Concrete curing agent as well as preparation method and application thereof

Abstract

The invention relates to a concrete curing agent as well as a preparation method and application thereof. The concrete curing agent is prepared from the following raw materials in parts by weight: 100 to 300 parts of reactive monomer, 30 to 120 parts of nano magnetic particles, 5 to 20 parts of emulsifier, 1 to 5 parts of initiator and 200 to 500 parts of deionized water. The curing agent is prepared by two steps: firstly, preparing nano magnetic particles, and secondly, synthesizing and preparing the magnetic responsive curing agent. The magnetic responsive curing agent is prepared by emulsion polymerization, the synthesis temperature is 40-95 DEG C, and the reaction time is 2-5 hours. Compared with the prior art, in the application construction process, an external magnetic field is applied to induce the curing agent to directionally migrate in fresh concrete, so that the curing agent is enriched on the inner surface of the concrete, the water retention performance and durability of the concrete are effectively improved, meanwhile, the breaking strength and toughness of the concrete are improved, and the service life of the concrete is prolonged. The shrinkage and cracking of the concrete are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of concrete, and in particular to a preparation method of a concrete curing agent and an application method thereof. Background Art

[0002] Concrete maintenance is crucial in the construction process, as it is directly related to the strength, durability and overall performance of concrete. The hydration reaction of cement requires sufficient water, and effective maintenance can prevent water from evaporating too quickly, ensuring that the cement is fully hydrated, thereby promoting the strength of concrete. Lack of proper maintenance will lead to shrinkage cracks and loose internal structure, affecting the bearing capacity and service life of concrete. Therefore, taking appropriate maintenance measures is the key to ensuring project quality and safety.

[0003] Although traditional concrete curing methods such as water curing and steam curing are widely used, they have problems such as high labor costs, cumbersome operations, susceptibility to environmental influences, and unstable curing effects. At present, a commonly used alternative method is to use a curing agent to maintain moisture on the surface and inside of concrete to ensure the strength and durability of concrete. Chinese patent CN 111138209 A discloses a concrete external curing agent, which retains water through the film-forming effect of modified polyolefin wax emulsion and organic emulsion, and also plays a certain reinforcing role by adding a reinforcing agent. Chinese patent CN 116332673B discloses a concrete curing agent and a preparation method thereof, which improves the crack resistance of concrete by adding modified aluminum nitride and wollastonite to a paraffin-type concrete curing agent. However, these existing curing agents are all external curing agents, and the film formed by the external curing agent is easily destroyed or falls off in harsh environments, thereby affecting the curing effect.

[0004] Patent application CN115073048A discloses a composite concrete curing agent and its preparation method and application. The composite curing agent includes a polymer emulsion, a liquid oil that is difficult to volatilize, and a hydration inducing agent. During the drying process, it can form a unique three-layer water-retaining structure of "water-retaining liquid film-polymer film-dense concrete layer" on the concrete surface. The raw materials for preparing the polymer emulsion include water, a first emulsifier, a reactive monomer, and a water-soluble initiator; the moisture inside the concrete is blocked by the above three-layer water-retaining structure, and the volatilization rate is greatly reduced, ensuring that there is sufficient water for hydration during the concrete curing process, so as to obtain ideal flexural strength, improve surface wear resistance, and reduce shrinkage. However, this curing agent is only an oil-in-water emulsion, which must be internally mixed into concrete when used. This emulsion is not responsive, so the dosage is high.

[0005] Patent application CN118812184A discloses a concrete curing agent modified concrete. The preparation method of the curing agent comprises the following steps: (1) preparing hollow nano-silica particles; (2) preparing aramid nanofiber dispersion; (3) sequentially adding hollow nano-silica particles and deionized water to the aramid nanofiber dispersion to obtain a mixed solution; (4) steam bath treatment and freeze drying to obtain a concrete curing agent. Using hollow nano-silica particles to modify aramid nanofiber gel as a concrete curing agent can inhibit the volume shrinkage of the curing agent after water release and improve the strength and durability of the concrete. The vapor of the protonated solvent protonates the aramid nanofibers in the solution. The gel preparation process is simple and efficient, avoiding the complex cross-linking process in the traditional method of directly preparing gel compounds. The technology is to pre-absorb some materials through porous materials and then mix them into concrete together. During the drying process of the concrete, the pre-absorbed substances in the porous materials will be gradually released, thereby playing the role of internal curing. However, this technology will greatly affect the strength. Summary of the invention

[0006] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and to provide a concrete curing agent with strong environmental adaptability, low cost and good curing effect, as well as a preparation method and application thereof.

