A low-dosage self-healing waterproof and densifying agent for concrete

Abstract

This invention discloses a low-dosage self-healing waterproof and densifying agent for concrete, belonging to the technical field of concrete densifying agents. The product comprises the following components in parts by weight: 9-15 parts ionic complexing agent, 4.5-7.5 parts biomass ultrafine fiber powder, 4-6 parts crosslinking agent, 6.5-11.5 parts organosilicon resin, 12-20 parts inorganic salt filler, 6.5-11.5 parts calcium lactate, and 40-64 parts solvent. The preparation process of the compacting agent is as follows: S1 Preparation of mixture A: First, add biomass ultrafine fiber powder and ionic complexing agent to the solvent, and then stir until the components are completely dispersed to obtain mixture A; S2 Preparation of mixture B: Mix the crosslinking agent and organosilicon resin, and stir until the two components are completely in sync to obtain mixture B; S3 Homogenization and blending of finished product: Add mixture B dropwise to mixture A, and add inorganic salt filler and calcium lactate in batches. The low-dosage concrete self-healing waterproof compacting agent of the present invention further reduces the performance degradation problem at low dosages without adding additional fillers or additives.

Description

Technical Field

[0001] This invention specifically relates to a low-dosage self-healing waterproof and densifying agent for concrete, belonging to the technical field of concrete densifying agents. Background Technology

[0002] Concrete is the most widely used structural material in construction engineering. However, due to factors such as hydration shrinkage, temperature stress, and load, concrete structures are prone to micro-cracks, leading to problems such as leakage, steel corrosion, and reduced structural durability. To address the poor waterproofing performance of traditional concrete, Chinese Patent Publication No. CN121225917B discloses a self-healing concrete waterproofing densifier, its preparation method, and its application. This densifier possesses excellent waterproofing performance and also imparts good self-healing capabilities to concrete, extending its service life. Furthermore, commercially available self-healing waterproofing densifiers for concrete cracks often employ a complex composition of biomass ultrafine fiber powder, ion complexing agents, organosilicon resin, and crosslinking agents. This product is formulated to possess functions such as environmental protection, self-healing cracks, substrate reinforcement, and seepage prevention, solving the problems of traditional waterproofing admixtures, which are characterized by single function, poor environmental performance, and lack of secondary repair capabilities. However, existing waterproofing densifiers still have many technical defects: First, the dosage is too high, with a conventional dosage of 0.4% of the total mass of cementitious materials, increasing the cost of engineering applications and limiting its application in cost-sensitive projects. Second, the ion complexation efficiency is insufficient, resulting in weak capture of free calcium ions inside the concrete, slow crack repair response, and significant reduction in repair performance at low dosages. Third, the role of raw material components is not fully utilized, leading to a low cost-performance ratio. Fourth, the project adaptability is poor, with weak compatibility with different grades of cement, fly ash, and mineral powder composite concrete systems, which can easily cause fluctuations in concrete workability. Summary of the Invention

[0003] To address the aforementioned issues, this invention proposes a low-dosage self-healing waterproofing densifier for concrete. This densifier is formed through biomass fibers, ion complexation, and organosilicon crosslinking, further reducing performance degradation at low dosages without the need for additional fillers or additives.

[0004] The low-dosage self-healing waterproof and dense concrete agent of the present invention comprises the following components in parts by weight: 9-15 parts of ionic complexing agent, 4.5-7.5 parts of biomass ultrafine fiber powder, 4-6 parts of crosslinking agent, 6.5-11.5 parts of organosilicon resin, 12-20 parts of inorganic salt filler, 6.5-11.5 parts of calcium lactate, and 40-64 parts of solvent; The ionic complexing agent is composed of the following activated and modified compound in the following mass ratio: titanium isopropoxide: tetrabutyl titanate: tetraethyl orthosilicate = 2-3:3-4:4-5; the crosslinking agent is composed of dicumyl peroxide and vinyltriethoxysilane in a mass ratio of 1:1.2-1.5; the inorganic salt filler is composed of sodium silicate, sodium bentonite, calcium sulfate, and powdered quartz in a mass ratio of 2-3:3-4:2-3:1-2; the solvent is composed of ethanol, dibutyl phthalate, and n-propyl acetate in a mass ratio of 5-6:2-3:1-2; the dosage of the waterproofing and densifying agent is 0.25-0.3% of the total mass of the cementitious material. The preparation process of the densifying agent is as follows: S1 Preparation of Mixture A: First, add biomass ultrafine fiber powder and ion complexing agent into the solvent, then stir at a speed of 160-190 rpm for 9-11 min until the components are completely dispersed to obtain mixture A; S2 Preparation of Mixture B: Mix the crosslinking agent with the organosilicon resin and stir at 420-500 rpm for 9-11 minutes until the two components are completely mixed to obtain Mixture B; S3 Finished product homogenization preparation: Add mixture B dropwise to mixture A, add inorganic salt filler and calcium lactate in batches, and continue stirring until it is uniformly viscous, without layering or precipitation to obtain the finished waterproof and sealing agent. Calcium lactate provides the calcium ions needed for self-repair, while biomass microfibers guide water and calcium ions to migrate directionally to microcracks through capillary channels, prolonging the ion complexation reaction time and achieving a combination of physical filling and chemical crystallization.

[0005] Further, the biomass ultrafine fiber powder is one or more of industrial hemp fiber, sisal fiber, and agricultural and forestry straw fiber, which is ground to 800-1500 mesh after steam flash explosion treatment; the steam flash explosion treatment conditions for the biomass ultrafine fiber powder are: steam pressure 1.5-2.0 MPa, pressure holding time 3-5 min, instantaneous pressure release to obtain expanded fiber, which is then dried and ultrafine ground to the target mesh size; the activation and modification method of the ion complexing agent is as follows: titanium isopropoxide, tetrabutyl titanate, and tetraethyl orthosilicate are mixed in proportion, and glacial acetic acid accounting for 3-5% of the total mass of the ion complexing agent is added as a chelating agent at 40-50℃ and stirring speed 200-250 rpm. After the addition is completed, the activated and modified ion complexing agent is obtained.

[0006] Furthermore, the silicone resin is a polyalkyl silicone resin.

[0007] Further, the components include the following parts by weight: 12.1 parts of ionic complexing agent, 5.7 parts of biomass ultrafine fiber powder, 5.1 parts of crosslinking agent, 9.0 parts of organosilicon resin, 16.0 parts of inorganic salt filler, 9.0 parts of calcium lactate, and 52 parts of solvent.

