Wall cracking joint filling agent and wall joint filling process

Abstract

The invention belongs to the technical field of wall joint filling, and relates to a wall cracking joint filling agent and a wall joint filling process, the wall cracking joint filling agent comprises a cement-based cementing material, fine aggregate, modified toughening fiber, modified nano zinc oxide, a dispersing agent, a defoaming agent, a water-retaining agent and a mildew preventive; the modified toughened fiber is obtained by sequentially carrying out alkali etching, dopamine coating and intercalated kaolin loading on polyacrylonitrile fiber; the modified nano-zinc oxide is obtained by modifying nano-zinc oxide through a silane coupling agent and coating and modifying the nano-zinc oxide through chitosan. According to the wall crack repairing agent provided by the invention, the modified toughening fibers and the modified nano zinc oxide which are subjected to surface functionalization treatment are introduced, so that the crack resistance and toughness of a cement-based crack repairing material can be remarkably improved, the occurrence probability of secondary cracking after repairing can be remarkably reduced, meanwhile, lasting and effective mildew-proof and antibacterial capabilities can be provided, microbial erosion can be inhibited, and the service life of the wall crack repairing agent is prolonged. And good construction operability and basic mechanical properties of the material are maintained.

Description

Technical Field

[0001] The invention belongs to the technical field of wall repairing, and relates to a wall crack repairing agent and a wall repairing process. Background Art

[0002] In the field of building maintenance, wall cracks are a common and troubling problem. Cracks not only detract from a building's aesthetics but, more importantly, weaken its integrity, thermal insulation, and durability. They can even serve as pathways for moisture leakage, accelerating corrosion of internal structural steel, and endangering building safety. Therefore, efficient and durable wall crack repair is of vital practical importance.

[0003] Currently, the most common method for repairing wall cracks, especially non-structural cracks, is filling. Cement-based caulking materials are widely used due to their excellent adhesion, strength, and compatibility with the substrate. However, conventional ordinary cement mortar has many inherent drawbacks when used for crack repair. One of the main issues is the material's inherent brittleness and poor toughness. Under the stress caused by shrinkage, temperature fluctuations, or slight substrate displacement, the repaired area is prone to secondary cracking at the bonding interface on both sides of the crack or within the repair itself, resulting in a "patch-and-re-crack" phenomenon, making the repair effect difficult to maintain.

[0004] To address brittleness, various fibers (such as polypropylene fibers and polyester fibers) are often added to mortar for toughening and crack resistance. However, the interfacial bonding between conventional fibers and the cement matrix is ​​often less than ideal, which affects the effective transfer of stress and results in limited toughening effects. Furthermore, the long-term aging resistance of fibers in highly alkaline cement environments also presents certain challenges. Furthermore, building walls, especially in humid and poorly ventilated areas, are prone to the growth of mold and algae on the surface and within the cracks of the repair layer. This not only affects the aesthetics but also decomposes organic components and undermines the structural integrity of the repair material. Conventional anti-mildew additives are often prone to migration, dissolution, or degradation, resulting in insufficient long-term anti-mildew capabilities. Furthermore, their interference with cement hydration may affect the strength development of the repaired structure.

[0005] Furthermore, existing repair processes often have flaws. For example, while the use of interface agents can help improve adhesion, their performance stability and versatility are sometimes insufficient. The preparation and filling of repair materials rely heavily on worker experience, impacting the uniformity of repair quality. Inadequate or inappropriate post-treatment maintenance can easily lead to shrinkage and cracking, or surface pulverization and sanding. Ensuring sufficient penetration, dense filling, and a strong overall bond of the repair slurry is particularly challenging for fine cracks or complex interfaces.

[0006] Therefore, there is an urgent need in this field to develop a wall crack sealing agent with better performance and its supporting process. Summary of the Invention

[0007] In response to the shortcomings of the existing technology, the purpose of the present invention is to provide a wall crack sealing agent and a wall sealing process, which introduces modified toughening fibers and modified nano zinc oxide that have undergone surface functionalization treatment, which can significantly improve the crack resistance of cement-based crack repair materials and significantly reduce the probability of secondary cracking after repair. At the same time, it can provide long-lasting and effective anti-mildew and antibacterial capabilities, inhibit microbial erosion, and maintain the material's good construction operability and basic mechanical properties.

[0008] To achieve this object, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a wall crack sealing agent, which comprises a cement-based gelling material, fine aggregate, modified toughening fiber, modified nano zinc oxide, a dispersant, a defoaming agent, a water retaining agent and a mildew inhibitor; The modified toughened fiber is a polyacrylonitrile fiber obtained by sequentially undergoing alkali etching, dopamine coating, and kaolin loading; The modified nano zinc oxide is obtained by modifying nano zinc oxide with a silane coupling agent and then coating with chitosan.

[0009] The wall crack sealant provided by the present invention introduces modified toughening fibers and modified nano zinc oxide that have undergone surface functionalization treatment, which can significantly improve the crack resistance of cement-based crack repair materials and significantly reduce the probability of secondary cracking after repair. At the same time, it can provide long-lasting and effective anti-mildew and antibacterial capabilities, inhibit microbial erosion, and maintain the material's good construction operability and basic mechanical properties.

[0010] Traditionally incorporated fibers often have weak interfacial bonding with the cement matrix, resulting in low stress transfer efficiency and limited toughening effect. The present invention adds modified toughening fibers to the cement matrix. The polyacrylonitrile fibers are alkali-etched to increase the roughness and activity of the fiber surface; then, dopamine is coated on its surface to form a polydopamine layer with strong adhesion and certain toughness; finally, kaolin is intercalated to further introduce a nanoscale reinforcement phase into the interface region between the fiber and the cement matrix. Through the combined effect of multi-level surface modification, the physical meshing and chemical bonding strength between the fiber and the cement matrix can be greatly optimized. When the repair body is subjected to shrinkage stress, temperature stress or slight displacement of the substrate, the reinforced interface can more effectively transfer and disperse stress, significantly inhibiting the initiation and expansion of microcracks, thereby reducing the risk of secondary cracking in the repaired area and improving the long-term durability of the repair.

[0011] Ordinary anti-mildew additives are easy to migrate, dissolve or degrade, and their durability is insufficient. The present invention effectively solves the problem that cement-based repair materials are prone to breeding mold and algae in humid environments by adding modified zinc oxide to the cement matrix, and provides long-term protection function. The modified nano zinc oxide provided by the present invention undergoes two-step modification: first, it is treated with a silane coupling agent to improve the dispersion stability of nano zinc oxide in strong alkaline cement slurry and enhance its compatibility with inorganic substrates; then, it is coated with chitosan to form an organic protective layer on the surface of the zinc oxide particles. This chitosan coating layer has a dual role: on the one hand, it itself has certain broad-spectrum antibacterial properties; on the other hand, as a slow-release carrier, it can control the release rate of zinc ions in zinc oxide, avoid the rapid consumption and loss of active ingredients, and thus provide a more lasting and stable antibacterial and anti-mildew effect. Combined with the mildew inhibitor in the wall crack sealant, it effectively inhibits the growth of microorganisms on the surface and inside the repair seam, protecting the structural integrity of the material.

[0012] The cementitious binder and graded fine aggregate (quartz sand and calcium carbonate) form the strength framework. Surface modification of the modified toughening fibers improves their dispersibility in the aqueous slurry, and the use of a dispersant reduces the risk of fiber agglomeration. The introduction of a defoamer and water-retaining agent helps reduce air bubbles during mixing and construction, ensuring sufficient water supply for full cement hydration. Silane treatment of the modified nano-zinc oxide also promotes its uniform distribution in the slurry. The synergistic effect of these components ensures the slurry possesses excellent fluidity and filling properties, facilitating deep and dense filling of cracks during construction, while also ensuring a dense, structurally dense repair with sufficient early and late strength after hardening.

[0013] As a preferred technical solution of the present invention, based on 100 parts by weight of the wall crack sealing agent, it includes the following components in parts by weight: 45-50 parts of cement-based gelling materials; 45-50 parts of fine aggregate; 1~3 parts of modified toughening fiber; 1.5-2.5 parts of modified nano zinc oxide; Dispersant 0.5~1 part; 0.1~0.3 parts of defoaming agent; 0.1~0.2 parts of water-retaining agent; 0.1~0.5 parts of anti-fungal agent.

[0014] The weight of the cement-based cementitious material can be 45 parts, 45.5 parts, 46 parts, 46.5 parts, 47 parts, 47.5 parts, 48 ​​parts, 48.5 parts, 49 parts, 49.5 parts or 50 parts, the weight of the fine aggregate can be 45 parts, 45.5 parts, 46 parts, 46.5 parts, 47 parts, 47.5 parts, 48 ​​parts, 48.5 parts, 49 parts, 49.5 parts or 50 parts, and the weight of the modified toughening fiber can be 45 parts, 45.5 parts, 46 parts, 46.5 parts, 47 parts, 47.5 parts, 48 ​​parts, 48.5 parts, 49 parts, 49.5 parts or 50 parts. The weight parts of the modified nano zinc oxide can be 1.0 parts, 1.2 parts, 1.4 parts, 1.6 parts, 1.8 parts, 2.0 parts, 2.2 parts, 2.4 parts, 2.6 parts, 2.8 parts or 3.0 parts, the weight parts of the modified nano zinc oxide can be 1.5 parts, 1.6 parts, 1.7 parts, 1.8 parts, 1.9 parts, 2.0 parts, 2.1 parts, 2.2 parts, 2.3 parts, 2.4 parts or 2.5 parts, and the weight parts of the dispersant can be 0.5 parts, 0. The weight portion of the defoaming agent can be 0.1 part, 0.12 part, 0.14 part, 0.16 part, 0.18 part, 0.2 part, 0.22 part, 0.24 part, 0.26 part, 0.28 part or 0.3 part, and the weight portion of the water retaining agent can be 0.1 part, 0.11 part, 0.12 part, 0.14 part, 0.16 part, 0.18 part, 0.2 part, 0.22 part, 0.24 part, 0.26 part, 0.28 part or 0.3 part. , 0.12 parts, 0.13 parts, 0.14 parts, 0.15 parts, 0.16 parts, 0.17 parts, 0.18 parts, 0.19 parts or 0.2 parts by weight of the mildew inhibitor can be 0.1 parts, 0.15 parts, 0.2 parts, 0.25 parts, 0.3 parts, 0.35 parts, 0.4 parts, 0.45 parts or 0.5 parts by weight, but are not limited to the listed values, and other unlisted values ​​within the numerical range are equally applicable.

