 parts air-entraining agent.

[0010] Furthermore, the initial addition amount of the polymer monomer is 30-40% of the total polymer monomer amount; the initial addition amount of the initiator is 30-40% of the total initiator amount. The amount of water in the aqueous solution containing the macromolecular thickener and air-entraining agent is 30-40% of the total water amount. By adding a portion of the polymer monomer and initiator first, the polymer monomer undergoes preliminary polymerization. At the same time, the macromolecular thickener and air-entraining agent are dispersed and adsorbed on the polymer surface. Then, the remaining polymer monomer and initiator are added to continue polymerization. In this way, the macromolecular thickener and air-entraining agent are uniformly dispersed in the gaps between the polymer molecular chains, which can significantly improve toughening, air entrainment, and foam stabilization functions.

[0011] In some specific embodiments, the macromolecular thickener is added to 1 / 3 of the deionized water, heated to 90°C and stirred until completely dissolved, then the air-entraining agent is added, heating is stopped and stirring is continued until room temperature is reached to form solution 1; the emulsifier is added to the remaining water, heated to 40°C and stirred evenly, then 1 / 3 of the polymer monomer and initiator and solution 1 are slowly added dropwise, and stirring is continued for 0.5 to 1.5 hours to form solution 2; solution 2 is heated to 65°C, then the remaining polymer monomer and initiator are slowly added, and stirring is continued for 3 to 4 hours, and the emulsion obtained after cooling to room temperature is the multifunctional concrete admixture with toughening, air-entraining and foam stabilizing properties.

[0012] Furthermore, the polymer monomers include one or more of vinyl acetate, acrylamide monomers, acrylic monomers, butyl methacrylate, ethylene glycol dimethacrylate, and hydroxyethyl methacrylate, preferably vinyl acetate and butyl methacrylate in a mass ratio of (45-55):1, more preferably vinyl acetate and butyl methacrylate in a mass ratio of 50:1. The polymer formed by these two monomers has high toughness and a significant toughening effect on concrete.

[0013] Furthermore, the macromolecular thickener includes one or more of polyacrylamide, polyvinyl alcohol, and fibers, preferably polyacrylamide.

[0014] Furthermore, the air-entraining agent includes one or more of rosin resins, alkylbenzene sulfonates, and fatty alcohol sulfonates, preferably sodium dodecylbenzene sulfonate.

[0015] Furthermore, the initiator includes one or more of persulfates, sulfites, and peroxides. Ammonium persulfate is preferred, as it requires mild initiation conditions.

[0016] Furthermore, the emulsifier includes one or more of alkylbenzene sulfonic acid emulsifiers, polypolyol emulsifiers, and polyester emulsifiers. Preferably, it is op-10 (dodecylphenol polyoxyethylene ether), which has good emulsifying effect and good compatibility in concrete.

[0017] The present invention also provides a multifunctional concrete admixture that combines toughening, air-entraining, and foam stabilizing properties, prepared by any of the preparation methods described above.

[0018] The present invention also provides a concrete comprising a cementitious material and the multifunctional concrete admixture described above.

[0019] Furthermore, the dosage of the multifunctional concrete admixture is 0.01 to 0.1% of the mass of the cementitious material; the cementitious material comprises, by weight, 250 to 300 parts of cement, 60 to 85 parts of fly ash, 780 to 830 parts of sand, 980 to 1030 parts of aggregate, 140 to 170 parts of water, and 6 to 10 parts of polycarboxylate superplasticizer.

[0020] The beneficial effects of this invention are as follows:

[0021] 1. The preparation method of the multifunctional concrete admixture that combines toughening, air entrainment and foam stabilization provided by the present invention introduces other admixture components during emulsion polymerization, so that the admixture has multiple functions such as toughening, air entrainment and foam stabilization. This can not only improve the dispersibility of the admixture in concrete, but also improve the stability of the admixture and ensure the performance of concrete.

[0022] 2. Adding an air-entraining agent system during emulsion polymerization can not only increase the compatibility between the air-entraining agent and the polymer and improve the dispersion uniformity of the air-entraining agent, but also further improve the stability of bubbles in the polymer emulsion. The air-entraining agent system can also improve the structural toughness of the polymer, achieving a synergistic improvement.

[0023] 3. The polymer generated by emulsion polymerization in this invention not only has low viscosity and uniform dispersion, but also has strong structural toughness, resulting in a significant toughening effect on concrete. The use of macromolecular thickeners can not only increase viscosity and stabilize foam, but also improve the workability of concrete mixtures. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention are described clearly and completely below. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0025] Example 1

[0026] A multifunctional concrete admixture that combines toughening, air-entraining, and foam stabilizing properties comprises, by weight: 100 parts deionized water, 90 parts polymer monomer (vinyl acetate: butyl methacrylate ratio 50:1), 2 parts ammonium persulfate, 4 parts OP-10, 4 parts polyacrylamide, and 3 parts sodium dodecylbenzenesulfonate. The preparation method is as follows:

[0027] Add the macromolecular thickener polyacrylamide to 1 / 3 of deionized water, heat to 90°C and stir until completely dissolved. Then add the air-entraining agent sodium dodecylbenzenesulfonate, stop heating and continue stirring until room temperature to form solution 1. Add the emulsifier op-10 to the remaining water, heat to 40°C and stir evenly. Then slowly add 1 / 3 of the polymer monomers vinyl acetate and butyl methacrylate, along with the initiator ammonium persulfate and solution 1, and continue stirring for 1 hour to form solution 2. Heat solution 2 to 65°C, then slowly add the remaining polymer monomers and initiator, and continue stirring for 3 hours. The emulsion obtained after cooling to room temperature is the multifunctional concrete admixture with toughening, air-entraining and foam stabilizing properties.

