Cement mortar based on recycled basalt fibers and recycled concrete, and preparation method and application thereof, and composite repair coating system

Abstract

The application provides a cement mortar based on recycled basalt fiber and recycled concrete as well as a preparation method and application thereof and a composite repair coating system, and belongs to the technical field of building materials. In the application, a large amount of activated recycled concrete is used to replace traditional cement, the matrix toughness of the modified recycled basalt fiber reinforced cement mortar is supplemented, and silica ash and modified SiO2 are used to improve the compactness of the mixture, so that the synergistic optimization of high toughness, high strength and low carbon emission is realized. The 28d compressive strength of the cement mortar provided by the application is greater than or equal to 60MPa, the bending strength is greater than or equal to 20MPa, the dry shrinkage rate is less than or equal to 0.1%, the carbon emission is reduced by about 40% compared with that of the traditional cement mortar, and the high-value-added utilization and high-performance green application of building solid waste are realized.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to a cement mortar based on recycled basalt fiber and recycled concrete, its preparation method and application, and a composite repair coating system. Background Technology

[0002] The cement industry is a source of carbon emissions, with traditional cement mortar production consuming large amounts of natural resources and emitting significant amounts of carbon dioxide. Meanwhile, building demolition generates massive amounts of waste concrete and waste basalt fiber products, whose landfill disposal occupies land and pollutes the environment. How to utilize these two types of solid waste for high-value resource recovery, while simultaneously achieving high-performance and low-carbon building materials, is an important research direction in the current building materials field.

[0003] Currently, there are studies on using recycled concrete powder (RCP) prepared from waste concrete to replace part of the cement. However, RCP has low activity and high water demand, and high admixture (45~50wt%) will lead to a significant decrease in mortar strength and durability. On the other hand, basalt fiber is a high-performance inorganic fiber, but its waste short fiber or waste basalt fiber powder (RBFP) is usually discarded. In addition, the interfacial bond between RBFP and cement matrix is ​​weak and it is easy to agglomerate. Direct incorporation often leads to a decrease in strength. Summary of the Invention

[0004] The purpose of this invention is to provide a cement mortar based on recycled basalt fiber and recycled concrete, its preparation method and application. This invention utilizes recycled concrete and recycled basalt fiber as supplementary cementitious materials and reinforcing cores to partially replace cement and mineral powder in traditional formulations. It can significantly improve the cementitious activity of RCP and improve the dispersibility and interfacial bonding of RBFP in the cement matrix, thereby preparing a new type of cement mortar with high strength, high toughness, low shrinkage and significant low carbon benefits.

[0005] To achieve the objectives of this invention, the following technical solutions are provided: A cement mortar based on recycled basalt fiber and recycled concrete comprises the following raw materials in parts by weight: 500-550 parts cement, 450-500 parts activated recycled concrete, 250-300 parts modified recycled basalt fiber, 350-400 parts quartz sand, 80-100 parts silica fume, 20-33 parts water-reducing agent, 210-250 parts water, 6-10 parts modified SiO2, and 1-3 parts dispersant. The modified recycled basalt fiber is a silane coupling agent modified recycled basalt fiber, and the specific surface area of ​​the modified recycled basalt fiber is ≥500 m². 2 / kg; The activated recycled concrete is prepared by sequentially carbonizing and thermally activating waste concrete.

[0006] Preferably, the carbonization activation is carried out in a CO2 atmosphere with a CO2 concentration of 20-30% for 2-4 hours. The thermal activation temperature is 600~750℃, and the time is 30~60min.

[0007] Preferably, the silane coupling agent includes one of KH550, KH560 and KH570; the mass of the silane coupling agent is 1.0 to 2.5% of the mass of the regenerated basalt fiber.

[0008] Preferably, the method for preparing the modified recycled basalt fiber includes the following steps: Modified regenerated basalt fibers are obtained by mixing and modifying them with an ethanol solution of a silane coupling agent; the mixing and modification temperature is 40~60℃ and the time is 1~2h.

[0009] Preferably, the concentration of the ethanol solution of the silane coupling agent is 1.0~2.5wt%.

[0010] Preferably, the modified SiO2 is silane coupling agent surface-modified nano-SiO2 with an average particle size of 15~30 nm.

[0011] Preferably, the quartz sand is graded quartz sand with a particle size range of 0.15~0.6mm; The silica fume has a fineness of 200-400 mesh.

[0012] This invention also provides a method for preparing cement mortar based on recycled basalt fiber and recycled concrete as described in the above technical solution, comprising the following steps: The cement mortar is obtained by mixing cement, activated recycled concrete, quartz sand, silica fume, modified recycled basalt fiber, modified SiO2, dispersant, water-reducing agent and water.

[0013] The present invention also provides the application of the cement mortar based on recycled basalt fiber and recycled concrete as described in the above technical solution, or the cement mortar prepared by the preparation method described in the above technical solution, in building engineering, road engineering, or precast components.

[0014] The present invention also provides a composite repair coating system, which comprises, from bottom to top, a bottom leveling mortar layer, a middle reinforcing mesh cloth, a surface protective cloth, and a topcoat mortar; the bottom leveling mortar layer is formed by the cement mortar based on recycled basalt fiber and recycled concrete as described in the above technical solution or the cement mortar prepared by the preparation method described in the above technical solution.

