A high-permeability concrete protective coating and preparation method thereof

Abstract

The present invention provides a highly permeable concrete protective coating and a preparation method thereof. The raw materials for preparing the concrete protective coating include a powder and a liquid. The powder comprises, by weight, 40 to 60 parts of Portland cement, 2 to 4 parts of nano-silica, 30 to 40 parts of quartz sand, and 8 to 12 parts of silicate. The liquid comprises, by weight, 15 to 20 parts of siloxane oligomers, 20 to 30 parts of acrylic emulsion, and 4 to 6 parts of sustained-release capsules. The sustained-release capsules use graphene oxide as the capsule wall and zirconium silicone as the capsule core. In the present invention, siloxane oligomers are introduced to replace traditional volatile, non-environmentally friendly solvents. Nano-silica and silicate are combined to react with concrete to hydrate and fill the micropores of the mortar, synergistically enhancing the density and impermeability of the concrete and improving the permeability of the coating. The introduction of sustained-release capsules can enhance the compressive strength of the concrete and extend its service life.

Description

Technical Field

[0001] The invention belongs to the field of concrete protection, and in particular relates to a high-permeability concrete protective coating and a preparation method thereof. Background Art

[0002] In a complex and ever-changing external environment, reinforced concrete suffers severe corrosion due to long-term exposure to water, carbon dioxide, oxygen, salt spray, ocean currents, seawater erosion, and other factors, leading to structural damage. Concrete damage is primarily caused by the corrosion of steel bars, carbonization within the concrete, chloride and sulfate attack, microbial attack, and erosion. Therefore, the primary cause of concrete structural damage is water. The presence of H2O causes a series of corrosion events in concrete, including carbonization, steel corrosion, and sulfate attack. Therefore, water is both a primary factor and a necessary condition for concrete corrosion, making waterproofing imperative.

[0003] In existing technologies, products such as organosilicon hydrophobes can penetrate into concrete, forming a hydrophobic coating that renders the concrete hydrophobic and blocks the entry of chloride ions, sulfate ions, and other corrosive agents brought in by water. Penetrating coatings penetrate concrete, forming a hydrophobic film or plugging pores to prevent water from entering, effectively waterproofing the concrete. Currently, these coatings are primarily divided into two categories: inorganic penetrating crystals (which generate hydration products such as CSH gel and CaCO3 within the concrete, reducing the porosity of the concrete and making it more difficult for water to penetrate) and organosilicon coatings (which reduce chloride ion penetration into the concrete, providing excellent protective properties).

[0004] However, the currently commonly used penetrating silicone waterproofing agent contains trialkoxysilane. This coating has low viscosity and is extremely volatile. In a wind speed environment of 5m / s, the volatilization loss of isobutyltriethoxysilane after spraying can reach more than 90%, and the volatilization loss of isooctyltriethoxysilane after spraying can also reach more than 33%, causing certain pollution to the environment, harmful to the human body, and easily losing the protective effect on concrete. Summary of the Invention

[0005] In order to improve the problem that permeable concrete protective coatings are easy to volatilize and lose effectiveness, the present invention provides a high-permeability concrete protective coating and a preparation method thereof.

[0006] According to one aspect of the present invention, a high-permeability concrete protective coating is provided. The raw materials for preparing the concrete protective coating include powder and liquid. Calculated by weight, the powder includes 40 to 60 parts of Portland cement, 2 to 4 parts of nano-silicon dioxide, 30 to 40 parts of quartz sand, and 8 to 12 parts of silicate. Calculated by weight, the liquid includes 15 to 20 parts of siloxane oligomer, 20 to 30 parts of acrylic emulsion, and 4 to 6 parts of sustained-release capsules. The sustained-release capsules use graphene oxide as the capsule wall and silicone zirconium as the capsule core.

