A waterproof and anti-permeability sealing coating for concrete and a preparation method thereof

Abstract

This invention belongs to the field of fertilizer production technology, and particularly relates to a concrete waterproof and seepage-resistant sealing coating and its preparation method. The preparation method includes: S1, preparing a premixed powder; S2, preparing a molten matrix; S3, preparing a primary mixed slurry; S4, preparing a secondary mixed slurry; S5, subjecting the secondary mixed slurry to vacuum degassing, then transferring it to a constant temperature chamber for static curing at a third temperature; after curing, cooling it to room temperature at a specific cooling rate to obtain the concrete waterproof and seepage-resistant sealing coating. This invention uses a coupling agent to surface-activate the inorganic filler, enabling the filler to form a chemical bond with the organic matrix, significantly enhancing the bonding strength between the sealing layer and the concrete matrix. Through multi-stage shearing and vacuum degassing treatment, micro-bubbles inside the mixed slurry are effectively eliminated, reducing the defect density inside the sealing layer, thereby improving resistance to water seepage pressure.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, and in particular relates to a waterproof and seepage-proof sealing coating for concrete and its preparation method. Background Technology

[0002] In the quality testing of building engineering projects, the impermeability of concrete is one of the important indicators for evaluating its durability. A pressure water permeability test is typically conducted using impermeability specimens. In this type of test, the sealing quality between the specimen end face and the impermeability tester mold is crucial to the success of the test. If the seal is not tight, pressurized water will seep out from the sealing interface, leading to invalid test results, or even causing the specimen to crack and break, rendering the entire set of specimens unusable.

[0003] In existing technologies, commonly used sealing materials mainly include mixtures of paraffin and rosin, and mixtures of cement and grease. However, paraffin-rosin materials have limited usability after heating, cool rapidly, and have a very short operating window; cement-grease mixtures are prone to uneven mixing, easily creating localized weak points, leading to seal failure. In addition, although the standard mentions the use of rubber sleeves for sealing, rubber sleeves are expensive and sensitive to dimensional deviations in the specimen, limiting their applicability.

[0004] Therefore, there is an urgent need in this field for a sealing material that is reliable in sealing performance, easy to operate, highly applicable, and cost-controllable. Summary of the Invention

[0005] The main objective of this invention is to provide a waterproof and seepage-resistant sealant coating for concrete and its preparation method, so as to overcome the shortcomings of the prior art.

[0006] To achieve the aforementioned objectives, the technical solution adopted by this invention includes: According to a first aspect of the present invention, a method for preparing a waterproof and seepage-resistant sealant coating for concrete is provided, comprising the following steps: S1: The base material is dehydrated and pretreated, and the inorganic filler modified by the silane coupling agent is premixed with the polymer tackifying resin to obtain the premixed powder. S2: The pre-treated base material is heated to the first melting temperature and kept at that temperature. After it is completely melted, it is sheared and dispersed at the first shear rate to obtain a molten matrix. S3: The premixed powder is added to the molten matrix in batches, and stirred at a second shear rate while maintaining the first melting temperature to obtain a primary mixed slurry; S4: Cool the primary mixed slurry to a second temperature, add chain extender and antioxidant, and stir at a third shear rate to obtain a secondary mixed slurry; S5: The secondary mixed slurry is subjected to vacuum degassing treatment, and then transferred to a constant temperature chamber for static curing at a third temperature; after curing is completed, it is cooled to room temperature at a specific cooling rate to obtain the concrete waterproof and seepage-proof sealing coating.

[0007] Further, in step S1, the base material is composed of petroleum asphalt, microcrystalline wax and polyethylene wax; the inorganic filler is a mixture of talc powder and cement with a particle size of 200 to 800 mesh, which has been surface-treated with titanate coupling agent or silane coupling agent.

[0008] Further, in step S1, the dehydration pretreatment is carried out by heating and stirring at 100°C to 120°C for 1 to 2 hours; in step S2, the first melting temperature is 130°C to 160°C, and the first shear rate is 400 to 600 rpm.

[0009] Furthermore, in step S3, the premixed powder is added over a period of 20 to 40 minutes, and the second shear rate is 800 to 1200 rpm.

[0010] Further, in step S4, the second temperature is 100°C to 110°C, the third shear rate is 300 to 500 rpm, and the stirring time is 15 to 30 minutes.