[0015] This invention provides a cement mortar based on recycled basalt fiber and recycled concrete, comprising the following raw materials in parts by weight: 500-550 parts cement, 450-500 parts activated recycled concrete, 250-300 parts modified recycled basalt fiber, 350-400 parts quartz sand, 80-100 parts silica fume, 20-33 parts water-reducing agent, 210-250 parts water, 6-10 parts modified SiO2, and 1-3 parts dispersant; the modified recycled basalt fiber is silane coupling agent modified recycled basalt fiber; the activated recycled concrete is prepared from waste concrete through sequential carbonization activation and thermal activation. This invention uses a large amount of activated RCP to replace cement (replacement rate of approximately 45%-50%), significantly reducing cement usage and carbon emissions. The carbonization-thermal activation synergistic treatment of this invention can effectively decompose the inert hydration products in RCP, exposing active CaO and SiO2, and improving its cementitious activity. Modified recycled basalt fiber powder originates from the recycling of waste basalt fibers. After surface modification with a silane coupling agent, the fiber surface roughness increases, enhancing the interfacial bonding ability with the cement matrix and effectively playing a bridging and crack-preventing role. Modified SiO2 and silica fume work synergistically to fill matrix pores, promote hydration reactions, and improve density and strength.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1) Synergistic Enhancement of High Strength and High Toughness: This invention achieves synergistic optimization of high strength and high toughness in cement mortar through multiple reinforcement and toughening mechanisms. The resulting cement mortar has a 28-day compressive strength ≥60MPa, reaching or even exceeding the strength grade of ordinary structural concrete; its flexural strength ≥20MPa, approximately 2.5 times that of traditional cement mortar, significantly improving the material's resistance to flexural failure. Regarding the toughness enhancement mechanism, modified recycled basalt fibers form a three-dimensional randomly distributed network in the matrix. When microcracks occur in the matrix, the fibers transmit stress and dissipate fracture energy through bridging, effectively preventing crack propagation and penetration. Silane coupling agent modification treatment enables chemical bonding and mechanical interlocking between the fibers and the cement matrix, increasing the interfacial bond strength by more than 30%, preventing direct fiber pull-out, and fully leveraging the reinforcing and toughening effects of the fibers. Regarding the densification effect, modified nano-SiO2 and silica fume synergistically fill the nano- and micro-sized pores between cement particles, making the matrix structure denser and reducing stress concentration points, thereby improving toughness while increasing strength. Tests show that the drying shrinkage rate of the cement of this invention is ≤0.1%, which is more than 50% lower than that of traditional mortar, and it has excellent volume stability. 2) Significant Low-Carbon and Environmental Benefits: In terms of carbon emission reduction, compared to traditional pure cement mortar, this invention reduces cement usage by approximately 45% to 50%, resulting in a reduction of approximately 400 to 500 kg of cement per cubic meter of mortar. Based on the calculation that each ton of cement production emits approximately 0.8 tons of CO2, each cubic meter of mortar can reduce CO2 emissions by approximately 320 to 400 kg, resulting in an overall carbon emission reduction of approximately 40%. This carbon emission reduction effect is among the leading levels in similar recycled material products. Regarding solid waste resource utilization, this invention extensively utilizes two main types of construction solid waste—waste concrete and waste basalt fiber. The activated recycled concrete has a high admixture content, roughly equivalent to that of traditional cement, realizing the transformation of waste concrete from "low-value landfill" to "high-value utilization." The recycling of waste basalt fiber solves the industry pain point of difficult waste disposal of fiber composite materials and expands the green circular path of basalt fiber throughout its entire life cycle. In terms of energy consumption optimization, the carbonization-thermal activation synergistic treatment process adopted in this invention has a further geothermal activation temperature of only 600~750℃, which is far lower than the 1450℃ of cement clinker calcination, and the processing time is short, resulting in a significant reduction in overall energy consumption. 3) Synergistic Effects and Performance Optimization of Multi-Components: Regarding the synergistic effect of the cementitious system, activated RCP and ordinary silicate cement form a composite cementitious system. The active SiO2 and CaO in RCP undergo a secondary hydration reaction with Ca(OH)2 produced during cement hydration, generating additional CSH gel, which not only improves strength but also refines the pore structure. The pre-carbonization followed by thermal activation process creates an active intermediate phase with a "memory effect" in RCP, increasing hydration activity by 20%–30% compared to single activation treatment. In terms of micro / nano-scale synergy, silica fume (micrometer-scale) and modified nano-SiO2 (nanometer-scale) form a continuous gradation filling effect. SiO2 fills the interlayer pores of the CSH gel, while silica fume fills the voids between cement particles. Their synergistic effect reduces the porosity of the matrix by more than 40%, significantly reducing the proportion of harmful pores (>100 nm), fundamentally improving the material's durability and mechanical properties. Regarding fiber-matrix interface synergy, silane coupling agent modification acts simultaneously on both the fiber surface and the SiO2 surface, enabling them to form a "bridging structure" during dispersion. Modified SiO2 can preferentially adsorb on the modified fiber surface, further strengthening the interfacial transition zone between the fiber and the matrix, forming a multi-level interfacial reinforcement structure; 4) Excellent dispersibility and workability: Addressing the technical challenge of easy agglomeration of recycled materials and nanomaterials, this invention ensures the workability and uniformity of the material through the synergistic effect of surface modification and dispersants. Regarding dispersibility, the modified nano-SiO2, after surface modification with a silane coupling agent, has reduced surface energy and weakened agglomeration tendency; combined with the steric hindrance effect of dispersants such as sodium carboxymethyl cellulose, the nanoparticles and fiber powders are uniformly dispersed in the cement paste. Flowability tests show that the initial flowability of the mortar of this invention can reach 180~200 mm, meeting construction requirements. Regarding water-reducing agent compatibility, the polycarboxylate water-reducing agent has good compatibility with the modified material system, maintaining good workability while ensuring a low water-cement ratio (approximately 0.23~0.25), providing a prerequisite for high-strength development. 5) Good technical and economic efficiency: This invention not only has significant environmental benefits but also good economic feasibility. Waste concrete and waste basalt fiber are industrial wastes with extremely low raw material costs; the activation treatment process is simple and controllable, and the equipment investment is moderate; the added value brought by the improved product performance far exceeds the increase in cost. Taking into account the savings in raw materials, the reduction in solid waste treatment costs, and the premium in product performance, this invention has significant comprehensive economic benefits. Detailed Implementation

[0017] This invention provides a cement mortar based on recycled basalt fiber and recycled concrete, comprising the following raw materials in parts by weight: 500-550 parts cement, 450-500 parts activated recycled concrete, 250-300 parts modified recycled basalt fiber, 350-400 parts quartz sand, 80-100 parts silica fume, 20-33 parts water-reducing agent, 210-250 parts water, 6-10 parts modified SiO2, and 1-3 parts dispersant; The modified recycled basalt fiber is a silane coupling agent modified recycled basalt fiber, and the specific surface area of ​​the modified recycled basalt fiber is ≥500 m². 2 / kg; The activated recycled concrete is prepared by sequentially carbonizing and thermally activating waste concrete.

