Multifunctional concrete external curing agent, preparation method and application thereof

Abstract

The application discloses a multifunctional concrete external curing agent and a preparation method and application thereof, and belongs to the technical field of concrete admixtures, and comprises the following raw materials in parts by weight: 40-85 parts of water-based resin emulsion, 1-3 parts of thermal expansion microspheres, 0.3-5 parts of film-forming aids, 0.02-0.06 parts of defoaming agents, and 0-1 parts of pH regulators. The multifunctional concrete external curing agent provided by the application has composite functions and excellent environmental protection, and meets the green and environmentally-friendly building material requirements. The product provided by the application can replace traditional curing processes, is suitable for concrete engineering under harsh conditions such as high temperature, dryness and strong wind, significantly improves construction efficiency, reduces curing cost, and has wide market value.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of concrete admixtures, and particularly relates to a multifunctional concrete external curing agent and a preparation method and application thereof. BACKGROUND

[0002] If the concrete is not maintained in time after construction, the internal water evaporates to the outside through the capillary pores of the system, leading to insufficient hydration of the cementitious material, reduction of hydration products, and further causing a series of performance declines of the concrete; especially, the shrinkage cracks and loose structure caused by too fast evaporation of water will reduce the strength and durability of the concrete. Therefore, it is particularly important to take effective curing measures to reduce or avoid the evaporation of water during the plastic stage of the concrete. A large number of engineering practices show that the strain gradient caused by the migration and loss of water and the uneven change of temperature plays an important role in the initiation, cracking and expansion of the cracks or defects of the concrete. In summer, the temperature is high, the humidity is low, and the drying is fast, and the newly poured concrete may have adverse effects such as accelerated setting speed and reduced strength. During the service of the concrete, the temperature fluctuation caused by strong sunlight will also adversely affect the durability of the concrete.

[0003] However, the traditional curing methods (such as covering and watering, plastic film) have problems of water resource waste, low efficiency, high cost, etc., and the existing commercially available external curing agents mainly focus on single function (such as only water retention or only film formation), lack comprehensive performance, and some contain organic solvents or toxic substances, which do not meet the green and environmental protection requirements.

[0004] Therefore, how to provide a multifunctional, environmentally friendly and efficient external curing agent is a technical problem that those skilled in the art need to solve. SUMMARY

[0005] To solve the above technical problems, the application provides a multifunctional concrete external curing agent and a preparation method and application thereof.

[0006] To achieve the above-mentioned purpose, the application provides the following technical solutions.

[0007] A multifunctional concrete external curing agent comprises the following raw materials in parts by weight:

[0008] 40-85 parts of a water-based resin emulsion, 1-3 parts of thermal expansion microspheres, 0.3-5 parts of a film-forming aid, 0.02-0.06 parts of a defoaming agent, and 0-1 parts of a pH adjuster.

[0009] Preferably, the solvent of the multifunctional concrete external curing agent is water.

[0010] More preferably, the sum of the addition amounts of the water and other raw materials is 100 parts.

[0011] Preferably, the aqueous resin emulsion comprises a styrene-acrylic emulsion or a self-crosslinking pure acrylic elastomeric emulsion.

[0012] Beneficial effects: the external curing agent made of these two types of emulsion has excellent elongation and elasticity, and can adapt to the movement of the cracks in the mortar layer, so that the polymer film layer is difficult to break or wrinkle. Especially, the water-based self-crosslinking pure acrylic elastomeric emulsion can self-crosslink, has excellent adhesion and stain resistance, can effectively resist ultraviolet radiation, and has excellent long-term durability and water retention function.

[0013] Preferably, the thermal expansion microspheres have a median particle size of 10-40 μm, which can improve the solar reflectance and make the film of the external curing agent resin more dense.

[0014] More preferably, the thermal expansion microspheres have a core-shell structure, which is composed of a thermoplastic polymer shell and a low-boiling-point solvent (liquid alkane or other compounds). When heated to a suitable temperature, the polymer shell softens and the core solvent vaporizes, so that the volume of the microsphere can expand to tens of times of the initial volume, and the microsphere can still maintain the volume at the time of expansion after cooling.

