Basalt fiber modified cement-based capillary crystalline waterproof coating and preparation method thereof

Abstract

The invention discloses a basalt fiber modified cement-based capillary crystalline waterproof coating and a preparation method thereof, and relates to the technical field of waterproof coatings, the waterproof coating is prepared from Portland cement, surface modified basalt fibers, a gradient crystallization accelerator, nano-silica, a polycarboxylic acid water reducer, quartz sand, a functional additive and water; through composite pretreatment of the surface modified basalt fiber, a three-dimensional network structure is formed in the concrete, shrinkage stress is accurately compensated in combination with the magnesium oxide expanding agent, the crack resistance is remarkably improved, and the capillary adsorption effect of mesoporous nano-silica and the slow release design of the gradient crystallization accelerant are utilized to synergistically break through the penetration depth of active substances, so that the crack resistance of the concrete is improved. In addition, the viscosity of the slurry is reduced and the migration of active ions is accelerated by optimizing the molecular structure of the polycarboxylate superplasticizer, and the hydration process is regulated and controlled in cooperation with calcium lignosulphonate, so that the growth rate of ettringite crystals is multiplied, the crack repair can be completed in a short time, and the anti-permeability pressure is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of waterproof coatings, and in particular to a basalt fiber modified cement-based penetrating crystalline waterproof coating and a preparation method thereof. Background Art

[0002] Paint refers to a liquid or powdered material that forms a continuous thin film on the surface of an object and can provide protection, decoration or special functions (such as waterproofing, fireproofing, conductivity, etc.). Its core components are film-forming substances, functional components and media. The film-forming substances mainly include resins / polymers and cement bases. The functional components mainly include pigments, fillers and additives. The media mainly include water-based paints and solvent-based paints. Paints can be divided into waterproof paints, fire-retardant paints, anti-corrosion paints and permeable crystalline paints according to their functional types.

[0003] Waterproof coating refers to a functional coating material that forms a continuous waterproof film on the surface of a building to prevent water penetration. It is mainly composed of synthetic polymers, polymers and asphalt, polymers and cement as the main film-forming substances; it is a solvent-based, water-based or powder-based coating made by adding various additives, modifying materials, filling materials, etc. This coating is applied to the base surface that needs waterproofing, such as the roof, basement, toilet, bathroom and exterior wall of the building, and can form a continuous, integral coating waterproof layer with a certain thickness under normal temperature conditions.

[0004] Existing waterproof coating products generally have defects such as weak crack resistance, insufficient penetration depth and slow crystallization rate. In actual construction, weak crack resistance can easily lead to a low crack repair rate, insufficient penetration depth will limit the migration of active substances, and slow crystallization rate will require a long time to form effective self-repair, which makes it difficult to meet the requirements of harsh engineering environments for structural durability. Therefore, the present invention proposes a basalt fiber modified cement-based penetrating crystallization waterproof coating and a preparation method thereof to solve the problems existing in the prior art. Summary of the Invention

[0005] In response to the above problems, the purpose of the present invention is to propose a basalt fiber modified cement-based penetrating crystallization waterproof coating and a preparation method thereof, so as to solve the common problems of weak crack resistance, insufficient penetration depth and slow crystallization speed of existing waterproof coating products.

[0006] In order to achieve the purpose of the present invention, the present invention is implemented by the following technical scheme: a basalt fiber modified cement-based penetrating crystallization waterproof coating comprises the following raw materials in parts by weight: 40 to 50 parts of Portland cement, 1.2 to 2.0 parts of surface-modified basalt fiber, 5 to 8 parts of gradient crystallization accelerator, 2 to 4 parts of nano-silica, 0.5 to 1.2 parts of polycarboxylate water reducer, 25 to 35 parts of quartz sand, 0.25 to 0.6 parts of functional additives and 12 to 16 parts of water;

[0007] The gradient crystallization accelerator is compounded by stearic acid-modified nano-calcium carbonate and beta-cyclodextrin-coated silicate in a molar ratio of 1:2-3.

[0008] A further improvement is that the surface-modified basalt fiber has a length of 3 to 5 mm and a diameter of 10 to 15 μm, and is pretreated with an ethanol solution containing a silane coupling agent KH550 and nanographene sheets accounting for 0.1 to 0.3% of the fiber mass.