[0018] In this invention, unless otherwise specified, all raw materials used in the preparation are commercially available products well known to those skilled in the art.

[0019] In this invention, the raw materials of the cement mortar include 500-550 parts of cement by weight, which may be 510, 520, 530 or 545 parts in specific embodiments; the cement is silicate cement.

[0020] In this invention, the raw materials of the cement mortar, based on the mass fraction of cement, include 450-500 parts of activated recycled concrete, which may be 470 or 480 parts in specific embodiments; the activated recycled concrete is prepared from waste concrete through sequential carbonation activation and thermal activation; the CO2 concentration of the carbonation activation is 20-30 wt%, and the time is 2-4 h; the temperature of the thermal activation is 600-750 °C, and the time is 30-60 min.

[0021] In this invention, the raw materials of the cement mortar, based on the mass fraction of cement, include 250-300 parts of modified recycled basalt fiber, and in specific embodiments, this can be 280 or 290 parts; the specific surface area of ​​the modified recycled basalt fiber is ≥500 m². 2 / kg; the silane coupling agent includes one of KH550, KH560 and KH570; the mass of the silane coupling agent is 1.0~2.5% of the mass of the regenerated basalt fiber.

[0022] In this invention, the method for preparing the modified recycled basalt fiber includes the following steps: Waste basalt fibers are mixed and modified with a silane coupling agent ethanol solution to obtain modified regenerated basalt fibers; the mixing and modification temperature is 40~60℃ and the time is 1~2h; the concentration of the silane coupling agent ethanol solution is 1.0~2.5wt%.

[0023] In this invention, the raw materials of the cement mortar, based on the mass fraction of cement, include 6-10 parts of modified SiO2, and in specific embodiments, it may be 7 or 8 parts; the modified SiO2 is silane coupling agent-modified hydrophilic nano-SiO2 with an average particle size of 15-30 nm; the specific surface area of ​​the modified SiO2 is ≥150 m². 2 / g; the silane coupling agent is the same as the above-mentioned silane coupling agent, and will not be described again here; the preparation method of the modified SiO2 includes the following steps: SiO2 was dispersed in ethanol, a silane coupling agent was added, and the mixture was reacted at 50-70℃ for 2-4 hours. After centrifugation, washing, and drying, modified SiO2 was obtained.

[0024] In this invention, the raw materials of the cement mortar include 350-400 parts of quartz sand, based on the mass of cement, and the quartz sand is graded quartz sand with a particle size range of 0.15-0.6 mm. In this invention, the raw materials of the cement mortar include 80 to 100 parts of silica fume by mass of cement, and in specific embodiments, these can be 83, 87, 90, or 95 parts; the fineness of the silica fume is 200 to 400 mesh.

[0025] In this invention, the raw materials of the cement mortar include 20 to 33 parts of water-reducing agent based on the mass of cement, and in specific embodiments, it can be 25, 28, or 30 parts; the water-reducing agent is a polycarboxylate-based high-efficiency water-reducing agent with a water reduction rate of 35 to 40%.

[0026] In this invention, the raw materials of the cement mortar include 1 to 3 parts of dispersant based on the mass of cement, which may be 2 or 2.5 parts in specific embodiments; the water-reducing agent is sodium carboxymethyl cellulose (CMC) or polyvinyl alcohol (PVA).

[0027] In this invention, the raw materials of the cement mortar also include 2 to 5 parts of an early-strength agent, which may be 3 or 4 parts in a specific embodiment; the early-strength agent is triethanolamine.

[0028] This invention also provides a method for preparing cement mortar based on recycled basalt fiber and recycled concrete as described in the above technical solution, comprising the following steps: The cement mortar is obtained by mixing cement, activated recycled concrete, quartz sand, silica fume, modified recycled basalt fiber, modified SiO2, dispersant, water-reducing agent and water.

[0029] In this invention, the mixing specifically includes: adding cement, activated recycled concrete, quartz sand and silica fume into a mortar mixer and dry mixing for 1-3 minutes; then adding modified recycled basalt fiber, modified SiO2 and dispersant, and dry mixing for 1-2 minutes to obtain a dry mix; dissolving water-reducing agent in water, and wet mixing the dry mix in a mixer for 3-5 minutes to obtain the cement mortar.

[0030] In this invention, the mixing process further includes molding and curing; the molding process specifically involves: injecting the cement mortar mixture into a mold, vibrating it to compact it, and then molding it; this invention does not have any special limitations on curing, and conventional room temperature curing or low temperature curing can be used; the standard curing temperature is 20±2℃, and the relative humidity is ≥95%; the low temperature curing temperature is 5±2℃.

[0031] The present invention also provides the application of the cement mortar based on recycled basalt fiber and recycled concrete as described in the above technical solution, or the cement mortar prepared by the preparation method described in the above technical solution, in building engineering, road engineering, or precast components.

[0032] This invention provides a composite repair coating system, which comprises, from bottom to top, a base leveling mortar layer, a middle reinforcing mesh fabric, a surface protective fabric, and a topcoat mortar; the base leveling mortar is formed from the cement mortar based on recycled basalt fiber and recycled concrete as described in the above technical solution or the cement mortar prepared by the preparation method described in the above technical solution.

[0033] In this invention, the composite repair coating system may further include, from bottom to top, a bottom leveling mortar layer, a middle reinforcing mesh, another middle leveling mortar layer, a surface protective cloth, and a topcoat mortar; the bottom leveling mortar layer has the same formula as the cement mortar in the middle leveling mortar layer used to wrap the middle reinforcing mesh.