[0028] The multifunctional concrete admixture is added to the concrete. The concrete by weight includes: 280 parts cement, 73 parts fly ash, 810 parts sand, 1011 parts stone, 158 parts water, and 8.6 parts polycarboxylate superplasticizer. The dosage of the multifunctional admixture is fixed at 0.03% of the cementitious materials.

[0029] Example 2

[0030] A multifunctional concrete admixture that combines toughening, air-entraining, and foam stabilizing properties comprises, by weight: 100 parts deionized water, 90 parts polymer monomer (vinyl acetate), 2 parts ammonium persulfate, 4 parts op-10, 4 parts polyacrylamide, and 3 parts sodium dodecylbenzenesulfonate.

[0031] The preparation method of the multifunctional concrete admixture and the composition of the concrete are the same as in Example 1, and will not be repeated here.

[0032] Example 3

[0033] A multifunctional concrete admixture that combines toughening, air-entraining, and foam stabilizing properties comprises, by weight: 100 parts deionized water, 90 parts polymer monomer (vinyl acetate: butyl methacrylate in a ratio of 50:1), 3 parts hydrogen peroxide, 4 parts op-10, 4 parts polyvinyl alcohol, and 3 parts sodium dodecylbenzenesulfonate.

[0034] The preparation method of the multifunctional concrete admixture and the composition of the concrete are the same as in Example 1, and will not be repeated here.

[0035] Example 4

[0036] A multifunctional concrete admixture that combines toughening, air-entraining, and foam stabilizing properties comprises, by weight: 100 parts deionized water, 90 parts polymer monomer (butyl methacrylate), 2 parts ammonium persulfate, 4 parts op-10, 4 parts polyacrylamide, and 3 parts sodium dodecylbenzenesulfonate.

[0037] The preparation method of the multifunctional concrete admixture and the composition of the concrete are the same as in Example 1, and will not be repeated here.

[0038] Example 5

[0039] A multifunctional concrete admixture that combines toughening, air-entraining, and foam stabilizing properties comprises, by weight: 100 parts deionized water, 90 parts polymer monomer (vinyl acetate: butyl methacrylate in a ratio of 30:1), 2 parts ammonium persulfate, 4 parts op-10, 4 parts polyacrylamide, and 3 parts sodium dodecylbenzenesulfonate.

[0040] The preparation method of the multifunctional concrete admixture and the composition of the concrete are the same as in Example 1, and will not be repeated here.

[0041] Example 6

[0042] A multifunctional concrete admixture that combines toughening, air-entraining, and foam stabilizing properties comprises, by weight: 100 parts deionized water, 90 parts polymer monomer (vinyl acetate: butyl methacrylate ratio 50:1), 2 parts ammonium persulfate, 4 parts OP-10, 4 parts polyacrylamide, and 3 parts sodium dodecylbenzenesulfonate. The preparation method is as follows:

[0043] Add the macromolecular thickener polyacrylamide to 2 / 3 of the deionized water, heat to 90°C and stir until completely dissolved. Then add the air-entraining agent sodium dodecylbenzenesulfonate, stop heating and continue stirring until room temperature to form solution 1. Add the emulsifier op-10 to the remaining water, heat to 40°C and stir evenly. Then slowly add 2 / 3 of the polymer monomers vinyl acetate and butyl methacrylate, along with the initiator ammonium persulfate and solution 1, and continue stirring for 1 hour to form solution 2. Heat solution 2 to 65°C, then slowly add the remaining polymer monomers and initiator, and continue stirring for 3 hours. The emulsion obtained after cooling to room temperature is the multifunctional concrete admixture with toughening, air-entraining and foam stabilizing properties.

[0044] The multifunctional concrete admixture is added to the concrete. The concrete by weight includes: 280 parts cement, 73 parts fly ash, 810 parts sand, 1011 parts stone, 158 parts water, and 8.6 parts polycarboxylate superplasticizer. The dosage of the multifunctional admixture is fixed at 0.03% of the cementitious materials.

[0045] Comparative Example 1

[0046] A multifunctional concrete admixture comprises, by weight: 66 parts deionized water, 90 parts polymer monomer (vinyl acetate: butyl methacrylate in a 50:1 ratio), 2 parts ammonium persulfate, and 4 parts OP-10. It does not contain any macromolecular thickeners or air-entraining agents.

[0047] The composition of the concrete is the same as in Example 1, and will not be repeated here.