[0015] Cement-based cementitious materials serve as the core binder phase of the sealant, providing primary mechanical strength and a hardened skeleton. Their hydration products consolidate the other components. Fine aggregate (quartz sand and calcium carbonate) fills the gaps in the cementitious material, optimizing particle size to increase density, reduce shrinkage, and lower costs. Modified toughening fibers undergo a three-step modification process (alkaline etching, dopamine coating, and kaolin loading) to significantly strengthen the fiber-cement matrix interfacial bond. Bridging and pull-out dissipation inhibit crack propagation, imparting high toughness to the material and preventing stress concentration-induced cracking in the repair layer. Modified nano-zinc oxide, modified with a silane coupling agent and coated with chitosan, combines efficient dispersibility with durable antimicrobial properties. It disrupts microbial metabolism through the slow release of zinc ions and synergizes with antifungal agents to provide dual protection.

[0016] The present invention limits the weight of cement-based binder in the sealant to 45-50 parts. Within this range, sufficient hydration products can be formed to firmly bond aggregates and fibers, while controlling shrinkage stress within an acceptable range. When the weight of cement-based binder is less than 45 parts, insufficient cementitious phase will lead to insufficient aggregate wrapping, loose hardened structure, significantly reduced bonding strength, and easy peeling of the repair layer from the crack edge. At the same time, the reduction in hydration products will weaken the ability to fix the fibers, affecting the toughening effect. When the weight of cement-based binder exceeds 50 parts, the excessive cement content exacerbates the hydration heat and drying shrinkage, easily inducing shrinkage cracks in thin layer repairs. At the same time, the high alkaline environment may also accelerate the degradation of some additives and increase material costs.

[0017] The present invention limits the weight of fine aggregate in the sealant to 45-50 parts. Within this range, dense packing reduces porosity, inhibits shrinkage deformation, and forms a rigid support skeleton under the bonding of the cementitious material, providing a uniformly dispersed carrier for fibers and nanoparticles. When the weight of fine aggregate is less than 45 parts, insufficient aggregate filling causes excess slurry, increases drying shrinkage, and the repair layer is prone to cracking due to shrinkage stress; at the same time, the physical barrier effect of the aggregate on cracks is weakened. When the weight of fine aggregate exceeds 50 parts, the cement-based cementitious material cannot fully wrap the aggregate particles, increasing the weak interface area and reducing the compressive strength and bonding force. At the same time, excessive aggregate will also reduce the fluidity of the slurry and affect the filling density deep in the crack.

[0018] The present invention limits the weight of the modified toughening fiber in the sealant to 1 to 3 parts. Within this range, it can ensure that the fiber has high interfacial bonding strength after modification, consumes fracture energy by bridging cracks, and significantly improves the crack resistance of the repair layer under deformation conditions. When the weight of the modified toughening fiber is less than 1 part, the number of modified toughening fibers is insufficient to form an effective crack-resistant network, the stress transfer ability is weak, it is difficult to inhibit the expansion of microcracks, and the crack resistance of the repair layer is close to that of ordinary mortar. When the weight of the modified toughening fiber is higher than 3 parts, it is easy to cause the modified toughening fiber to agglomerate, hinder cement hydration, and reduce the homogeneity of the matrix; at the same time, excessive modified toughening fibers will also increase the viscosity of the slurry, resulting in incomplete construction filling and increased costs.

[0019] The present invention limits the weight of modified nano zinc oxide in the sealant to 1.5 to 2.5 parts. Within this range, the modified nano zinc oxide can be ensured to be uniformly dispersed, and the long-term antibacterial concentration can be maintained through the slow-release characteristics of chitosan, while avoiding interference with the mechanical properties of the matrix, and complementing the antifungal agent. When the weight of the modified nano zinc oxide is less than 1.5 parts, the distribution density of the modified nano zinc oxide in the matrix is ​​insufficient, and a continuous antibacterial barrier cannot be formed. Local antifungal blind spots are prone to microbial growth. When the weight of the modified nano zinc oxide is higher than 2.5 parts, the specific surface area of ​​the modified nano zinc oxide is large, and excessive free water is adsorbed, which affects the normal hydration of cement and leads to slow strength development. At the same time, excessive modified nano zinc oxide will increase the viscosity of the slurry, resulting in incomplete construction and increased costs.

[0020] As a preferred technical solution of the present invention, the cement-based gelling material includes Portland cement and slag powder.

[0021] In some optional examples, the mass ratio of the silicate cement to the slag powder is (3~5):1, for example, it can be 3.0:1, 3.2:1, 3.4:1, 3.6:1, 3.8:1, 4.0:1, 4.2:1, 4.4:1, 4.6:1, 4.8:1 or 5.0:1, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0022] Portland cement provides high early activity, rapidly generating calcium silicate hydrate (CSH) gel and calcium hydroxide, providing the initial strength of the repair layer. Slag powder, through a later secondary hydration reaction, consumes the calcium hydroxide generated by the Portland cement, converting it into additional CSH gel, significantly enhancing the later density and strength of the repair layer. This reaction not only reduces the accumulation of calcium hydroxide at the interface but also significantly reduces shrinkage. The micro-filling effect of slag powder refines the pore structure and suppresses shrinkage stress caused by water evaporation. Furthermore, the retarded setting properties of slag powder balance the rapid exotherm of Portland cement, reducing the risk of thermal cracking. The synergistic effect of the two ensures early construction strength while the slag powder continuously optimizes long-term durability, creating a dense, low-shrinkage cementitious matrix.

[0023] In some optional examples, the fine aggregate includes quartz sand and calcium carbonate.

[0024] In some optional examples, the mesh size of the quartz sand is 40 to 50 mesh, for example, it can be 40 mesh, 41 mesh, 42 mesh, 43 mesh, 44 mesh, 45 mesh, 46 mesh, 47 mesh, 48 mesh, 49 mesh or 50 mesh, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0025] In some optional examples, the mass ratio of quartz sand to calcium carbonate is (4~5):1, for example, it can be 4.0:1, 4.1:1, 4.2:1, 4.3:1, 4.4:1, 4.5:1, 4.6:1, 4.7:1, 4.8:1, 4.9:1 or 5.0:1, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0026] Quartz sand serves as the primary framework, providing rigid support. Its angular particles interlock tightly, enhancing the compressive strength of the matrix. Fine calcium carbonate particles fill the gaps between the quartz sand and coat the surface of the cementitious material, optimizing the particle size distribution, significantly increasing the density of the system, and reducing capillary porosity. Furthermore, the calcium ions produced by the slight solubility of calcium carbonate promote early hydration of the cement and accelerate the formation of CSH gels. Simultaneously, their surface forms ionic bonds with the intercalated kaolin layer of the modified toughening fiber, strengthening the interfacial bond between the fiber and the matrix.

[0027] As a preferred technical solution of the present invention, the modified toughened fiber is prepared by the following method: (I) soaking polyacrylonitrile fiber in a sodium hydroxide solution, heating in a constant temperature water bath to complete alkaline etching, and obtaining etched fiber after filtering, washing and drying; (II) soaking the etched fiber in a dopamine solution, heating and shaking to form a polydopamine layer on the surface of the etched fiber, and obtaining a coated fiber after filtering, washing and drying; (III) intercalating and modifying sodium-based kaolin to obtain an intercalated kaolin solution, dispersing the coated fiber in the intercalated kaolin solution, heating and aging, and filtering, washing and drying to obtain the modified toughened fiber.

[0028] The fiber modification method provided by the present invention is divided into three steps. First, the alkaline etching step (sodium hydroxide solution treatment) selectively oxidizes the surface of the polyacrylonitrile fiber, introduces polar groups such as carboxyl groups on the polyacrylonitrile molecular chain and forms micron-scale grooves, significantly improving the surface roughness of the fiber. This process not only increases the specific surface area of ​​the fiber, but also exposes active sites, laying the foundation for subsequent interfacial reactions.

[0029] Dopamine coating is then applied. Under heating and oscillation conditions, dopamine molecules undergo oxidative self-polymerization on the etched fiber surface, forming a highly adhesive polydopamine coating. This polymer layer contains a large number of catechol / quinone groups, which function to: first, firmly bond to the fiber surface through hydrogen bonding and π-π stacking; second, exposed active groups (such as amino groups) serve as chemical bonding sites for subsequent intercalation of kaolin; and third, the inherent flexibility of the polydopamine coating can buffer stress impacts. Compared to untreated polyacrylonitrile fibers, the polydopamine coating upgrades physical mechanical meshing to a strong interfacial bond dominated by chemical bonds.

[0030] The final kaolin loading step achieves nanoscale reinforcement. After sodium-based kaolin is intercalated and modified, the sheets are exfoliated into nanoscale dispersions. During the heating and aging process, the amino groups of polydopamine form a strong hydrogen bond network with the hydroxyl groups on the surface of the kaolin sheets. At the same time, the aluminum oxygen sites at the edges of the kaolin sheets coordinate with the quinone groups of polydopamine. High-temperature aging promotes the directional arrangement of kaolin nanosheets on the surface of the coated fiber. In the resulting "fiber-polydopamine coating-intercalated kaolin" structure, the kaolin nanosheets exert a "pinning effect": on the one hand, they embed into the cement matrix to hinder the propagation of microcracks, and on the other hand, the high specific surface area enhances the friction resistance between the fiber and the matrix, increasing the fiber pull-out energy consumption capacity by 2-3 times.

[0031] The three-step modification provided by the present invention has the following effects: on the one hand, alkaline etching and polydopamine coating significantly improve the wettability and dispersibility of hydrophobic fibers in hydrophilic cement slurry; on the other hand, the kaolin nanolayer blocks the erosion of the polydopamine coating layer by the cement alkaline environment, ensuring long-term performance stability; and on the other hand, the micro-nano composite structure on the surface of the modified toughened fiber promotes the directional growth of cement hydration products and enhances the density of the interface area.

[0032] As a preferred technical solution of the present invention, in step (I), the mass fraction of the sodium hydroxide solution is 3 to 5 wt%, for example, it can be 3.0 wt%, 3.2 wt%, 3.4 wt%, 3.6 wt%, 3.8 wt%, 4.0 wt%, 4.2 wt%, 4.4 wt%, 4.6 wt%, 4.8 wt% or 5.0 wt%, but is not limited to the enumerated values, and other unlisted values ​​within the numerical range are also applicable.

