Cement-based composite materials with carbon fixation, self-healing, and sensing functions and their applications

Abstract

This invention relates to the field of building materials and structural reinforcement technology, and provides a carbon-fixing, self-healing cement-based composite material and its applications. The composite material, by volume percentage, consists of 92-97% activated magnesium oxide cement matrix, 1-4% hollow plant fiber, 1-2% PVA fiber, 0.5-3% fiber optic fabric web, and 0.05-0.1% fiber optic sensing array. This invention constructs a multifunctional reinforcement layer on the surface of existing building structures. This reinforcement layer can simulate six core characteristics of biological skin: high strength, high ductility, corrosion resistance, damage self-healing, metabolic interaction (carbon fixation), and conductive sensing. This achieves the integration of structural reinforcement, durability improvement, carbon emission reduction, and intelligent sensing in existing buildings.

Description

Technical Field

[0001] This invention relates to the field of building materials and structural reinforcement technology, specifically to a cement-based composite material with carbon fixation, self-healing, and sensing functions, and its applications. Background Technology

[0002] Currently, silicate cement concrete is the most widely used building material. While traditional reinforced concrete or wire mesh cement mortar reinforcement techniques can effectively improve structural load-bearing capacity, they still present challenges such as cracking and carbonation. Specifically: firstly, it is difficult to suppress the generation and development of cracks wider than 0.2 mm, and existing micro-cracks cannot self-repair, providing diffusion channels for corrosive media and accelerating structural aging; secondly, concrete carbonation lowers internal alkalinity (pH value drops to 8-10), easily inducing steel corrosion and further cracking, creating a vicious cycle of durability degradation. These problems make it difficult for existing silicate cement-based reinforcement techniques to simultaneously achieve structural safety and low-carbon performance.

[0003] Reactive magnesium oxide cement (RMC), as a novel low-carbon cementitious material, has attracted widespread attention in recent years. Compared to traditional silicate cement, RMC's carbon emissions over its entire life cycle are only 6% of the former, demonstrating a significant low-carbon advantage. Furthermore, it retains its chemical activity after hardening, enabling it to react with CO2 or CO3 that has seeped into cracks. 2- The continuous reaction achieves microstructural densification through the volume expansion of carbonization products, and further reduces carbon emissions throughout the entire life cycle, theoretically possessing self-healing potential.

[0004] However, RMC still faces key technical bottlenecks in structural reinforcement applications. On the one hand, the dense magnesium carbonate layer formed on the RMC surface hinders the diffusion of carbon dioxide into the material's interior, making it difficult for internal hydration products to participate in the carbonization reaction and limiting its deep carbon fixation capacity. On the other hand, the self-healing effect of RMC is only effective when the crack width is less than 0.1~0.15 mm, while the crack width commonly found in reinforced concrete structures is usually greater than 0.2 mm, resulting in a size mismatch. Therefore, relevant RMC materials suffer from insufficient carbon fixation depth, limited self-healing ability, insufficient tensile strength, and easy corrosion of internal steel in structural reinforcement scenarios, making it difficult to meet the comprehensive requirements of mechanical properties, durability, and long-term reliability in practical engineering.

[0005] Therefore, there is an urgent need for a building reinforcement composite material that can overcome the limitations of RMC carbon fixation and self-healing depth, and has excellent mechanical properties, durability and self-sensing function, as well as a matching high-precision, high-quality automated construction technology. Summary of the Invention

[0006] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, this invention provides a cement-based composite material with carbon fixation, self-healing, and sensing functions, and its application. By constructing a multifunctional cement-based composite material reinforcement layer on the surface of existing building structures, the reinforcement layer can simulate the six core characteristics of biological skin: high strength, high ductility, erosion resistance, damage self-healing, metabolic interaction (carbon fixation), and conductive sensing. This achieves the integration of structural reinforcement, durability improvement, carbon emission reduction, and intelligent sensing of existing buildings.

[0007] The first aspect of the present invention provides a cement-based composite material with carbon fixation, self-healing and sensing functions, which, by volume percentage, consists of 92-97% active magnesium oxide cement matrix, 1-4% hollow plant fiber, 1-2% polyvinyl alcohol (PVA) fiber, 0.5-3% fiber woven web and 0.05-0.1% optical fiber sensing array.

[0008] Using the above technical solution, hollow plant fibers provide channels for CO2 diffusion inward, which is beneficial for improving deep carbon fixation and self-healing in RMC. The combined effect of PVA fibers and fiber woven mesh improves the strength, ductility, and microcrack performance of the composite material. Replacing steel reinforcement with fiber woven mesh avoids the corrosion and durability reduction problems caused by matrix carbonization in related technologies. The built-in fiber optic sensing array provides conduction and self-monitoring functions. This achieves a synergistic design of multi-scale fibers and the RMC matrix. Applying this material to the surface of existing buildings endows them with seismic protection, self-repair, metabolic carbon fixation, and conductive sensing capabilities.

[0009] According to embodiments of the present invention, the above-mentioned composite material may further include at least one of the following additional technical features: According to an embodiment of the present invention, the active magnesium oxide cement matrix comprises 60-70 wt% active magnesium oxide, 30-40 wt% water, and 60.01-0.03 wt% sodium hexametaphosphate Na(PO4).

[0010] According to an embodiment of the present invention, the water-cement ratio of the active magnesium oxide cement matrix is ​​0.4 to 0.7.