[0009] A further improvement is that the specific steps of the composite pretreatment are:

[0010] A1. Add silane coupling agent KH550 to anhydrous ethanol to prepare a solution with a mass concentration of 2-4%, and adjust the pH to 4.5-5.5 to prepare a hydrolyzate;

[0011] A2. adding nanographene sheets accounting for 0.1 to 0.3% of the fiber mass to the hydrolyzed solution and performing ultrasonic dispersion treatment to prepare a mixed treatment solution;

[0012] A3. Place the basalt fiber in a vacuum impregnation tank, evacuate the tank, and inject the mixed treatment liquid for impregnation treatment, so that the mixed treatment liquid can fully penetrate the micropores on the fiber surface;

[0013] A4. After the impregnation, the fiber is taken out, centrifuged to remove excess liquid, and then dried, and then solidified to obtain surface-modified basalt fiber.

[0014] A further improvement is that: the specific preparation method of the β-cyclodextrin-coated silicate is: first, sodium silicate and calcium nitrate are mixed in a molar ratio of 3:1 to react to generate a calcium silicate precursor, and then a β-cyclodextrin aqueous solution with a mass concentration of 8 to 12% is added for ultrasonic oscillation treatment, the mass ratio of the solution to the precursor is 0.8 to 1.2:1, and after ultrasonic oscillation treatment, spray drying is performed to form a coating structure to obtain coated particles, namely β-cyclodextrin-coated silicate.

[0015] Further improvements are: the molecular weight of the polycarboxylate water reducer is 8000-12000, the molecular weight distribution index is ≤1.25, the molecular chain is grafted with hydroxyethyl acrylate monomer accounting for 5-8% of the total amount of the water reducer, and forms a hydrogen bond network with nano-silica.

[0016] A further improvement is that the functional additive is compounded by a magnesium oxide expander and a calcium lignin sulfonate retarder in a mass ratio of 1:4-5, wherein the activity index of the magnesium oxide expander is ≥92% and the sulfonation degree of the calcium lignin sulfonate is ≥2.0 mmol / g.

[0017] The preparation method of basalt fiber modified cement-based penetrating crystallization waterproof coating comprises the following steps:

[0018] Step 1: Put the pre-weighed silicate cement, quartz sand and nano-silicon dioxide into a double-shaft planetary mixer, and mix and stir to obtain a mixed dry material;

[0019] Step 2: adding pre-weighed surface-modified basalt fiber, gradient crystallization accelerator, functional additive, polycarboxylate water-reducing agent and water to the mixed dry material in sequence, stirring and mixing in two stages to obtain a mixed wet material;

[0020] Step 3: Transfer the mixed wet material into a vacuum filling machine and pack it into aluminum-plastic composite film bags. Inject nitrogen into each bag before sealing to obtain the finished waterproof coating.

[0021] A further improvement is that in step 2, the two-stage stirring and mixing processes are both carried out under nitrogen protection, the oxygen concentration is ≤0.5%, and the stirring temperature is controlled at 25±2°C.

[0022] The beneficial effects of the present invention are as follows: the present invention integrates three major technical features to synergistically improve the performance of waterproof coatings:

[0023] Through the composite pretreatment of surface-modified basalt fiber (silane coupling agent KH550 hydrolysis grafting + nanographene enhanced interfacial bonding), a three-dimensional network structure is formed in the concrete. Combined with magnesium oxide expansion agent, it accurately compensates for shrinkage stress, significantly improves crack resistance and increases crack self-repair rate.

[0024] The capillary adsorption effect of mesoporous nano-silica (pore size 2-5nm, PVP grafting to enhance dispersibility) and the sustained-release design of the gradient crystallization promoter (β-cyclodextrin-coated silicate controlled release in an alkaline environment + stearic acid-modified nano-calcium carbonate nucleation catalysis) are used to synergistically break through the penetration depth of active substances;

[0025] By optimizing the molecular structure of polycarboxylate water-reducing agent (hydroxyethyl acrylate grafting to form a hydrogen bond network), the slurry viscosity is reduced, the migration of active ions is accelerated, and calcium lignin sulfonate is used to regulate the hydration process, doubling the growth rate of ettringite crystals. This allows cracks to be repaired in a short period of time, thereby improving the anti-seepage pressure.