[0034] In this invention, the intermediate reinforcing mesh is a modified basalt fiber mesh; the modified basalt fiber mesh is obtained by impregnation modification with a silane coupling agent, the amount of which is 1.5~2.0% of the mesh mass; the unit area mass of the basalt fiber mesh is 300~400 g / m². 2 Tensile strength (warp) ≥2000 MPa, tensile strength (weft) ≥1800 MPa, elastic modulus ≥85 GPa, elongation at break ≤2.5%.

[0035] In this invention, the surface protective fabric is a modified basalt plain weave fabric; the modified basalt plain weave fabric is obtained by impregnation modification with a silane coupling agent, and the amount of the silane coupling agent is 1.5~2.0% of the mass of the mesh fabric; the basalt plain weave fabric has a plain weave structure and a unit area mass of 200~300 g / m². 2 The single-layer thickness is 0.2 mm, the tensile strength (warp) is ≥2200 MPa, the tensile strength (weft) is ≥2000 MPa, and the elastic modulus is ≥90 GPa.

[0036] In this invention, the overlay mortar comprises the following raw materials in parts by weight: 500-600 parts cement, 400-500 parts activated recycled concrete, 10-15 parts modified SiO2, 450-500 parts quartz sand, 30-50 parts silica fume, 10-20 parts water-reducing agent, 220 parts water, and 1.5 parts dispersant; the cement, activated recycled concrete, modified SiO2, silica fume, water-reducing agent, and dispersant are the same as the above raw materials, and will not be repeated here; the particle size of the quartz sand is 140-200 mesh.

[0037] To further illustrate the present invention, the following detailed description, in conjunction with embodiments, provides the cement mortar based on recycled basalt fiber and recycled concrete, its preparation method and application, and the composite repair coating system provided by the present invention. However, these descriptions should not be construed as limiting the scope of protection of the present invention.

[0038] Example 1 This embodiment provides a high-performance cement mortar formulation suitable for structural reinforcement, beam-column joint repair, and thin-layer repair of concrete surfaces, emphasizing ultra-high mechanical properties, excellent bond strength, and low shrinkage characteristics. The specific preparation steps are as follows: 1. Raw material ratio (parts by weight) 520 parts of ordinary Portland cement (PO 42.5 grade), 480 parts of activated recycled concrete powder (RCP), 280 parts of modified recycled basalt fiber powder (RBFP), 380 parts of graded quartz sand (mixed at a mass ratio of 3:2, with particle sizes of 40-70 mesh and 70-140 mesh), and silica fume (SiO2 content ≥92wt%, specific surface area 20 m²). 2 90 parts of modified nano-SiO2 (average particle size 30 nm, pretreated with KH550) 8 parts of polycarboxylate superplasticizer (water reduction rate 35%) 25 parts of sodium carboxymethyl cellulose and 240 parts of water.

[0039] 2. Preparation method (1) Raw material pretreatment and modification ① Preparation of activated recycled concrete powder: Waste concrete was crushed by a jaw crusher and ground by a ball mill to a particle size ≤75 μm (passing through a 200-mesh sieve). The obtained recycled concrete powder was placed in a carbonization reactor, and a mixed gas with a CO2 concentration of 25% was introduced and treated at a pressure of 0.1 MPa for 3 hours. The powder was then removed and placed in a muffle furnace, heated to 700℃ at a rate of 5℃ / min, held at that temperature for 45 minutes, and then naturally cooled to room temperature to obtain activated recycled concrete powder.

[0040] ② Preparation of modified recycled basalt fiber powder: Waste basalt fibers were collected, washed with water to remove surface impurities, dried at 60℃ for 24 hours, and ground into short-cut fiber powder with a length of 0.1~0.5 mm and a diameter of 7~15 μm using an air jet mill. A 1.8% KH550 ethanol solution (ethanol:water volume ratio = 9:1) was prepared, and the recycled basalt fiber powder was added to the solution. The mixture was stirred and reacted in a reactor at 50℃ for 1.5 hours. After filtration, the mixture was vacuum dried at 60℃ to constant weight to obtain modified recycled basalt fiber powder.

[0041] ③ Preparation of modified SiO2: Nano-SiO2 with an average particle size of 30 nm was dispersed in anhydrous ethanol and ultrasonically dispersed for 30 min. 3% KH550 (by mass of nano-SiO2) was added, and the mixture was stirred at 60℃ for 3 h. After centrifugation, the nano-SiO2 was washed three times with anhydrous ethanol and vacuum dried at 60℃ for 24 h to obtain modified nano-SiO2.

[0042] (2) Dry powder premix The following ingredients were added sequentially to a horizontal ribbon mixer: 520 parts silicate cement, 480 parts activated recycled concrete powder, 380 parts graded quartz sand, 90 parts silica fume, 280 parts modified recycled basalt fiber powder, 8 parts modified nano-silica, and 2 parts sodium carboxymethyl cellulose. The mixer speed was set to 35 r / min, and the mixing time was 8 min. After mixing, a premixed dry powder with uniform color and no lumps was obtained.

[0043] (3) Mixing wet materials Dissolve 25 parts of polycarboxylate superplasticizer in 240 parts of water and stir until homogeneous to obtain a mixed aqueous solution. Add all the premixed dry powder obtained in step (2) to a planetary cement mortar mixer, start the mixer, and dry mix at low speed (140±5 r / min) for 1 min to allow the components to mix initially. Then, slowly pour in the mixed aqueous solution while stirring, and continue stirring at low speed for 2 min. Then switch to high speed (285±10 r / min) and stir for 3 min. Observe the mortar state until the materials are uniformly mixed, exhibit flow dynamics and good thixotropic properties, then stop stirring.

[0044] (4) Molding and Curing The mixed mortar was poured into standard steel molds (40mm×40mm×160mm) coated with mineral oil release agent in two batches. After each filling, the molds were vibrated on a cement mortar vibrating table for 30 seconds to ensure thorough compaction and remove air bubbles. The surface was then smoothed with a scraper. The molds were placed in a standard curing chamber at (20±2)℃ and relative humidity ≥95%. After standing for 24 hours, the molds were carefully demolded. The demolded specimens were then cured under standard curing conditions (temperature 20±2℃, humidity ≥95%) for the specified test ages, such as 7 days and 28 days.