[0008] Furthermore, during the densifying agent processing, the biomass ultrafine fiber powder and calcium lactate are simply mixed together. A large amount of calcium lactate dissociates prematurely during the mixing stage, leading to rapid early calcium consumption and insufficient calcium source for secondary cracking later. Therefore, the surface and pores of the biomass ultrafine fiber powder are impregnated with a calcium lactate filling layer under negative pressure. The specific process is as follows: the biomass ultrafine fiber powder, after flash-blast grinding, is soaked in a saturated calcium lactate aqueous solution, subjected to negative pressure adsorption for 30-40 minutes, left to stand at normal pressure for 2 hours, and then dried at 80℃.

[0009] Biomass ultrafine fiber powder simultaneously achieves physical anchoring and serves as a calcium ion enrichment carrier. Specifically, the modified biomass ultrafine fiber possesses capillary anchoring to fill microcracks, while simultaneously releasing calcium through fiber pores and surface-loaded calcium lactate, coupling in situ with an ion complexing agent to significantly increase local calcium ion concentration and accelerate crack crystallization and sealing. No additional calcium lactate dosage is required, and the continuity of crystallization products can be improved even at low dosages, as detailed below: The function of calcium lactate is: water-soluble organic calcium, which dissociates upon contact with water to release free calcium. 2+ The calcium source for the titanium-silicon ion complexing agent is provided, resulting in complexation precipitation and crystallization to seal microcracks. However, the diffusion of free calcium ions is untargeted, the calcium concentration at the crack is uneven, the crystallization is intermittent, and the repair cycle is long. Biomass ultrafine fiber powder relies on capillary action to adsorb water and physically fill cracks, restricting crack expansion. However, the fiber itself does not supply calcium ions and only acts as a physical barrier, unable to generate sealing crystals on its own. When water enters the crack, the water quickly seeps into the depth of the crack along the fiber capillary channels. The fiber network locks in the water, prolonging the duration of the complexation reaction. Calcium ions dissociated from calcium lactate are directionally transported to the crack cross-section along the fiber capillary channels, increasing the local calcium concentration. By blending biomass ultrafine fiber powder and calcium lactate, the crack has a certain degree of improved crystallization continuity and chemical self-repair ability, but the improvement ability is limited. Therefore, by impregnating biomass ultrafine fiber powder with calcium lactate under negative pressure, the functions of biomass ultrafine fiber powder and calcium lactate are complementary, as follows: Calcium lactate is adsorbed under negative pressure inside the pores of the flash-bursting fiber. The biomass ultrafine fiber powder has the dual function of anchoring the crack and acting as a slow-release calcium carrier. It releases calcium ions at specific points upon contact with water, significantly increasing the local calcium concentration and accelerating the precipitation of titanium-silicon complex crystals. The crystallized products tightly coat the fiber to form a composite sealing layer, while the fiber constrains crack expansion and prevents the crystal layer from becoming brittle. Furthermore, the fiber binds calcium lactate to achieve long-term slow release, solving the defects of current densifiers that deplete the calcium source early and have no ability to repair secondary cracks later. This simultaneously shortens the repair time, increases the number of repair cycles, and enhances the interfacial mechanical strength.

[0010] Furthermore, during the activation and modification process, the ionic complexing agent is chelated by the dropwise addition of glacial acetic acid. After the glacial acetic acid is added, the trace amounts of water contained in the glacial acetic acid are used for alkoxyl hydrolysis. The mixture is then kept warm and stirred for 25-30 minutes to enrich the active hydroxyl groups. Finally, it is cooled, sealed, and cured to obtain the ionic complexing agent. Specifically, during the activation and modification stage of the ionic complexing agent, trace amounts of hydrolyzed hydroxyl groups are introduced simultaneously with the glacial acetic acid chelation, enabling the modified titanium-silicon composite complexing agent to capture free CaO in concrete. 2+ While generating crystals to seal cracks, it can also act as a hydrolysis and crosslinking catalyst for organosilicon resin and crosslinking agent, reducing the activation energy of crosslinking and curing, and can quickly form a dense waterproof membrane even at low temperatures; the whole system does not require the addition of crosslinking accelerators, and the anti-seepage performance of low-temperature engineering is greatly improved.

[0011] Furthermore, the sodium-based bentonite in the inorganic salt filler is pre-activated by ion exchange with calcium lactate solution. Specifically, sodium-based bentonite and saturated calcium lactate solution are stirred at a solid-liquid ratio of 1:10 for 2 hours, filtered, and dried. After activation, the bentonite thickens and prevents stratification, improving the storage stability of the finished product. At the same time, it uses interlayer calcium ions as crystallization induction nuclei, reduces the nucleation barrier of calcium complex crystallization, and increases the crystal growth rate at micro-cracks. This can improve the storage stability period of the solidifying agent and simultaneously enhance the self-repair efficiency.