[0026] The above three innovative technical features form a synergistically enhanced closed loop of crack resistance, penetration and crystallization speed, overcoming the defects of traditional waterproof coatings such as weak crack resistance, shallow penetration and slow curing. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic flow chart of a method for preparing a long-lasting and durable waterproof coating with a self-repairing function according to the present invention. DETAILED DESCRIPTION

[0028] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0029] Crystalline waterproof coatings are a type of intelligent waterproof material that generates insoluble crystals within concrete through chemical reactions. Their core principle is to utilize the active chemical substances contained in the coating (such as silicates and catalysts) to react with free calcium ions and moisture in the concrete, continuously generating needle-shaped or network-like crystal structures. These crystals automatically fill the pores and microcracks within the concrete, forming a deep protective layer. Compared with traditional physical barrier coatings, their unique feature is their "self-healing" ability—when new cracks form in the concrete due to external forces, the unreacted active substances will come into contact with water and restart the crystallization process, achieving dynamic repair.

[0030] The advantages of crystalline coatings lie not only in their long-lasting protection but also in their deep integration with the building substrate. Because crystals and concrete are homogeneous products, their thermal expansion coefficients perfectly match, avoiding the "shelling" phenomenon common with traditional membranes. Experiments have shown that after 50 freeze-thaw cycles, concrete specimens coated with this material experienced a mass loss rate of less than 0.8%, far exceeding the industry average of 3.5% for conventional waterproofing treatments. The advantages of crystalline coatings lie not only in their long-lasting protection but also in their deep integration with the building substrate. From an engineering perspective, crystalline coatings are reshaping building waterproofing systems.

[0031] It should be noted that the technical means not described in detail in the embodiments of the present invention can be implemented by conventional means, and are not the key points of the invention and will not be described in detail.

[0032] Example 1

[0033] This embodiment provides a basalt fiber-modified cement-based penetrating crystallization waterproof coating, comprising the following raw materials in parts by weight: 40 parts of Portland cement, 1.2 parts of surface-modified basalt fiber, 5 parts of a gradient crystallization accelerator, 2 parts of nano-silica, 0.5 parts of a polycarboxylate water-reducing agent, 25 parts of quartz sand, 0.25 parts of a functional additive, and 12 parts of water, wherein:

[0034] The surface-modified basalt fibers have a length of 3 to 5 mm and a diameter of 10 to 15 μm, and are pretreated with an ethanol solution containing a silane coupling agent KH550 (concentration 2%) and nanographene sheets accounting for 0.1% of the fiber mass. The nanographene sheets have a thickness of ≤5 nm and a lateral dimension of 200 to 500 nm.

[0035] Gradient crystallization promoter is stearic acid modified nano calcium carbonate (particle size 30 ~ 50nm, specific surface area ≥ 60m 2 / g) and β-cyclodextrin-coated silicate are compounded in a 1:2 molar ratio (the stearic acid coating amount is 1.2% of the mass of calcium carbonate). The coating layer thickness of the β-cyclodextrin-coated silicate in this embodiment is ≤200 nm, and the release rate is ≥85% within 48 hours in an alkaline environment of pH ≥10.5;

[0036] Nano-silica has a mesoporous structure with a pore diameter of 2 to 5 nm and a pore volume of 0.8 to 1.2 m 3 / g;

[0037] The functional additive is prepared by compounding magnesium oxide expansion agent and calcium lignin sulfonate retarder in a mass ratio of 1:4, wherein the activity index of magnesium oxide expansion agent is ≥92%, the particle size D50 is 5-8 μm, the sulfonation degree of calcium lignin sulfonate is ≥2.0 mmol / g, and the sugar content is ≤12%. The compound system produces 400-450×10 -6 The expansion amount (measured by dial gauge method) and the initial setting time are extended to 45min (penetration resistance method).