[0033] In some optional examples, the ratio of the polyacrylonitrile fiber to the sodium hydroxide solution is 1g:(10~20)mL, for example, it can be 1g:10mL, 1g:11mL, 1g:12mL, 1g:13mL, 1g:14mL, 1g:15mL, 1g:16mL, 1g:17mL, 1g:18mL, 1g:19mL or 1g:20mL, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0034] In some optional examples, the constant temperature water bath heating temperature is 40~50℃, for example, it can be 40℃, 41℃, 42℃, 43℃, 44℃, 45℃, 46℃, 47℃, 48℃, 49℃ or 50℃, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0035] In some optional examples, the constant temperature water bath heating time is 2 to 4 hours, for example, it can be 2.0 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours, 3.0 hours, 3.2 hours, 3.4 hours, 3.6 hours, 3.8 hours or 4.0 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0036] In step (II), the dopamine solution consists of dopamine hydrochloride, copper sulfate and Tris-HCl buffer.

[0037] In the present invention, dopamine hydrochloride is used as a reaction monomer, and its catechol group undergoes intramolecular cyclization under oxidative conditions, thereby forming a polydopamine coating with strong adhesion through covalent / non-covalent cross-linking. Tris-HCl buffer (pH ≈ 8.5) provides an alkaline oxidative environment, which not only prevents strong alkali from damaging the fiber body, but also ensures the continuous progress of the dopamine oxidative self-polymerization reaction. Copper sulfate acts as a redox catalyst, Cu 2+ / Cu + The cycle accelerates the oxidation of dopamine monomers by dissolved oxygen, significantly increases the polymerization rate and regulates the molecular structure of polydopamine, forming a highly reactive surface rich in quinone groups, creating binding sites for subsequent intercalated kaolin loading.

[0038] In some optional examples, the mass fraction of dopamine hydrochloride in the dopamine solution is 1~2wt%, for example, it can be 1.0wt%, 1.1wt%, 1.2wt%, 1.3wt%, 1.4wt%, 1.5wt%, 1.6wt%, 1.7wt%, 1.8wt%, 1.9wt% or 2.0wt%, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0039] In some optional examples, the mass ratio of dopamine hydrochloride to copper sulfate is 100:(1~3), for example, it can be 100:1.0, 100:1.2, 100:1.4, 100:1.6, 100:1.8, 100:2.0, 100:2.2, 100:2.4, 100:2.6, 100:2.8 or 100:3.0, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0040] The present invention limits the mass ratio of dopamine hydrochloride to copper sulfate to 100:(1-3). When the amount of copper sulfate added is too low, the amount of catalyst is insufficient, resulting in a slow oxidation reaction rate, incomplete polydopamine deposition, uncoated areas on the fiber surface, and significantly weakened interface strengthening effects. At the same time, the molecular weight of the generated polydopamine is low, the quinone group density is insufficient, and the chemical bonding effect with the kaolin nanosheets is weakened. When the amount of copper sulfate added is too high, the excess Cu 2+It triggers severe oxidation, causing excessive cross-linking of polydopamine to form a brittle thick layer, reducing the efficiency of interfacial stress transfer; at the same time, side reactions produce a large number of free radicals, which erode the fiber surface structure; in addition, residual copper ions generate copper hydroxide precipitates in an alkaline cement environment, destroying the fiber dispersion.

[0041] In some optional examples, the mass ratio of the etched fiber to the dopamine hydrochloride in the dopamine solution is 1:(2~3), for example, it can be 1:2.0, 1:2.1, 1:2.2, 1:2.3, 1:2.4, 1:2.5, 1:2.6, 1:2.7, 1:2.8, 1:2.9 or 1:3.0, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0042] The present invention specifically limits the mass ratio of the etched fiber to the dopamine hydrochloride in the dopamine solution to 1:(2~3). Within this range, the dopamine hydrochloride molecules fully infiltrate the groove structure formed by micro-etching on the fiber surface. During the oxidative polymerization process, the catechol groups thereof form a high-density hydrogen bond network with polar groups such as carboxyl groups (-COOH) and amino groups (-NH2) on the fiber surface. At the same time, adsorption is enhanced through π-π conjugation, completely covering the fiber surface without affecting the micro-nano structure. In addition, sufficient quinone group (-C=O) active sites are retained in the coating layer, providing chemical anchor points for subsequent kaolin nanosheet loading.

[0043] When the amount of dopamine hydrochloride added is lower than the lower limit of the range specified in the present invention, the monomer supply is seriously insufficient. On the one hand, the micro-etched area on the fiber surface cannot be completely covered, and the uncoated hydrophobic groups are exposed, reducing the wettability with the cement slurry; on the other hand, due to the insufficient amount of dopamine monomer, the polymerization reaction is insufficient, forming a discontinuous island coating structure, which is easy to become the starting point of peeling during the subsequent stirring and cement curing process; on the other hand, the quinone group generation density is too low, resulting in the inability to effectively bond the kaolin nanosheets, resulting in insufficient loading rate of the kaolin nanosheets and reduced crack resistance of the repair layer.

[0044] When the amount of dopamine hydrochloride added is higher than the upper limit of the range defined in the present invention, a high concentration of dopamine monomer undergoes a violent cross-linking reaction on the fiber surface, generating an excessively thick brittle polydopamine coating layer, the internal stress of which causes microcracks in the polydopamine coating layer during the drying stage; at the same time, the excessively high concentration of free monomers in the solution promotes homogeneous nucleation, forming a large number of polydopamine particles independent of the fibers. These particles are adsorbed on the fiber surface to form a weak interface zone in the subsequent process, and hinder the growth of the mineral phase during cement hydration; in addition, the excessively thick polydopamine coating layer completely fills the micro-nano grooves on the fiber surface, affecting the mechanical anchoring effect.

[0045] In some optional examples, the temperature of the heating oscillation is 45~55°C, for example, it can be 45°C, 46°C, 47°C, 48°C, 49°C, 50°C, 51°C, 52°C, 53°C, 54°C or 55°C, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0046] In some optional examples, the rotation speed of the heating oscillation is 100~200rpm, for example, it can be 100rpm, 110rpm, 120rpm, 130rpm, 140rpm, 150rpm, 160rpm, 170rpm, 180rpm, 190rpm or 200rpm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0047] In some optional examples, the heating oscillation time is 8 to 10 hours, for example, it can be 8.0 hours, 8.2 hours, 8.4 hours, 8.6 hours, 8.8 hours, 9.0 hours, 9.2 hours, 9.4 hours, 9.6 hours, 9.8 hours or 10.0 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0048] As a preferred technical solution of the present invention, in step (III), the intercalation modification operation of the sodium kaolin includes: Sodium kaolin and octadecyltrimethylammonium bromide solution are mixed, stirred and heated to obtain a kaolin suspension; the kaolin suspension is centrifuged, the supernatant is discarded and a precipitate is collected; the precipitate is washed and ultrasonically dispersed in deionized water to obtain the intercalated kaolin solution.

[0049] In some optional examples, the mass fraction of the octadecyltrimethylammonium bromide solution is 5~10wt%, for example, it can be 5.0wt%, 5.5wt%, 6.0wt%, 6.5wt%, 7.0wt%, 7.5wt%, 8.0wt%, 8.5wt%, 9.0wt%, 9.5wt% or 10.0wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0050] In some optional examples, the ratio of the sodium kaolin to the octadecyltrimethylammonium bromide solution is 1g:(10~15)mL, for example, it can be 1g:10mL, 1g:10.5mL, 1g:11mL, 1g:11.5mL, 1g:12mL, 1g:12.5mL, 1g:13mL, 1g:13.5mL, 1g:14mL, 1g:14.5mL or 1g:15mL, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0051] In some optional examples, the temperature of mixing, stirring and heating the sodium kaolin and octadecyltrimethylammonium bromide solution is 70~80°C, for example, it can be 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C or 80°C, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0052] In some optional examples, the mixing, stirring and heating time of the sodium kaolin and the octadecyltrimethylammonium bromide solution is 8 to 10 hours, for example, it can be 8.0 hours, 8.2 hours, 8.4 hours, 8.6 hours, 8.8 hours, 9.0 hours, 9.2 hours, 9.4 hours, 9.6 hours, 9.8 hours or 10.0 hours, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0053] In some optional examples, the centrifugal speed is 10000~15000rpm, for example, it can be 10000rpm, 10500rpm, 11000rpm, 11500rpm, 12000rpm, 12500rpm, 13000rpm, 13500rpm, 14000rpm, 14500rpm or 15000rpm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0054] In some optional examples, the centrifugation time is 20 to 30 min, for example, it can be 20 min, 21 min, 22 min, 23 min, 24 min, 25 min, 26 min, 27 min, 28 min, 29 min or 30 min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0055] In some optional examples, the mass ratio of the precipitate to deionized water is 1:(10~15), for example, it can be 1:10, 1:10.5, 1:11, 1:11.5, 1:12, 1:12.5, 1:13, 1:13.5, 1:14, 1:14.5 or 1:15, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0056] In some optional examples, the ultrasonic power of the ultrasonic dispersion is 400~500W, for example, it can be 400W, 410W, 420W, 430W, 440W, 450W, 460W, 470W, 480W, 490W or 500W, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0057] In some optional examples, the ultrasonic time of the ultrasonic dispersion is 30~40min, for example, it can be 30min, 31min, 32min, 33min, 34min, 35min, 36min, 37min, 38min, 39min or 40min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0058] In some optional examples, the ratio of the coated fiber to the intercalated kaolin solution is 1g:(10~20)mL, for example, it can be 1g:10mL, 1g:11mL, 1g:12mL, 1g:13mL, 1g:14mL, 1g:15mL, 1g:16mL, 1g:17mL, 1g:18mL, 1g:19mL or 1g:20mL, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0059] The present invention particularly limits the ratio of the coated fiber to the intercalated kaolin solution to 1g:(10-20)mL. Within this range, the kaolin nanosheets in the intercalated kaolin solution can fully cover the quinone groups and amino groups exposed by the polydopamine coating layer. The kaolin nanosheets are directionally anchored on the surface of the coated fiber through hydrogen bonds and ionic bonds to form a homogeneous composite layer with a thickness of about 200-500nm. The kaolin nanosheets are partially embedded in the polydopamine layer to form a "root-like" bond to enhance interface stability; the edges of the unembedded kaolin nanosheets become nucleation sites in the cement hydration environment, promoting the interwoven growth of hydration products on the fiber surface; the nano-gaps retained between the sheets can ensure water penetration, promote local hydration reactions, and avoid the formation of weak interface areas.