[0045] 3. Performance test results of the cement mortar obtained in Example 1 after curing: 28-day compressive strength: 68.5 MPa; 28-day flexural strength: 23.2 MPa; 28-day drying shrinkage rate: 0.08% (i.e., 800×10⁻⁶) -6 ); Initial flowability: 185 mm; Bond strength with new concrete: 4.2 MPa; Impermeability grade: ≥P12; 28-day elastic modulus: 38.5 GPa.

[0046] 4. Analysis of the characteristics and applicability of the cement mortar obtained in Example 1: This embodiment employs a synergistic process of carbonization followed by thermal activation to prepare RCP, combined with KH550-modified recycled basalt fiber powder. This achieves high-volume solid waste utilization (RCP content 48%) while maintaining excellent mechanical properties (compressive strength 68.5 MPa, flexural strength 23.2 MPa). The synergistic effect of modified nano-SiO2 and silica fume significantly reduces drying shrinkage (only 0.08%), ensuring the volumetric stability of the repair layer and the substrate. This formulation exhibits superior overall performance and is particularly suitable for structural reinforcement and repair projects requiring high bond strength and volumetric stability, such as beam-column joint reinforcement, concrete crack repair, and bridge deck repair.

[0047] Example 2 This embodiment provides a cement mortar formulation suitable for applications requiring high wear resistance and impact resistance, such as industrial floors, warehousing and logistics areas, and parking lot wear layers. The formulation emphasizes high wear resistance, excellent impact resistance, and good workability. The specific preparation steps are as follows: 1. Raw material ratio (parts by weight) 540 parts of ordinary Portland cement (PO 42.5 grade), 460 parts of activated recycled concrete powder (RCP), 300 parts of modified recycled basalt fiber powder (RBFP), 350 parts of graded quartz sand (mixed at a mass ratio of 2:1, with particle sizes of 20-40 mesh and 40-70 mesh), and silica fume (SiO2 content ≥94%, specific surface area 22 m²). 2 100 parts of modified nano-silica (average particle size 20 nm, pretreated with KH550), 10 parts of polycarboxylate-based high-efficiency water-reducing agent (water reduction rate 30%), 3 parts of polyvinyl alcohol, and 250 parts of water.

[0048] 2. Preparation method (1) Raw material pretreatment and modification ① Preparation of activated recycled concrete powder: Waste concrete is ground to a particle size ≤75 μm, placed in a carbonization reactor, and treated for 2 hours under a CO2 concentration of 30%; the powder is then removed and placed in a muffle furnace, heat-treated at 750℃ for 30 minutes, and then cooled naturally.

[0049] ② Preparation of modified recycled basalt fiber powder: Waste basalt fibers are cleaned, dried, and ground to a length of 0.3~1.0 mm. A 2.2% KH550 ethanol solution (ethanol:water = 9:1) is prepared, and the fiber powder is added to the solution. The mixture is stirred at 60℃ for 1 hour, then filtered and dried.

[0050] ③ Preparation of modified nano-silica: Nano-SiO2 with an average particle size of 20 nm was dispersed in ethanol, and 4% KH550 by mass of nano-SiO2 was added. The mixture was stirred at 70℃ for 2 h, centrifuged, washed, and dried.

[0051] (2) Dry powder premix The above-mentioned 540 parts cement, 460 parts activated RCP, 350 parts graded quartz sand, 100 parts silica fume, 300 parts modified RBFP, 10 parts modified nano SiO2 and 3 parts PVA were added to a double cone rotary vacuum dryer in sequence, the speed was set to 20 r / min, and the mixture was mixed for 15 min to obtain premixed dry powder.

[0052] (3) Mixing wet materials Dissolve 30 parts of polycarboxylate superplasticizer in 250 parts of water. Add the premixed dry powder to a forced mortar mixer and dry mix at low speed for 1 minute; then slowly add the mixed aqueous solution while stirring and stir at low speed for 2 minutes; then stir at high speed for 3 minutes until the material is uniform.

[0053] (4) Molding and Curing The mixed mortar was molded into 40mm×40mm×160mm specimens, vibrated to compact, and the surface was smoothed. After standard curing (20±2℃, humidity ≥95%) for 24 hours, the specimens were demolded and continued to be cured until the test age.

[0054] 3. Performance test results of the cement mortar obtained in Example 2 after curing: 28-day compressive strength: 72.3 MPa; 28-day flexural strength: 25.1 MPa; 28-day drying shrinkage rate: 0.07% Initial flowability: 165 mm; Abrasion resistance (wear loss, according to JC / T 906 standard): 0.015 g / cm 2 ; Impact resistance (falling weight method, according to GB / T 9966 standard): 14.8 J; Surface hardness (Mohs hardness): 7.2; 28-day flexural modulus of elasticity: 42.6 GPa; 4. Analysis of the characteristics and applicability of the cement mortar obtained in Example 2 This embodiment utilizes a high dosage of modified recycled basalt fiber powder (300 parts) and a high dosage of modified nano-SiO2 (10 parts), significantly improving the abrasion resistance and impact resistance of the mortar. Abrasion resistance testing shows an abrasion loss of only 0.015 g / cm³. 2 With an impact resistance of 14.8 J, it far surpasses ordinary cement mortar. The higher fiber content creates a denser three-dimensional network structure, effectively resisting impact loads; the densification effect of nano-SiO2 further enhances surface hardness and wear resistance. This formula is suitable for heavy-duty industrial floors, machine shop floors, logistics and storage areas, parking lot wear-resistant layers, and other applications with stringent impact and wear resistance requirements.