[0038] In this embodiment, the specific steps of composite pretreatment of surface-modified basalt fiber are as follows:

[0039] A1. First, add the silane coupling agent KH550 to anhydrous ethanol to prepare a 2% solution (2% concentration is 2g KH550 + 98g ethanol), and adjust the pH to 4.5 with acetic acid. Then, stir at 300 rpm in a 40°C water bath for 30 minutes to fully hydrolyze KH550 to generate silanols, thereby preparing a hydrolyzate.

[0040] A2. Add 0.1% of the fiber mass of nanographene sheets to the prepared hydrolyzate (0.1 g of graphene is required to treat 100 g of fiber), and then ultrasonically treat for 20 min at an ultrasonic power of 400 W and a frequency of 40 kHz to uniformly disperse the graphene without agglomeration, thereby preparing a mixed treatment solution;

[0041] A3. Place the prepared basalt fiber in a vacuum impregnation tank, evacuate to -0.08 MPa and maintain for 10 minutes. Then inject the mixed treatment solution into the vacuum impregnation tank until the basalt fiber is immersed. Then, immerse the fiber at a temperature of 60°C and a pressure of 0.5 MPa for 30 minutes to allow the solution to fully penetrate the micropores on the fiber surface.

[0042] A4. Remove the impregnated fiber material, use a centrifuge at 800 rpm to remove excess liquid (residual liquid ≤ 5%), then dry it in a hot air circulation oven at 60°C for 2 hours. After drying, cure it at 120°C for 30 minutes to allow silanol to condense with the fiber surface to form Si-O-Si covalent bonds, completing the composite pretreatment and producing surface-modified basalt fiber.

[0043] In this embodiment, the preparation method of β-cyclodextrin-coated silicate includes the following steps: first, sodium silicate and calcium nitrate are mixed in a molar ratio of 3:1 to react to form a calcium silicate precursor, and then a β-cyclodextrin aqueous solution with a mass concentration of 8% is added, and the mass ratio of the β-cyclodextrin aqueous solution to the calcium silicate precursor is 0.8:1, followed by ultrasonic oscillation for 2 hours at a temperature of 50°C, and then spray drying (spray drying parameters: inlet air temperature 180°C, outlet air temperature 90°C, atomization pressure 0.3 MPa). After drying, a coating structure is formed to obtain coated particles with a coating thickness of ≤200 nm, namely β-cyclodextrin-coated silicate, whose cumulative release rate in 10% NaOH solution within 48 hours reaches 87-92% (the β-cyclodextrin coating layer of the gradient crystallization promoter decomposes and releases silicate in an alkaline environment within 48 hours, and synergistically catalyzes the growth of calcium aluminate crystals with nano-calcium carbonate, so that the crack self-repair is completed within 72 hours).

[0044] In this embodiment, the molecular weight (Mn) of the polycarboxylate water-reducing agent is 8000 to 12000, and the molecular weight distribution index (PDI) is ≤1.25. This molecular weight range is in the oligomer-prepolymer transition zone, which can balance adsorption efficiency and dispersion ability. The molecular chain of the polycarboxylate water-reducing agent is grafted with hydroxyethyl acrylate monomers accounting for 5% of the total amount of the water-reducing agent, and forms a hydrogen bond network with nano-silica, which can reduce the slurry viscosity by 15 to 20%. The hydroxyl group (-OH) acts as a hydrogen bond donor and bonds with the silanol group (-SiOH) on the surface of the nano-SiO2, which can increase the anchoring density of the water-reducing agent on the surface of the cement particles.

[0045] The preparation process of the polycarboxylate water reducer is as follows:

[0046] S1, EPEG melting: EPEG macromonomer (molecular weight 2400) was melted into liquid at 75 °C;

[0047] S2. Copolymerization grafting: Synchronously add dropwise a mixed monomer containing hydroxyethyl acrylate (HEA) and a redox initiator system (hydrogen peroxide / sodium hypophosphite), and control the HEA addition rate to stabilize the grafting rate at 5-8%.