[0007] The purpose of the present invention can be achieved by the following technical scheme: a concrete curing agent, the raw materials include the following components in parts by weight: 100-300 parts of reaction monomers, 30-120 parts of nano-magnetic particles, 5-20 parts of emulsifiers, 1-5 parts of initiators, and 200-500 parts of deionized water.

[0008] The reactive monomers include one or more of styrene, butyl acrylate, vinyl acetate, butadiene, methyl methacrylate, vinyl acetate and acrylate.

[0009] Furthermore, the nano magnetic particles are one or more of nano Fe3O4, NiFe2O4, CoFe2O4, and MnFe2O4.

[0010] Furthermore, the nano magnetic particles are prepared by the following method: mixing a precipitant with a metal ion solution, heating to 40-95° C., stirring for 1-3 hours at a stirring speed of 100-500 rpm; and obtaining nano magnetic particles.

[0011] Further, the precipitant includes one of NH3·H2O, NaOH, KOH, and CO(NH2)2;

[0012] Furthermore, the metal ion solution includes two of FeCl3, Fe(NO3)3, Fe2(SO4)3, FeCl2, FeSO4, NiCl2, Ni(NO3)2, CoCl2, Co(NO3)2, MnCl2, and Mn(NO3)2.

[0013] The molar ratio of the precipitant to the metal ions in the metal ion solution is (8-12):(3-4).

[0014] Furthermore, the emulsifier is one or more of sodium dodecyl sulfonate, sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, sodium stearate, polyoxyethylene ether, and polyoxypropylene ether.

[0015] Furthermore, the initiator is one or more of azobisisobutyronitrile, ammonium persulfate, and hydrogen peroxide.

[0016] The present invention also provides a method for preparing the above concrete curing agent, comprising stirring and mixing nano magnetic particles, reaction monomers, emulsifiers, initiators and deionized water in a mass ratio of (30-120): (100-300): (5-20): (1-5): (200-500) for 2-5 hours, with a synthesis temperature of 40-95° C. and a stirring speed of 100-500 rpm to obtain a concrete curing agent.

[0017] The present invention also provides an application of the above-mentioned concrete curing agent. During the application and construction process, the curing agent is added to cement mortar or concrete. By applying an external magnetic field on the surface of the concrete, the curing agent is induced to migrate inside the concrete, so that it is enriched on the inner surface of the concrete, which plays a role in toughening the surface concrete and sealing the pores, thereby reducing the shrinkage and cracking of the concrete.

[0018] Furthermore, the dosage of the curing agent is 2%-20% of the mass of cement mortar or concrete.

[0019] Furthermore, the intensity of the external magnetic field is 0.1-1.5 T, the distance between the magnetic field and the concrete surface is 0.5-5 cm, and the magnetic field application time per unit area is 5 s-1 h.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) The concrete curing agent of the present invention has magnetic response performance. During the construction process, an external magnetic field is applied to induce the curing agent to migrate inside the fresh concrete, so that the curing agent is enriched on the inner surface of the concrete. This can not only reduce the use cost of the curing agent, but also has excellent water retention capacity and anti-cracking performance, and has a good curing effect.