[0012] Further, the mixture B is added dropwise to the continuously stirred mixture A at a rate of 0.8-1.2 parts / minute, with the stirring speed controlled at 200 rpm during the dropwise addition stage; the system temperature is maintained at 25℃ throughout the dropwise addition process, and the inorganic salt filler is added simultaneously in two batches; after all mixture B has been added, the stirring speed is increased to 300 rpm, and stirring continues for 15 minutes until homogeneous, thus obtaining the finished product; the preparation process of the compacting agent completely adopts the above-mentioned S1-S3 preparation process, only refining the S3 dropwise addition parameters, without adding any new steps or additional raw materials; the specific process is as follows: S1 Preparation of mixture A: Add the biomass ultrafine fiber powder loaded with calcium lactate and the activated ion complexing agent to the compound solvent, stir at 175 rpm for 10 minutes, and the fiber is uniformly dispersed to obtain mixture A, with the system temperature controlled at 25℃; S2 Preparation of mixture B: Mix dicumyl peroxide and vinyltriethoxysilane into polyalkyl organosilicon resin in a certain proportion, and stir at 460 rpm for 10 minutes until homogeneous, thus obtaining the finished product. Completely miscible, resulting in a homogeneous oil phase mixture B; S3 involves stepwise controlled-rate dripping, specifically: mixture B is slowly dripped into continuously stirred mixture A at a rate of 0.8-1.2 parts / minute, with the stirring speed controlled at 200 rpm during the dripping stage; the system temperature is maintained at 25℃ throughout the dripping process, and the inorganic salt filler is added simultaneously in two batches; after all mixture B has been dripped, the stirring speed is increased to 300 rpm, and stirring continues for 15 minutes until homogeneous, yielding the finished product; the processing includes slow dripping and low-speed stages, during which silane molecules are gradually dispersed with the oil phase, preferentially migrating and adsorbing onto the surface of the modified fibers with polarity, utilizing the hydroxyl and calcium lactate polar groups on the fiber surface to complete the initial interfacial coupling bond; then, the accelerated curing stage is carried out, and when the silane concentration in the mixture is sufficient, a free radical cross-linking reaction is carried out to complete the bulk organosilicon waterproof film formation; when mixture B is dripped at a rate of 1 part / minute, the effective grafting rate of interfacial silane is not less than 35%; A step-by-step, rate-controlled dripping process is employed to achieve the dual effects of silane: a mixture B containing vinyltriethoxysilane is slowly dripped into a fiber-dispersed mixture A at a rate of 1 part / minute. During the dripping stage, the stirring speed is controlled at 200 rpm, allowing silane molecules to preferentially migrate to the surface of calcium lactate-modified fibers and undergo interfacial coupling. After the dripping is completed, the stirring speed is increased to 300 rpm for solidification, completing the bulk cross-linking and film formation of the organosilicon. In other words, by controlling the reaction sequence through the dripping rate, the same silane molecule can simultaneously participate in interfacial coupling and bulk film formation. During processing, no additional additives or steps are required; simply by adjusting the dripping rate and stirring speed, vinyltriethoxysilane can simultaneously possess the dual functions of cross-linking and film formation and interfacial anchoring.

[0013] Further, the preparation process of the mixture A is as follows: First, 52 parts of compound solvent are added to a mixing container, then 5.7 parts of calcium lactate-loaded modified fiber are added, and the mixture is stirred at a low speed of 100 rpm for 10 min for pre-wetting; then 12.1 parts of activated ion complexing agent are added, and the mixture is stirred at 175 rpm for 10 min. During the pre-wetting stage, the calcium lactate loaded on the fiber surface undergoes a small amount of pre-complexation with the complexing agent to pre-crystallize the precursor, thus obtaining mixture A.

[0014] Compared with the prior art, the low-dosage self-healing waterproof and densifying concrete agent of the present invention has the following advantages: 1. Significantly reduced application costs: The optimal dosage of the product has been reduced from 0.4% to 0.3% or less, a reduction of over 25%, which reduces production and engineering costs and makes it suitable for various infrastructure projects.

[0015] 2. Significantly improved self-healing efficiency of cracks: The modified ion complexing system has stronger calcium ion capture activity, and the ion complexing efficiency is increased by more than 30%. The response time for repairing micro-cracks within 0.4 mm is shortened by more than 20%, which can realize dynamic cyclic self-healing of cracks.

[0016] 3. Excellent and stable overall performance: It solves the problem of reduced waterproof, crack-resistant, and bonding and reinforcing performance under low dosage. The finished product can reach the P20 impermeability grade. It has excellent resistance to freezing, chloride ion and sulfate corrosion. It does not stratify or precipitate after 6 months of sealed storage at room temperature, and its performance remains unchanged.

[0017] 4. Wider range of engineering compatibility: It is compatible with various concrete systems such as ordinary silicate cement, fly ash, and mineral powder, and will not cause fluctuations in concrete workability. It is suitable for various engineering scenarios such as water conservancy, tunnels, pipe corridors, basements, and municipal structures.

[0018] 5. Significant component gain: Without adding any new components, the repair rate, interface strength, storage stability, and low-temperature film-forming performance are simultaneously improved, and the overall performance gain far exceeds the effect of single modification. Detailed Implementation

[0019] Example 1: The low-dosage self-healing waterproof and dense concrete agent of the present invention comprises the following components in parts by weight: 9-15 parts of ionic complexing agent, 4.5-7.5 parts of biomass ultrafine fiber powder, 4-6 parts of crosslinking agent, 6.5-11.5 parts of organosilicon resin, 12-20 parts of inorganic salt filler, 6.5-11.5 parts of calcium lactate, and 40-64 parts of solvent; The ionic complexing agent is composed of the following activated and modified compound in the following mass ratio: titanium isopropoxide: tetrabutyl titanate: tetraethyl orthosilicate = 2-3:3-4:4-5; the crosslinking agent is composed of dicumyl peroxide and vinyltriethoxysilane in a mass ratio of 1:1.2-1.5; the inorganic salt filler is composed of sodium silicate, sodium bentonite, calcium sulfate, and powdered quartz in a mass ratio of 2-3:3-4:2-3:1-2; the solvent is composed of ethanol, dibutyl phthalate, and n-propyl acetate in a mass ratio of 5-6:2-3:1-2; the dosage of the waterproofing and densifying agent is 0.25-0.3% of the total mass of the cementitious material. The preparation process of the densifying agent is as follows: S1 Preparation of Mixture A: First, add biomass ultrafine fiber powder and ion complexing agent into the solvent, then stir at a speed of 160-190 rpm for 9-11 min until the components are completely dispersed to obtain mixture A; S2 Preparation of Mixture B: Mix the crosslinking agent with the organosilicon resin and stir at 420-500 rpm for 9-11 minutes until the two components are completely mixed to obtain Mixture B; S3 Finished Product Homogenization Preparation: Add mixture B dropwise to mixture A, add inorganic salt filler and calcium lactate in batches, and continue stirring until it is uniformly viscous, without layering or precipitation to obtain the finished waterproof and sealing agent.

[0020] The biomass ultrafine fiber powder is one or more of industrial hemp fiber, sisal fiber, and agricultural and forestry straw fiber, which is ground to 800-1500 mesh after steam flash explosion treatment. The steam flash explosion treatment conditions for the biomass ultrafine fiber powder are: steam pressure 1.5-2.0 MPa, pressure holding time 3-5 min, instantaneous pressure release to obtain expanded fiber, which is then dried and ultrafine ground to the target mesh size. The activation and modification method of the ion complexing agent is as follows: titanium isopropoxide, tetrabutyl titanate, and tetraethyl orthosilicate are mixed in proportion, and glacial acetic acid accounting for 3-5% of the total mass of the ion complexing agent is added as a chelating agent at 40-50℃ and stirring speed 200-250 rpm. After the addition is completed, the activated and modified ion complexing agent is obtained.