[0060] If the amount of intercalated kaolin solution added exceeds the upper limit of the range defined in the present invention, the excessive concentration of kaolin nanosheets leads to a serious agglomeration effect, and the kaolin nanosheets are excessively accumulated on the surface of the coated fiber to form a multi-layer barrier, completely blocking the active sites of the polydopamine coating, making it impossible for subsequent cement hydration products to establish a chemical connection with the fiber. In addition, the stacked kaolin nanosheets curl and peel due to internal stress, and fall off from the surface of the coated fiber during the stirring process. The fallen fragments mix with the cement slurry to form rigid inclusions, which become the initiation source of microcracks. At the same time, the excess unloaded kaolin nanosheets occupy the gaps between cement particles, interfering with the normal hydration process and causing local strength weaknesses.

[0061] If the amount of intercalated kaolin solution added falls below the lower limit of the range specified in this invention, the kaolin nanosheet concentration is too low, causing coating defects. The sparse kaolin nanosheets cannot completely cover the surface of the coated fibers, leaving part of the polydopamine coating directly exposed to the alkaline cement environment (pH > 12.5), leading to hydrolysis and degradation of the polydopamine coating. Furthermore, the sparsely distributed kaolin nanosheets make it difficult to form a continuous reinforcement network, affecting the "pinning effect" on microcracks. Furthermore, excess free sodium ions migrate into the cement matrix with the water, forming white salting-out crystals at the interface during the later stages of curing. The expansion stress of these crystals can induce peeling at the edge of the repair layer.

[0062] In some optional embodiments, the heating and aging are carried out under stirring conditions, and the stirring speed is 100~200rpm, for example, it can be 100rpm, 110rpm, 120rpm, 130rpm, 140rpm, 150rpm, 160rpm, 170rpm, 180rpm, 190rpm or 200rpm, but is not limited to the listed values, and other values ​​not listed within this numerical range are also applicable.

[0063] In some optional examples, the heating and aging temperature is 60~70℃, for example, it can be 60℃, 61℃, 62℃, 63℃, 64℃, 65℃, 66℃, 67℃, 68℃, 69℃ or 70℃, but is not limited to the listed values. Other values ​​not listed within this numerical range are also applicable.

[0064] In some optional embodiments, the heating and aging time is 1 to 2 hours, for example, it can be 1.0h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h or 2.0h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0065] As a preferred technical solution of the present invention, the modified nano zinc oxide is prepared by the following method: adding nano zinc oxide to a silane coupling agent solution for ultrasonic dispersion, followed by filtering, washing and drying to obtain silane-modified zinc oxide; Chitosan is dissolved in a glacial acetic acid solution to obtain a chitosan solution, the silane-modified zinc oxide and the chitosan solution are mixed, stirred, and heated, and then filtered, washed, and dried to obtain modified nano zinc oxide.

[0066] Under ultrasonic dispersion conditions, the silanol groups (Si-OH) generated by the hydrolysis of silane molecules undergo a condensation reaction with the hydroxyl groups (Zn-OH) on the surface of the zinc oxide particles, forming a stable Si-O-Zn covalent bond. This creates an organosilane monolayer on the zinc oxide surface, with its hydrophobic alkyl chains extending outward. This significantly improves the dispersion stability of the zinc oxide nanoparticles in the strongly alkaline cement paste, effectively blocking the van der Waals forces between the particles through steric hindrance, and avoiding the loss of active surface area due to agglomeration. At the same time, the active groups at the end of the silane layer (such as amino or epoxy groups) can form chemical bonds with cement hydration products, enhancing the interfacial bonding between the modified nano-zinc oxide and the matrix.

[0067] After chitosan molecules are protonated in a weak acid environment (glacial acetic acid solution), their positively charged amino groups (-NH3 + ) binds to the negatively charged sites on the surface of silane-modified zinc oxide through electrostatic attraction. During heating and stirring, chitosan chains further crosslink on the particle surface through hydrogen bonding and hydrophobic interactions to form a film. The resulting chitosan coating acts as a physical barrier, slowing the dissolution of zinc ions in the slurry and preventing rapid depletion of the active ingredient, thus prolonging the antibacterial and mildew-proofing effects. Furthermore, chitosan possesses broad-spectrum antimicrobial properties, and its cationic properties can disrupt microbial cell membranes, creating a synergistic effect with the metal ion antimicrobial activity of zinc oxide.

[0068] In some optional examples, as a preferred technical solution of the present invention, the silane coupling agent solution consists of a silane coupling agent and an ethanol aqueous solution.

[0069] In some optional examples, the mass fraction of the silane coupling agent in the silane coupling agent solution is 1-2 wt%, for example, 1.0 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, 1.6 wt%, 1.7 wt%, 1.8 wt%, 1.9 wt% or 2.0 wt%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0070] In some optional examples, the mass ratio of the nano zinc oxide to the silane coupling agent in the silane coupling agent solution is 1:(0.2~0.3), for example, it can be 1:0.2, 1:0.21, 1:0.22, 1:0.23, 1:0.24, 1:0.25, 1:0.26, 1:0.27, 1:0.28, 1:0.29 or 1:0.3, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0071] In some optional examples, the ultrasonic power of the ultrasonic dispersion is 200~300W, for example, it can be 200W, 210W, 220W, 230W, 240W, 250W, 260W, 270W, 280W, 290W or 300W, but is not limited to the listed values. Other values ​​not listed within this numerical range are also applicable.

[0072] In some optional examples, the ultrasonic time of the ultrasonic dispersion is 30~40min, for example, it can be 30min, 31min, 32min, 33min, 34min, 35min, 36min, 37min, 38min, 39min or 40min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0073] In some optional examples, the mass fraction of the glacial acetic acid solution is 1~2wt%, for example, it can be 1.0wt%, 1.1wt%, 1.2wt%, 1.3wt%, 1.4wt%, 1.5wt%, 1.6wt%, 1.7wt%, 1.8wt%, 1.9wt% or 2.0wt%, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0074] In some optional examples, the mass fraction of chitosan in the chitosan solution is 1~2wt%, for example, it can be 1.0wt%, 1.1wt%, 1.2wt%, 1.3wt%, 1.4wt%, 1.5wt%, 1.6wt%, 1.7wt%, 1.8wt%, 1.9wt% or 2.0wt%, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0075] In some optional examples, the mass ratio of the silane-modified zinc oxide to the chitosan in the chitosan solution is 1:(1-2), for example, 1:1.0, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9 or 1:2.0, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0076] The present invention specifically limits the mass ratio of silane-modified zinc oxide to chitosan in the chitosan solution to 1:(1-2). Within this range, chitosan molecules form a complete monolayer on the surface of zinc oxide through electrostatic attraction and hydrogen bonds, and the dense coating effectively blocks the initial release of zinc ions into cement. At the same time, sufficient chitosan provides a high density of cationic amino groups, which produces a synergistic effect with the antibacterial mechanism of zinc oxide, greatly improving the antibacterial rate. In addition, the chitosan coating completely covers the active groups at the end of the silane layer, preventing them from excessively complexing with calcium ions in the cement and interfering with the hydration process.

[0077] When the amount of chitosan added is lower than the lower limit of the range defined in the present invention, the chitosan concentration is insufficient to completely coat the zinc oxide particles, and the coating on the particle surface is distributed in an island shape. The exposed silane layer in the uncovered area accelerates the dissolution of zinc ions. In addition, the locally exposed zinc oxide is directly exposed to the strong alkaline environment, generating [Zn(OH)4] 2- Dissolution loss occurs, and the uncoated area becomes the starting point of corrosion; at the same time, the particles selectively agglomerate due to surface energy differences, resulting in a decrease in the fluidity of the sealant slurry.

[0078] When the amount of chitosan added exceeds the upper limit of the range defined in the present invention, multi-layer coating forms a soft shell with a thickness of >200 nm, which significantly increases the diffusion resistance of zinc ions and reduces the cumulative release of zinc ions. In addition, the entanglement of polymer chains causes bridging and agglomeration between zinc oxide particles, forming aggregates in the slurry, which not only reduces the effective antibacterial surface area, but also blocks the cement pores and hinders hydration. At the same time, the high viscosity of the chitosan solution increases the difficulty of coating, and cracks are easily generated after drying, which accelerates the penetration of corrosive media.

[0079] In some optional embodiments, the temperature for mixing, stirring and heating the silane-modified zinc oxide and chitosan solution is 50-60°C, for example, 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, 56°C, 57°C, 58°C, 59°C or 60°C, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0080] In some optional examples, the mixing, stirring and heating time of the silane-modified zinc oxide and chitosan solution is 2 to 3 hours, for example, it can be 2.0 hours, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours, 2.5 hours, 2.6 hours, 2.7 hours, 2.8 hours, 2.9 hours or 3.0 hours, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0081] In a second aspect, the present invention provides a wall crack repair process using the wall crack repair agent described in the first aspect, the wall crack repair process comprising: Cut a V-shaped groove along the crack, remove the dust and apply the interface agent, and form an interface layer after the surface dries; Mixing the wall crack sealing agent with water to obtain a sealing slurry, and filling the sealing slurry into the V-shaped groove until it is slightly raised; Use a scraper to smooth the groove so that the filling slurry is compacted in the V-shaped groove, apply SiO2 reinforcing agent on the surface of the filling slurry, and then cover it with a film for maintenance.

[0082] The wall crack repair process provided by this invention significantly improves the interfacial bonding strength, structural density, and long-term durability of crack repairs. First, a V-shaped groove is cut along the crack, and after removing loose dust, a styrene-acrylic emulsion interface agent is applied. The polymer particles penetrate the concrete's capillary pores and, after drying, form a transition layer that combines flexibility and adhesion. The active groups (such as carboxyl groups) in this layer form chemical bonds with the hydration products of the cement-based binder, significantly enhancing the bond strength between the repair and the original substrate, effectively preventing the risk of interfacial delamination.

[0083] The slurry is adjusted at a mass ratio of 100:(20~30) to ensure that the slurry achieves optimal rheological properties. Sufficient water supports full hydration of the cement, while water-retaining agents (such as cellulose ether) delay water evaporation to avoid premature water loss and cracking. Through scraper compaction operation, the slurry is forced to penetrate into the bottom of the V-groove and the micro-cracks on the side walls under mechanical pressure to eliminate void defects. Through the directional arrangement of modified toughening fibers, a three-dimensional crack-resistant network is formed in the repair body.