[0015] Beneficial effects: as a functional filler, the thermal expansion microspheres have very low density, which can greatly increase the volume solid content of the curing agent without significantly increasing the weight and viscosity of the product. In the case of the same wet film thickness, the curing agent with high volume solid content can form a thicker dry film, thereby having lower permeability and better water retention effect. At the same time, in the process of water evaporation of the aqueous resin emulsion and the approach of the polymer particles to form a film, the thermal expansion microspheres play the role of "skeleton" or "pivot". After film formation, they also form countless closed and water-impermeable micro-obstacles in the aqueous resin matrix. When water vapor penetrates this composite film, it must bypass these densely packed microspheres, and its migration path is greatly lengthened. This "labyrinth effect" significantly reduces the water vapor transmission rate of the external curing agent film layer, and the water retention performance is guaranteed.

[0016] Meanwhile, the thermal expansion microspheres in the present application have super elasticity and compressibility, and when the shrinkage stress of the curing film formed by the external curing agent on the surface of the concrete occurs in the process of hydration heat release or diurnal temperature variation, the microspheres can absorb and buffer part of the stress like tiny sponges, preventing stress concentration from causing micro-cracks in the film. The synchronous expansion and shrinkage characteristics with the concrete substrate enable the external curing agent film to deform without cracks, ensuring efficient water retention. In addition, the hollow structure of the thermal expansion microspheres has the characteristic of low thermal conductivity, thereby significantly improving the heat preservation performance. On the other hand, the thermal expansion microspheres have excellent reflection ability for sunlight including visible light and near-infrared band due to the refractive index contrast caused by the hollow structure, so that the curing agent significantly reduces the absorption of direct sunlight by the concrete, and the shell polymer material can effectively radiate heat in the infrared band through the atmospheric window (8-13 μm band), thereby avoiding the dramatic rise in temperature caused by the sun, controlling the temperature fluctuation of the concrete, and ultimately improving the durability and service life of the concrete member.

[0017] Preferably, the film-forming aid includes propylene glycol phenyl ether and / or dodecanol ester.

[0018] Beneficial effects: the above-mentioned film-forming aid can improve the compactness and water resistance of the formed external curing film layer, and can efficiently prevent the evaporation of water in the concrete, effectively improving the volume shrinkage and crack resistance of the concrete.

[0019] Preferably, the defoaming agent is a silicone defoaming agent.

[0020] Beneficial effects: the silicone defoaming agent can quickly break bubbles, and the low surface tension of the defoaming agent droplets can continuously flow into the adjacent bubble liquid film, continuously and repeatedly break bubbles, and have a long-term and durable bubble suppression effect. The present application can effectively control bubbles to improve the production efficiency of the external curing agent and the dispersion effect of the thermal expansion microspheres, and improve the compactness of the film layer after drying.

[0021] Preferably, the pH regulator includes 2-amino-2-methyl-1-propanol and / or ammonia.

[0022] Beneficial effects: the present application uses the above-mentioned pH regulator to control the pH value of the product to 7-9, which can improve the storage stability of the external curing agent, inhibit the growth of microorganisms, and also has better compatibility with the alkalinity of the concrete itself.

[0023] A preparation method of a multifunctional concrete external curing agent, comprising the following steps:

[0024] After dispersing the thermal expansion microspheres in the defoaming agent solution, the water-based resin emulsion, the film-forming aid and the pH regulator are added while stirring, and the stirring is continued, to obtain the multifunctional concrete external curing agent.

[0025] Preferably, the preparation method specifically comprises the following steps:

[0026] The defoaming agent is added to the water, the thermal expansion microspheres are added under stirring at a linear speed of 2 m / s, the linear speed is increased to 10 m / s, and after 10 min of continuous dispersion, the linear speed is reduced to 2 m / s, and the water-based resin emulsion, the film-forming aid, and the pH regulator are added while stirring, and the stirring is continued for 20 min, to obtain the multifunctional concrete external curing agent.

[0027] Beneficial effects: The preparation method provided by the application is beneficial to the uniform mixing of each component and the full play of the performance advantages of each raw material. By controlling the stirring speed and time, the thermal expansion microspheres are ensured to be well dispersed in the system, and the agglomeration phenomenon is avoided, so that the quality stability and performance consistency of the external curing agent are ensured.

[0028] Application of a multifunctional concrete external curing agent in surface curing of a concrete structure.