[0021] The silicone resin is a polyalkyl silicone resin.

[0022] The components include the following parts by weight: 12.1 parts ion complexing agent, 5.7 parts biomass ultrafine fiber powder, 5.1 parts crosslinking agent, 9.0 parts organosilicon resin, 16.0 parts inorganic salt filler, 9.0 parts calcium lactate, and 52 parts solvent.

[0023] In the densifying agent processing, biomass ultrafine fiber powder and calcium lactate are simply mixed together. However, a large amount of calcium lactate dissociates prematurely during the mixing stage, resulting in rapid early calcium consumption and insufficient calcium source for secondary cracking in the later stage. Therefore, the surface and pores of the biomass ultrafine fiber powder are impregnated with a calcium lactate filling layer under negative pressure. The specific working process is as follows: the biomass ultrafine fiber powder after flash explosion grinding is soaked in a saturated calcium lactate aqueous solution, adsorbed under negative pressure for 30-40 minutes, left to stand under normal pressure for 2 hours, and dried at 80℃.

[0024] The role of calcium lactate is as follows: it is a water-soluble organic calcium that dissociates into free Ca upon contact with water. 2+ The calcium source for the titanium-silicon ion complexing agent is provided, resulting in complexation precipitation and crystallization to seal microcracks. However, the diffusion of free calcium ions is untargeted, the calcium concentration at the crack is uneven, the crystallization is intermittent, and the repair cycle is long. Biomass ultrafine fiber powder relies on capillary action to adsorb water and physically fill cracks, restricting crack expansion. However, the fiber itself does not supply calcium ions and only acts as a physical barrier, unable to generate sealing crystals on its own. When water enters the crack, the water quickly seeps into the depth of the crack along the fiber capillary channels. The fiber network locks in the water, prolonging the duration of the complexation reaction. Calcium ions dissociated from calcium lactate are directionally transported to the crack cross-section along the fiber capillary channels, increasing the local calcium concentration. By blending biomass ultrafine fiber powder and calcium lactate, the crack has a certain degree of improved crystallization continuity and chemical self-repair ability, but the improvement ability is limited. Therefore, by impregnating biomass ultrafine fiber powder with calcium lactate under negative pressure, the functions of biomass ultrafine fiber powder and calcium lactate are complementary, as follows: Calcium lactate is impregnated onto the fiber surface under negative pressure, solidifying the carrier and calcium source into a single unit. This addresses the issue of insufficient calcium concentration at low dosages through directional enrichment of calcium ions. Specifically, a large amount of calcium lactate is adsorbed and fixed onto the pores and surface of the biomass ultrafine fiber powder, forming an in-situ slow-release source in the cracks. This eliminates the need for a bulking agent to increase the overall lactate content, allowing for targeted release of calcium only at the water ingress points in the cracks. 2+The local calcium ion concentration is increased several times, significantly accelerating the crystallization and precipitation rate of the titanium-silicon complexing agent. Compared with the blended calcium lactate, calcium ions are evenly dispersed in the concrete matrix with the mixing water, resulting in a lower calcium concentration in the crack area. Furthermore, it enables load-bearing fiber coupling; when the crack encounters water, the calcium lactate on the surface of the biomass ultrafine fiber powder dissolves simultaneously, and the complexation reaction occurs instantly, shortening the repair response time by more than 25% (measured from 40 hours to 30 hours). It also possesses a dual sealing function combining physical anchoring and chemical crystallization, forming a dense layer in one step. The biomass ultrafine fiber powder acts as a fiber skeleton, first bridging the structure and supporting the crack cross-section, preventing… It stops the continuous expansion of cracks and provides an adhesion substrate for crystallization products; the calcium source dissolved from the fiber surface immediately forms a calcium complex crystal with the titanium-silicon complexing agent, which tightly wraps the fiber surface and forms a composite sealing skeleton of fiber and crystal; in addition, it has a long-term slow-release effect, which solves the problems of short-term calcium depletion and later repair failure. Due to the large amount of premature dissociation during the mixing stage of ordinary blended calcium lactate, the early calcium consumption is fast and there is no sufficient calcium source for secondary cracking in the later stage; by using mixed calcium lactate and biomass ultrafine fiber powder for negative pressure impregnation, the calcium lactate is bound by the fiber pores and only gradually dissolves when water enters the crack and water permeates, forming a slow release system and extending the long-term self-repair cycle; Furthermore, after industrial hemp / straw fibers undergo flash explosion at 1.5-2.0 MPa, the fiber cell walls are torn, forming numerous closed pores and micron-sized semi-closed capillary pores. Under normal pressure, air trapped within these pores creates air resistance, making it difficult for liquid to penetrate deep into the pores. Soaking under normal pressure only allows calcium lactate to adhere to the outer surface of the fiber, preventing it from entering the pores. This results in only a small amount of calcium lactate adhering to the outer surface of the fiber. When mixing concrete, the surface calcium dissolves rapidly, leading to an early depletion of calcium ions and a lack of calcium source for secondary cracking later. Therefore, after soaking biomass ultrafine fiber powder in a saturated calcium lactate aqueous solution, negative pressure adsorption is employed. This involves using a pressure difference to expel air from the pores, allowing the calcium lactate solution to deeply wet the pores, achieving a uniform high load inside and outside the fiber. Specifically, this is achieved by using a pressure difference of -0.07 to -0.09... The negative pressure environment of MPa extracts air from the fiber pores, eliminating air resistance. After restoring normal pressure, the external atmospheric pressure forces the saturated calcium lactate solution into all the micropores and grooves of the fiber, achieving deep impregnation inside and outside the channels. The internal pores of the fiber significantly increase the overall calcium lactate loading capacity and serve as a calcium source storage area. Calcium lactate only gradually dissolves when water slowly seeps into the channels, achieving a slow and long-term supply of calcium ions. This addresses the short-term repair and long-term failure defects of densifiers, constructing a long-term slow-release calcium source. Furthermore, the uniformity of loading is greatly improved; the negative pressure ensures that every microfiber and every segment of capillary uniformly adsorbs calcium lactate. When water enters through a 0.4mm microcrack, the water permeates along the fiber network, and calcium is simultaneously released from the fiber pores along the way. 2+The local calcium ion concentration at the crack cross-section is significantly increased, which greatly accelerates the crystallization and precipitation of the titanium-silicon complexing agent, and the repair response time can be shortened from 40h to 30h. Finally, after drying, the bond is strong and it is not easy to fall off during the mixing process. Only the calcium lactate adsorbed on the surface is easily washed away by water flow during stirring and mixing, and cannot be retained in the fiber network. The calcium lactate that seeps into the pores under negative pressure is embedded in the micropores inside the fiber in the form of crystals after drying. It has strong mechanical bonding force and is not easily lost during the high-speed mixing stage of concrete, ensuring that the fiber still has the function of slow-release calcium source at the crack.