[0048] S3, nanocomposite: PVP modified nano-SiO2 (3% of solid content) was added and dispersed under 400W ultrasound for 20 minutes to build a hydrogen bond network;

[0049] S4, heat preservation and aging: react at 80°C for 3 hours, and adjust the molecular weight to 8000-12000 and the distribution index ≤1.25 by using mercaptopropionic acid (0.5 parts);

[0050] S5. Spray drying: air inlet temperature 180°C, air outlet temperature 85°C, to obtain a flowable powder with a hydrogen bond structure retention rate of >95%.

[0051] See also Figure 1 This embodiment also provides a method for preparing a basalt fiber modified cement-based penetrating crystallization waterproof coating, comprising the following steps:

[0052] Step 1: Dry Mix

[0053] The raw materials were weighed in advance according to the weight ratio of the above raw materials. The weighed silicate cement, quartz sand and nano-silica were first put into a double-shaft planetary mixer and mixed at a speed of 500 rpm for 3 minutes. The coefficient of variation of the mixing uniformity was ≤5% (near infrared spectroscopy analysis). After the mixing was completed, a mixed dry material was obtained;

[0054] Step 2: Wet Mixing

[0055] To the mixed dry material prepared in step 1, weighed surface-modified basalt fiber, gradient crystallization accelerator, functional additive, polycarboxylate water-reducing agent and water are added in sequence, and stirred in two stages. After stirring, a mixed wet material is obtained, which is specifically as follows:

[0056] The first stage: stirring at 800 rpm for 3 min to make the fibers uniformly dispersed, with a fiber dispersion index ≥ 0.85 (image analysis method);

[0057] The second stage: stirring at 1500 rpm for 5 min to activate the surface active groups of the nanomaterials, and the fiber dispersion index is ≥0.85 (image analysis method);

[0058] The above two stages of stirring are carried out under nitrogen protection, with an oxygen concentration of ≤0.5% (monitored by an online oxygen analyzer), and the temperature of the stirring tank is controlled at 25±2°C to prevent oxidation of the nanographene sheets (Raman spectrum D / G peak intensity ratio ≤0.15);

[0059] Step 3: Filling

[0060] The mixed wet material obtained in step 2 is transferred to a vacuum filling machine and packed into aluminum-plastic composite film bags under a vacuum environment of -0.06 MPa. Nitrogen is injected into each bag for replacement (oxygen content ≤ 0.3%) before sealing. The filling temperature is controlled at 5° C. to obtain a finished waterproof coating, i.e., a basalt fiber modified cement-based penetrating crystalline waterproof coating;

[0061] This embodiment adopts three-level filling control:

[0062] First-stage filling: press the paint into the metering cylinder at a pressure of 0.2MPa, with an accuracy error of ≤0.5%;

[0063] Secondary filtration: remove agglomerated particles ≥75μm through a 200-mesh metal filter;

[0064] Level 3 sealing: sealed by laser welding, with weld strength ≥8N / 15mm, and implanted with RFID temperature tracking chip.

[0065] Example 2

[0066] This embodiment provides a basalt fiber-modified cement-based penetrating crystallization waterproof coating, comprising the following raw materials in parts by weight: 50 parts of Portland cement, 2.0 parts of surface-modified basalt fiber, 8 parts of gradient crystallization accelerator, 4 parts of nano-silica, 1.2 parts of polycarboxylate water reducer, 35 parts of quartz sand, 0.6 parts of functional additives, and 16 parts of water, wherein:

[0067] The surface-modified basalt fibers have a length of 3 to 5 mm and a diameter of 10 to 15 μm, and are pretreated with a 4% ethanol solution containing a silane coupling agent KH550 and 0.3% of the fiber mass of nanographene sheets. The nanographene sheets have a thickness of ≤5 nm and a lateral dimension of 200 to 500 nm.