[0007] In the present invention, siloxane oligomers are introduced to replace traditional volatile, non-environmentally friendly solvents, and nano-silica and silicates are used to react with cement to form a hydration reaction to fill the micropores of the mortar, thereby synergistically enhancing the density and impermeability of the cement and increasing the penetration depth of the coating in the concrete. In addition, by introducing the sustained-release capsules prepared by the present invention, the waterproof and impermeability of the concrete can be improved and the service life of the concrete can be extended. Among them, graphene oxide as the capsule wall can extend the transmission path of water molecules and delay the corrosion of concrete, and the rich hydroxyl groups of graphene oxide can enhance the compressive properties of cement; in addition, the silicone zirconium as the capsule core will not be activated during mixing due to the protection of graphene oxide during mixing. When cracks and water immersion occur in the concrete, the silicone zirconium is activated when it meets water and hydrolyzes in an alkaline environment to generate siloxy groups and zirconium ions. The siloxy groups further react with cement to fill the pores. In addition, Zr 2+ It can catalyze the secondary reaction of incompletely hydrated cement particles in concrete, further filling pores and thereby blocking microcracks within the concrete. Therefore, the concrete protective coating provided by the present invention has good anti-permeability performance and a long service life.

[0008] Preferably, the particle size of the quartz sand is 0.1 to 0.5 mm.

[0009] Preferably, the silicate comprises at least one of sodium silicate, sodium metasilicate pentahydrate or sodium metasilicate nonahydrate.

[0010] Preferably, calculated by mass ratio, the powder: liquid = 1.5 to 4:1.

[0011] Preferably, the sustained-release capsules are prepared by ball milling.

[0012] Preferably, calculated by mass ratio, graphene oxide: zirconium silicone = 10-25:1.

[0013] Preferably, the particle size of graphene oxide is 10 to 30 μm.

[0014] Preferably, the particle size of zirconium silicone is 0.5 to 3 μm.

[0015] Preferably, the powder further comprises calcium carbonate and a complexing agent, wherein the molar ratio of calcium carbonate to complexing agent is 1 to 1.05:1. Calcium carbonate and the complexing agent can reduce the anti-seepage pressure of the waterproof coating.

[0016] Preferably, the complexing agent includes at least one of disodium edetate, hydroxyethylene diphosphate, and ethylenediaminetetraacetic acid.

[0017] Preferably, the powder material further comprises latex powder and silica fume, wherein, calculated by mass ratio, latex powder: silica fume = 1:1-1.5.

[0018] Preferably, the latex powder includes at least one of vinyl acetate-ethylene copolymer latex powder and polyvinyl homopolymer latex powder.

[0019] Preferably, the viscosity of the siloxane oligomer is no more than 30 mPa·s. Siloxane oligomers can penetrate several millimeters or even more than ten millimeters into the concrete, distributing themselves on the inner walls of the capillary pores deep within the concrete surface. They react chemically with air and moisture, polymerizing to form a network of cross-linked silicone polymer hydroxyl groups. These hydroxyl groups condense with the matrix and themselves, gradually crosslinking and accumulating, ultimately solidifying and bonding to the inner walls and surface of the capillary pores, forming a strong, rigid, flexible, corrosion-resistant, and permeation-resistant water-repellent layer.

[0020] Preferably, the siloxane oligomer includes at least one of polymethyltriethoxysiloxane, polymethyltrimethoxysiloxane, methyl-terminated polydimethylsiloxane, hydroxy-terminated polydimethylsiloxane, methyl hydrogen silicone oil, and methylphenyl hydrogen silicone oil.

[0021] According to another aspect of the present invention, there is provided a method for preparing the above-mentioned concrete protective coating, the method comprising the following steps: preparing a powder: mixing silicate cement, quartz sand and silicate to obtain a mixed powder I, wherein the powder temperature of the mixed powder I is lower than 40°C, and adding the remaining materials included in the powder to the mixed powder I. During the above process, the mixing speed is 40 to 80 rpm; preparing a liquid: mixing an acrylic emulsion and a siloxane oligomer using a high-speed dispersion treatment, the mixing speed of the high-speed dispersion treatment is 800 to 1200 rpm, and then adding a sustained-release capsule to obtain a liquid; a mixing step: mixing the powder and the liquid in a mass ratio of 1.5 to 4:1, and the mixing speed is 100 to 200 rpm. DETAILED DESCRIPTION

[0022] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0023] Example 1

[0024] 1. Prepare the raw materials for concrete protective coating

[0025] The raw materials for preparing the concrete protective coating in this embodiment are shown in Table 1.