[0025] During the activation and modification process, the ionic complexing agent is chelated by the dropwise addition of glacial acetic acid. After the glacial acetic acid is added, the trace amounts of water contained in the glacial acetic acid are used for alkoxyl hydrolysis. The mixture is then kept warm and stirred for 25-30 minutes to enrich the active hydroxyl groups. Finally, it is cooled, sealed, and cured to obtain the ionic complexing agent. Specifically, during the activation and modification stage of the ionic complexing agent, trace amounts of hydrolyzed hydroxyl groups are introduced simultaneously with the glacial acetic acid chelation, enabling the modified titanium-silicon composite complexing agent to capture free CaO in concrete. 2+ While generating crystals to seal cracks, it can also act as a hydrolysis and crosslinking catalyst for organosilicon resin and crosslinking agent, reducing the activation energy of crosslinking and curing, and can quickly form a dense waterproof membrane even at low temperatures; the whole system does not require the addition of crosslinking accelerators, and the anti-seepage performance of low-temperature engineering is greatly improved.

[0026] The ionic complexing agent is hydrolyzed by the trace amount of water contained in glacial acetic acid, introducing Ti-OH and Si-OH hydrolyzed hydroxyl groups. Specifically, titanium isopropoxide, tetrabutyl titanate, and tetraethyl orthosilicate are mixed and kept at a constant temperature of 43-47℃ in a sealed container. The stirring speed is 210-230 rpm, and glacial acetic acid, accounting for 3-5% of the total mass of titanium and silicon, is added dropwise at a rate of 2-3 mL / min. After the addition is completed, the temperature is maintained and stirred for 25-30 min. The trace amount of water contained in glacial acetic acid is used to achieve mild hydrolysis of alkoxy groups. After cooling and sealing for curing, a modified ionic complexing agent rich in active hydroxyl groups is obtained. The modified ionic complexing agent can capture free calcium ions in concrete to form calcium complex crystals to seal microcracks. At the same time, it can also rely on the surface hydrolyzed hydroxyl groups to catalyze the cross-linking and curing of organosilicon resin and cross-linking agent, reduce the cross-linking activation energy, and accelerate the formation of a dense waterproof membrane under low temperature conditions.

[0027] The sodium-based bentonite in the inorganic salt filler is pre-activated by ion exchange with calcium lactate solution. Specifically, sodium-based bentonite and saturated calcium lactate solution are stirred at a solid-liquid ratio of 1:10 for 2 hours, filtered, and dried. After activation, the bentonite thickens and prevents stratification, improving the storage stability of the finished product. At the same time, it uses interlayer calcium ions as crystallization induction nuclei, reduces the nucleation barrier of calcium complex crystallization, and increases the crystal growth rate at micro-cracks. This can improve the storage stability period of the solidifying agent and simultaneously enhance the self-repair efficiency.

[0028] The mixture B is added dropwise to the continuously stirred mixture A at a rate of 0.8-1.2 parts / minute, with the stirring speed controlled at 200 rpm during the dropwise addition stage. The system temperature is maintained at 25°C throughout the dropwise addition process, and the inorganic salt filler is added simultaneously in two batches. After all the mixture B has been added, the stirring speed is increased to 300 rpm, and stirring is continued for 15 minutes until homogeneous, thus obtaining the finished product. The preparation process of the compacting agent completely adopts the above-mentioned preparation processes S1-S3, only refining the dropwise addition parameters of S3, without adding any new steps or additional raw materials. The specific process is as follows: S1 Preparation of mixture A: Add the biomass ultrafine fiber powder loaded with calcium lactate and the activated ion complexing agent to the compound solvent, stir at 175 rpm for 10 minutes, and the fiber is uniformly dispersed to obtain mixture A, with the system temperature controlled at 25°C; S2 Preparation of mixture B: Mix dicumyl peroxide and vinyltriethoxysilane into polyalkyl organosilicon resin in a certain proportion, and stir at 460 rpm for 10 minutes until completely dissolved. The mixtures are miscible to obtain a homogeneous oil phase mixture B. S3 involves stepwise, rate-controlled dropwise addition, specifically: mixture B is slowly added dropwise to continuously stirred mixture A at a rate of 0.8-1.2 parts / minute, with the stirring speed controlled at 200 rpm during the dropwise addition stage; the system temperature is maintained at 25℃ throughout the dropwise addition process, and the inorganic salt filler is added simultaneously in two batches; after all mixture B has been added, the stirring speed is increased to 300 rpm, and stirring is continued for 15 minutes until homogeneous, yielding the finished product; the processing includes slow dropwise and low-speed stages, during which silane molecules are gradually dispersed with the oil phase and preferentially migrate and adsorb onto the surface of the modified fiber with polarity, utilizing the hydroxyl and calcium lactate polar groups on the fiber surface to complete the initial interfacial coupling bond; then, the accelerated curing stage is carried out, and when the silane concentration in the mixture is sufficient, a free radical cross-linking reaction is carried out to complete the bulk organosilicon waterproof film formation; when mixture B is added dropwise at a rate of 1 part / minute, the effective grafting rate of interfacial silane is not less than 35%; This embodiment employs a step-by-step, rate-controlled dripping process to achieve the dual effects of silane: a mixture B containing vinyltriethoxysilane is slowly dripped into a fiber-dispersed mixture A at a rate of 1 part / minute. During the dripping stage, the stirring speed is controlled at 200 rpm, allowing silane molecules to preferentially migrate to the surface of the calcium lactate-modified fiber and undergo interfacial coupling. After the dripping is completed, the stirring speed is increased to 300 rpm for solidification, completing the bulk cross-linking and film formation of the organosilicon. In other words, by controlling the reaction sequence through the dripping rate, the same silane molecule can simultaneously participate in interfacial coupling and bulk film formation. During processing, no additional additives or processes are required; simply by adjusting the dripping rate and stirring speed, vinyltriethoxysilane can simultaneously possess the dual functions of cross-linking and film formation and interfacial anchoring.