[0022] (2) The concrete curing agent of the present invention is prepared by emulsifying agents, initiators and reaction monomers, and the emulsion is modified with nano-magnetic particles. The obtained curing agent is added to cement mortar or concrete. The magnetic particles inside the emulsion give the emulsion an effect of exciting migration and enrichment inside the concrete, and the emulsion may aggregate into a polymer film after migration, thereby improving the flexural and crack resistance of the concrete, thereby playing an effect of avoiding cracking. Through adsorption and film formation on cement particles, an interlaced and interpenetrating network structure is formed inside the concrete, which effectively enhances the flexural strength, bonding strength and durability of the concrete, improves the bonding between concrete and aggregate, and increases the toughness of the concrete, thereby effectively reducing the occurrence of brittle cracks. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the appearance picture of the curing agent of Example 1;

[0024] Figure 2 The cracking conditions of the surface and side of the hardened cement slurry after using the curing agent prepared in Example 1 and curing at 40°C for 1 day are compared with those of the hardened cement slurry without curing agent and the cement slurry of Comparative Example 2. DETAILED DESCRIPTION

[0025] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] The present invention provides an internally mixed curing agent, which solves the problem that a film formed by an external curing agent is easily damaged or falls off in a harsh environment, and also avoids the problem of high dosage and low strength of the existing internally mixed curing agent.

[0027] The concrete curing agent of the present invention is prepared by the following method: the preparation process is divided into two steps, firstly, the preparation of nanomagnetic particles, and secondly, the synthesis preparation of magnetic response curing agent; the specific preparation method is as follows:

[0028] (1) Preparation of nanomagnetic particles: Mix a precipitant and a metal ion solution (the molar ratio of the precipitant to the metal ions in the metal ion solution is (8-12): (3-4)), heat to 40-95°C, and stir the reaction for 1-3 hours at a stirring speed of 100-500 rpm to obtain nanomagnetic particles.

[0029] (2) Synthesis of magnetic responsive curing agent: Mix nanomagnetic particles, reaction monomer, emulsifier, initiator and deionized water in a mass ratio of (30-120):(100-300):(5-20):(1-5):(200-500) for 2-5 hours at a synthesis temperature of 40-95°C and a stirring speed of 100-500 rpm to obtain a concrete curing agent.

[0030] During the application and construction process, the curing agent is added to cement mortar or concrete. By applying an external magnetic field on the concrete surface, the curing agent is induced to migrate inside the concrete and accumulate on the inner surface of the concrete, thereby toughening the surface concrete and sealing the pores, thereby reducing the shrinkage and cracking of the concrete.

[0031] Unless otherwise specified, the various raw materials and reagents used in the present invention are commonly used commercially available raw materials and reagents in the art.

[0032] Example 1

[0033] A preparation method of a concrete curing agent and an application method thereof, the specific steps are as follows:

[0034] (1) Add 50 g of FeCl3·6H2O, 30 g of FeSO4·7H2O, 100 g of deionized water, and 35 g of NH3·H2O into a stirrer in sequence, raise the temperature to 80°C, and stir at 300 rpm for 2 h. Separate, wash, and dry the reactants to obtain nanomagnetic particles.

[0035] (2) Add 10 g of nano magnetic particles, 2 g of sodium dodecyl sulfate, 10 g of styrene, 20 g of butyl acrylate, 0.3 g of AIBN and 45 g of deionized water into a stirrer, heat to 90° C., stir at 300 rpm for 4 h, and react to obtain a concrete curing agent.

[0036] (3) Weigh 450 parts by weight of cement, 800 parts by weight of river sand, 900 parts by weight of gravel, 4 parts by weight of water reducer, 40 parts by weight of curing agent and 180 parts by weight of water, mix them evenly, then apply a magnetic field with a strength of 1.0 T at a distance of 1 cm from the concrete surface for 10 min and cure to the test age.

[0037] Example 2

[0038] A preparation method of a concrete curing agent and an application method thereof, the specific steps are as follows:

[0039] (1) 50 g of FeCl3·6H2O, 15 g of FeCl2, 100 g of deionized water, and 40 g of NaOH were added to a stirrer in sequence, the temperature was raised to 80°C, and the mixture was stirred at 300 rpm for 2 h. The reactants were separated, washed, and dried to obtain nanomagnetic particles.