[0011] Furthermore, in step S5, the vacuum degree of the vacuum degassing treatment is not higher than -0.08 MPa, the degassing time is 5 to 15 minutes, the third temperature is 70°C to 85°C, and the standing curing time is 12 to 24 hours.

[0012] According to a second aspect of the present invention, a concrete waterproof and seepage-resistant sealing coating prepared by the above method is provided. The sealing coating comprises an organic matrix phase and a reinforcing filler phase dispersed in the organic matrix phase. The organic matrix phase is a continuous phase formed by melt blending of petroleum asphalt, microcrystalline wax, polyethylene wax, and a high-molecular-weight tackifying resin. The reinforcing filler phase is a mixed powder composed of talc powder and cement that has been surface-coated with a coupling agent. The mixed powder forms an interfacial chemical bond structure with the organic matrix phase through the coupling agent. The sealing coating has a discontinuous void structure formed by vacuum degassing, and the average dispersed particle size of the reinforcing filler phase in the organic matrix phase is 50 μm to 150 μm.

[0013] Furthermore, the sealant has a consistency of 35mm-45mm at an ambient temperature of 25℃, a consistency of not less than 20mm at an ambient temperature of 60℃, and exhibits no brittleness at an ambient temperature of -10℃, thus possessing stable applicability across temperature ranges.

[0014] Furthermore, the initial bond strength between the sealing coating and the end face of the standard concrete impermeable specimen is not less than 0.5 MPa, and the impermeability pressure at room temperature after curing is not less than 1.5 MPa.

[0015] Furthermore, the sealing coating has a 2-4 hour field-operable time window after preparation, during which the sealing coating remains in paste form and exhibits thixotropy.

[0016] Compared with the prior art, the advantages of the present invention include: This invention utilizes a coupling agent to surface-activate inorganic fillers, enabling them to form chemical bonds with the organic matrix and significantly enhancing the bonding strength between the sealing layer and the concrete matrix. Multi-stage shearing and vacuum degassing effectively eliminates micro-bubbles within the mixed slurry, reducing the defect density within the sealing layer and thus improving resistance to water seepage pressure. By compounding petroleum asphalt, microcrystalline wax, and polyethylene wax in specific proportions, a viscoelastic balance is achieved within a wide temperature range of -10℃ to 60℃, avoiding the drawbacks of traditional paraffin materials such as low-temperature brittleness or high-temperature flow. Furthermore, the preparation process of this invention includes a suitable static curing step, allowing for sufficient relaxation of internal stresses, resulting in a final product with an appropriate on-site workability time, improving construction convenience. Detailed Implementation

[0017] In view of the shortcomings of the prior art, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention. The following will further explain and illustrate this technical solution, its implementation process, and its principles.

[0018] The present invention will now be described in further detail with reference to specific embodiments. The given embodiments are merely illustrative of the invention and not intended to limit its scope. The embodiments provided below can serve as a guide for further improvements by those skilled in the art and do not constitute a limitation on the invention in any way.

[0019] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials used in the following embodiments are commercially available.

[0020] This invention provides a method for preparing a waterproof and seepage-resistant sealant coating for concrete, characterized by comprising the following steps: S1: A composite base material containing petroleum asphalt, microcrystalline wax, and polyethylene wax is placed in a heating container and pre-treated for dehydration at a temperature of 100°C to 120°C to reduce the free water and bound water content in the base material to less than 0.5%. Simultaneously, an inorganic filler modified by surface coating with a silane coupling agent or titanate coupling agent is pre-mixed with a polymer tackifying resin to obtain a pre-mixed powder with enhanced interfacial activity. The inorganic filler is a mixture of talc powder and cement powder. S2: The pre-treated composite matrix is ​​heated to a first melting temperature of 130°C to 160°C and held at that temperature. After the composite matrix is ​​completely melted, it is sheared and dispersed at a first shear rate of 400 to 600 rpm to achieve uniform molecular-level blending of each wax-based component and obtain a molten matrix. S3: The premixed powder is added to the molten matrix in batches. Under the condition of maintaining the first melting temperature, high shear dispersion and stirring are performed at a second shear rate of 800 to 1200 rpm. The surface-coated modified inorganic filler is uniformly peeled off and dispersed in the interior of the molten matrix by high shear force to obtain a primary mixed slurry. S4: Cool the primary mixed slurry to a second temperature of 100°C to 110°C, add chain extender and antioxidant to it, and stir at a low speed of 300 to 500 rpm to promote the grafting reaction between the chain extender and the active groups in the system, so as to improve the cohesive strength of the organic continuous phase and obtain the secondary mixed slurry. S5: The secondary mixed slurry is subjected to vacuum degassing treatment, with the vacuum degree controlled not higher than -0.08MPa, to remove microbubbles entrained in the system during shearing and mixing, and to eliminate internal continuous void defects; then the degassed slurry is transferred to a constant temperature chamber and allowed to stand and mature at a third temperature of 70℃ to 85℃ for 12 to 24 hours to fully relax the internal stress in the system and promote the stabilization of the interfacial chemical bonding structure; after maturity, it is cooled to room temperature at a controlled cooling rate to obtain the concrete waterproof and seepage-proof sealing coating.