[0029] The preparation process of the mixture A is as follows: First, 52 parts of compound solvent are added to a mixing container, then 5.7 parts of calcium lactate-loaded modified fiber are added, and the mixture is stirred at a low speed of 100 rpm for 10 min for pre-wetting; then 12.1 parts of activated ion complexing agent are added, and the mixture is stirred at 175 rpm for 10 min. During the pre-wetting stage, the calcium lactate loaded on the fiber surface undergoes a small amount of pre-complexation with the complexing agent, and a pre-crystallization precursor is prepared to obtain mixture A; that is, this step enables the calcium source on the fiber surface to undergo a small amount of pre-complexation with the complexing agent through pre-wetting, and the repair reaction can be quickly activated when it comes into contact with water after being added to concrete.

[0030] Example 2: The preparation process of the low-dosage concrete self-healing waterproof and densifying agent in this embodiment is as follows: Preparation of ion complexing agent: The raw materials were weighed according to the mass ratio of titanium isopropoxide: tetrabutyl titanate: tetraethyl orthosilicate 2.5:3.5:4.0 and added to the reaction vessel. The stirring was started and the speed was controlled at 220 rpm, and the temperature was raised to 45℃. Glacial acetic acid, accounting for 4% of the total mass, was slowly added dropwise as a chelating agent at a rate of 2-3 mL / min. The temperature of the system was kept stable during the addition process. After the addition was completed, the mixture was kept warm and stirred for 25 min to allow partial pre-hydrolysis and chelation reactions of titanate and silicate esters to increase the number of active sites, thus obtaining the activated and modified ion complexing agent. After modification by this process, the capture activity of the complexing agent for free calcium ions was increased by more than 30%, the initiation time of the complexation reaction was shortened, and it could still maintain a high efficiency in crystallization repair even at low doping levels. Preparation of biomass ultrafine fiber powder: The biomass ultrafine fiber powder is made from agricultural and forestry straw fiber as raw material, through steam flash explosion and ultrafine grinding process. The specific process is as follows: First, the raw material fiber is cut to a length of 3-5cm, cleaned and impurities removed, and then placed in a flash explosion tank; then saturated steam is introduced, pressurized to 1.8MPa, and held for 4min to allow the steam to fully penetrate into the fiber interior; then the pressure relief valve is opened instantly, and the pressure inside the tank drops sharply to atmospheric pressure, the intercellular layer of the fiber is exploded and separated to obtain expanded coarse fiber; then the expanded fiber is dried at 80℃ to a moisture content of ≤5%, and then put into an ultrafine grinder for grinding to 1000 mesh to obtain biomass ultrafine fiber powder; after flash explosion treatment, the specific surface area of ​​the fiber increases, the exposure of surface active hydroxyl groups increases, and the capillary adsorption and physical anchoring effect is enhanced, which can effectively assist calcium ion anchoring and crystal growth, and compensate for the performance loss under low doping; Crosslinking agent preparation: Dicumyl peroxide and vinyltriethoxysilane are compounded at a mass ratio of 1:1.3, which has the dual function of free radical crosslinking and siloxane crosslinking, and forms a dense crosslinking network in synergy with organosilicon resin; The inorganic salt filler is prepared by compounding sodium silicate, sodium bentonite, calcium sulfate, and powdered quartz in a mass ratio of 2.5:3.5:2.5:1.5 to achieve crystal nucleation, thickening, thixotropic and filling compaction effects. Solvent preparation: Ethanol, dibutyl phthalate, and n-propyl acetate are compounded in a mass ratio of 5.5:2.5:2.0, which has solubility, volatility and system compatibility, and ensures uniform dispersion of each component; Organosilicon resin: Polyalkyl organosilicon resin, solid content ≥98%, hydroxyl value 30~50mgKOH / g.

[0031] The low-dosage self-healing waterproofing and densifying agent for concrete in this embodiment has the following composition ratio by weight: 9 parts ion complexing agent, 4.5 parts biomass ultrafine fiber powder, 4 parts crosslinking agent, 6.5 parts organosilicon resin, 12 parts inorganic salt filler, 6.5 parts calcium lactate, and 40 parts solvent; the preparation method is as follows: S1 Preparation of Mixture A: Biomass ultrafine fiber powder and ion complexing agent are slowly added to the compound solvent and stirred at 160 rpm for 11 min until the components are completely dispersed to obtain Mixture A; S2 Preparation of Mixture B: Mix the crosslinking agent with the organosilicon resin and stir at 420 rpm for 11 min until the two components are completely mixed to obtain Mixture B; S3 Finished Product Homogenization Preparation: Slowly and uniformly add mixture B to mixture A, add inorganic salt filler and calcium lactate in batches, and continue stirring until the system is uniformly viscous, without layering or precipitation, to obtain the finished product.

[0032] Example 3: The low-dosage concrete self-healing waterproofing and densifying agent of this embodiment has the following composition ratio by mass: 12 parts ion complexing agent, 5.5 parts biomass ultrafine fiber powder, 5 parts crosslinking agent, 9 parts organosilicon resin, 16 parts inorganic salt filler, 9 parts calcium lactate, and 52 parts solvent; the preparation method is the same as in Example 2.

[0033] Example 4: The low-dosage self-healing waterproof and dense concrete agent of this embodiment has the following composition ratio by mass: 15 parts ion complexing agent, 7.5 parts biomass ultrafine fiber powder, 6 parts crosslinking agent, 11.5 parts organosilicon resin, 20 parts inorganic salt filler, 11.5 parts calcium lactate, and 64 parts solvent; the preparation method is the same as in Example 2.

[0034] Example 5: The low-dosage self-healing waterproof and dense concrete agent of this embodiment has the following composition ratio by mass: 12.1 parts ion complexing agent, 5.7 parts biomass ultrafine fiber powder, 5.1 parts crosslinking agent, 9.0 parts organosilicon resin, 16.0 parts inorganic salt filler, 9.0 parts calcium lactate, and 52 parts solvent; the preparation method is the same as in Example 2.

[0035] Comparative Example 1: The dosage was 0.4% of the mass of the cementitious material, and the composition ratio was: 12 parts of ionic complexing agent, 5.5 parts of biomass ultrafine fiber powder (500 mesh), 5 parts of crosslinking agent, 9 parts of organosilicon resin, 16 parts of inorganic salt filler, 9 parts of calcium lactate, and 52 parts of solvent; it was prepared by conventional one-step mixing method.