[0048] Comparative Example 2

[0049] A multifunctional concrete admixture comprises, by weight: 33 parts deionized water, 4 parts polyacrylamide, and 3 parts sodium dodecylbenzenesulfonate. That is, no polymer monomers, emulsifiers, or initiators are added.

[0050] The composition of the concrete is the same as in Example 1, and will not be repeated here.

[0051] Comparative Example 3

[0052] No admixtures. Concrete mix proportions: 280 parts cement, 73 parts fly ash, 810 parts sand, 1011 parts aggregate, 158 parts water, and 8.6 parts polycarboxylate superplasticizer.

[0053] Comparative Example 4

[0054] The concrete composition by weight includes: 280 parts cement, 73 parts fly ash, 810 parts sand, 1011 parts aggregate, 158 parts water, 8.6 parts polycarboxylate superplasticizer, and a fixed dosage of 0.03% of the cementitious materials for the multifunctional admixture. The multifunctional concrete admixture by weight includes: 100 parts deionized water, 90 parts polymer (polyvinyl acetate: polybutyl methacrylate ratio of 50:1), OP-104 parts, 4 parts polyacrylamide, and 3 parts sodium dodecylbenzenesulfonate. The polymer and air-entraining agent are directly added to the concrete.

[0055] The concrete performance test results are shown in the table below. As can be seen from Examples 1-6, the multifunctional admixture prepared by this invention has no negative impact on concrete strength, reduces the air permeability coefficient of concrete, and improves the impermeability and frost resistance of concrete. Compared to Comparative Example 3, Comparative Example 1 incorporated a polymer system, which improved internal cohesion and consequently enhanced impermeability and freeze-thaw resistance. However, compared to Examples 1-6, Comparative Example 1 did not incorporate an air-entraining agent system, resulting in fewer microbubbles forming inside the concrete, thus leading to relatively poor impermeability and freeze-thaw resistance. Compared to Comparative Example 3, Comparative Example 2 incorporated an air-entraining agent system, which enhanced impermeability and freeze-thaw resistance by forming microbubbles, while significantly reducing strength. However, compared to Examples 1-6, Comparative Example 2 did not incorporate a polymer system, resulting in poor internal cohesion within the concrete, thus leading to relatively poor impermeability and freeze-thaw resistance. Compared to Comparative Example 3, Comparative Example 4 showed improved impermeability and freeze-thaw resistance. However, the experiment revealed poor stability of the compound admixture in Comparative Example 4, leading to significant deviations in concrete test results. Ultimately, the results were even inferior to those of Comparative Example 1 (which incorporated only a polymer system) and Comparative Example 2 (which incorporated only an air-entraining agent system).

[0056] Table 1. Performance test results of the examples and comparative examples.

[0057]

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a multifunctional concrete admixture that combines toughening, air-entraining, and foam-stabilizing properties, characterized in that, include: Add the emulsifier to water and heat to 35-45°C. Then, simultaneously add the polymer monomer, initiator, and an aqueous solution containing macromolecular thickener and air-entraining agent. Stir and react for 0.5-1.5 hours. Then, raise the temperature to 60-70°C and continue to add the remaining polymer monomer and initiator. Continue stirring and react for 3-4 hours. Cool to room temperature to obtain a multifunctional concrete admixture. The raw materials of the multifunctional concrete admixture are provided by weight as follows: 100 parts water, 90-110 parts polymer monomer, 1-3 parts initiator, 2-5 parts emulsifier, 2-4 parts macromolecular thickener, and 1-3 parts air-entraining agent. The initial amount of the polymer monomer added is 30-40% of the total amount of polymer monomer; the initial amount of the initiator added is 30-40% of the total amount of initiator. The amount of water in the aqueous solution containing macromolecular thickener and air-entraining agent is 30-40% of the total water content; The polymer monomers are vinyl acetate and butyl methacrylate in a mass ratio of (45~55):1; The macromolecular thickener is polyacrylamide.

2. The preparation method of the multifunctional concrete admixture with toughening, air-entraining, and foam-stabilizing properties according to claim 1, characterized in that, The air-entraining agent includes one or more of rosin resins, alkylbenzene sulfonates, and fatty alcohol sulfonates.

3. The preparation method of the multifunctional concrete admixture with toughening, air-entraining, and foam-stabilizing properties according to claim 1, characterized in that, The initiator includes one or more of persulfate, sulfite and peroxide; And / or, the emulsifier includes one or more of alkylbenzene sulfonic acid emulsifiers, polyol emulsifiers, and polyester emulsifiers.

4. A multifunctional concrete admixture that combines toughening, air-entraining, and foam-stabilizing properties, characterized in that, It is prepared by the preparation method according to any one of claims 1-3.

5. A type of concrete, characterized in that, It includes cementitious materials and the multifunctional concrete admixture as described in claim 4.

6. The concrete according to claim 5, characterized in that, The dosage of the multifunctional concrete admixture is 0.01~0.1% of the mass of the cementitious material; And / or, the cementitious material comprises, by weight, 250-300 parts cement, 60-85 parts fly ash, 780-830 parts sand, 980-1030 parts stone, 140-170 parts water, and 6-10 parts polycarboxylate superplasticizer.

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