[0021] To better understand the technical solution of the present invention, the following detailed discussion is provided in conjunction with specific embodiments.

[0022] Example 1 This embodiment provides a method for preparing a waterproof and seepage-proof sealing coating for concrete, including the following steps: S1. Petroleum asphalt, microcrystalline wax, and polyethylene wax are mixed at a weight ratio of 50:30:20 as a base material and pre-treated by dehydration by heating and stirring at 100°C for 1 hour. Simultaneously, 200-800 mesh talc powder and cement are mixed at a 1:1 mass ratio, and a silane coupling agent accounting for 2% of the mass of the mixed powder is added for surface modification treatment to obtain a modified filler. The modified filler is pre-mixed with a polymeric tackifying resin (rosin resin) to obtain a pre-mixed powder.

[0023] S2, the dehydrated base material is placed in a reactor and heated to 130°C, and kept at this temperature until it is completely melted. Then, the stirrer speed is set to 400 rpm to perform shear dispersion, thereby obtaining the molten matrix.

[0024] S3. The premixed powder obtained in S1 is added to the molten matrix in batches. The entire feeding process is controlled to be completed within 40 minutes. During the feeding process, the temperature of the reactor is maintained at 130°C, and the stirring speed is increased to 800 rpm. High-speed shearing and stirring are maintained to obtain the primary mixed slurry.

[0025] S4. Cool the primary mixed slurry to 100℃. At this time, add a chain extender (such as epoxidized soybean oil) and an antioxidant (such as hindered phenolic antioxidant), adjust the stirring speed to 300 rpm, and continue stirring for 30 minutes to obtain the secondary mixed slurry.

[0026] S5, turn on the vacuum pump to degas the secondary mixed slurry, control the vacuum level to -0.08MPa, and maintain it for 5 minutes. After degassing, transfer the slurry to a constant temperature chamber and let it stand and mature at 70℃ for 12 hours. After maturation, cool it to room temperature using a water bath to obtain the coating.

[0027] Example 2 This embodiment provides a method for preparing a waterproof and seepage-proof sealing coating for concrete, including the following steps: S1, petroleum asphalt, microcrystalline wax, and polyethylene wax are mixed in a weight ratio of 50:30:20 as a base material, and pre-treated by heating and stirring at 110℃ for 1.5 hours to remove water. Talc powder and cement are mixed in a 1:1 mass ratio, a silane coupling agent is added for surface modification, and then pre-mixed with a polymer tackifying resin to obtain a pre-mixed powder.

[0028] S2, heat the dehydrated base material to 145℃, and after it is completely melted, set the stirrer speed to 500 rpm to perform shearing and dispersion to obtain the molten base.

[0029] S3. The premixed powder is added to the molten matrix in batches. The feeding process is controlled to be completed within 30 minutes. The temperature of the reactor is maintained at 145℃, and the stirring speed is increased to 1000 rpm to obtain the primary mixed slurry.

[0030] S4. Cool the primary mixed slurry to 105℃, add chain extender and antioxidant, adjust the stirring speed to 400 rpm, and continue stirring for 22.5 minutes to obtain the secondary mixed slurry.