[0084] After initial setting, a SiO2 reinforcing agent is applied to the surface of the caulking slurry. Its silica sol component penetrates the surface of the repaired material to a depth of 0.5-2 mm through capillary action. Reacting in an alkaline environment, the resulting calcium silicate gel fills the surface micropores, forming a densified reinforcement layer. This increases surface hardness and effectively prevents edge pulverization during use. Coating curing ensures that the secondary hydration reaction of the slag powder proceeds fully, enhancing long-term strength while also preventing shrinkage cracks caused by sudden changes in temperature and humidity. The antibacterial properties of modified nano-zinc oxide are particularly enhanced by the continuous moist environment, which activates the ion-release function of the chitosan coating, allowing the zinc ions to establish an initial antibacterial barrier during the curing period.

[0085] As a preferred technical solution of the present invention, the interface agent consists of polymer emulsion and deionized water.

[0086] In some optional examples, the polymer emulsion includes styrene acrylic emulsion.

[0087] In some optional examples, the solid content of the polymer emulsion is 40-50%, for example, it can be 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49% or 50%, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0088] In some optional examples, the mass ratio of the polymer emulsion to deionized water is 1:(1~1.5), for example, it can be 1:1.0, 1:1.05, 1:1.1, 1:1.15, 1:1.2, 1:1.25, 1:1.3, 1:1.35, 1:1.4, 1:1.45 or 1:1.5, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0089] In some optional embodiments, the coating amount of the interface agent is 50-150 g / m 2 , for example, it can be 50g / m 2 , 60g / m 2 , 70g / m 2 , 80g / m 2 , 90g / m 2 , 100g / m 2 , 110g / m 2 , 120g / m 2 , 130g / m 2 , 140g / m 2 or 150g / m 2 , but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0090] In some optional examples, the mass ratio of the wall crack sealant to water is 100:(20~30), for example, it can be 100:20, 100:21, 100:22, 100:23, 100:24, 100:25, 100:26, 100:27, 100:28, 100:29 or 100:30, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0091] In some optional examples, the SiO2 reinforcing agent consists of silica sol, polycarboxylic acid dispersant and water.

[0092] In some optional examples, the mass fraction of silicon dioxide in the silica sol is 20~30wt%, for example, it can be 20wt%, 21wt%, 22wt%, 23wt%, 24wt%, 25wt%, 26wt%, 27wt%, 28wt%, 29wt% or 30wt%, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0093] In some optional examples, the mass ratio of the silica sol, the polycarboxylic acid dispersant and water is 100:(0.1~0.2):(50~60), for example, it can be 100:0.1:50, 100:0.11:51, 100:0.12:52, 100:0.13:53, 100:0.14:54, 100:0.15:55, 100:0.16:56, 100:0.17:57, 100:0.18:58, 100:0.19:59 or 100:0.2:60, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0094] In some optional examples, the amount of SiO2 reinforcing agent applied is 50-100 g / m 2 , for example, it can be 50g / m 2 , 55g / m 2 , 60g / m 2 , 65g / m 2 , 70g / m 2 , 75g / m 2 , 80g / m 2 , 85g / m 2 , 90g / m 2 , 95g / m 2 or 100g / m 2 , but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0095] In some optional examples, the film curing time is 7 to 14 days, for example, it can be 7 days, 8 days, 9 days, 10 days, 11 days, 12 days, 13 days or 14 days, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0096] Compared with the prior art, the present invention has the following beneficial effects: The wall crack sealant provided by the present invention introduces modified toughening fibers and modified nano zinc oxide that have undergone surface functionalization treatment, which can significantly improve the crack resistance of cement-based crack repair materials and significantly reduce the probability of secondary cracking after repair. At the same time, it can provide long-lasting and effective anti-mildew and antibacterial capabilities, inhibit microbial erosion, and maintain the material's good construction operability and basic mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0097] Figure 1 This is a flow chart of the wall repair process provided in Examples 1-11 of the present invention. DETAILED DESCRIPTION

[0098] The technical solutions of the present invention are described in detail below in conjunction with specific embodiments and the accompanying drawings. The examples described herein are specific embodiments of the present invention and are used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary and should not be understood as limiting the embodiments of the present invention and the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the contents disclosed in the claims of this application and its specification, including technical solutions that adopt any obvious replacements and modifications to the embodiments described herein.

[0099] Example 1 This embodiment provides a wall crack sealing agent, which includes the following components in parts by weight based on 100 parts by weight of the wall crack sealing agent:

[0100] Among them, the cement-based binder is composed of silicate cement (model A00092, purity 99%, purchased from Wuhan Jiyesheng Chemical Co., Ltd.) and slag powder (model S95 grade, purchased from Shijiazhuang Xibang Mineral Products Co., Ltd.) with a mass ratio of 3:1, and the fine aggregate is composed of quartz sand (average mesh size of 40 mesh) and calcium carbonate with a mass ratio of 4:1.

[0101] The modified toughened fiber is prepared by the following method: (1) Soak the polyacrylonitrile fiber in a 3 wt% sodium hydroxide solution at a ratio of 1 g of polyacrylonitrile fiber to the sodium hydroxide solution of 10 mL. Heat the solution in a constant temperature water bath at 40 °C for 4 h to complete the alkaline etching. The etched fiber is then filtered, washed with deionized water, and dried. (2) Dopamine hydrochloride and copper sulfate were added to Tris-HCl buffer and mixed evenly to obtain a dopamine solution, wherein the mass fraction of dopamine hydrochloride in the dopamine solution was 1 wt %, and the mass ratio of dopamine hydrochloride to copper sulfate was 100:1; the etched fiber was immersed in the dopamine solution, wherein the mass ratio of the etched fiber to the dopamine hydrochloride in the dopamine solution was 1:2, and the etched fiber was heated and oscillated at a heating temperature of 45°C and an oscillation speed of 100 rpm for 10 h to form a polydopamine layer on the surface of the etched fiber, and the coated fiber was obtained after filtration, washing with deionized water and drying; (3) Sodium kaolin and 5 wt% octadecyltrimethylammonium bromide solution were mixed at a ratio of 1 g:10 mL, and stirred at 70 ° C for 10 h to obtain a kaolin suspension; the kaolin suspension was centrifuged at a speed of 10000 rpm for 30 min, the supernatant was discarded to collect the precipitate, the precipitate was washed with deionized water and then ultrasonically dispersed in deionized water, the mass ratio of precipitate to deionized water was 1:10, the ultrasonic power of ultrasonic dispersion was 400 W, and the ultrasonic time of ultrasonic dispersion was 40 min to obtain an intercalated kaolin solution; The coated fiber was dispersed in the intercalated kaolin solution at a ratio of 1 g:10 mL. The fiber was aged at a heating temperature of 60° C. and a stirring speed of 100 rpm for 2 h. The modified toughened fiber was obtained after filtration, washing with deionized water and drying.

[0102] Modified nano zinc oxide is prepared by the following method: adding nano-zinc oxide to a silane coupling agent solution consisting of a silane coupling agent KH550 and an ethanol aqueous solution (the volume ratio of ethanol to deionized water is 8:2), wherein the mass fraction of the silane coupling agent KH550 in the silane coupling agent solution is 1 wt%, and the mass ratio of the nano-zinc oxide to the silane coupling agent in the silane coupling agent solution is 1:0.2; ultrasonically dispersing the mixture at 200 W for 40 minutes, followed by filtration, washing with deionized water, and drying to obtain silane-modified zinc oxide; Chitosan was dissolved in a 1 wt % glacial acetic acid solution to obtain a chitosan solution, wherein the mass fraction of chitosan in the chitosan solution was 1 wt %. Silane-modified zinc oxide was mixed with the chitosan solution, wherein the mass ratio of silane-modified zinc oxide to chitosan in the chitosan solution was 1:1. The mixture was stirred and heated at 50° C. for 3 h, and then filtered, washed with deionized water, and dried to obtain modified nano-zinc oxide.

[0103] This embodiment also provides a wall crack repair process using the above-mentioned wall crack repair agent, such as Figure 1 As shown, the wall seam repair process includes: Cut a V-shaped groove along the crack, remove the dust and apply the interface agent. The interface agent is composed of a styrene acrylic emulsion with a solid content of 40% (model Y17677-100g, purchased from Shanghai Yuanye Biotechnology Co., Ltd.) and deionized water in a mass ratio of 1:1. The application amount of the interface agent is 50g / m 2 , forming an interface layer after surface drying; Mix the wall crack sealant and water in a mass ratio of 100:20 to obtain a sealing slurry, and fill the sealing slurry into the V-shaped groove until it is slightly raised; Use a scraper to flatten the groove so that the filling slurry is compacted in the V-shaped groove, and apply SiO2 reinforcing agent on the surface of the filling slurry. The SiO2 reinforcing agent is composed of silica sol, polycarboxylic acid dispersant (polycarboxylic acid sodium salt dispersant, model PA93102, purchased from Guangdong Wengjiang Chemical Reagent Co., Ltd.) and water in a mass ratio of 100:0.1:50. The mass fraction of silicon dioxide in the silica sol is 20wt%, and the application amount of SiO2 reinforcing agent is 50g / m 2 , then cover with film and maintain for 7 days, and remove the film after the maintenance is completed.

[0104] Example 2 This embodiment provides a wall crack sealing agent, which includes the following components in parts by weight based on 100 parts by weight of the wall crack sealing agent:

[0105] Among them, the cement-based binder is composed of silicate cement and slag powder in a mass ratio of 3.5:1, and the fine aggregate is composed of quartz sand (mesh size 42) and calcium carbonate in a mass ratio of 4.2:1.