[0036] Performance testing: The densifiers from Examples 2-5 and Comparative Example 1 were added to ordinary Portland cement concrete at the corresponding dosages. Testing was conducted according to the standards "Mortar and Concrete Waterproofing Agents," "Concrete Admixtures," and "Test Methods for Concrete Permeability." The results are shown in Table 1. Table 1: Performance Test Tables for Examples and Comparative Examples

[0037] The test results show that the overall performance of the embodiments of the present invention at a low dosage of 0.3% is better than or equal to that of the comparative products at a dosage of 0.4%. Among them, Example 5 has the best overall performance in terms of impermeability, freeze resistance, compatibility and storage stability, achieving a dosage reduction of 0.3% or less of the total mass of cementitious materials, with a dosage reduction of more than 25%. At the same time, the ion complexation efficiency is improved by more than 30%, the repair response time of micro-cracks within 0.4mm is shortened by more than 20%, and the impermeability grade can reach P20.

[0038] Example 6: This embodiment is based on the components of Example 5, and the specific implementation method is as follows: the straw fiber, which is flash-milled to 1200 mesh, is soaked in a saturated calcium lactate aqueous solution, adsorbed under a negative pressure of -0.08 MPa for 35 min, left to stand at normal pressure for 2 h, and dried at 80℃ until the moisture content is ≤5%; the biomass ultrafine fiber powder in Example 5 is replaced with the original mass fraction, and the remaining components and preparation process are the same as in Example 5; the biomass ultrafine fiber powder in this embodiment retains the physical anchoring and filling effect, and can also slowly release calcium ions at the cracks, and couple with the complexing agent in situ to accelerate crystallization.

[0039] Example 7: This embodiment is based on the components of Example 5, and the specific implementation method is as follows: When ion complexing agent is activated, after the glacial acetic acid is added dropwise, the heat preservation and stirring time is extended to 30 min to control the degree of hydrolysis and introduce an appropriate amount of active hydroxyl groups; the remaining components and processes are the same as in Example 5; the modified complexing agent not only captures calcium ion crystallization, but also catalyzes organosilicon crosslinking and curing, and the low-temperature film-forming performance is significantly improved.

[0040] Example 8: This embodiment is based on the components of Example 5, and the specific implementation method is as follows: Sodium-based bentonite and saturated calcium lactate solution are stirred at a solid-liquid ratio of 1:10 for 2 hours, filtered, dried at 105°C, and ground to 300 mesh; the bentonite in Example 5 is replaced with the original mass fraction, and the remaining components and processes are the same as in Example 5; after activation, the bentonite not only thickens and prevents delamination, but also uses interlayer calcium ions as crystal nuclei to accelerate crystal growth at cracks.

[0041] Example 9: This embodiment is based on the components of Example 5, and the specific implementation method is as follows: keeping the crosslinking agent ratio and components unchanged, only in the preparation process, a controlled-rate dripping process is adopted, in which the mixture B containing vinyltriethoxysilane is slowly dripped into the fiber-dispersed mixture A at a rate of 1 part / minute. During the dripping stage, the stirring speed is controlled at 200 rpm. Relying on the difference in the dripping sequence, the silane molecules preferentially migrate to the surface of the calcium lactate modified fiber and undergo interfacial coupling; subsequently, the organosilicon bulk crosslinking film is completed, and waterproof film formation and fiber interface anchoring are achieved simultaneously.

[0042] Example 10: This embodiment is based on the components of Example 5, and the specific implementation method is as follows: The straw fiber processed in Example 6 replaces the biomass ultrafine fiber powder in Example 5, and an appropriate amount of active hydroxyl groups are introduced during ion complexation activation according to Example 7; the sodium-based bentonite processed in Example 8 replaces the bentonite in Example 5 according to the original mass proportions, and the remaining components are the same as in Example 5; the preparation method of this embodiment is as follows: S1 Pre-impregnation: First, add 52 parts of solvent, then add 5.7 parts of calcium lactate-loaded modified fiber, and stir at low speed of 100 rpm for 10 min to pre-impregnate; then add 12.1 parts of activating ion complexing agent, and stir at 175 rpm for 10 min to obtain mixture A. S2 is the same as step S2 in Example 5; S3 Finished Product Homogenization: Add mixture B dropwise to mixture A at a rate of 1 part / minute. Add 16.0 parts of inorganic salt filler and 9.0 parts of calcium lactate in 3 portions, and stir at 300 rpm for 15 minutes until the system is uniform and viscous to obtain the finished product. Then, test according to "Mortar and Concrete Waterproofing Agent", "Concrete Admixtures" and "Test Method for Concrete Permeability". The results are shown in Table 2. Table 2: Performance Test Tables for Examples 5 to 10

[0043] As shown in Table 2, the formulation of Example 6 is exactly the same as that of Example 5, except that the flash-bursting fiber is replaced with calcium lactate negative pressure impregnation modified fiber, while the other raw materials and preparation process remain unchanged. The crack repair response is shortened to 30 hours (25% reduction), the fiber-matrix interface bonding strength is increased by 14%, and the storage stability is maintained for 6 months without increasing the raw material cost or changing the dosage, while simultaneously enhancing both repair and crack resistance properties. The raw material ratio of Example 7 is the same as that of Example 5, except that the ion complexing agent activation process is adjusted. The trace moisture contained in glacial acetic acid and the glacial acetic acid heat preservation and stirring time are extended to introduce hydrolyzed hydroxyl groups. The crosslinking speed of organosilicon is increased by 32% at a low temperature of 5°C, the concrete impermeability grade is increased to P23, the complexed calcium ion capture efficiency is increased by an additional 12%, and the components simultaneously catalyze crosslinking and complexation crystallization. The formulation of Example 8 is the same as that of Example 5, except that the inorganic salt filler is used. Sodium-based bentonite is activated by calcium lactate ion exchange, resulting in a stable product that remains stratified for 12 months during storage. The rate of crack crystallization and nucleation is increased by 28%, simultaneously addressing the two major shortcomings of easy sedimentation during storage and slow repair crystallization. A single filler achieves stability and self-healing. Example 9 employs a step-by-step, rate-controlled dripping process to achieve the dual effect of silane, increasing the 28-day tensile strength of concrete by 12%. A 0.4mm crack can be repaired in 5 cycles, and the crosslinking component simultaneously achieves waterproof film formation and fiber anchoring. Example 10 is a combination of Examples 5 to 9, with the same formulation proportions as Example 5. Its overall performance is as follows: repair response 26 hours, 12-month storage, low-temperature impermeability (P25), 6 cycles of repair, and a 15% increase in tensile strength. Compared to any of Examples 5 to 9, Example 10 shows a significant and simultaneous optimization of all performance characteristics without any reduction in individual performance indicators.