[0068] Gradient crystallization promoter is stearic acid modified nano calcium carbonate (particle size 30 ~ 50nm, specific surface area ≥ 60m 2 / g) and β-cyclodextrin-coated silicate are compounded in a 1:3 molar ratio (the stearic acid coating amount is 1.8% of the mass of calcium carbonate), the coating layer thickness of the β-cyclodextrin-coated silicate of this embodiment is ≤200 nm, and the release rate is ≥85% within 48 hours in an alkaline environment of pH ≥10.5;

[0069] Nano-silica has a mesoporous structure with a pore diameter of 2 to 5 nm and a pore volume of 0.8 to 1.2 m 3 / g;

[0070] The functional additive is prepared by compounding magnesium oxide expansion agent and calcium lignin sulfonate retarder in a mass ratio of 1:5, wherein the activity index of magnesium oxide expansion agent is ≥92%, the particle size D50 is 5-8 μm, the sulfonation degree of calcium lignin sulfonate is ≥2.0 mmol / g, and the sugar content is ≤12%. The compound system produces 400-450×10 -6 The expansion amount (measured by dial gauge method) and the initial setting time are extended to 55min (penetration resistance method).

[0071] In this embodiment, the specific steps of composite pretreatment of surface-modified basalt fiber are as follows:

[0072] A1. First, add the silane coupling agent KH550 to anhydrous ethanol to prepare a 4% solution (4% concentration is 4g KH550 + 96g ethanol), and adjust the pH to 5.5 with acetic acid. Then, stir at 300 rpm in a 40°C water bath for 30 minutes to fully hydrolyze KH550 to generate silanols, thereby preparing a hydrolyzate.

[0073] A2. Add 0.3% of the fiber mass of nanographene sheets to the prepared hydrolyzate (0.3 g of graphene is required to treat 100 g of fiber), and then ultrasonically treat for 20 min at an ultrasonic power of 400 W and a frequency of 40 kHz to uniformly disperse the graphene without agglomeration, thereby preparing a mixed treatment solution;

[0074] A3. Place the prepared basalt fiber in a vacuum impregnation tank, evacuate to -0.08 MPa and maintain for 10 minutes. Then inject the mixed treatment solution into the vacuum impregnation tank until the basalt fiber is immersed. Then, immerse the fiber at a temperature of 60°C and a pressure of 0.5 MPa for 60 minutes to allow the solution to fully penetrate the micropores on the fiber surface.

[0075] A4. Remove the impregnated fiber material, use a centrifuge at 800 rpm to remove excess liquid (residual liquid ≤ 5%), then dry it in a hot air circulation oven at 60°C for 2 hours. After drying, cure it at 120°C for 30 minutes to allow silanol to condense with the fiber surface to form Si-O-Si covalent bonds, completing the composite pretreatment and producing surface-modified basalt fiber.

[0076] In this embodiment, the preparation method of β-cyclodextrin-coated silicate includes the following steps: first, sodium silicate and calcium nitrate are mixed in a molar ratio of 3:1 to react to form a calcium silicate precursor, and then a 12% mass concentration of β-cyclodextrin aqueous solution is added, and the mass ratio of the β-cyclodextrin aqueous solution to the calcium silicate precursor is 1.2:1, followed by ultrasonic oscillation for 2 hours at a temperature of 50°C, and then spray drying (spray drying parameters: inlet air temperature 180°C, outlet air temperature 90°C, atomization pressure 0.3 MPa). After drying, a coating structure is formed to obtain coated particles with a coating thickness of ≤200 nm, namely β-cyclodextrin-coated silicate, whose cumulative release rate in 10% concentration NaOH solution within 48 hours reaches 87-92% (the β-cyclodextrin coating layer of the gradient crystallization promoter decomposes and releases silicate in an alkaline environment within 48 hours, and synergistically catalyzes the growth of calcium aluminate crystals with nano-calcium carbonate, so that the crack self-repair is completed within 72 hours).

[0077] In this embodiment, the molecular weight (Mn) of the polycarboxylate water-reducing agent is 8000 to 12000, and the molecular weight distribution index (PDI) is ≤1.25. This molecular weight range is in the oligomer-prepolymer transition zone, which can balance adsorption efficiency and dispersion ability. The molecular chain of the polycarboxylate water-reducing agent is grafted with hydroxyethyl acrylate monomers, which account for 8% of the total amount of the water-reducing agent, and forms a hydrogen bond network with nano-silica, which can reduce the slurry viscosity by 15 to 20%. The hydroxyl group (-OH) acts as a hydrogen bond donor and bonds with the silanol group (-SiOH) on the surface of the nano-SiO2, which can increase the anchoring density of the water-reducing agent on the surface of the cement particles.