[0106] The modified toughened fiber is prepared by the following method: (1) The polyacrylonitrile fiber was immersed in a 3.5 wt% sodium hydroxide solution with a ratio of 1 g of polyacrylonitrile fiber to the sodium hydroxide solution of 12 mL. The fiber was heated in a constant temperature water bath at 42 °C for 3.5 h to complete the alkaline etching. The etched fiber was obtained after filtration, washing with deionized water, and drying. (2) Dopamine hydrochloride and copper sulfate were added to Tris-HCl buffer and mixed evenly to obtain a dopamine solution, wherein the mass fraction of dopamine hydrochloride in the dopamine solution was 1.2 wt %, and the mass ratio of dopamine hydrochloride to copper sulfate was 100:1.5; the etched fiber was immersed in the dopamine solution, wherein the mass ratio of the etched fiber to the dopamine hydrochloride in the dopamine solution was 1:2.2, and heated and oscillated at a heating temperature of 48°C and an oscillation speed of 120 rpm for 9.5 h to form a polydopamine layer on the surface of the etched fiber, and the coated fiber was obtained after filtration, washing with deionized water and drying; (3) Sodium kaolin and 6 wt% octadecyltrimethylammonium bromide solution were mixed in a ratio of 1 g:11 mL and stirred at 72 °C for 9.5 h to obtain a kaolin suspension; the kaolin suspension was centrifuged at a speed of 11000 rpm for 28 min, the supernatant was discarded to collect the precipitate, the precipitate was washed with deionized water and then ultrasonically dispersed in deionized water, the mass ratio of the precipitate to deionized water was 1:11, the ultrasonic power of the ultrasonic dispersion was 420 W, and the ultrasonic time of the ultrasonic dispersion was 38 min to obtain an intercalated kaolin solution; The coated fiber was dispersed in the intercalated kaolin solution at a ratio of 1 g:12 mL. The solution was aged at a heating temperature of 62°C and a stirring speed of 120 rpm for 1.8 h. The modified toughened fiber was obtained after filtration, washing with deionized water and drying.

[0107] Modified nano zinc oxide is prepared by the following method: Nano-zinc oxide was added to a silane coupling agent solution consisting of a silane coupling agent KH550 and an ethanol aqueous solution (the volume ratio of ethanol to deionized water was 8:2), the mass fraction of the silane coupling agent KH550 in the silane coupling agent solution was 1.2 wt%, and the mass ratio of the nano-zinc oxide to the silane coupling agent in the silane coupling agent solution was 1:0.22. The mixture was ultrasonically dispersed at 220 W for 38 minutes, and then filtered, washed with deionized water, and dried to obtain silane-modified zinc oxide. Chitosan was dissolved in a 1.2 wt % glacial acetic acid solution to obtain a chitosan solution, wherein the mass fraction of chitosan in the chitosan solution was 1.2 wt %. Silane-modified zinc oxide was mixed with the chitosan solution, wherein the mass ratio of silane-modified zinc oxide to chitosan in the chitosan solution was 1:1.2. The mixture was stirred and heated at 52° C. for 2.8 h, and then filtered, washed with deionized water, and dried to obtain modified nano-zinc oxide.

[0108] This embodiment also provides a wall crack repair process using the above-mentioned wall crack repair agent, such as Figure 1 As shown, the wall seam repair process includes: Cut a V-shaped groove along the crack, remove the dust and apply the interface agent. The interface agent is composed of styrene acrylic emulsion with a solid content of 42% and deionized water in a mass ratio of 1:1.2. The application amount of the interface agent is 80g / m 2 , forming an interface layer after surface drying; Mix the wall crack sealant and water in a mass ratio of 100:22 to obtain a sealing slurry, and fill the sealing slurry into the V-shaped groove until it is slightly raised; Use a scraper to flatten the groove so that the filling slurry is compacted in the V-shaped groove, and apply SiO2 reinforcing agent on the surface of the filling slurry. The SiO2 reinforcing agent is composed of silica sol, polycarboxylic acid dispersant and water in a mass ratio of 100:0.12:52. The mass fraction of silicon dioxide in the silica sol is 22wt%, and the amount of SiO2 reinforcing agent applied is 60g / m 2 , then cover with film and maintain for 9 days, and remove the film after the maintenance is completed.

[0109] Example 3 This embodiment provides a wall crack sealing agent, which includes the following components in parts by weight based on 100 parts by weight of the wall crack sealing agent:

[0110] Among them, the cement-based binder is composed of silicate cement and slag powder in a mass ratio of 4:1, and the fine aggregate is composed of quartz sand (mesh size 45) and calcium carbonate in a mass ratio of 4.5:1.

[0111] The modified toughened fiber is prepared by the following method: (1) Soak the polyacrylonitrile fiber in a 4 wt% sodium hydroxide solution at a ratio of 1 g of polyacrylonitrile fiber to the sodium hydroxide solution of 15 mL. Heat the solution in a constant temperature water bath at 45 °C for 3 h to complete the alkaline etching. The etched fiber is then filtered, washed with deionized water, and dried. (2) Dopamine hydrochloride and copper sulfate were added to Tris-HCl buffer and mixed evenly to obtain a dopamine solution, wherein the mass fraction of dopamine hydrochloride in the dopamine solution was 1.5 wt %, and the mass ratio of dopamine hydrochloride to copper sulfate was 100:2; the etched fiber was immersed in the dopamine solution, wherein the mass ratio of the etched fiber to the dopamine hydrochloride in the dopamine solution was 1:2.5, and heated and oscillated at a heating temperature of 50°C and an oscillation speed of 150 rpm for 9 h to form a polydopamine layer on the surface of the etched fiber, and the coated fiber was obtained after filtration, washing with deionized water and drying; (3) Sodium kaolin and 7 wt% octadecyltrimethylammonium bromide solution were mixed in a ratio of 1 g:12 mL, and stirred at 75 ° C for 9 h to obtain a kaolin suspension; the kaolin suspension was centrifuged at a speed of 12000 rpm for 25 min, the supernatant was discarded to collect the precipitate, the precipitate was washed with deionized water and then ultrasonically dispersed in deionized water, the mass ratio of precipitate to deionized water was 1:12, the ultrasonic power of ultrasonic dispersion was 450 W, and the ultrasonic time of ultrasonic dispersion was 35 min to obtain an intercalated kaolin solution; The coated fiber was dispersed in the intercalated kaolin solution at a ratio of 1 g:15 mL. The solution was aged at a heating temperature of 65° C. and a stirring speed of 150 rpm for 1.5 h. The modified toughened fiber was obtained after filtration, washing with deionized water and drying.

[0112] Modified nano zinc oxide is prepared by the following method: adding nano-zinc oxide to a silane coupling agent solution consisting of a silane coupling agent KH550 and an ethanol aqueous solution (the volume ratio of ethanol to deionized water is 8:2), wherein the mass fraction of the silane coupling agent KH550 in the silane coupling agent solution is 1.5 wt %, and the mass ratio of the nano-zinc oxide to the silane coupling agent in the silane coupling agent solution is 1:0.25; ultrasonically dispersing the mixture at 250 W for 35 minutes, followed by filtration, washing with deionized water, and drying to obtain silane-modified zinc oxide; Chitosan was dissolved in a 1.5 wt % glacial acetic acid solution to obtain a chitosan solution, wherein the mass fraction of chitosan in the chitosan solution was 1.5 wt %. Silane-modified zinc oxide was mixed with the chitosan solution, wherein the mass ratio of silane-modified zinc oxide to chitosan in the chitosan solution was 1:1.5. The mixture was stirred and heated at 55° C. for 2.5 h, and then filtered, washed with deionized water, and dried to obtain modified nano-zinc oxide.

[0113] This embodiment also provides a wall crack repair process using the above-mentioned wall crack repair agent, such as Figure 1 As shown, the wall seam repair process includes: Cut a V-shaped groove along the crack, remove the dust and apply the interface agent. The interface agent is composed of styrene acrylic emulsion with a solid content of 45% and deionized water in a mass ratio of 1:1.3. The application amount of the interface agent is 100g / m 2 , forming an interface layer after surface drying; Mix the wall crack sealant and water in a mass ratio of 100:25 to obtain a sealing slurry, and fill the sealing slurry into the V-shaped groove until it is slightly raised; Use a scraper to flatten the groove so that the filling slurry is compacted in the V-shaped groove, and apply SiO2 reinforcing agent on the surface of the filling slurry. The SiO2 reinforcing agent is composed of silica sol, polycarboxylic acid dispersant and water in a mass ratio of 100:0.15:55. The mass fraction of silicon dioxide in the silica sol is 25wt%, and the amount of SiO2 reinforcing agent applied is 70g / m 2 , then cover with film and maintain for 10 days, and remove the film after the maintenance is completed.

[0114] Example 4 This embodiment provides a wall crack sealing agent, which includes the following components in parts by weight based on 100 parts by weight of the wall crack sealing agent:

[0115] Among them, the cement-based binder is composed of silicate cement and slag powder in a mass ratio of 4.5:1, and the fine aggregate is composed of quartz sand (mesh size 48) and calcium carbonate in a mass ratio of 4.8:1.

[0116] The modified toughened fiber is prepared by the following method: (1) The polyacrylonitrile fiber was immersed in a 4.5 wt% sodium hydroxide solution with a ratio of 1 g of polyacrylonitrile fiber to the sodium hydroxide solution of 18 mL. The fiber was heated in a constant temperature water bath at 48 °C for 2.5 h to complete the alkaline etching. The etched fiber was then filtered, washed with deionized water, and dried. (2) Dopamine hydrochloride and copper sulfate were added to Tris-HCl buffer and mixed evenly to obtain a dopamine solution, wherein the mass fraction of dopamine hydrochloride in the dopamine solution was 1.8 wt %, and the mass ratio of dopamine hydrochloride to copper sulfate was 100:2.5; the etched fiber was immersed in the dopamine solution, wherein the mass ratio of the etched fiber to the dopamine hydrochloride in the dopamine solution was 1:2.8, and heated and oscillated at a heating temperature of 52°C and an oscillation speed of 180 rpm for 8.5 h to form a polydopamine layer on the surface of the etched fiber, and the coated fiber was obtained after filtration, washing with deionized water and drying; (3) Sodium kaolin and 8 wt% octadecyltrimethylammonium bromide solution were mixed in a ratio of 1 g:13 mL, and stirred at 78 ° C for 8.5 h to obtain a kaolin suspension; the kaolin suspension was centrifuged at a speed of 13000 rpm for 22 min, the supernatant was discarded to collect the precipitate, the precipitate was washed with deionized water and then ultrasonically dispersed in deionized water, the mass ratio of precipitate to deionized water was 1:13, the ultrasonic power of ultrasonic dispersion was 480 W, and the ultrasonic time of ultrasonic dispersion was 32 min to obtain an intercalated kaolin solution; The coated fiber was dispersed in the intercalated kaolin solution at a ratio of 1 g:18 mL. The solution was aged at a heating temperature of 68°C and a stirring speed of 180 rpm for 1.2 h. The modified toughened fiber was obtained after filtration, washing with deionized water and drying.