[0044] The above embodiments are merely preferred embodiments of the present invention. Therefore, all equivalent changes or modifications made to the structure, features and principles described in the claims of the present invention are included within the scope of the present invention.

Claims

1. A low-dosage self-healing waterproof and densifying agent for concrete, characterized in that, The product comprises the following components in parts by weight: 9-15 parts ion complexing agent, 4.5-7.5 parts biomass ultrafine fiber powder, 4-6 parts crosslinking agent, 6.5-11.5 parts organosilicon resin, 12-20 parts inorganic salt filler, 6.5-11.5 parts calcium lactate, and 40-64 parts solvent. The ionic complexing agent is composed of the following activated and modified compound in the following mass ratio: titanium isopropoxide: tetrabutyl titanate: tetraethyl orthosilicate = 2-3:3-4:4-5; the crosslinking agent is composed of dicumyl peroxide and vinyltriethoxysilane in a mass ratio of 1:1.2-1.5; the inorganic salt filler is composed of sodium silicate, sodium bentonite, calcium sulfate, and powdered quartz in a mass ratio of 2-3:3-4:2-3:1-2; the solvent is composed of ethanol, dibutyl phthalate, and n-propyl acetate in a mass ratio of 5-6:2-3:1-2. The preparation process of the densifying agent is as follows: S1 Preparation of Mixture A: First, add biomass ultrafine fiber powder and ion complexing agent into the solvent, then stir at a speed of 160-190 rpm for 9-11 min until the components are completely dispersed to obtain mixture A; S2 Preparation of Mixture B: Mix the crosslinking agent with the organosilicon resin and stir at 420-500 rpm for 9-11 minutes until the two components are completely mixed to obtain Mixture B; S3 Finished Product Homogenization Preparation: Add mixture B dropwise to mixture A, add inorganic salt filler and calcium lactate in batches, and continue stirring until it is uniformly viscous, without layering or precipitation to obtain the finished waterproof and sealing agent.

2. The low-dosage self-healing waterproof and densifying concrete agent according to claim 1, characterized in that: The biomass ultrafine fiber powder is one or more of industrial hemp fiber, sisal fiber, and agricultural and forestry straw fiber, which is ground to 800-1500 mesh after steam flash explosion treatment. The steam flash explosion treatment conditions for the biomass ultrafine fiber powder are: steam pressure 1.5-2.0 MPa, pressure holding time 3-5 min, instantaneous pressure release to obtain expanded fiber, which is then dried and ultrafine ground to the target mesh size. The activation and modification method of the ion complexing agent is as follows: titanium isopropoxide, tetrabutyl titanate, and tetraethyl orthosilicate are mixed in proportion, and glacial acetic acid accounting for 3-5% of the total mass of the ion complexing agent is added as a chelating agent at 40-50℃ and stirring speed 200-250 rpm. After the addition is completed, the activated and modified ion complexing agent is obtained.

3. The low-dosage self-healing waterproof and densifying concrete agent according to claim 1, characterized in that: The silicone resin is a polyalkyl silicone resin.

4. The low-dosage self-healing waterproof and densifying concrete agent according to claim 1, characterized in that: The components include the following parts by weight: 12.1 parts ion complexing agent, 5.7 parts biomass ultrafine fiber powder, 5.1 parts crosslinking agent, 9.0 parts organosilicon resin, 16.0 parts inorganic salt filler, 9.0 parts calcium lactate, and 52 parts solvent.

5. The low-dosage self-healing waterproof and densifying concrete agent according to claim 4, characterized in that: The surface and pores of the biomass ultrafine fiber powder are impregnated with a calcium lactate layer under negative pressure. The specific working process is as follows: the biomass ultrafine fiber powder after flash explosion grinding is soaked in a saturated calcium lactate aqueous solution, adsorbed under negative pressure for 30-40 minutes, left to stand under normal pressure for 2 hours, and dried at 80℃.

6. The low-dosage self-healing waterproof and densifying concrete agent according to claim 5, characterized in that: During the activation and modification process, the ionic complexing agent is chelated by adding glacial acetic acid dropwise. After the glacial acetic acid is added, the alkoxy groups are hydrolyzed by the trace amount of water contained in the glacial acetic acid. The mixture is then kept warm and stirred for 25-30 minutes to enrich the active hydroxyl groups. Finally, it is cooled, sealed, and cured to obtain the ionic complexing agent.

7. The low-dosage self-healing waterproof and densifying concrete agent according to claim 6, characterized in that: The sodium-based bentonite in the inorganic salt packing is pre-activated by ion exchange with calcium lactate solution, specifically by stirring sodium-based bentonite and saturated calcium lactate solution at a solid-liquid ratio of 1:10 for 2 hours, followed by filtration and drying.

8. The low-dosage self-healing waterproof and densifying concrete agent according to claim 7, characterized in that: The mixture B is added dropwise to the continuously stirred mixture A at a rate of 0.8-1.2 parts / minute, with the stirring speed controlled at 200 rpm during the dropwise addition stage. The system temperature is maintained at 25°C throughout the dropwise addition process, and the inorganic salt filler is added simultaneously in two batches. After all the mixture B has been added, the stirring speed is increased to 300 rpm, and stirring is continued for 15 minutes until homogeneous, thus obtaining the finished product.

9. The low-dosage self-healing waterproof and densifying concrete agent according to claim 8, characterized in that: The preparation process of the mixture A is as follows: First, 52 parts of compound solvent are added to the mixing container, then 5.7 parts of calcium lactate-loaded modified fiber are added, and the mixture is stirred at a low speed of 100 rpm for 10 min for pre-wetting; then 12.1 parts of activated ion complexing agent are added, and the mixture is stirred at 175 rpm for 10 min. During the pre-wetting stage, the calcium lactate loaded on the fiber surface undergoes a small amount of pre-complexation with the complexing agent to prepare a pre-crystallization precursor, thus obtaining mixture A.

10. The low-dosage concrete self-healing waterproofing and densifying agent according to any one of claims 1 to 9, characterized in that: The dosage of the waterproofing and densifying agent is 0.25-0.3% of the total mass of the cementitious material.

Images