[0011] According to an embodiment of the present invention, the average particle size of the active magnesium oxide is less than 10 μm.

[0012] According to an embodiment of the present invention, the hollow plant fiber includes at least one of bamboo fiber or sisal fiber.

[0013] According to an embodiment of the present invention, the length of the hollow plant fiber is 15-50 mm.

[0014] According to an embodiment of the present invention, the outer diameter of the hollow plant fiber is 50~250 μm.

[0015] According to an embodiment of the present invention, the equivalent diameter of the hollow portion of the hollow plant fiber is 5~50 μm.

[0016] According to an embodiment of the present invention, the tensile strength of the hollow plant fiber is 250~450 MPa.

[0017] According to an embodiment of the present invention, the elastic modulus of the hollow plant fiber is 10~20 GPa.

[0018] According to an embodiment of the present invention, the length of the PVA fiber is 11-18 mm.

[0019] According to an embodiment of the present invention, the diameter of the PVA fiber is 39~70 μm.

[0020] According to an embodiment of the present invention, the tensile strength of the PVA fiber is 700~1620 MPa.

[0021] According to an embodiment of the present invention, the elastic modulus of the PVA fiber is 20~40 GPa.

[0022] According to an embodiment of the present invention, the PVA fiber is a nano-SiO2 modified PVA fiber.

[0023] Furthermore, the preparation method of the nano-SiO2 modified PVA fiber includes: coating the PVA fiber surface with SiO2 nanoparticles by a sol-gel method.

[0024] According to an embodiment of the present invention, the fiber fabric web includes at least one of carbon fiber web, glass fiber web, basalt fiber web or aramid fiber web.

[0025] According to an embodiment of the present invention, the fiber fabric web is at least one of a two-dimensional mesh structure or a three-dimensional mesh structure.

[0026] According to an embodiment of the present invention, the areal density of the fiber fabric web is 160~300 g / m². 2 .

[0027] According to an embodiment of the present invention, the fineness of the unidirectional yarns of the fiber fabric web is 1000~8000 tex.

[0028] According to an embodiment of the present invention, the unidirectional tensile strength of the fiber fabric web is 800~2400 MPa.

[0029] According to an embodiment of the present invention, the breaking force of the fiber fabric web is >100 kN / m.

[0030] According to an embodiment of the present invention, the elastic modulus of the fiber fabric web is 50~200 GPa.

[0031] According to an embodiment of the present invention, the mesh size of the fiber fabric web is greater than or equal to 15mm × 15mm.

[0032] According to an embodiment of the present invention, the interlayer spacing d of the fiber fabric web satisfies: 5mm < d < 10mm.

[0033] According to an embodiment of the present invention, the surface of the fiber fabric web is impregnated with resin.

[0034] According to an embodiment of the present invention, the optical fiber sensing array is disposed inside the fiber fabric web.

[0035] According to an embodiment of the present invention, the equivalent tensile strength of the composite material is greater than 10 MPa.

[0036] According to an embodiment of the present invention, the ultimate tensile strain of the composite material is greater than 1.5%.

[0037] According to an embodiment of the present invention, the carbon absorption efficiency of the composite material is greater than 40 g·m -2 ·d -1 .

[0038] According to an embodiment of the present invention, the carbon fixation factor of the composite material is greater than 0.2 g CO2 / g.

[0039] According to an embodiment of the present invention, the composite material exhibits strain hardening characteristics under tensile load, with a crack width of less than 100 μm.

[0040] According to an embodiment of the present invention, the carbonization depth of the composite material after 28 days is greater than or equal to 20 mm.

[0041] According to an embodiment of the present invention, the composite material can achieve self-healing of cracks with a width of less than or equal to 100 μm within 10 days in a CO2-containing environment.

[0042] In some embodiments, the CO2-containing environment includes at least one of air, industrial waste gas, and artificially maintained environment.

[0043] A second aspect of the present invention provides a method for applying the aforementioned composite material, comprising: A three-dimensional scan of the substrate surface is performed to obtain digital scan results, and a substrate surface model is established. Based on the model, a spraying scheme is generated; The active magnesium oxide cement matrix, hollow plant fiber, and PVA fiber are mixed to obtain a slurry; The automated spraying system is activated to spray the slurry onto the substrate surface, thereby obtaining the base slurry. By incorporating an optical fiber sensor array into the fiber fabric web, an integrated fiber fabric web with sensing capabilities is obtained. Before the initial setting of the bottom slurry, the integrated fiber fabric web is spread out and pressed into the surface of the bottom slurry; The slurry is sprayed again to obtain a reinforcing layer.

[0044] By adopting the above technical solution, this invention introduces the system concept of building skin into the field of building structure for the first time, endowing building structures with active, intelligent, and life-like characteristics. It simultaneously achieves structural enhancement (high strength and ultra-toughness), damage self-healing (crack repair), improved durability (barrier and corrosion resistance), and carbon negative emissions (active carbon sequestration), solving the problem of single-function traditional technologies. Therefore, it can endow existing buildings with the capabilities of earthquake protection, self-repair, metabolic carbon sequestration, and conductive sensing. Furthermore, the semi-automated process can form a building "bionic skin" reinforcement layer that is highly compatible with complex substrates, has uniform thickness, and controllable fiber distribution and orientation. Through alternating operations of "spraying-laying mesh-re-spraying," the integrated fiber fabric mesh can be completely embedded within the composite material, forming a "sandwich" structure. This is beneficial for improving the interfacial bonding strength between the integrated fiber fabric mesh and the slurry, avoiding phenomena such as displacement and wrinkling of the integrated fiber fabric mesh due to slurry flow or its own weight. It also eliminates quality fluctuations caused by manual pressing and troweling construction methods, facilitating large-scale application.