[0055] Example 3 This embodiment describes the preparation of a rapid-strength and fast-hardening cement mortar for rapid construction and emergency repair projects. It provides a cement mortar formulation suitable for scenarios requiring high early strength, such as road repair, airport pavement emergency repair, and winter construction, emphasizing rapid-strength and fast-hardening characteristics and good low-temperature adaptability. The preparation steps are as follows: 1. Raw material ratio (parts by weight) 500 parts of ordinary Portland cement (PO 42.5 grade), 500 parts of activated recycled concrete powder (RCP), 250 parts of modified recycled basalt fiber powder (RBFP), 400 parts of graded quartz sand (mixed in a 1:1 mass ratio of 70-140 mesh and 140-200 mesh particle sizes), and silica fume (SiO2 content ≥90%, specific surface area 18 m²). 2 80 parts of modified SiO2 (average particle size 50 nm, pretreated with KH550), 6 parts of polycarboxylate superplasticizer (water reduction rate 35%), 20 parts of sodium carboxymethyl cellulose, 1 part of triethanolamine, and 230 parts of water. 2. Preparation method (1) Raw material pretreatment and modification ① Preparation of activated recycled concrete powder: Grind waste concrete to a particle size ≤75 μm, place it in a carbonization reactor, and treat it for 4 hours under a CO2 concentration of 20%; take out the powder and place it in a muffle furnace, heat treat it at 600℃ for 60 minutes, and then cool it naturally.

[0056] ② Preparation of modified recycled basalt fiber powder: Waste basalt fibers are cleaned, dried, and ground to a length of 0.1~0.3 mm. A 1.0% KH550 ethanol solution (ethanol:water = 9:1) is prepared, and the fiber powder is added to the solution. The mixture is stirred at 40℃ for 2 hours, then filtered and dried.

[0057] ③ Preparation of modified nano-silica: Nano-SiO2 with an average particle size of 50 nm was dispersed in ethanol, and KH550 with a mass of 2% of nano-SiO2 was added. The mixture was stirred at 50℃ for 4 h, centrifuged, washed and dried.

[0058] (2) Dry powder premix 500 parts cement, 500 parts activated RCP, 400 parts graded quartz sand, 80 parts silica fume, 250 parts modified RBFP, 6 parts modified nano SiO2, 1 part CMC and 2 parts triethanolamine were added to a three-dimensional motion mixer in sequence. The speed was set to 30 r / min and the mixture was mixed for 10 min to obtain premixed dry powder.

[0059] (3) Mixing wet materials Dissolve 20 parts of polycarboxylate superplasticizer in 230 parts of water. Add the premixed dry powder to a planetary cement mortar mixer and dry mix at low speed for 2 minutes. Then, slowly add the mixed aqueous solution while stirring and stir at low speed for 2 minutes. Finally, stir at high speed for 3 minutes until the material is uniform.

[0060] (4) Molding and Curing The mixed mortar was molded into 40mm×40mm×160mm specimens, vibrated to compact, and the surface was smoothed. The specimens were then cured under standard curing conditions (20±2℃, humidity ≥95%) or low-temperature curing conditions (5℃) to test their strength at different ages.

[0061] 3. Performance test results of cement mortar after standard oxidation and low-temperature oxidation curing obtained in Example 3 Standard maintenance (20℃): 3-day compressive strength: 42.6 MPa; 3-day flexural strength: 15.3 MPa; 7-day compressive strength: 58.4 MPa; 7-day flexural strength: 19.8 MPa; 28-day compressive strength: 65.8 MPa; 28-day flexural strength: 22.5 MPa; 28-day drying shrinkage rate: 0.09%; Initial flowability: 175 mm.

[0062] Low temperature curing (5℃): 3-day compressive strength: 28.5 MPa; 3-day flexural strength: 10.2 MPa; 7-day compressive strength: 45.7 MPa; 7-day flexural strength: 16.1 MPa; 4. Analysis of the characteristics and applicability of the cement mortar obtained in Example 3: This embodiment employs a low fiber content (250 parts) and nano-SiO2 content (6 parts), combined with a triethanolamine early-strength agent, to optimize early strength development. Under standard curing conditions, the 3-day compressive strength reaches 42.6 MPa, achieving 65% of the 28-day strength; under low-temperature curing conditions (5℃), the 3-day strength still reaches 28.5 MPa, meeting the requirements for winter construction. The composite cementitious system of activated RCP and silica fume exerts a pozzolanic effect in the early stages of hydration, promoting CSH gel formation. This formulation is suitable for engineering scenarios with high early strength requirements, such as airport runway emergency repairs, highway emergency repairs, rapid repair of bridge expansion joints, and low-temperature construction in winter. It can open traffic in a short time, minimizing the impact of construction on traffic operations.

[0063] Example 4 This embodiment of the composite reinforced structural repair coating system, based on the high-strength, high-toughness cement mortar formula for structural reinforcement and repair obtained in Example 1, further introduces basalt plain weave fabric and basalt mesh fabric to construct a multi-layer composite repair coating system consisting of "mortar with internal fiber powder reinforcement + middle layer mesh fabric reinforcement + surface plain weave fabric protection." It is suitable for high-requirement scenarios such as concrete structure crack repair, surface protection, and durability improvement. Its preparation and construction steps are as follows: 1. Material System Composition This coating system consists of four parts: a base leveling mortar, a middle layer of reinforcing mesh, a surface protective fabric, and a topcoat mortar, as detailed below: (1) Base leveling mortar (with internal fiber powder) The basic formula used in Example 1 is as follows: 520 parts of ordinary silicate cement (PO 42.5 grade), 480 parts of activated recycled concrete powder (RCP), 280 parts of modified recycled basalt fiber powder (RBFP), 380 parts of graded quartz sand, 90 parts of silica fume, 8 parts of modified nano silica, 25 parts of polycarboxylate-based high-efficiency water-reducing agent, 2 parts of sodium carboxymethyl cellulose, and 240 parts of water.

[0064] Note: Modified recycled basalt fiber powder has been incorporated into the bottom mortar to initially enhance the toughness and bonding properties of the matrix.