[0029] Beneficial effects: After the multifunctional concrete external curing agent provided by the application is dried, a dense polymer film is formed on the surface of the concrete, and the evaporation of water on the surface of the concrete is reduced. Due to the introduction of the radiation cooling function, the temperature of the concrete in strong sunlight can be reduced, so that the temperature fluctuation is reduced and the durability is improved. In summary, the external curing agent can not only play a curing role, but also adjust the temperature change and improve the durability of the concrete.

[0030] Compared with the prior art, the application has the following advantages and technical effects:

[0031] The multifunctional concrete external curing agent provided by the application has a synergistic effect of composite functions, realizes "one dose, multiple effects" through the synergistic effect of dense film formation, radiation cooling, and elastic crack resistance, and has excellent environmental protection. The application adopts a water-based system and low VOC components, which meets the green and environmentally friendly building material requirements. The product provided by the application can replace the traditional curing process, is suitable for concrete engineering under harsh conditions such as high temperature, dryness, and strong wind, significantly improves the construction efficiency, reduces the curing cost, and has wide market value. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the application will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the application.

[0033] In order to make the above-mentioned purposes, characteristics and advantages of the application more obvious and easy to understand, the application will be further described in detail below with reference to specific embodiments.

[0034] The embodiment of the present application discloses a multifunctional concrete external curing agent, which comprises the following raw materials in parts by weight:

[0035] The water-based resin emulsion is 40-85 parts, the thermal expansion microspheres are 1-3 parts, the film forming aid is 0.3-5 parts, the defoaming agent is 0.02-0.06 parts, and the pH regulator is 0-1 part.

[0036] In a preferred embodiment, the solvent of the multifunctional concrete external curing agent is water.

[0037] In a more preferred embodiment, the sum of the added amounts of the water and other raw materials is 100 parts.

[0038] In a preferred embodiment, the water-based resin emulsion comprises a styrene-acrylic emulsion or a self-crosslinking pure acrylic elastic emulsion.

[0039] In a preferred embodiment, the thermal expansion microspheres have a median particle size of 10-40 μm, which can improve the solar reflectance and make the film forming of the external curing agent resin more dense.

[0040] In a more preferred embodiment, the thermal expansion microspheres have a core-shell structure, are composed of a thermoplastic high polymer outer shell and a low-boiling-point solvent (liquid alkane or other compounds), and can expand to tens of times of the initial volume after being heated to a suitable temperature and then cooled.

[0041] In a preferred embodiment, the film forming aid comprises propylene glycol phenyl ether and / or dodecanol ester.

[0042] In a preferred embodiment, the defoaming agent is a silicone defoaming agent.

[0043] In a preferred embodiment, the pH regulator comprises 2-amino-2-methyl-1-propanol and / or ammonia.

[0044] The embodiment of the present application also discloses a preparation method of the multifunctional concrete external curing agent.

[0045] The thermal expansion microspheres are dispersed in the defoaming agent solution, and then the water-based resin emulsion, the film forming aid and the pH regulator are added while stirring, and the multifunctional concrete external curing agent is obtained after continuous stirring.

[0046] In a preferred embodiment, the preparation method specifically comprises the following steps.

[0047] The defoaming agent is added to water, the heat-expandable microspheres are added under stirring at a linear speed of 2 m / s, the linear speed is increased to 10 m / s, after 10 min of dispersion, the linear speed is decreased to 2 m / s, the water-based resin emulsion, the film-forming aid, and the pH regulator are added under stirring, and the stirring is continued for 20 min, to obtain the multifunctional concrete external curing agent.

[0048] The application further discloses application of the multifunctional concrete external curing agent to surface curing of a concrete structure.

[0049] Unless otherwise specified, the "parts" in the embodiments of the application refer to weight parts.

[0050] Unless otherwise specified, the raw materials in the embodiments of the application are all purchased through a commercial channel.

[0051] Unless otherwise specified, the room temperature or the normal temperature in the embodiments of the application refers to 25±3 ℃.

[0052] Embodiment 1

[0053] A multifunctional concrete external curing agent comprises the following steps:

[0054] 0.04 parts of a silicone defoaming agent (BASF FoamStar ED 2522) is added to 18.66 parts of water, 3 parts of heat-expandable microspheres (Nolane 044 WE 20 d36, D50=20 μm) are added under stirring at a linear speed of 2 m / s, the linear speed is increased to 10 m / s, after 10 min of dispersion, the linear speed is decreased to 2 m / s, 73 parts of a water-based styrene-acrylate emulsion (BASF Acronal 4040) and 5 parts of a film-forming aid (Dow PPH) are added, 0.3 parts of a pH regulator (Dow AMP-95) is added to adjust the pH of the system to 8, and the stirring is continued for 20 min, to obtain the multifunctional concrete external curing agent.