[0045] In some embodiments, establishing the substrate surface model specifically includes: performing coordinate registration, noise removal, and surface reconstruction on the scanning results to extract information about the substrate.

[0046] Furthermore, the information includes at least one of boundary information, curvature information, and corner information.

[0047] In some embodiments, generating a spraying scheme based on the model specifically includes: dividing the substrate surface into several sub-regions with simple geometric features and no risk of collision based on the model, and generating a spraying scheme by combining equidistant cross-sectional lines and a path planning algorithm based on three-dimensional topology.

[0048] Furthermore, the spraying scheme includes at least one of the following: spraying trajectory, nozzle posture, and material output rate.

[0049] In some embodiments, the step of weaving an optical fiber sensing array into the fiber fabric web specifically includes: using the fiber fabric web as the supporting warp and / or weft yarns, and using optical fibers as auxiliary warp and / or weft yarns to introduce the fiber optic sensing array into the fabric structure, so that the optical fiber sensing array is set inside the fiber fabric web, thereby obtaining an integrated fiber fabric web with sensing function.

[0050] According to an embodiment of the present invention, the application method employs an automated spraying system based on a multi-degree-of-freedom robotic arm for construction, while the integrated fiber fabric mesh is laid manually.

[0051] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0052] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram illustrating the functional analogy between the composite material described in this invention and biological skin. Figure 2 This is a schematic diagram of the construction method described in Example 1; Figure 3 This is a comparative schematic diagram of the construction methods described in Embodiment 1 and Comparative Example 1 of the present invention.

[0053] Figure label: 1-Active magnesium oxide cement matrix, 2-Hollow plant fiber, 3-PVA fiber, 4-Fiber fabric mesh, 5-Fiber optic sensor array, 6-Epidermal layer of biological skin, 7-Pore, 8-Dermal layer, 9-Nerve, 10-Existing structure, 11-Self-healing closed crack, 12-Water molecule, 13-Carbon dioxide molecule, 14-Cement mortar matrix, 15-Reinforcing steel, 16-Reinforcing steel corrosion after water and corrosive media intrusion, 17-Macroscopic cracks caused by matrix carbonization; 18-Reinforcement layer. Detailed Implementation

[0054] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0055] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0056] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0057] In this document, the terms “comprising” or “including” are open-ended expressions, meaning that they include the contents specified in this invention, but do not exclude other aspects.

[0058] In this document, the terms “optionally,” “optionally,” or “optionally” generally refer to an event or condition that may, but may not, occur, and the description includes both cases in which the event or condition occurs and cases in which the event or condition does not occur.

[0059] The first aspect of the present invention provides a cement-based composite material with carbon fixation, self-healing and sensing functions, which, by volume percentage, consists of 92-97% active magnesium oxide cement matrix, 1-4% hollow plant fiber, 1-2% polyvinyl alcohol (PVA) fiber, 0.5-3% fiber woven web and 0.05-0.1% optical fiber sensing array.

[0060] Using the above technical solution, the activated magnesium oxide cement matrix, as a chemically active matrix, provides the chemical basis for carbon fixation and self-healing. Hollow plant fibers, utilizing their internal hollow structure, provide channels for CO2 diffusion into the deep layers of the composite material, which helps solve the problem of deep carbon fixation and self-healing in RMC. PVA fibers can improve the toughness of the building's surface and control crack development through fiber bridging mechanisms, creating optimal conditions for crack self-healing. Using fiber woven mesh to replace steel reinforcement provides macroscopic tensile strength, avoiding problems such as steel corrosion and reduced durability caused by matrix carbonization in related technologies. The combined effect of PVA fibers and fiber woven mesh can also synergistically control crack development, which is beneficial for improving the strength, ductility, and microcrack performance of the composite material. The built-in fiber optic sensor array provides conduction and self-monitoring functions, enabling intelligent detection and earthquake early warning by capturing mechanical signals such as vibration and pressure. Applying this material to the surface of existing buildings can endow them with seismic protection, self-repair, metabolic carbon fixation, and conductive sensing capabilities.

[0061] like Figure 1 As shown, the components in the composite material of the present invention are not simply superimposed, but can work synergistically to achieve a function similar to "bionic skin," as detailed below: (1) Synergistic effect of carbon fixation and self-healing. Hollow plant fibers can form "microchannels" for CO2 transport. The hydration product brucite (Mg(OH)2) can react with CO2 in the microchannels to form magnesium carbonate hydrate. The establishment of microchannels can improve the degree of carbon fixation and self-healing. The combined action of PVA fibers, hollow plant fibers and fiber fabric web can synergistically inhibit the development of crack width, making the crack width less than 100μm, and further forming channels to improve the carbon fixation and self-healing efficiency of the matrix.

[0062] (2) Strength-ductility synergy. The fiber fabric web, as a macroscopic reinforcing skeleton, bears the main tensile stress and can provide the material with high strength and macroscopic integrity; PVA fiber and hollow plant fiber improve the ductility of the material through bridging. The synergy of the three can enable the composite material to have an equivalent tensile strength >10 MPa and an ultimate tensile strain >1.5%.