[0065] (2) Middle layer reinforcement material—modified basalt fiber mesh, using bidirectional basalt fiber mesh, with the following specifications: Grid size: 50mm × 50mm; Mass per unit area: 300 g / m² 2 ; Tensile strength (warp): ≥2000 MPa; Tensile strength (weft direction): ≥1800 MPa; Elastic modulus: ≥85 GPa; Elongation at break: ≤2.5%; Surface treatment: KH550 silane coupling agent is used for impregnation treatment, with an amount of 1.5% of the mesh fabric mass, to improve the interfacial adhesion performance with cement-based materials.

[0066] (3) Surface protective material – modified basalt plain weave fabric, using basalt fiber plain weave fabric, with the following specifications: Fabric structure: plain weave; Mass per unit area: 200 g / m² 2 ; Single layer thickness: 0.2 mm; Tensile strength (warp): ≥2200 MPa; Tensile strength (weft direction): ≥2000 MPa; Elastic modulus: ≥90 GPa; Surface treatment: KH550 silane coupling agent is used for impregnation treatment, with an amount of 1.5% of the plain weave fabric mass.

[0067] (4) Finishing mortar (fine-textured protective type): To coordinate with the surface fabric laying, a fine-textured finishing mortar is prepared, with the following mix proportions: 600 parts of ordinary silicate cement, 400 parts of activated recycled concrete powder, 10 parts of modified nano silica, 450 parts of fine quartz sand (140-200 mesh), 50 parts of silica fume, 20 parts of polycarboxylate superplasticizer, 220 parts of water, and 1.5 parts of dispersant.

[0068] 2. Construction process flow (1) Grassroots processing Clean the concrete repair substrate, removing surface laitance, oil, and loose layers. Use sandblasting or high-pressure water jetting to roughen and clean the substrate surface. For cracked areas, pre-cut V-grooves (10-15mm deep, 15-20mm wide). Thoroughly wet the substrate 24 hours before application and maintain a dry, saturated surface during application.

[0069] (2) Preparation and construction of the base leveling mortar Prepare the base leveling mortar according to the preparation method of Example 1: ①Preparation of activated recycled concrete powder, modified recycled basalt fiber powder, and modified nano-silica; ② Dry powder premixing: Add cement, activated RCP, quartz sand, silica fume, modified RBFP, modified nano SiO2, and dispersant to the mixer and dry mix for 3 minutes; ③Wet mixing: Dissolve the water-reducing agent in water, add it to the mixer, and wet mix for 4 minutes to obtain the bottom leveling mortar; ④ Apply the mixed base mortar evenly to the treated base surface, with a thickness controlled at 8-10 mm. Smooth it with a scraper and roughen it with a wooden trowel to facilitate adhesion to subsequent layers.

[0070] (3) Laying the first layer of mesh fabric Before the initial setting of the base mortar (approximately 30-60 minutes), the first layer of basalt fiber mesh fabric is laid: ① Cut the mesh fabric according to the size of the repair area, leaving an overlap length of ≥100 mm; ② Lay the mesh fabric flat on the surface of the wet base mortar, and gently press it into the mortar with a rubber roller or trowel so that the mesh fabric is partially embedded in the mortar layer; ③ The overlap width of adjacent mesh fabrics should be ≥100 mm, and the overlap areas should be staggered to avoid being on the same cross section; ④ Use a scraper to apply a small amount of base mortar to cover the mesh nodes, ensuring that the mesh is fully bonded to the base mortar.

[0071] (4) Leveling of the middle layer After the first layer of mesh fabric is laid and initially stabilized (about 2-4 hours), prepare the second batch of bottom leveling mortar (with the same ratio as before), and apply it evenly to the surface of the mesh fabric, with the thickness controlled at 5-8 mm, so that the mesh fabric is completely wrapped in the middle of the mortar layer, forming a "mortar-mesh fabric-mortar" sandwich structure.

[0072] (5) Laying the second layer of mesh fabric (two-way reinforcement) For areas under high stress or with dense cracks, a second layer of mesh fabric can be laid, with its direction intersecting the first layer at 45° or 90°: ① Cut the second layer of basalt fiber mesh to the same specifications; ② Lay the second layer of mesh cloth before the intermediate leveling mortar has initially set; ③ Press in the mortar layer, ensuring that it is staggered with the underlying mesh to form a two-way reinforcing network.

[0073] (6) Laying plain fabric on the surface After the final layer of mesh fabric is laid, apply basalt plain weave fabric to the wet mortar surface: ① Cut plain weave fabric according to the size of the repair area, leaving an overlap length of ≥50 mm; ② Lay the plain weave fabric flat on the surface of the wet mortar, and gently press it down with a soft brush or rubber roller to ensure that the plain weave fabric adheres tightly to the mortar; ③ For curved or irregularly shaped areas, plain weave fabric can be cut appropriately to fit the shape and avoid wrinkles; ④ The overlap width of plain weave fabric should be ≥50 mm, and the overlap area should be smoothly transitioned.

[0074] (7) Topcoat mortar application Prepare the topcoat mortar (according to the above topcoat mortar mixing ratio) within 1-2 hours after the plain weave fabric is laid: ① Prepare the finishing mortar according to the preparation method; ② Apply the finishing mortar evenly to the surface of the plain weave fabric, with a thickness controlled at 3-5 mm; ③ Use a steel trowel to smooth and flatten the surface to ensure it is flat and smooth; ④ For exposed decorative surfaces, roughening or embossing can be applied.

[0075] (8) Maintenance After construction is completed, immediately cover with a moisturizing film or damp burlap sack for moisturizing and maintenance: After initial setting (approximately 4-6 hours), begin spraying to maintain surface moisture; The maintenance period should be no less than 7 days, and the first 3 days should be protected from sun and wind. When the ambient temperature is below 5℃, insulation measures should be taken.