[0040] (2) Add 10 g of nano magnetic particles, 2 g of sodium dodecyl sulfate, 9 g of styrene, 21 g of vinyl acetate, 0.3 g of AIBN and 45 g of deionized water into a stirrer, heat to 90° C., stir at 300 rpm for 4 h, and react to obtain a concrete curing agent.

[0041] (3) Weigh 450 parts by weight of cement, 800 parts by weight of river sand, 900 parts by weight of gravel, 4 parts by weight of water reducer, 40 parts by weight of curing agent and 180 parts by weight of water, mix them evenly, then apply a magnetic field with a strength of 1.0 T at a distance of 1 cm from the concrete surface for 10 min and cure to the test age.

[0042] Example 3

[0043] A preparation method of a concrete curing agent and an application method thereof, the specific steps are as follows:

[0044] (1) Add 75 g of Fe2(SO4)3, 15 g of FeCl2, 100 g of deionized water, and 55 g of KOH in a stirrer, heat to 80°C, and stir at 300 rpm for 2 h. Separate, wash, and dry the reactants to obtain nanomagnetic particles.

[0045] (2) Add 10 g of nano magnetic particles, 2 g of sodium stearate, 10 g of styrene, 20 g of butadiene, 0.3 g of AIBN and 45 g of deionized water into a stirrer, heat to 90° C., stir at 300 rpm for 4 h, and react to obtain a concrete curing agent.

[0046] (3) Weigh 450 parts by weight of cement, 800 parts by weight of river sand, 900 parts by weight of gravel, 4 parts by weight of water reducer, 40 parts by weight of curing agent and 180 parts by weight of water, mix them evenly, then apply a magnetic field with a strength of 1.0 T at a distance of 1 cm from the concrete surface for 10 min and cure to the test age.

[0047] Example 4

[0048] A preparation method of a concrete curing agent and an application method thereof, the specific steps are as follows:

[0049] (1) 75 g of Fe2(SO4)3, 30 g of FeSO4·7H2O, 100 g of deionized water, and 40 g of NaOH were added to a stirrer in sequence, the temperature was raised to 80°C, and the mixture was stirred at 300 rpm for 2 h. The reactants were separated, washed, and dried to obtain nanomagnetic particles.

[0050] (2) Add 10 g of nano magnetic particles, 2 g of sodium dodecylbenzene sulfonate, 9 g of methyl methacrylate, 21 g of butyl acrylate, 0.3 g of AIBN and 45 g of deionized water into a stirrer, heat to 90° C., stir at 300 rpm for 4 h, and react to obtain a concrete curing agent.

[0051] (3) Weigh 450 parts by weight of cement, 800 parts by weight of river sand, 900 parts by weight of gravel, 4 parts by weight of water reducer, 40 parts by weight of curing agent and 180 parts by weight of water, mix them evenly, then apply a magnetic field with a strength of 1.0 T at a distance of 1 cm from the concrete surface for 10 min and cure to the test age.

[0052] Example 5

[0053] A preparation method of a concrete curing agent and an application method thereof, the specific steps are as follows:

[0054] (1) Add 50 g of FeCl3·6H2O, 30 g of FeSO4·7H2O, 100 g of deionized water, and 40 g of NaOH into a stirrer in sequence, raise the temperature to 80°C, and stir at 300 rpm for 2 h. Separate, wash, and dry the reactants to obtain nanomagnetic particles.

[0055] (2) Add 10 g of nano magnetic particles, 2 g of sodium dodecylbenzene sulfonate, 9 g of ethylene, 21 g of vinyl acetate, 0.3 g of AIBN and 45 g of deionized water into a stirrer, heat to 90° C., stir at 300 rpm for 4 h, and react to obtain a concrete curing agent.

[0056] (3) Weigh 450 parts by weight of cement, 800 parts by weight of river sand, 900 parts by weight of gravel, 4 parts by weight of water reducer, 40 parts by weight of curing agent and 180 parts by weight of water, mix them evenly, then apply a magnetic field with a strength of 1.0 T at a distance of 1 cm from the concrete surface for 10 min and cure to the test age.