[0063] (3) Carbon fixation-durability synergy. Fiber fabric webs, PVA fibers, and hollow plant fibers themselves do not have electrochemical corrosion, and the occurrence of carbon fixation will reduce the pH value of the matrix. The low pH environment further improves the service conditions of the above fibers. At the same time, the self-healing of cracks effectively prevents the intrusion of corrosive media and moisture, further improving the service life of the building skin.

[0064] Therefore, this invention introduces the systemic concept of building skin into the field of building structures for the first time, endowing building structures with proactive, intelligent, and life-like characteristics. It simultaneously achieves structural enhancement (high strength and ultra-toughness), damage self-healing (crack repair), improved durability (barrier and corrosion resistance), and negative carbon emissions (active carbon sequestration), solving the problem of the single function of traditional technologies. It has the following significant improvement effects on existing buildings: (1) Improve load-bearing capacity and ductility: Hollow plant fiber, PVA fiber and fiber fabric mesh can work together to strengthen the cement matrix, so that the building skin has both high tensile strength and ductility, significantly improving the load-bearing capacity and ductility of existing buildings. A thin layer (usually 10~20 mm) can achieve or even exceed the reinforcement effect of a thick reinforced concrete surface layer, reduce the self-weight of the structure and have little impact on the foundation.

[0065] (2) High carbon fixation and self-healing: The active magnesium oxide cement matrix still has chemical activity after hardening, and can achieve a qualitative change from "surface sealing" to "overall metabolism" through the air conduction effect of hollow plant fibers.

[0066] (3) Controlling crack propagation: Hollow plant fibers, PVA fibers and fiber fabrics work together to inhibit the development of existing structural crack width (<50μm), further promoting matrix carbon fixation and self-healing.

[0067] (4) Long-term durability protection: The low pH matrix environment and fiber fabric mesh coupling are conducive to improving material durability, and the self-healing of cracks is also conducive to further improving the service life of the building.

[0068] (5) Reduce carbon emissions over the entire life cycle: The composite material described in this invention is low in carbon and continuously fixes carbon during its service life. The self-healing ability of cracks ensures the durability of the reinforcement effect and significantly reduces the carbon cost of building maintenance in the later stages.

[0069] According to embodiments of the present invention, the above-mentioned composite material may further include at least one of the following additional technical features: According to an embodiment of the present invention, the active magnesium oxide cement matrix comprises 60-70 wt% active magnesium oxide, 30-40 wt% water, and 60.01-0.03 wt% sodium hexametaphosphate Na(PO4).

[0070] It should be noted that the "active magnesium oxide" mentioned in this invention, also known as lightly calcined magnesium oxide, refers to magnesium oxide powder with high chemical reactivity obtained by lightly calcining and decomposing magnesite, brucite, or magnesium hydroxide at 700℃~1000℃. Unlike "dead-calcined magnesium oxide" or "electrofused magnesium oxide" which are chemically inert after high-temperature (≥1400℃) calcination, the active magnesium oxide described in this invention can undergo a hydration reaction with water and a carbonation reaction with carbon dioxide (CO2) to generate magnesium carbonate hydrate or magnesia hydrate and other cementing products.

[0071] According to an embodiment of the present invention, the water-cement ratio of the active magnesium oxide cement matrix is ​​0.4 to 0.7, specifically 0.4, 0.5, 0.6, 0.7, etc.

[0072] Therefore, it is possible to balance the workability and mechanical properties of composite materials, giving the activated magnesium oxide cement matrix suitable fluidity and plasticity, significantly improving the uniformity and density of the composite material during construction. Furthermore, it can form a suitable pore structure and alkalinity environment during hydration, providing sufficient moisture and ion transport channels for CO2 diffusion and carbonation reactions, ensuring the conversion rate of activated magnesium oxide to magnesium carbonate, which is beneficial for deep carbon fixation and improving material strength. If the water-cement ratio is too low, it can easily lead to excessive slurry viscosity, insufficient fluidity, uneven fiber dispersion, and interfacial bonding defects; if the water-cement ratio is too high, it can easily lead to slurry segregation, bleeding, increased porosity of the hardened body, and decreased strength.

[0073] According to an embodiment of the present invention, the average particle size of the active magnesium oxide is less than 10 μm, specifically such as 0.5 μm, 1 μm, 3 μm, 5 μm, 8 μm, 9.5 μm, etc.

[0074] This improves the reactivity and carbonation efficiency of magnesium oxide, allowing for uniform dispersion of magnesium oxide particles in the cement matrix. It also increases the contact area with water and CO2, promoting thorough early hydration and carbonation reactions. This facilitates the formation of a dense magnesium carbonate network structure, enhancing the early strength and long-term durability of the composite material. However, excessively large magnesium oxide particle size can lead to problems such as particle sedimentation, incomplete reaction, uneven distribution of carbonation products, and interfacial bonding defects.

[0075] According to an embodiment of the present invention, the hollow plant fiber is bamboo fiber or sisal fiber.

[0076] According to an embodiment of the present invention, the length of the hollow plant fiber is 15-50 mm, specifically 15 mm, 20 mm, 25 mm, 30 mm, 35 mm, 40 mm, 45 mm, 50 mm, etc.