[0117] Modified nano zinc oxide is prepared by the following method: Nano-zinc oxide was added to a silane coupling agent solution consisting of a silane coupling agent KH550 and an ethanol aqueous solution (the volume ratio of ethanol to deionized water was 8:2), the mass fraction of the silane coupling agent KH550 in the silane coupling agent solution was 1.8 wt%, and the mass ratio of the nano-zinc oxide to the silane coupling agent in the silane coupling agent solution was 1:0.28. The mixture was ultrasonically dispersed at 280 W for 32 minutes, and then filtered, washed with deionized water, and dried to obtain silane-modified zinc oxide. Chitosan was dissolved in a 1.8 wt % glacial acetic acid solution to obtain a chitosan solution, wherein the mass fraction of chitosan in the chitosan solution was 1.8 wt %. Silane-modified zinc oxide was mixed with the chitosan solution, wherein the mass ratio of silane-modified zinc oxide to chitosan in the chitosan solution was 1:1.8, and the mixture was stirred and heated at 58° C. for 2.2 h, and then filtered, washed with deionized water, and dried to obtain modified nano-zinc oxide.

[0118] This embodiment also provides a wall crack repair process using the above-mentioned wall crack repair agent, such as Figure 1 As shown, the wall seam repair process includes: Cut a V-shaped groove along the crack, remove the dust and apply the interface agent. The interface agent is composed of styrene acrylic emulsion with a solid content of 48% and deionized water in a mass ratio of 1:1.4. The application amount of the interface agent is 120g / m 2 , forming an interface layer after surface drying; Mix the wall crack sealant and water in a mass ratio of 100:28 to obtain a sealing slurry, and fill the sealing slurry into the V-shaped groove until it is slightly raised; Use a scraper to flatten the groove so that the filling slurry is compacted in the V-shaped groove, and apply SiO2 reinforcing agent on the surface of the filling slurry. The SiO2 reinforcing agent is composed of silica sol, polycarboxylic acid dispersant and water in a mass ratio of 100:0.18:58. The mass fraction of silicon dioxide in the silica sol is 28wt%, and the amount of SiO2 reinforcing agent applied is 80g / m 2 , then cover with film and maintain for 12 days, and remove the film after the maintenance is completed.

[0119] Example 5 This embodiment provides a wall crack sealing agent, which includes the following components in parts by weight based on 100 parts by weight of the wall crack sealing agent:

[0120] Among them, the cement-based binder is composed of silicate cement and slag powder in a mass ratio of 5:1, and the fine aggregate is composed of quartz sand (mesh size is 50 mesh) and calcium carbonate in a mass ratio of 5:1.

[0121] The modified toughened fiber is prepared by the following method: (1) Soak the polyacrylonitrile fiber in a 5 wt% sodium hydroxide solution at a ratio of 1 g of polyacrylonitrile fiber to the sodium hydroxide solution of 20 mL. Heat the solution in a constant temperature water bath at 50 °C for 2 h to complete the alkaline etching. The etched fiber is then filtered, washed with deionized water, and dried. (2) Dopamine hydrochloride and copper sulfate were added to Tris-HCl buffer and mixed evenly to obtain a dopamine solution, wherein the mass fraction of dopamine hydrochloride in the dopamine solution was 2 wt %, and the mass ratio of dopamine hydrochloride to copper sulfate was 100:3; the etched fiber was immersed in the dopamine solution, wherein the mass ratio of the etched fiber to the dopamine hydrochloride in the dopamine solution was 1:3, and heated and oscillated at a heating temperature of 55°C and an oscillation speed of 200 rpm for 8 h to form a polydopamine layer on the surface of the etched fiber, and the coated fiber was obtained after filtration, washing with deionized water and drying; (3) Sodium kaolin and 10 wt% octadecyltrimethylammonium bromide solution were mixed in a ratio of 1 g:15 mL, and stirred at 80 ° C for 8 h to obtain a kaolin suspension; the kaolin suspension was centrifuged at a speed of 15000 rpm for 20 min, the supernatant was discarded to collect the precipitate, the precipitate was washed with deionized water and then ultrasonically dispersed in deionized water, the mass ratio of the precipitate to deionized water was 1:15, the ultrasonic power of the ultrasonic dispersion was 500 W, and the ultrasonic time of the ultrasonic dispersion was 30 min to obtain an intercalated kaolin solution; The coated fiber was dispersed in the intercalated kaolin solution at a ratio of 1 g:20 mL. The fiber was aged at a heating temperature of 70° C. and a stirring speed of 200 rpm for 1 h. The modified toughened fiber was obtained after filtration, washing with deionized water and drying.

[0122] Modified nano zinc oxide is prepared by the following method: adding nano-zinc oxide to a silane coupling agent solution consisting of a silane coupling agent KH550 and an ethanol aqueous solution (the volume ratio of ethanol to deionized water is 8:2), wherein the mass fraction of the silane coupling agent KH550 in the silane coupling agent solution is 2 wt %, and the mass ratio of the nano-zinc oxide to the silane coupling agent in the silane coupling agent solution is 1:0.3; ultrasonically dispersing the mixture at 300 W for 30 minutes, followed by filtration, washing with deionized water, and drying to obtain silane-modified zinc oxide; Chitosan was dissolved in a 2 wt % glacial acetic acid solution to obtain a chitosan solution, wherein the mass fraction of chitosan in the chitosan solution was 2 wt %. Silane-modified zinc oxide was mixed with the chitosan solution, wherein the mass ratio of silane-modified zinc oxide to chitosan in the chitosan solution was 1:2. The mixture was stirred and heated at 60° C. for 2 h, and then filtered, washed with deionized water, and dried to obtain modified nano-zinc oxide.

[0123] This embodiment also provides a wall crack repair process using the above-mentioned wall crack repair agent, such as Figure 1 As shown, the wall seam repair process includes: Cut a V-shaped groove along the crack, remove the dust and apply the interface agent. The interface agent is composed of styrene acrylic emulsion with a solid content of 50% and deionized water in a mass ratio of 1:1.5. The application amount of the interface agent is 150g / m 2 , forming an interface layer after surface drying; Mix the wall crack sealant and water in a mass ratio of 100:30 to obtain a sealing slurry, and fill the sealing slurry into the V-shaped groove until it is slightly raised; Use a scraper to flatten the groove so that the filling slurry is compacted in the V-shaped groove, and apply SiO2 reinforcing agent on the surface of the filling slurry. The SiO2 reinforcing agent is composed of silica sol, polycarboxylic acid dispersant and water in a mass ratio of 100:0.2:60. The mass fraction of silicon dioxide in the silica sol is 30wt%, and the amount of SiO2 reinforcing agent applied is 100g / m 2 , then cover with film and maintain for 14 days, and remove the film after the maintenance is completed.

[0124] Example 6 This embodiment provides a wall crack sealant, which differs from Example 1 in that the mass ratio of the etching fiber to the dopamine hydrochloride in the dopamine solution is adjusted to 1:1, and the other process parameters and operating steps are exactly the same as those in Example 1.

[0125] Example 7 This embodiment provides a wall crack sealant, which differs from Example 1 in that the mass ratio of the etched fiber to the dopamine hydrochloride in the dopamine solution is adjusted to 1:4, and the other process parameters and operating steps are exactly the same as those in Example 1.

[0126] Example 8 This embodiment provides a wall crack sealing agent, which differs from Example 1 in that the ratio of coated fiber to intercalated kaolin solution is adjusted to 1 g:5 mL, and other process parameters and operating steps are exactly the same as those in Example 1.

[0127] Example 9 This embodiment provides a wall crack sealing agent, which differs from Example 1 in that the ratio of coated fiber to intercalated kaolin solution is adjusted to 1 g:25 mL, and other process parameters and operating steps are exactly the same as those in Example 1.

[0128] Example 10 This embodiment provides a wall crack sealing agent, which differs from Example 1 in that the mass ratio of silane-modified zinc oxide to chitosan in the chitosan solution is adjusted to 1:0.5, and the other process parameters and operating steps are exactly the same as those in Example 1.

[0129] Example 11 This embodiment provides a wall crack sealing agent, which differs from Example 1 in that the mass ratio of silane-modified zinc oxide to chitosan in the chitosan solution is adjusted to 1:2.5, and the other process parameters and operating steps are exactly the same as those in Example 1.

[0130] Comparative Example 1 This comparative example provides a wall crack sealing agent, which differs from Example 1 in that the modified toughening fiber in the wall crack sealing agent adopts unmodified polyacrylonitrile fiber, and the other process parameters and operation steps are exactly the same as those in Example 1.

[0131] Comparative Example 2 This comparative example provides a wall crack sealing agent, which differs from Example 1 in that the modified nano zinc oxide in the wall crack sealing agent adopts unmodified nano zinc oxide, and the other process parameters and operation steps are exactly the same as those in Example 1.

[0132] The flexural strength, bonding strength, antibacterial rate and fungal resistance grade of the wall crack sealants provided in Examples 1-11 and Comparative Examples 1-2 were tested. The specific testing steps are as follows: (1) Flexural strength The flexural strength is used to characterize the ability of wall crack sealants to resist bending stress. The higher the value, the stronger the crack resistance. The test steps are as follows: The wall crack sealant provided in the embodiment was mixed with water to prepare a slurry to obtain a sealing slurry. The sealing slurry was filled into a mold to prepare a 40 mm × 40 mm × 160 mm prism specimen. A three-point bending test was performed using a universal testing machine at a loading rate of 50 N / s. The maximum load at fracture was recorded, and the flexural strength was calculated using the following formula: ; Among them, F f is the fracture load; L is the support distance; b is the side length of the specimen.

[0133] (2) Bond strength The bonding strength is used to characterize the bonding performance of the wall crack sealant and the substrate. The higher the value, the stronger the anti-peeling ability. The test steps are as follows: Prepare "8"-shaped cement mortar specimens, apply interface agent on the cross section, the interface agent consists of styrene acrylic emulsion and deionized water, and form an interface layer after surface drying. Fill with sealant slurry, standard curing for 28 days, use a tensile fixture to load at a rate of 5mm / min, and record the failure load.

[0134] The bond strength is calculated using the following formula: ; Where F is the failure load and A is the bonding area.

[0135] (3) Antibacterial rate Experimental group was set up: the test blocks were cast using the ratio provided in the example to obtain a sample of 50 mm × 50 mm × 5 mm, 100 μL of Escherichia coli suspension (1 × 10 5 ~10 6 CFU / mL) was added dropwise to the sample surface and evenly spread with a sterile coating stick.

[0136] Set up the control group: The same operation was performed on a sterile polished glass slide.