[0057] Example 6

[0058] A preparation method of a concrete curing agent and an application method thereof, the specific steps are as follows:

[0059] (1) Add 50 g of FeCl3·6H2O, 30 g of FeSO4·7H2O, 100 g of deionized water, and 35 g of NH3·H2O into a stirrer in sequence, raise the temperature to 80°C, and stir at 300 rpm for 2 h. Separate, wash, and dry the reactants to obtain nanomagnetic particles.

[0060] (2) Add 10 g of nano-magnetic particles, 2 g of sodium dodecyl sulfate, 30 g of acrylate, 0.3 g of AIBN and 45 g of deionized water into a stirrer, heat to 90° C., stir at 300 rpm for 4 h, and react to obtain a concrete curing agent.

[0061] (3) Weigh 450 parts by weight of cement, 800 parts by weight of river sand, 900 parts by weight of gravel, 4 parts by weight of water reducer, 40 parts by weight of curing agent and 180 parts by weight of water, mix them evenly, then apply a magnetic field with a strength of 1.0 T at a distance of 1 cm from the concrete surface for 10 min and cure to the test age.

[0062] Example 7

[0063] A preparation method of a concrete curing agent and an application method thereof are different from those of Example 1 in that the nano magnetic particles used are nano NiFe2O4.

[0064] Example 8

[0065] A preparation method of a concrete curing agent and an application method thereof are different from those of Example 1 in that the nano magnetic particles used are nano CoFe2O4.

[0066] Example 9

[0067] A preparation method of a concrete curing agent and an application method thereof are different from those of Example 1 in that the nano magnetic particles used are nano MnFe2O4.

[0068] Example 10

[0069] A preparation method of a concrete curing agent and an application method thereof, which are different from those in Example 1 in that the concrete curing agent is 20 parts by weight.

[0070] Embodiment 11

[0071] A preparation method of a concrete curing agent and an application method thereof, which are different from those in Example 1 in that the concrete curing agent is 60 parts by weight.

[0072] Comparative Example 1

[0073] The paraffin emulsion concrete external curing agent produced by a building materials company is used at a dosage of 0.1kg / m 2 The concrete used includes the following components: 450 parts by weight of cement, 800 parts by weight of river sand, 900 parts by weight of gravel, 4 parts by weight of water reducing agent and 180 parts by weight of water.

[0074] Comparative Example 2

[0075] The styrene-acrylic emulsion concrete external curing agent produced by a building materials company was used at a dosage of 0.1 kg / m 2 The concrete used includes the following components: 450 parts by weight of cement, 800 parts by weight of river sand, 900 parts by weight of gravel, 4 parts by weight of water reducing agent and 180 parts by weight of water.

[0076] Comparative Example 3

[0077] The pure acrylic emulsion concrete external curing agent produced by a building materials company was used, and the usage was 0.1kg / m 2 The concrete used includes the following components: 450 parts by weight of cement, 800 parts by weight of river sand, 900 parts by weight of gravel, 4 parts by weight of water reducing agent and 180 parts by weight of water.

[0078] Blank Group

[0079] The rest is the same as in Example 1, except that the amount of curing agent is 0.

[0080] Performance testing

[0081] Detection Methods

[0082] (1) Concrete compressive and flexural strength test: Refer to the standard GB / T 50081-2019 "Standard for test methods for physical and mechanical properties of concrete" to test the average compressive strength and average flexural strength of the sample after 28 days.

[0083] (2) Test of concrete crack resistance in early stage: Refer to GB / T 50082-2009 "Standard for test methods of long-term performance and durability of ordinary concrete" to test the total crack area per unit area of ​​the sample

[0084] Table 1

[0085]

[0086] Table 2

[0087]

[0088] Table 3

[0089]

[0090] As shown in Table 1-2, after the curing agent prepared by Example 1-11 was added to the concrete, compared with the blank group, the 28d compressive strength and 28d flexural strength were improved, the 28d compressive strength ratio was above 100.0%, and the 28d flexural strength ratio was between 100.0% and 120.0%. At the same time, the total crack area per unit area was reduced by 68% to 80%, and the crack resistance of the concrete in the early stage was significantly improved.