[0026] Table 1. Raw materials for concrete protective coatings

[0027]

[0028] 2. Preparation of concrete protective coating

[0029] Preparation of sustained-release capsules: Graphene oxide (particle size 10 μm) and zirconium silicone (particle size 0.8 ± 0.5 μm) were mixed in a mass ratio of 10:1 and compounded by ball milling to obtain a first precursor. The ball milling parameters were as follows: ball milling time 24 hours, ball milling speed 150 rpm, grinding medium 2 mm zirconium oxide, and ball-to-material ratio 1:10.

[0030] Preparation of powder: Portland cement, quartz sand, and silicate are mixed to obtain mixed powder I, wherein the powder temperature of mixed powder I is lower than 40° C., a complexing agent, calcium carbonate, latex powder, silica fume, and nano-silicon dioxide are added to mixed powder I. During the above process, the mixing speed is 60 rpm and the stirring is carried out for 20 minutes to obtain the powder;

[0031] Preparation of liquid material: acrylic emulsion and silicone oligomer were mixed using a high-speed dispersion process at a mixing speed of 1000 rpm, and then the sustained-release capsules were added and stirred for 30 minutes to obtain a liquid material;

[0032] Mixing step: mixing the powder and the liquid in a mass ratio of 3:1, stirring at a mixing speed of 150 rpm for 30 minutes to obtain a concrete protective coating.

[0033] Example 2

[0034] This embodiment prepares the concrete protective coating with reference to the formula and method provided in Example 1. Compared with Example 1, this embodiment does not add latex powder and silica fume. Except for the above differences, the operating steps for preparing the concrete protective coating in this embodiment are strictly consistent with those in Example 1.

[0035] Example 3

[0036] This embodiment prepares the concrete protective coating with reference to the formula and method provided in Example 1. Compared with Example 1, this embodiment does not add silica fume. Except for the above differences, the operating steps for preparing the concrete protective coating in this embodiment are strictly consistent with those in Example 1.

[0037] Example 4

[0038] This embodiment prepares a concrete protective coating by referring to the formula and method provided in Example 1. Compared with Example 1, this embodiment does not add latex powder. Except for the above differences, the operating steps for preparing the concrete protective coating in this embodiment are strictly consistent with those in Example 1.

[0039] Example 5

[0040] This example prepares a concrete protective coating with reference to the formula and method provided in Example 1. Compared with Example 1, this example does not add a chelating agent and calcium carbonate. Apart from the above differences, the operating steps for preparing the concrete protective coating in this example are strictly consistent with those in Example 1.

[0041] Example 6

[0042] This example prepares a concrete protective coating with reference to the formula and method provided in Example 1. Compared with Example 1, this example does not add a chelating agent. Apart from the above differences, the operating steps for preparing the concrete protective coating in this example are strictly consistent with those in Example 1.

[0043] Example 7

[0044] This example prepares a concrete protective coating with reference to the formula and method provided in Example 1. Compared with Example 1, this example does not add calcium carbonate. Apart from the above differences, the operating steps for preparing the concrete protective coating in this example are strictly consistent with those in Example 1.

[0045] Example 8

[0046] This example prepared a concrete protective coating using the formula and method described in Example 1. Unlike Example 1, this example did not use ball milling to prepare the sustained-release capsules. Aside from these differences, the operational steps for preparing the concrete protective coating in this example were strictly consistent with those in Example 1. Specifically, the sustained-release capsules in this example were prepared as follows: Zirconium silicone was prepared into a 0.1 mol / L aqueous solution and graphene oxide was prepared into a 1% ethanol dispersion according to the material ratios described in Example 1. The zirconium silicone solution was then dripped into the graphene oxide dispersion, ultrasonically dispersed, and freeze-dried to produce the sustained-release capsules.

[0047] Comparative Example 1

[0048] This comparative example prepares the concrete protective coating by referring to the formula and method provided in Example 1. Compared with Example 1, this comparative example does not add sustained-release capsules. Apart from the above differences, the operating steps for preparing the concrete protective coating in this comparative example are strictly consistent with those in Example 1.