[0055] Embodiment 2

[0056] 0.02 parts of a silicone defoaming agent (BASF FoamStar SI 2292) is added to 31.08 parts of water, 2 parts of heat-expandable microspheres (Nolane 461 WE 20 d36, D50=30 μm) are added under stirring at a linear speed of 2 m / s, the linear speed is increased to 10 m / s, after 10 min of dispersion, the linear speed is decreased to 2 m / s, 66 parts of a self-crosslinking pure-acrylic elastic emulsion (Borchigel BLJ-968M) and 0.8 parts of a film-forming aid (dodecanol ester) are added, 0.1 parts of a pH regulator (ammonia water) is added to adjust the pH of the system to 8, and the stirring is continued for 20 min, to obtain the multifunctional concrete external curing agent.

[0057] Embodiment 3

[0058] 0.06 parts of silicone antifoam agent (BASF FoamStar SI 2292) was added to 9.04 parts of water, then 1 part of thermal expansion microspheres (Norbond 920 WE 40 d24, D50=40 μm) was added under stirring at a linear speed of 2 m / s, the linear speed was increased to 10 m / s, after 10 min of dispersion, the linear speed was reduced to 2 m / s, then 85 parts of self-crosslinking pure acrylic elastomeric emulsion (Lubrizol Carbocure TSR-72), 4.5 parts of film-forming aid (dodecanol ester) were added, and 0.4 parts of pH regulator (Dow AMP-95) was added to adjust the pH of the system to 8, and stirring was continued for 20 min, to obtain a multifunctional concrete external curing agent.

[0059] Comparative Example 1

[0060] Commercially available concrete curing liquid produced by Beijing Building Material Co., Ltd.

[0061] Comparative Example 2

[0062] The raw materials in the prior art CN112143355A example 1 were used: water-based resin emulsion 38 parts, water 14.7 parts, thermal expansion microspheres 8 parts, halogen-free phosphorus-based flame retardant 2 parts, inorganic powder 30 parts, microbeads 5 parts, antifoam agent 0.15 parts, pH regulator 0.15 parts, dispersant 0.5 parts, wetting agent 0.15 parts, film-forming aid 0.5 parts, ethylene glycol 0.25 parts, propylene glycol 0.25 parts, preservative 0.2 parts, thickening agent 0.3 parts, toning agent 0.05 parts.

[0063] The preparation method comprises the following steps:

[0064] S1, prepare the raw materials according to the parts, add the antifoam agent, the pH regulator, the dispersant and the wetting agent to the water, disperse and stir until uniform, then add the phosphorus-based flame retardant and stir until uniform;

[0065] During the preparation of the coating, the phosphorus-based flame retardant can be added or not added according to the fireproofing requirements of the material;

[0066] S2, add inorganic powder to the above mixture and disperse and stir until uniform, wherein the inorganic powder is any one of calcium powder, mica powder, sepiolite powder and talc powder;

[0067] S3, add water-based resin emulsion to the above mixture and disperse and stir until uniform, wherein the water-based resin emulsion is self-crosslinking pure acrylic elastomeric emulsion (Lubrizol Carbocure TSR-72);

[0068] S4, add thermal expansion microspheres (Norbond 044 WE 20 d36, D50=20 μm) to the above mixture and disperse and stir until uniform;

[0069] S5, adding microbeads to the mixture, and dispersing uniformly, wherein the microbeads are any one of ceramic microbeads and hollow glass microbeads;

[0070] S6, adding film-forming aids, ethylene glycol and propylene glycol to the mixture, and dispersing and stirring uniformly;

[0071] S7, adding preservatives to the mixture, and dispersing and stirring uniformly;

[0072] S8, adjusting the viscosity of the paint according to requirements by using thickening agents, wherein the thickening agents are any one of alkali-swellable thickening agents, polyurethane thickening agents and cellulose;

[0073] S9, adding toning agents to adjust the color and prepare the paint according to requirements, wherein the toning agents are any one of toner and color paste.

[0074] The dispersion and stirring in the preparation of the paint is performed by using a disperser or a real stone paint stirrer.