[0091] By comparing Examples 1-11 and Comparative Examples 1-3, it is found that compared with the three external curing agents on the market, the concrete curing agent prepared by the present invention can achieve higher 28d compressive strength ratio and 28d flexural strength ratio. At the same time, the crack area is reduced. This is attributed to the adsorption and film formation of polymer particles on cement particles, which in turn forms an interlaced and interpenetrating network structure inside the concrete, thereby affecting the mechanical properties and crack resistance of the concrete.

[0092] Figure 1 This is a picture of the appearance of the curing agent of Example 1. It can be seen from the picture that the curing agent has magnetic responsiveness and its directional movement can be controlled by applying an external magnetic field.

[0093] Figure 2 The cracking of the surface and sides of the hardened cement slurry after using the curing agent prepared in Example 1 and curing for 1 day at 40°C is compared with the cement slurry without curing agent and the hardened cement slurry of Comparative Example 2. It can be found that when the curing agent of the present invention is used under the induction of magnetic field, no cracking occurs on the surface and sides, while the blank sample and Comparative Example 2 show obvious surface and side cracking.

[0094] Those skilled in the art should appreciate that the protection scope of the present invention is not limited to these specific embodiments. Various modifications and supplements made without departing from the essence of the present invention are still within the protection scope of the present invention.

Claims

1. A concrete curing agent, characterized in that: The raw materials include the following components in parts by weight: 100-300 parts of reaction monomers, 30-120 parts of nano-magnetic particles, 5-20 parts of emulsifiers, 1-5 parts of initiators, and 200-500 parts of deionized water.

2. A concrete curing agent according to claim 1, characterized in that: The reactive monomers include one or more of styrene, butyl acrylate, vinyl acetate, butadiene, methyl methacrylate, vinyl acetate and acrylate.

3. A concrete curing agent according to claim 1, characterized in that: The nano magnetic particles are one or more of nano Fe3O4, NiFe2O4, CoFe2O4 and MnFe2O4.

4. A concrete curing agent according to claim 1 or 3, characterized in that: The nano magnetic particles are prepared by the following method: mixing a precipitant with a metal ion solution, heating to 40-95° C., stirring for reaction for 1-3 hours at a stirring speed of 100-500 rpm to obtain the nano magnetic particles.

5. A concrete curing agent according to claim 1, characterized in that: The emulsifier is one or more of sodium dodecyl sulfonate, sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, sodium stearate, polyoxyethylene ether, and polyoxypropylene ether.

6. A concrete curing agent according to claim 1, characterized in that: The initiator is one or more of azobisisobutyronitrile, ammonium persulfate and hydrogen peroxide.

7. A method for preparing a concrete curing agent according to any one of claims 1 to 6, characterized in that: The nano-magnetic particles, reaction monomers, emulsifiers, initiators and deionized water are mixed, and reacted for 2-5 hours at 40-95° C. and a stirring speed of 100-500 rpm to prepare a magnetic response curing agent.

8. An application of a concrete curing agent as claimed in any one of claims 1 to 6, characterized in that: During the application and construction process, the curing agent is added to cement mortar or concrete. By applying an external magnetic field on the concrete surface, the curing agent is induced to migrate inside the concrete and accumulate on the inner surface of the concrete, thereby toughening the surface concrete and sealing the pores, thereby reducing the shrinkage and cracking of the concrete.

9. The use of a concrete curing agent according to claim 8, characterized in that: The dosage of the curing agent is 2%-20% of the mass of cement mortar or concrete.

10. The use of a concrete curing agent according to claim 8, characterized in that: The intensity of the external magnetic field is 0.1-1.5 T, the distance between the magnetic field and the concrete surface is 0.5-5 cm, and the magnetic field application time per unit area is 5s-1h.

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