[0078] The preparation process of the polycarboxylate water reducer is as follows:

[0079] S1, EPEG melting: EPEG macromonomer (molecular weight 2400) was melted into liquid at 75 °C;

[0080] S2. Copolymerization grafting: Synchronously add dropwise a mixed monomer containing hydroxyethyl acrylate (HEA) and a redox initiator system (hydrogen peroxide / sodium hypophosphite), and control the HEA addition rate to stabilize the grafting rate at 5-8%.

[0081] S3, nanocomposite: PVP modified nano-SiO2 (5% of solid content) was added and dispersed under 400W ultrasound for 20 minutes to build a hydrogen bond network;

[0082] S4, heat preservation and aging: react at 80°C for 3 hours, and adjust the molecular weight to 8000-12000 and the distribution index ≤1.25 by using mercaptopropionic acid (0.8 parts);

[0083] S5. Spray drying: air inlet temperature 180℃, air outlet temperature 85℃, obtain fluid powder, hydrogen bond structure retention rate > 95%

[0084] See also Figure 1 This embodiment also provides a method for preparing a basalt fiber modified cement-based penetrating crystallization waterproof coating, comprising the following steps:

[0085] Step 1: Dry Mix

[0086] The raw materials were weighed in advance according to the weight ratio of the above raw materials. The weighed silicate cement, quartz sand and nano-silicon dioxide were first put into a double-shaft planetary mixer and mixed at a speed of 800 rpm for 5 minutes. The coefficient of variation of the mixing uniformity was ≤5% (near infrared spectroscopy analysis). After the mixing was completed, a mixed dry material was obtained;

[0087] Step 2: Wet Mixing

[0088] To the mixed dry material prepared in step 1, weighed surface-modified basalt fiber, gradient crystallization accelerator, functional additive, polycarboxylate water-reducing agent and water are added in sequence, and stirred in two stages. After stirring, a mixed wet material is obtained, which is specifically as follows:

[0089] The first stage: stirring at 800 rpm for 3 min to make the fibers uniformly dispersed, with a fiber dispersion index ≥ 0.85 (image analysis method);

[0090] The second stage: stirring at 1500 rpm for 5 min to activate the surface active groups of the nanomaterials, and the fiber dispersion index is ≥0.85 (image analysis method);

[0091] The above two stages of stirring are carried out under nitrogen protection, with an oxygen concentration of ≤0.5% (monitored by an online oxygen analyzer), and the temperature of the stirring tank is controlled at 25±2°C to prevent oxidation of the nanographene sheets (Raman spectrum D / G peak intensity ratio ≤0.15);

[0092] Step 3: Filling

[0093] The mixed wet material obtained in step 2 is transferred to a vacuum filling machine and packed into aluminum-plastic composite film bags under a vacuum environment of -0.06 MPa. Nitrogen is injected into each bag for replacement (oxygen content ≤ 0.3%) before sealing. The filling temperature is controlled at 10° C. to obtain a finished waterproof coating, i.e., a basalt fiber modified cement-based penetrating crystalline waterproof coating;

[0094] This embodiment adopts three-level filling control:

[0095] First-stage filling: press the paint into the metering cylinder at a pressure of 0.2MPa, with an accuracy error of ≤0.5%;

[0096] Secondary filtration: remove agglomerated particles ≥75μm through a 200-mesh metal filter;

[0097] Level 3 sealing: sealed by laser welding, with weld strength ≥8N / 15mm, and implanted with RFID temperature tracking chip.

[0098] The properties of the finished waterproof coatings prepared in Example 1 and Example 2 of the present invention both meet the following requirements:

[0099] 28-day anti-seepage pressure ≥1.8MPa (GB / T 23445-2023)

[0100] Crack self-repair rate ≥90% (JC / T 311-2024)

[0101] The penetration depth of active substances is ≥50mm (determined by drilling sampling method).