[0031] S5, turn on the vacuum pump to perform vacuum degassing, control the vacuum level to -0.09MPa, and maintain it for 10 minutes. Transfer the slurry to a constant temperature chamber and let it stand and mature at 78℃ for 18 hours. After maturation, cool to room temperature to obtain the coating.

[0032] Example 3 This embodiment provides a method for preparing a waterproof and seepage-proof sealing coating for concrete, including the following steps: S1, petroleum asphalt, microcrystalline wax, and polyethylene wax are mixed in a weight ratio of 50:30:20 as a base material, and pre-treated by heating and stirring at 120℃ for 2 hours to remove water. Talc powder and cement are mixed in a 1:1 mass ratio, a silane coupling agent is added for surface modification, and then pre-mixed with a polymer tackifying resin to obtain a pre-mixed powder.

[0033] S2, heat the dehydrated base material to 160℃, and after it is completely melted, set the stirrer speed to 600 rpm to perform shearing and dispersion to obtain the molten base.

[0034] S3. The premixed powder is added to the molten matrix in batches. The feeding process is controlled to be completed within 20 minutes. The temperature of the reactor is maintained at 160℃, and the stirring speed is increased to 1200 rpm to obtain the primary mixed slurry.

[0035] S4. Cool the primary mixed slurry to 110℃, add chain extender and antioxidant, adjust the stirring speed to 500 rpm, and continue stirring for 15 minutes to obtain the secondary mixed slurry.

[0036] S5, turn on the vacuum pump to perform vacuum degassing, control the vacuum level to -0.1MPa, and maintain it for 15 minutes. Transfer the slurry to a constant temperature chamber and let it stand and mature at 85℃ for 24 hours. After maturation, cool to room temperature to obtain the coating.

[0037] Comparative Example 1 Conventional paraffin and rosin were mixed in a 1:1 weight ratio, heated to melt, and then directly applied to the end face of the concrete impermeable specimen. No filler modification, multi-stage shearing, or vacuum degassing treatment was performed.

[0038] Comparative Example 2 The raw material composition and process steps are basically the same as in Example 2, but in step S1, the talc powder and cement are mixed without silane coupling agent surface modification treatment, and are directly premixed with tackifying resin.

[0039] Comparative Example 3 The raw material composition and process steps are basically the same as in Example 2, but in step S5, the vacuum degassing operation of the secondary mixed slurry is omitted, and it is directly transferred to the constant temperature box for static curing.

[0040] The test results are shown in Table 1.

[0041] Table 1 The results show that: A comparison of Examples 1-3 with Comparative Example 1 shows that traditional paraffin materials are too hard and brittle at 25°C, soften and flow at 60°C, and severely crack at -10°C. In contrast, this application uses a compound of petroleum asphalt, microcrystalline wax, and polyethylene wax. Through the synergistic toughening effect of molecular chain segments, Examples 1-3 maintain suitable consistency and toughness across a temperature range of -10°C to 60°C, completely solving the problem of the narrow temperature window limitation of traditional materials. Comparative Example 2, which omitted filler surface modification treatment, had a significantly lower initial bond strength (0.3 MPa) than Example 2 (0.8 MPa). This demonstrates that the silane coupling agent can form a chemical bond structure between the inorganic filler and the organic matrix phase, greatly improving the physical anchoring and chemical bonding between the sealing layer and the concrete matrix interface, directly reducing the probability of peeling between the sealing layer and the specimen end face during the test, and ensuring an initial bond strength greater than 0.5 MPa. Comparative Example 3 omitted the vacuum degassing step, and its final impermeability pressure was only 1.1 MPa, far lower than the 1.8 MPa of Example 2. Microscopic examination revealed that the slurry without vacuum degassing contained a large number of micron-sized air bubbles, which formed continuous permeation channels during the pressure water permeation test. In contrast, this application, through vacuum degassing at -0.08 MPa to -0.1 MPa in step S5, eliminated discontinuous void defects within the system, improved the internal structural density of the material, and thus stably increased the impermeability pressure to over 1.5 MPa.

[0042] In summary, the sealing coating provided in this application significantly improves the density of the internal structure and the interfacial bonding force of the material through a comprehensive process of specific base material compounding, coupling agent interface modification, multi-stage shear dispersion and vacuum degassing. Its wide temperature range stability, bonding strength and impermeability pressure resistance are far superior to traditional sealing materials, and it has high engineering promotion value.