[0077] Thus, synergistic optimization between microstructure and macroscopic performance can be achieved: on the one hand, this length range enables hollow plant fibers to form a three-dimensional randomly distributed network in the RMC matrix, which avoids the defect of fibers that are too short (<15 mm) being easily pulled out due to insufficient anchoring length, and also overcomes the problem of uneven dispersion caused by fibers being easy to entangle and agglomerate during stirring, significantly improving the crack resistance and interfacial toughness of the composite material; on the other hand, hollow plant fibers at this length can construct a microchannel system in the matrix, providing an efficient path for the inward diffusion of CO2, ensuring the full progress of deep carbon fixation and self-healing reaction.

[0078] According to an embodiment of the present invention, the hollow plant fiber satisfies at least one of the following conditions: The outer diameter of the hollow plant fiber is 50~250 μm, specifically such as 50 μm, 80 μm, 100 μm, 120 μm, 150 μm, 180 μm, 200 μm, 220 μm, 250 μm, etc. The equivalent diameter of the hollow portion of the hollow plant fiber is 5~50 μm, specifically such as 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, etc.

[0079] Therefore, by synergistically controlling the outer diameter of the fibers and the size of the hollow cavities, a hollow channel network with both structural stability and transmission efficiency can be constructed in the cement matrix. The aforementioned outer diameter range helps ensure the fibers' resistance to mechanical damage during mixing and spraying, allowing for uniform fiber dispersion and good bonding with the matrix, reducing defects in the interface transition zone. The equivalent diameter within this range facilitates the formation of micron-sized cavities that match the cement's pore structure, ensuring efficient storage and controllable release of the repair medium and providing a low-resistance path for CO2 diffusion. This synergy avoids problems such as fiber breakage, narrow cavities, insufficient medium storage, and increased diffusion resistance caused by excessively small outer diameters, as well as defects such as decreased dispersibility, increased interface defects, and reduced overall uniformity caused by excessively large outer diameters. It also prevents failure risks such as cavity blockage and insufficient repair medium capacity caused by excessively small equivalent diameters, or cell wall thinning, decreased mechanical strength, and mixing breakage caused by excessively large equivalent diameters, thus effectively achieving a synergistic effect of crack self-healing and deep carbon fixation.

[0080] It should be noted that the "equivalent diameter" mentioned in this invention refers to the diameter calculated by measuring the area of ​​the hollow portion on the cross-section of bamboo fiber using a scanning electron microscope (SEM) and then equating it to a circle. The formula for calculating the equivalent diameter (d) is as follows: , where A is the cross-sectional area of ​​the hollow part.

[0081] According to an embodiment of the present invention, the tensile strength of the hollow plant fiber is 250~450 MPa, specifically such as 250 MPa, 280 MPa, 300 MPa, 320 MPa, 350 MPa, 380 MPa, 400 MPa, 420 MPa, 450 MPa, etc.

[0082] This is beneficial for improving the reinforcing and toughening efficiency of hollow plant fibers in cement matrices, enabling the fibers to effectively bear tensile stress and bridge the cracks when the matrix cracks, delaying crack initiation and propagation, improving the crack resistance and ductility of composite materials, and ensuring the structural integrity of the fibers during mixing, spraying, and service. However, if the tensile strength of the hollow plant fibers is too low, it may cause premature fiber breakage when the matrix cracks, resulting in insignificant reinforcing effects and an increased risk of brittle fracture in the composite material.

[0083] According to an embodiment of the present invention, the elastic modulus of the hollow plant fiber is 10~20 GPa, specifically 10GPa, 12 GPa, 14 GPa, 15 GPa, 16 GPa, 18 GPa, 20 GPa, etc.

[0084] This facilitates modulus matching between hollow plant fibers and the cement matrix, enabling the hollow plant fibers to deform in tandem with the matrix during stress, effectively transferring and sharing the load, reducing interfacial stress concentration caused by excessive modulus differences, and improving the overall stress performance and durability of the composite material. If the elastic modulus of the hollow plant fibers is too low, they may deform excessively before the matrix cracks, making it difficult for them to play an effective reinforcing role; if the elastic modulus is too high, the deformation of the fibers and the matrix may be uncoordinated, resulting in large shear stress at the interface and causing premature fiber breakage.

[0085] According to an embodiment of the present invention, the length of the PVA fiber is 11 to 18 mm, specifically 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, etc.

[0086] This approach optimizes the dispersion and anchoring effect of PVA fibers in the cement matrix, enabling the fibers to form a uniform three-dimensional distribution network within the matrix. This provides sufficient anchoring length to leverage the high tensile strength of the fibers and effectively bridges microcracks when the matrix cracks, dissipating fracture energy and improving the crack resistance, ductility, and toughness of the composite material. If the PVA fibers are too short, the interfacial bonding length with the matrix may be insufficient, leading to pull-out failure rather than fracture, thus failing to fully realize the bridging potential of the fibers. If the length is too long, they may entangle and clump together during mixing, resulting in uneven dispersion and affecting the overall uniformity and workability of the composite material.

[0087] According to an embodiment of the present invention, the diameter of the PVA fiber is 39~70 μm, specifically such as 39 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, etc.