[0049] Comparative Example 2

[0050] This comparative example prepares a concrete protective coating using the formula and method provided in Example 1. Compared with Example 1, this comparative example does not prepare sustained-release capsules, but directly adds graphene oxide and zirconium silicone. Apart from the above differences, the operating steps for preparing the concrete protective coating in this comparative example are strictly consistent with those in Example 1.

[0051] Comparative Example 3

[0052] This comparative example prepares a concrete protective coating using the formula and method provided in Example 1. Compared with Example 1, this comparative example does not prepare sustained-release capsules, but only adds graphene oxide. Apart from the above differences, the operating steps for preparing the concrete protective coating in this comparative example are strictly consistent with those in Example 1.

[0053] Comparative Example 4

[0054] This comparative example prepares a concrete protective coating by referring to the formula and method provided in Example 1. Compared with Example 1, this comparative example does not prepare sustained-release capsules and only adds zirconium silicone. Apart from the above differences, the operating steps for preparing the concrete protective coating in this comparative example are strictly consistent with those in Example 1.

[0055] Test Example 1

[0056] 1. Test subjects

[0057] The concrete protective coatings prepared in Examples 1-7 and Comparative Examples 1-4 were molded and applied to the surfaces of the test specimens in accordance with the requirements of GB 18445-2012, "Cement-based Penetrating Crystalline Waterproof Materials." A control group was prepared without molding or coating the surfaces of the test specimens. These samples were tested according to the following test method.

[0058] 2. Test Method

[0059] (1) Volatility test: Weigh approximately 1g of concrete protective coating onto a watch glass. Place the coating in a low-temperature oven and an oven at a set temperature. After 24 hours, measure the remaining concrete protective coating mass. The volatility can be calculated based on the rate of change in the concrete protective coating mass before and after drying.

[0060] (3) Penetration depth: Refer to the test method in JC / T 2235-2014 "Silica Protective Agent for Concrete" to conduct concrete protective coating application and penetration depth test. The penetration depth refers to the depth of the coating penetrating into the concrete. The greater the penetration depth, the longer the protection period of the concrete.

[0061] (4) Water absorption rate of concrete after painting: The water absorption rate of concrete protective coating was tested with reference to JTJ 275-2000 “Technical Code for Anti-corrosion of Concrete Structures in Harbor Engineering”.

[0062] (5) Compression and flexural strength test: The prepared coating was molded into 40 mm × 40 mm × 160 mm specimens according to GB / T17671-1999 “Test method for strength of cement mortar (ISO method)” and cured to 28 days for compressive strength and flexural strength tests.

[0063] 3. Test results and analysis

[0064] The test results for this example are shown in Table 2. Comparative Examples 1 through 4 explore the effects of the composition of sustained-release capsules on concrete protective coatings. In Comparative Example 1, where no sustained-release capsules were added, the resulting concrete protective coating exhibited significant variations in its impermeability pressure at different times, demonstrating that sustained-release capsules can both extend the lifespan of the concrete protective coating and enhance its impermeability. Comparative Examples 2 through 4, however, demonstrate that while the direct addition of graphene oxide and zirconium silicone enhances the concrete protective coating's impermeability, it lacks a sustained-release effect. The impermeability pressure at 28 days is consistent with or even slightly decreases at 7 days, indicating that the performance of the concrete protective coating deteriorates with use. Furthermore, the direct addition of zirconium silicone can react with cement hydration products to form insoluble complexes, which block capillary pores in the concrete and reduce porosity. This, in turn, affects the coating's penetration depth, hindering its ability to penetrate and protect the concrete, and reducing the concrete's long-term durability.

[0065] The test results of Examples 1 to 4 show that latex powder and silica fume can synergistically inhibit alkali reversion. In Examples 3 and 4, it is shown that the addition of silica fume and latex powder can improve the occurrence of white spots, but the synergistic effect of the two can better improve the problem of alkali reversion.