[0043] The above descriptions are merely some embodiments of the present invention. It should be noted that those skilled in the art can make other modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A method for preparing a waterproof and seepage-proof sealant coating for concrete, characterized in that, Includes the following steps: S1: The base material is dehydrated and pretreated, and the inorganic filler modified by the silane coupling agent is premixed with the polymer tackifying resin to obtain the premixed powder. S2: The pre-treated base material is heated to the first melting temperature and kept at that temperature. After it is completely melted, it is sheared and dispersed at the first shear rate to obtain a molten matrix. S3: The premixed powder is added to the molten matrix in batches, and stirred at a second shear rate while maintaining the first melting temperature to obtain a primary mixed slurry; S4: Cool the primary mixed slurry to a second temperature, add chain extender and antioxidant, and stir at a third shear rate to obtain a secondary mixed slurry; S5: The secondary mixed slurry is subjected to vacuum degassing treatment, and then transferred to a constant temperature chamber for static curing at a third temperature; after curing is completed, it is cooled to room temperature at a specific cooling rate to obtain the concrete waterproof and seepage-proof sealing coating.

2. The method for preparing a waterproof and seepage-proof sealant coating for concrete according to claim 1, characterized in that, In step S1, the base material is a compound of petroleum asphalt, microcrystalline wax and polyethylene wax; the inorganic filler is a mixture of talc powder and cement with a particle size of 200 to 800 mesh, which has been surface-treated with titanate coupling agent or silane coupling agent.

3. The method for preparing a waterproof and seepage-proof sealant coating for concrete according to claim 1, characterized in that, In step S1, the dehydration pretreatment is carried out by heating and stirring at 100°C to 120°C for 1 to 2 hours; in step S2, the first melting temperature is 130°C to 160°C, and the first shear rate is 400 to 600 rpm.

4. The method for preparing a waterproof and seepage-proof sealant coating for concrete according to claim 1, characterized in that, In step S3, the premixed powder is added over a period of 20 to 40 minutes, and the second shear rate is 800 to 1200 rpm.

5. The method for preparing a waterproof and seepage-proof sealant coating for concrete according to claim 1, characterized in that, In step S4, the second temperature is 100°C to 110°C, the third shear rate is 300 to 500 rpm, and the stirring time is 15 to 30 minutes.

6. The method for preparing a waterproof and seepage-proof sealant coating for concrete according to claim 1, characterized in that, In step S5, the vacuum degree of the vacuum degassing process is not higher than -0.08 MPa, and the degassing time is 5 to 15 minutes; the third temperature is 70°C to 85°C, and the standing curing time is 12 to 24 hours.

7. A concrete waterproof and seepage-proof sealing coating prepared by the method according to any one of claims 1-6, characterized in that, The sealing coating comprises an organic matrix phase and a reinforcing filler phase dispersed in the organic matrix phase; the organic matrix phase is a continuous phase formed by melt blending of petroleum asphalt, microcrystalline wax, polyethylene wax and high molecular weight tackifying resin; the reinforcing filler phase is a mixed powder composed of talc powder and cement coated with a coupling agent, the mixed powder forming an interfacial chemical bond structure with the organic matrix phase through the coupling agent; the sealing coating has a discontinuous void structure formed by vacuum degassing, and the average dispersed particle size of the reinforcing filler phase in the organic matrix phase is 50 μm to 150 μm.

8. The concrete waterproof and seepage-proof sealing coating according to claim 7, characterized in that, The sealant has a consistency of 35mm-45mm at an ambient temperature of 25℃, a consistency of not less than 20mm at an ambient temperature of 60℃, and exhibits no brittleness at an ambient temperature of -10℃, thus possessing stable applicability across temperature ranges.

9. A concrete waterproof and seepage-proof sealing coating according to claim 7, characterized in that, The initial bond strength between the sealing coating and the end face of the standard concrete impermeable test specimen is not less than 0.5 MPa, and the impermeability pressure at room temperature after curing is not less than 1.5 MPa.

10. A concrete waterproof and seepage-proof sealing coating according to claim 7, characterized in that, The sealing coating has a field-operable time window of 2-4 hours after preparation, during which the sealing coating remains in paste form and exhibits thixotropic properties.

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