[0076] 3. Performance Test Results 28-day compressive strength: 72.3 MPa; 28-day flexural strength: 26.8 MPa; Interlayer bond strength: 3.2 MPa; Crack resistance (crack width): <0.05mm; 28-day drying shrinkage rate: 0.06% (i.e., 600×10⁻⁶ mm) -6 ); Impermeability grade: ≥P14; Abrasion resistance: 0.012 g / cm 2 ; 4. Features and Applicability Analysis This embodiment constructs a multi-scale reinforcement system from micro to macro, achieving the organic integration of recycled basalt fiber powder (chopped fibers) with basalt fiber mesh and plain weave fabric (continuous fibers). At the micrometer scale, the modified recycled basalt fiber powder (0.1-0.5 mm in length) in the bottom mortar forms a three-dimensional randomly distributed network within the matrix, effectively filling micropores and inhibiting microcrack initiation. At the millimeter scale, the middle layer of basalt fiber mesh (50 mm mesh size) provides a bidirectional tensile skeleton, significantly improving the structure's ability to withstand tensile stress and controlling crack propagation width. At the centimeter scale, the surface basalt plain weave fabric forms a continuous fiber protective layer, greatly enhancing surface crack resistance and abrasion resistance, while also serving as a highly efficient waterproof barrier. This multi-scale synergistic reinforcement mechanism enables the composite system to achieve a 28-day flexural strength of 26.8 MPa, an impact energy of 18.5 J (48% higher than without a fabric layer), a drying shrinkage rate reduced to 0.06%, and an impermeability rating of P14 or higher, demonstrating significantly superior overall performance compared to single reinforcement methods.

[0077] From a green and environmentally friendly perspective, this system continues and expands upon the low-carbon advantages of this invention. The activated RCP content reaches 48%, significantly reducing cement usage and carbon emissions; recycled basalt fiber powder enables the high-value utilization of waste fibers; both the mesh fabric and plain weave fabric are made of basalt fiber, and their production process has far lower carbon emissions than carbon fiber or glass fiber, giving the entire repair system excellent environmental benefits throughout its entire life cycle. Compared with traditional carbon fiber reinforcement processes, this system reduces material costs by approximately 60% to 70%, and uses inorganic materials as the bonding medium, avoiding inherent defects such as epoxy resin aging, peeling, and impermeability, maintaining the "breathing function" of the concrete structure, and significantly improving the long-term durability of the reinforcement system.

[0078] This composite repair coating system has broad application prospects. In the field of concrete structure crack repair, it is suitable for treating cracks in load-bearing parts such as beams, slabs, and columns, and the mesh fabric can effectively inhibit the development of reflective cracks. In bridge deck reinforcement, combined with the bidirectional reinforcement characteristics of the mesh fabric, it can significantly improve the bending stiffness and fatigue life of the bridge deck. In tunnel lining protection, the combination design of plain weave fabric as a waterproof layer and mesh fabric as a crack-resistant layer is suitable for tunnel leakage control and lining reinforcement. In the protection of historical buildings, the thin-layer repair system with a total thickness of ≤25 mm does not encroach on building space and is suitable for the structural reinforcement of historical buildings. In the field of marine engineering corrosion protection, the excellent corrosion resistance of basalt fiber makes it particularly suitable for the protection and reinforcement of concrete structures in tidal and splash zones. This system provides an innovative technical path for improving the durability of concrete structures, integrating high performance, low cost, and environmental friendliness.

[0079] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A cement mortar based on recycled basalt fiber and recycled concrete, characterized in that, It contains the following raw materials in parts by weight: 500-550 parts cement, 450-500 parts activated recycled concrete, 250-300 parts modified recycled basalt fiber, 350-400 parts quartz sand, 80-100 parts silica fume, 20-33 parts water-reducing agent, 210-250 parts water, 6-10 parts modified SiO2, and 1-3 parts dispersant; The modified recycled basalt fiber is a silane coupling agent modified recycled basalt fiber, and the specific surface area of ​​the modified recycled basalt fiber is ≥500 m². 2 / kg; The activated recycled concrete is prepared by sequentially carbonizing and thermally activating waste concrete.

2. The cement mortar according to claim 1, characterized in that, The carbonization activation is carried out in a CO2 atmosphere with a CO2 concentration of 20-30% for 2-4 hours. The thermal activation temperature is 600~750℃, and the time is 30~60min.

3. The cement mortar according to claim 1, characterized in that, The silane coupling agent includes one of KH550, KH560 and KH570; the mass of the silane coupling agent is 1.0~2.5% of the mass of the regenerated basalt fiber.

4. The cement mortar according to claim 1, characterized in that, The method for preparing the modified recycled basalt fiber includes the following steps: Modified regenerated basalt fibers are obtained by mixing and modifying them with an ethanol solution of a silane coupling agent; the mixing and modification temperature is 40~60℃ and the time is 1~2h.

5. The cement mortar according to claim 4, characterized in that, The concentration of the ethanol solution of the silane coupling agent is 1.0~2.5wt%.

6. The cement mortar according to claim 1, characterized in that, The modified SiO2 is silane coupling agent surface-modified nano-SiO2 with an average particle size of 15~30 nm.

7. The cement mortar according to claim 1, characterized in that, The quartz sand is graded quartz sand with a particle size range of 0.15~0.6mm; The silica fume has a fineness of 200-400 mesh.

8. The method for preparing cement mortar based on recycled basalt fiber and recycled concrete as described in any one of claims 1 to 7, characterized in that, Includes the following steps: The cement mortar is obtained by mixing cement, activated recycled concrete, quartz sand, silica fume, modified recycled basalt fiber, modified SiO2, dispersant, water-reducing agent and water.

9. The application of the cement mortar based on recycled basalt fiber and recycled concrete as described in any one of claims 1 to 7, or the cement mortar prepared by the preparation method described in claim 8, in building construction, road construction, or precast components.

10. A composite repair coating system, characterized in that, From bottom to top, it includes a bottom leveling mortar layer, a middle reinforcing mesh cloth, a surface protective cloth, and a topcoat mortar; the bottom leveling mortar layer is formed by the cement mortar based on recycled basalt fiber and recycled concrete as described in any one of claims 1 to 7 or the cement mortar prepared by the preparation method described in claim 8.