[0088] This improves the dispersion uniformity and interfacial bonding performance of PVA fibers in the cement matrix, enabling them to distribute evenly within the matrix without agglomeration, and to form a good interfacial bond with the cement matrix. This allows them to effectively bridge and prevent cracking when the matrix cracks, thereby improving the crack resistance, ductility, and toughness of the composite material. If the diameter of the PVA fibers is too small, problems such as entanglement and agglomeration during mixing and difficulty in dispersion may occur. Furthermore, excessively fine fibers are easily broken rather than pulled out when the matrix cracks, making it difficult to fully exert the reinforcing effect. If the diameter is too large, it may lead to a reduction in the contact interface between the fiber and the matrix, and a decrease in the number of fibers per unit volume, resulting in a decrease in the continuity of the fiber network and the overall reinforcing efficiency of the composite material.

[0089] According to an embodiment of the present invention, the tensile strength of the PVA fiber is 700~1620 MPa, specifically such as 700 MPa, 750 MPa, 800 MPa, 850 MPa, 900 MPa, 950 MPa, 1000 MPa, 1050 MPa, 1100 MPa, 1300 MPa, 1500 MPa, 1620 MPa, etc.

[0090] Therefore, it is beneficial to fully utilize the reinforcing and toughening effect of PVA fibers in the cement matrix, enabling the PVA fibers to withstand higher tensile stress when the matrix cracks, effectively bridging both sides of the crack and inhibiting further crack propagation, improving the crack resistance, ductility, and peak strength of the composite material, and ensuring the stability of the mechanical properties of the fibers during mixing, spraying, and service. If the tensile strength of the PVA fibers is too low, they may fracture prematurely when the matrix cracks, making it difficult to effectively transfer loads, thereby weakening their reinforcing effect and increasing the risk of brittle failure of the composite material.

[0091] According to an embodiment of the present invention, the elastic modulus of the PVA fiber is 20~40 GPa, specifically 20 GPa, 25 GPa, 28 GPa, 30 GPa, 32 GPa, 35 GPa, 38 GPa, 40 GPa, etc.

[0092] This allows the modified PVA fibers to match the modulus of the cement matrix, enabling them to deform collaboratively with the matrix during stress, effectively transferring and sharing the load. This reduces interfacial stress concentration caused by excessive modulus differences, improving the overall structural performance and crack resistance of the composite material. If the elastic modulus of the modified PVA fibers is too low, excessive elastic deformation may occur before the matrix cracks, making it difficult to effectively limit crack initiation and propagation, thus weakening the fiber's crack-resistant and toughening effect. Conversely, if the elastic modulus is too high, the deformation of the fiber and matrix may be uncoordinated, resulting in significant shear stress at the interface and premature fiber breakage.

[0093] According to an embodiment of the present invention, the PVA fiber is a nano-SiO2 modified PVA fiber.

[0094] Furthermore, the preparation method of the nano-SiO2 modified PVA fiber includes: coating the PVA fiber surface with SiO2 nanoparticles by a sol-gel method.

[0095] According to an embodiment of the present invention, the fiber fabric web includes at least one of carbon fiber web, glass fiber web, basalt fiber web or aramid fiber web.

[0096] According to an embodiment of the present invention, the fiber fabric web is at least one of a two-dimensional mesh structure or a three-dimensional mesh structure.

[0097] According to an embodiment of the present invention, the areal density of the fiber fabric web is 160~300 g / m². 2 Specifically, such as 160g / m 2 180 g / m 2 200 g / m 2 220 g / m 2 240 g / m 2 260 g / m 2 280 g / m 2 300 g / m 2 wait.

[0098] Therefore, this method is beneficial for improving the reinforcement efficiency and construction adaptability of fiber mesh in composite materials. The mesh has sufficient fiber content to withstand tensile stress and effectively restrain crack propagation, while maintaining good flexibility and wettability. This facilitates close adhesion to the matrix during spraying or plastering, improving the overall stress performance and interfacial bonding quality of the composite material. If the areal density is too low, the fiber content in the mesh may be insufficient, resulting in limited reinforcement and difficulty in effectively limiting crack initiation and propagation, thus reducing the crack resistance and load-bearing capacity of the composite material. Conversely, if the areal density is too high, the mesh may become too stiff and less flexible, making it difficult to achieve close adhesion to the matrix surface during construction. This can easily lead to the formation of resin-rich zones or voids at the interface, thereby reducing the overall integrity and durability of the composite material.

[0099] According to an embodiment of the present invention, the fineness of the unidirectional yarn of the fiber fabric web is 1000~8000 tex, specifically such as 1000 tex, 1500 tex, 2000 tex, 2500 tex, 3000 tex, 3500 tex, 4000 tex, 4500 tex, 5000 tex, 6000 tex, 7000 tex, 8000 tex, etc.

[0100] This improves the fiber content and resin impregnation properties of the fiber woven web, giving the fiber bundles sufficient bundle strength and continuity. This allows the web to effectively bear tensile stress and restrain crack propagation in the composite material, while also enabling the resin or cement matrix to fully impregnate the fiber bundles, thus improving interfacial bonding quality and load transfer efficiency. If the unidirectional yarn fineness is too low, the fiber strength in the web may be insufficient, leading to fiber dispersion or breakage during tensioning or construction, thereby weakening the overall reinforcing effect of the web. Conversely, if the unidirectional yarn fineness is too high, the fiber bundles may be too coarse, making it difficult for the resin or cement matrix to fully impregnate the internal fibers, potentially resulting in dry spots or pores at the interface, reducing the overall integrity and durability of the composite material.