[0137] The experimental group and the control group were placed in sterile nutrient agar culture dishes, covered with wet filter paper, and placed in a constant temperature incubator at 37°C ± 1°C for 24 h. The dishes were taken out and placed in a test tube containing 10 mL of neutralizer (0.5% sodium thiosulfate + 0.3% lecithin + 0.1% Tween 80), vortexed for 5 min, and 1 mL of eluate (phosphate buffer containing 0.85% NaCl) was added to 9 mL of PBS and diluted to 10 -1 , 10 -2 , 10 -3 , take 0.1mL of each dilution of bacterial solution, evenly spread it on NA / PDA plate, incubate at 37℃ for 24~48h, and count the colony count (CFU). The antibacterial rate is calculated using the following formula: Antibacterial rate = [(number of colonies in the control group - number of colonies in the experimental group) / number of colonies in the control group] × 100%.

[0138] (4) Fungus resistance level With reference to the national standard GB / T 1741-2020 “Determination of mildew resistance of paint films”, the mildew resistance levels of the wall crack sealants provided in Examples 1-11 and Comparative Examples 1-2 were tested.

[0139] The test results are shown in Table 1.

[0140]

[0141] It can be seen from the test data of Examples 1, 6 and 7 that when the dosage of dopamine hydrochloride is too low (Example 6), the polydopamine coating layer becomes thinner, weakening the chemical bonding between the fiber and the cement matrix, resulting in a decrease in bonding strength; when the dosage of dopamine hydrochloride is too high (Example 7), the excess dopamine forms an uneven coating layer due to self-polymerization reaction, hindering the effective dispersion of the fibers, reducing the interfacial stress transfer efficiency, and reducing the bonding strength.

[0142] The test data from Examples 1, 8, and 9 show that when the amount of intercalated kaolin solution is too low (Example 8), the sheets fail to form an effective network structure, resulting in reduced flexural strength. When the amount of intercalated kaolin solution is too high (Example 9), the kaolin sheets agglomerate, weakening the reinforcement effect.

[0143] It can be seen from the test data of Example 1, Example 10 and Example 11 that when the dosage of chitosan is too low (Example 10), the zinc oxide particles are easy to agglomerate, the exposed area is reduced, and the antibacterial rate is reduced; when the dosage of chitosan is too high (Example 11), the chitosan wrapping is too thick, which hinders the release of zinc oxide ions and reduces the antibacterial rate.

[0144] The test data from Example 1 and Comparative Example 1 demonstrate that the use of unmodified polyacrylonitrile fibers directly lacks surface active groups to bind to the matrix, resulting in reduced fiber-matrix interfacial bond strength. Furthermore, the fibers are unable to form a three-dimensional reinforcing network with kaolin, leading to a decrease in overall mechanical properties. Furthermore, the loss of hydrophobicity on the fiber surface facilitates mold attachment, resulting in a decrease in mold resistance.

[0145] It can be seen from the test data of Example 1 and Comparative Example 2 that nano-zinc oxide that has not been treated with silane has poor hydrophobicity and is severely aggregated in the alkaline cement matrix, resulting in a sharp drop in specific surface area. Its antibacterial activity relies solely on physical contact and is unable to continuously release zinc ions, resulting in a decrease in antibacterial rate. At the same time, the agglomerates become structural defects, resulting in a decrease in flexural strength and bonding strength.

[0146] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. A wall crack sealing agent, characterized in that: The wall crack sealing agent comprises cement-based gelling material, fine aggregate, modified toughening fiber, modified nano zinc oxide, dispersant, defoaming agent, water retaining agent and mildew inhibitor; The modified toughened fiber is a polyacrylonitrile fiber obtained by sequentially undergoing alkali etching, dopamine coating, and kaolin loading; The modified nano zinc oxide is obtained by modifying nano zinc oxide with a silane coupling agent and then coating with chitosan.

2. The wall crack sealing agent according to claim 1, characterized in that: Based on 100 parts by weight of the wall crack sealing agent, it includes the following components in parts by weight: 45-50 parts of cement-based gelling materials; 45-50 parts of fine aggregate; 1~3 parts of modified toughening fiber; 1.5-2.5 parts of modified nano zinc oxide; Dispersant 0.5~1 part; 0.1~0.3 parts of defoaming agent; 0.1~0.2 parts of water-retaining agent; 0.1~0.5 parts of anti-fungal agent.

3. The wall crack sealing agent according to claim 1, characterized in that: The cement-based gelling material includes Portland cement and slag powder; The mass ratio of the silicate cement to the slag powder is (3-5):1; The fine aggregate includes quartz sand and calcium carbonate; The mesh number of the quartz sand is 40 to 50 meshes; The mass ratio of the quartz sand to calcium carbonate is (4-5):

1.

4. The wall crack sealing agent according to claim 1, characterized in that: The modified toughened fiber is prepared by the following method: (I) soaking polyacrylonitrile fiber in a sodium hydroxide solution, heating in a constant temperature water bath to complete alkaline etching, and obtaining etched fiber after filtering, washing and drying; (II) soaking the etched fiber in a dopamine solution, heating and shaking to form a polydopamine layer on the surface of the etched fiber, and obtaining a coated fiber after filtering, washing and drying; (III) intercalating and modifying sodium-based kaolin to obtain an intercalated kaolin solution, dispersing the coated fiber in the intercalated kaolin solution, heating and aging, and filtering, washing and drying to obtain the modified toughened fiber.

5. The wall crack sealing agent according to claim 4, characterized in that: In step (I), the mass fraction of the sodium hydroxide solution is 3-5wt%; The ratio of the polyacrylonitrile fiber to the sodium hydroxide solution is 1 g: (10-20) mL; The constant temperature water bath is heated at 40-50°C; The heating time of the constant temperature water bath is 2 to 4 hours; In step (II), the dopamine solution consists of dopamine hydrochloride, copper sulfate and Tris-HCl buffer; The mass fraction of dopamine hydrochloride in the dopamine solution is 1-2 wt %; The mass ratio of dopamine hydrochloride to copper sulfate is 100:(1-3); The mass ratio of the etched fiber to the dopamine hydrochloride in the dopamine solution is 1:(2-3); The temperature of the heating oscillation is 45-55°C; The rotation speed of the heating oscillation is 100-200 rpm; The heating and shaking time is 8 to 10 hours.

6. The wall crack sealing agent according to claim 4, characterized in that: In step (III), the intercalation modification operation of the sodium kaolin includes: Mixing sodium kaolin and octadecyltrimethylammonium bromide solution, stirring and heating to obtain a kaolin suspension; centrifuging the kaolin suspension, discarding the supernatant, collecting a precipitate, washing the precipitate, and then ultrasonically dispersing it in deionized water to obtain the intercalated kaolin solution; The mass fraction of the octadecyltrimethylammonium bromide solution is 5-10wt%; The ratio of the sodium kaolin to the octadecyltrimethylammonium bromide solution is 1 g: (10-15) mL; The temperature of mixing, stirring and heating the sodium kaolin and octadecyltrimethylammonium bromide solution is 70-80° C. The mixing, stirring and heating time of the sodium kaolin and octadecyltrimethylammonium bromide solution is 8 to 10 hours; The centrifugal speed is 10000~15000rpm; The centrifugal time is 20 to 30 minutes; The mass ratio of the precipitate to deionized water is 1:(10-15); The ultrasonic power of the ultrasonic dispersion is 400-500W; The ultrasonic dispersion time is 30 to 40 minutes; The ratio of the coated fiber to the intercalated kaolin solution is 1 g: (10-20) mL; The heating and aging is carried out under stirring conditions, and the stirring speed is 100-200 rpm; The heating and aging temperature is 60-70°C; The heating and aging time is 1 to 2 hours.

7. The wall crack sealing agent according to claim 1, characterized in that: The modified nano zinc oxide is prepared by the following method: adding nano zinc oxide to a silane coupling agent solution for ultrasonic dispersion, followed by filtering, washing and drying to obtain silane-modified zinc oxide; Chitosan is dissolved in a glacial acetic acid solution to obtain a chitosan solution, the silane-modified zinc oxide and the chitosan solution are mixed, stirred, and heated, and then filtered, washed, and dried to obtain modified nano zinc oxide.

8. The wall crack sealing agent according to claim 7, characterized in that: The silane coupling agent solution consists of a silane coupling agent and an ethanol aqueous solution; The mass fraction of the silane coupling agent in the silane coupling agent solution is 1-2 wt %; The mass ratio of the nano zinc oxide to the silane coupling agent in the silane coupling agent solution is 1:(0.2-0.3); The ultrasonic power of the ultrasonic dispersion is 200-300W; The ultrasonic dispersion time is 30 to 40 minutes; The mass fraction of the glacial acetic acid solution is 1-2wt%; The mass fraction of chitosan in the chitosan solution is 1-2 wt %; The mass ratio of the silane-modified zinc oxide to the chitosan in the chitosan solution is 1:(1-2); The temperature of mixing, stirring and heating the silane-modified zinc oxide and chitosan solution is 50-60° C. The mixing, stirring and heating time of the silane-modified zinc oxide and chitosan solution is 2 to 3 hours.

9. A wall crack repair process using the wall crack repair agent according to any one of claims 1 to 8, characterized in that: The wall filling process includes: Cut a V-shaped groove along the crack, remove the dust and apply the interface agent, and form an interface layer after the surface dries; Mixing the wall crack sealing agent with water to obtain a sealing slurry, and filling the sealing slurry into the V-shaped groove until it is slightly raised; Use a scraper to smooth the groove so that the filling slurry is compacted in the V-shaped groove, apply SiO2 reinforcing agent on the surface of the filling slurry, and then cover it with a film for maintenance.

10. The wall repair process according to claim 9, characterized in that: The interface agent consists of polymer emulsion and deionized water; The polymer emulsion includes styrene acrylic emulsion; The solid content of the polymer emulsion is 40-50%; The mass ratio of the polymer emulsion to deionized water is 1:(1-1.5); The coating amount of the interface agent is 50~150g / m 2 ; The mass ratio of the wall crack sealing agent to water is 100:(20-30); The SiO2 reinforcing agent is composed of silica sol, polycarboxylic acid dispersant and water; The mass fraction of silicon dioxide in the silica sol is 20-30 wt %; The mass ratio of the silica sol, the polycarboxylic acid dispersant and water is 100:(0.1-0.2):(50-60); The amount of SiO2 reinforcing agent applied is 50~100g / m 2 ; The film covering and curing time is 7 to 14 days.

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