[0066] The effectiveness of waterproof materials in protecting concrete is directly related to their penetration depth, especially for easily worn concrete structures. The greater the penetration depth, the easier it is for the coating to penetrate into the concrete and protect the concrete. However, if the pores in the concrete are too large, it means that the concrete is more susceptible to water erosion. Therefore, concrete protective coatings should be able to improve the density and impermeability of the concrete substrate. In Examples 5 to 7, the penetration depth of the concrete coatings prepared in Examples 5 to 7 showed an increasing trend compared to Example 1. This shows that in Example 1, the addition of calcium carbonate and chelating agent can synergistically improve the density of the cement substrate and reduce the total pore volume. Therefore, although the penetration depth of Example 1 is lower than that of the concrete coatings prepared in Examples 5 to 7, it is beneficial for the prepared concrete coating to reduce the water absorption rate of the concrete.

[0067] Compared with Example 1 in which sustained-release capsules were prepared by dry mixing, the long-term working performance of the concrete coating obtained by using the liquid phase drying method to prepare sustained-release capsules in Example 8 was reduced.

[0068] Table 2. Test results of test case 1

[0069]

[0070] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A high-permeability concrete protective coating, characterized in that: The raw materials for preparing the concrete protective coating include powder and liquid; Calculated by weight, the powder includes 40-60 parts of Portland cement, 2-4 parts of nano-silicon dioxide, 30-40 parts of quartz sand, and 8-12 parts of silicate; Calculated by weight, the liquid material includes 15 to 20 parts of silicone oligomer, 20 to 30 parts of acrylic ester emulsion, and 4 to 6 parts of sustained-release capsules; The sustained-release capsule uses graphene oxide as the capsule wall and zirconium silicone as the capsule core; wherein the particle size of the graphene oxide is 10 μm, and the particle size of the zirconium silicone is 0.8±0.5 μm; The preparation of the sustained-release capsule comprises the following steps: mixing the graphene oxide and the silicone zirconium in a mass ratio of 10:1, compounding them by ball milling to obtain the sustained-release capsule; wherein the parameters of the ball milling are: ball milling time of 24 hours, ball milling speed of 150 r / min, grinding medium of 2 mm zirconium oxide, and ball-to-material ratio of 1:

10.

2. The concrete protective coating according to claim 1, characterized in that: Calculated by mass ratio, the powder: the liquid = 1.5~4:

1.

3. The concrete protective coating according to claim 1 or 2, characterized in that: The powder further comprises calcium carbonate and a complexing agent, wherein the molar ratio of calcium carbonate to complexing agent is 1-1.05:

1.

4. The concrete protective coating according to claim 3, characterized in that: The complexing agent includes at least one of disodium ethylenediaminetetraacetate, hydroxyethylene diphosphate, and ethylenediaminetetraethylene phosphate.

5. The concrete protective coating according to claim 1, characterized in that: The powder material also includes latex powder and silica fume, wherein, calculated by mass ratio, the latex powder: the silica fume = 1:1-1.

5.

6. The concrete protective coating according to claim 1, characterized in that: The viscosity of the siloxane oligomer is not higher than 30 mPa·s.

7. The concrete protective coating according to claim 6, characterized in that: The siloxane oligomer includes at least one of polymethyltriethoxysiloxane, polymethyltrimethoxysiloxane, methyl-terminated polydimethylsiloxane, hydroxy-terminated polydimethylsiloxane, methyl hydrogenated silicone oil, and methylphenyl hydrogenated silicone oil.

8. A method for preparing the concrete protective coating according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: Preparing the powder: mixing the Portland cement, the quartz sand, and the silicate to obtain a mixed powder I, and adding the remaining materials included in the powder to the mixed powder I until the powder temperature of the mixed powder I is lower than 40° C. During the above process, the mixing speed is 40 to 80 rpm; Preparing the liquid material: mixing the acrylic emulsion and the silicone oligomer using a high-speed dispersion process at a mixing speed of 800 to 1200 rpm, and then adding the sustained-release capsule to obtain the liquid material; Mixing step: mixing the powder and the liquid in a mass ratio of 1.5 to 4:1 at a mixing speed of 100 to 200 revolutions per minute.

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