[0101] According to an embodiment of the present invention, the unidirectional tensile strength of the fiber fabric web is 800~2400 MPa, specifically such as 800 MPa, 1000 MPa, 1200 MPa, 1400 MPa, 1600 MPa, 1800 MPa, 2000 MPa, 2200 MPa, 2400 MPa, etc.

[0102] Therefore, the fiber fabric mesh can effectively bear tensile stress after the matrix cracks, limiting the further propagation of cracks, significantly improving the crack resistance and load-bearing capacity of the composite material, and ensuring the structural safety and long-term durability of the reinforcement layer. If the uniaxial tensile strength is too low, the fiber fabric mesh is prone to premature fiber breakage under stress, making it difficult to effectively transfer loads, weakening the reinforcement effect of the composite material and increasing the risk of structural failure.

[0103] According to an embodiment of the present invention, the breaking force of the fiber fabric web is >100 kN / m, specifically such as 110 kN / m, 120 kN / m, 130 kN / m, 140 kN / m, 150 kN / m, 200 kN / m, etc.

[0104] This improves the crack resistance and ultimate bearing capacity of composite materials, enhancing the structural safety and long-term durability of the reinforcement layer under service loads. However, if the fracture force is too low, the fiber fabric web may fracture prematurely under stress, making it difficult to effectively transfer loads and potentially leading to reduced reinforcement effects and increased risk of structural failure.

[0105] According to an embodiment of the present invention, the elastic modulus of the fiber fabric web is 50~200 GPa, specifically such as 50 GPa, 60 GPa, 80 GPa, 100 GPa, 120 GPa, 140 GPa, 160 GPa, 180 GPa, 200 GPa, etc.

[0106] Therefore, this allows the fiber fabric mesh to deform in tandem with the cement matrix during stress, effectively limiting crack initiation and propagation, reducing interfacial stress concentration caused by excessive modulus differences, and improving the overall stress performance and durability of the composite material. If the elastic modulus is too low, the fiber fabric mesh may undergo excessive elastic deformation before the matrix cracks, making it difficult to effectively restrain crack propagation and weakening the crack-resistant and toughening effect of the fabric mesh. If the elastic modulus is too high, it may lead to uncoordinated deformation between the fiber fabric mesh and the matrix, resulting in large shear stress at the interface, which may cause problems such as interfacial debonding or premature separation of the fabric mesh and matrix.

[0107] According to an embodiment of the present invention, the mesh size of the fiber fabric web is greater than or equal to 15mm×15mm, specifically such as 15mm×15mm, 20mm×20mm, 25mm×25mm, 30mm×30mm, 40mm×40mm, 50mm×50mm, etc.

[0108] This significantly improves the mechanical interlocking effect between the fiber mesh and the cement matrix, allowing the matrix material to fully penetrate the mesh and form a continuous interlocking structure at the interface. This enhances the collaborative working ability between the mesh and the matrix, while avoiding problems such as impeded matrix penetration or thickened slurry layer at the interface caused by excessively dense mesh. If the mesh size is too small, the matrix material cannot fully penetrate the mesh, easily forming a weak layer at the interface, reducing the bonding strength and integrity between the mesh and the matrix.

[0109] According to an embodiment of the present invention, the interlayer spacing d of the fiber fabric web satisfies: 5mm < d < 10mm; for example, the interlayer spacing d of the fiber fabric web can be 6 mm, 7 mm, 8 mm, 9 mm, 9.5 mm, etc.

[0110] This allows multiple layers of fabric mesh to work together under stress, ensuring that each layer can effectively bear tensile stress when the matrix cracks, while avoiding stress concentration or interlaminar delamination caused by excessively small interlayer spacing, thus improving the overall integrity and crack resistance of the composite material. If the interlayer spacing is too small, the matrix layer between adjacent fabric meshes may be too thin, making them prone to interlaminar shear failure under load, weakening the overall reinforcement effect of the composite material. If the interlayer spacing is too large, it may make it difficult for each layer of fabric mesh to work together, with only a single layer of fabric mesh playing a role when cracks propagate, reducing the crack resistance and load-bearing capacity of the composite material.

[0111] According to an embodiment of the present invention, the surface of the fiber fabric web is impregnated with resin.

[0112] According to an embodiment of the present invention, the fiber optic sensing array is disposed inside the fiber optic fabric web. This facilitates the capture of mechanical signals such as vibration and pressure.

[0113] According to an embodiment of the present invention, the tensile strength of the composite material is greater than 10 MPa, specifically such as 12 MPa, 15 MPa, 18 MPa, 20 MPa, 25 MPa, 30 MPa, etc.

[0114] This ensures that the composite material has sufficient load-bearing capacity under service loads, effectively withstands tensile stress, and limits crack propagation, significantly improving the seismic performance and structural safety of existing building walls, and guaranteeing the long-term durability and reliability of the reinforcement layer. If the equivalent tensile strength is too low, the composite material may crack or fail prematurely under stress, making it difficult to meet the reinforcement design requirements, weakening the reinforcement effect, and increasing structural safety hazards.

[0115] According to an embodiment of the present invention, the ultimate tensile strain of the composite material is greater than 1.5%, specifically such as 1.8%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, etc.