[0102] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. Basalt fiber modified cement-based penetrating crystallization waterproof coating, characterized in that: The invention comprises the following raw materials in parts by weight: 40-50 parts of Portland cement, 1.2-2.0 parts of surface-modified basalt fiber, 5-8 parts of gradient crystallization accelerator, 2-4 parts of nano-silica, 0.5-1.2 parts of polycarboxylate water reducer, 25-35 parts of quartz sand, 0.25-0.6 parts of functional additives and 12-16 parts of water; The gradient crystallization accelerator is compounded by stearic acid-modified nano-calcium carbonate and beta-cyclodextrin-coated silicate in a molar ratio of 1:2-3.

2. The basalt fiber modified cement-based penetrating crystallization waterproof coating according to claim 1, characterized in that: The surface-modified basalt fiber has a length of 3 to 5 mm and a diameter of 10 to 15 μm. The surface-modified basalt fiber is pretreated by composite treatment with an ethanol solution containing a silane coupling agent KH550 and nanographene sheets accounting for 0.1 to 0.3% of the fiber mass.

3. The basalt fiber modified cement-based penetrating crystallization waterproof coating according to claim 2, characterized in that: The specific steps of the composite pretreatment are: A1. Add silane coupling agent KH550 to anhydrous ethanol to prepare a solution with a mass concentration of 2-4%, and adjust the pH to 4.5-5.5 to prepare a hydrolyzate; A2. adding nanographene sheets accounting for 0.1 to 0.3% of the fiber mass to the hydrolyzed solution and performing ultrasonic dispersion treatment to prepare a mixed treatment solution; A3. Place the basalt fiber in a vacuum impregnation tank, evacuate the tank, and inject the mixed treatment liquid for impregnation treatment, so that the mixed treatment liquid can fully penetrate the micropores on the fiber surface; A4. After the impregnation, the fiber is taken out, centrifuged to remove excess liquid, and then dried, and then solidified to obtain surface-modified basalt fiber.

4. The basalt fiber modified cement-based penetrating crystallization waterproof coating according to claim 1, characterized in that: The specific preparation method of the β-cyclodextrin-coated silicate is as follows: sodium silicate and calcium nitrate are first mixed in a molar ratio of 3:1 to react to generate a calcium silicate precursor, and then a β-cyclodextrin aqueous solution with a mass concentration of 8-12% is added for ultrasonic oscillation treatment, wherein the mass ratio of the solution to the precursor is 0.8-1.2:

1. After the ultrasonic oscillation treatment, the solution is spray-dried to form a coating structure, and the obtained coated particles are the β-cyclodextrin-coated silicate.

5. The basalt fiber modified cement-based penetrating crystallization waterproof coating according to claim 1, characterized in that: The molecular weight of the polycarboxylate water reducer is 8000-12000, the molecular weight distribution index is ≤1.25, the molecular chain is grafted with hydroxyethyl acrylate monomer accounting for 5-8% of the total amount of the water reducer, and forms a hydrogen bond network with nano-silicon dioxide.

6. The basalt fiber modified cement-based penetrating crystallization waterproof coating according to claim 1, characterized in that: The functional additive is prepared by compounding a magnesium oxide expander and a calcium lignin sulfonate retarder in a mass ratio of 1:4-5, wherein the activity index of the magnesium oxide expander is ≥92%, and the sulfonation degree of the calcium lignin sulfonate is ≥2.0 mmol / g.

7. A method for preparing a basalt fiber modified cement-based penetrating crystallization waterproof coating according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step 1: Put the pre-weighed silicate cement, quartz sand and nano-silicon dioxide into a double-shaft planetary mixer, and mix and stir to obtain a mixed dry material; Step 2: adding pre-weighed surface-modified basalt fiber, gradient crystallization accelerator, functional additive, polycarboxylate water-reducing agent and water to the mixed dry material in sequence, stirring and mixing in two stages to obtain a mixed wet material; Step 3: Transfer the mixed wet material into a vacuum filling machine and pack it into aluminum-plastic composite film bags. Inject nitrogen into each bag before sealing to obtain the finished waterproof coating.

8. The method for preparing the basalt fiber modified cement-based penetrating crystallization waterproof coating according to claim 7, characterized in that: In the step 2, the two-stage stirring and mixing processes are both carried out under nitrogen protection, with an oxygen concentration of ≤0.5%, and the stirring temperature is controlled at 25±2°C.

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