[0075] Comparative Example 3

[0076] The difference from Example 1 is only that the heat-expandable microspheres are not included, and the following steps are included:

[0077] 0.04 parts of silicone defoamer (BASF FoamStar ED 2522) is added to 18.66 parts of water, the linear speed is increased to 10 m / s, and after 10 min of dispersion, the linear speed is reduced to 2 m / s, 76 parts of water-based styrene-acrylic emulsion (BASF Acronal 4040) and 5 parts of film-forming aids (Dow PPH) are added, 0.3 parts of pH regulator (Dow AMP-95) is added to adjust the pH of the system to 8, and the stirring is continued for 20 min, to obtain the concrete external curing agent.

[0078] Comparative Example 4

[0079] The difference from Example 1 is only that the heat-expandable microspheres are replaced by equal mass of heat-expandable microspheres with larger particle size (Waytop WP80W, D50=80 μm). The remaining process steps and parameters are the same as those of Example 1.

[0080] Technical effects:

[0081] Preparation of concrete:

[0082] Using the concrete external curing agent obtained from Examples 1-4 and Comparative Examples 1-4, the concrete test piece was formed and the effective water retention rate and compressive strength ratio were tested according to the industry standard JC901-2002 "Cement Concrete Curing Agent" Appendix A and Appendix B. The slump of the concrete mixture was 40 mm ± 10 mm according to the specification requirements during testing, and the concrete mix proportion is shown in Table 1 (GK-3000 concrete admixture was provided by Hebei Chang'an Yuchai Science and Technology Co., Ltd.). The volatile organic compound (VOC) content was detected according to the GB / T23986.2-2023 standard. In addition, the surface temperature of the concrete test block in the open natural environment was detected using a temperature automatic recorder. The specific test results are shown in Table 2:

[0083] Table 1 Concrete mix proportion for external curing agent test (kg)

[0084]

[0085] Table 2 Concrete performance test table

[0086]

[0087] The test results show that compared with ordinary commercially available products, the concrete external curing agent of the present application has significantly better water retention performance and higher compressive strength. At the same time, it has a lower surface temperature, improves the temperature rise caused by strong sunlight, thereby reducing temperature fluctuations and improving the service life of the concrete. In addition, the formulation raw materials use a water-based system and low VOC components, with low volatile organic compound content, meeting the green and environmentally friendly building material requirements. In addition, although the prior art CN112143355A also uses thermal expansion microspheres and resin raw materials, the specific raw material selection is not the same as in the present application, and the raw material composition in the present application is simpler, the raw material is easy to obtain, and the product obtained has better water retention rate, mechanical properties and environmental protection.

[0088] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any changes or replacements within the technical scope disclosed in the present application can be easily thought of by those skilled in the art, and should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A multifunctional concrete external curing agent, characterized by, The multifunctional concrete curing agent comprises the following raw materials in parts by weight: an aqueous resin emulsion 40-85 parts, heat-expandable microspheres 1-3 parts, a film-forming aid 0.3-5 parts, an antifoaming agent 0.02-0.06 parts, a pH regulator 0-1 parts; the aqueous resin emulsion comprises a styrene-acrylate emulsion or a self-crosslinking pure acrylic elastomeric emulsion; the heat-expandable microspheres have a median particle size of 10-40 μm.

2. The multifunctional concrete external curing agent according to claim 1, characterized in that, The solvent of the multifunctional concrete curing agent is water.

3. The multi-functional concrete external curing agent according to claim 1, characterized in that, The film-forming aid comprises propylene glycol phenyl ether and / or dodecanol ester.

4. The multi-functional concrete external curing agent according to claim 1, characterized in that, The antifoaming agent is a silicone antifoaming agent.

5. The multi-functional concrete external curing agent according to claim 1, characterized in that, The pH regulator comprises 2-amino-2-methyl-1-propanol and / or ammonia.

6. A method of preparing a multifunctional concrete external curing agent according to any one of claims 1 to 5, characterized in that, The method comprises the following steps: After the heat-expandable microspheres are dispersed in the antifoaming agent solution, the aqueous resin emulsion, the film-forming aid and the pH regulator are added while stirring, and the stirring is continued to obtain the multifunctional concrete curing agent.

7. Use of the multifunctional concrete curing agent according to any one of claims 1-5 in curing the surface of a concrete structure.

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