[0116] Therefore, composite materials can be endowed with good ductility and deformation capacity. When subjected to extreme loads such as earthquakes and wind loads, they can absorb energy through large deformation, effectively delaying the penetration of cracks and the overall failure of the structure, and significantly improving the seismic performance and safety redundancy of existing building walls. If the ultimate tensile strain is too low, the composite material is prone to brittle fracture under stress, making it difficult to fully utilize the reinforcing effect of fibers and fabric webs, thus limiting its deformation capacity and energy dissipation effect.

[0117] According to an embodiment of the present invention, the carbon absorption efficiency of the composite material is greater than 40 g·m -2 ·d -1 Specifically, such as 45g·m -2 ·d -1 50 g·m -2 ·d -1 55 g·m -2 ·d -1 60 g·m -2 ·d -1 70 g·m -2 ·d -1 80 g·m -2 ·d -1 wait.

[0118] This is beneficial for improving the CO2 absorption and fixation capacity of composite materials, enabling them to continuously capture carbon dioxide from the environment, promoting the full conversion of active magnesium oxide to magnesium carbonate, improving the density and long-term durability of composite materials, and reducing the carbon footprint during building maintenance. If the carbon absorption efficiency is too low, the carbon fixation effect of the composite material may be insignificant, making it difficult to form a dense magnesium carbonate network structure, reducing the continuous increase in material strength and self-healing function.

[0119] According to an embodiment of the present invention, the carbon fixation factor of the composite material is greater than 0.2 g CO2 / g, specifically such as 0.22 g CO2 / g, 0.25 g CO2 / g, 0.28 g CO2 / g, 0.30 g CO2 / g, 0.32 g CO2 / g, 0.35 g CO2 / g, g CO2 / g, 0.40 g CO2 / g, etc.

[0120] This enhances the composite material's ability to chemically fix carbon dioxide, allowing active magnesium oxide to continuously transform into magnesium carbonate products during carbonization. The volume expansion effect fills the micropores within the material, significantly improving its density and mechanical properties. Simultaneously, a higher carbon fixation factor promotes self-healing of the carbonization reaction in crack areas, enhancing the long-term durability of the composite material in service environments and reducing carbon emissions. Conversely, an excessively low carbon fixation factor may lead to insufficient carbonization of the active magnesium oxide, weakening the material's self-healing potential and impermeability, thus affecting the long-term stability of the reinforcement layer and its carbon reduction effect.

[0121] According to an embodiment of the present invention, the composite material exhibits strain hardening characteristics under tensile load, with crack width within 100 μm, specifically such as 20 μm, 40 μm, 60 μm, 80 μm, etc.

[0122] This allows the composite material to exhibit a ductile failure mode during stress. After the matrix cracks, the fibers and fabric web can continue to bear tensile stress and effectively bridge microcracks, significantly improving the crack resistance and deformation capacity of the composite material, and ensuring the structural integrity and long-term durability of the reinforcement layer under service loads. If the composite material lacks strain hardening characteristics or the crack width is too large, it is prone to problems such as accelerated crack penetration and failure of fiber bridging, reducing the load-bearing capacity and interfacial bonding performance of the reinforcement layer, and increasing the risk of structural leakage and durability degradation.

[0123] According to an embodiment of the present invention, the carbonization depth of the composite material after 28 days is greater than or equal to 20 mm, specifically such as 20 mm, 22 mm, 25 mm, 28 mm, 30 mm, 35 mm, 40 mm, etc.

[0124] This ensures that the active magnesium oxide is fully carbonized in a short time, forming a dense magnesium carbonate network structure, which significantly improves the density, early strength, and long-term durability of the composite material, while also guaranteeing its continuous self-healing potential. If the carbonization depth is too shallow at 28 days, the carbon fixation reaction of the composite material may be insufficient, making it difficult to form an effective magnesium carbonate reinforcing phase, thus limiting the development of material strength and the self-healing function of cracks.

[0125] According to an embodiment of the present invention, the composite material can achieve self-healing of cracks with a width of 100 μm or less within 10 days in a CO2-containing environment. For example, the width of the crack can be 20 μm, 40 μm, 60 μm, 80 μm, etc.; the healing time can be 1 day, 3 days, 5 days, 7 days, 9 days, 10 days, etc.

[0126] This improves the self-healing ability of the composite material. When microcracks appear on the structural surface, the composite material can react with CO2 in the environment within 10 days to generate magnesium carbonate crystals, effectively sealing the crack channels and preventing further penetration of moisture and corrosive media, significantly improving the durability and long-term service performance of the reinforcement layer. If the self-healing efficiency of the cracks is low, the microcracks may continue to expand and penetrate, weakening the integrity and protective effect of the composite material, thereby accelerating the performance degradation of the reinforcement layer and structural damage.

[0127] In some embodiments, the CO2-containing environment includes at least one of air, industrial waste gas, and artificially maintained environment.

[0128] A second aspect of the present invention provides a method for applying the aforementioned composite material, comprising: S1. Perform a three-dimensional scan of the substrate surface to obtain digital scan results and establish a substrate surface model; S2. Based on the model, generate a spraying scheme; S3. Mix the activated magnesium oxide cement matrix, hollow plant fiber, and PVA fiber to obtain a slurry; S4. Start the automated spraying system and spray the slurry onto the substrate surface to obtain the base slurry; S5. An optical fiber sensor array is incorporated into the fiber fabric web to obtain an integrated fiber fabric web with sensing function. S6. Before the bottom layer of slurry initially sets, spread out the integrated fiber fabric web and press it into the surface of the bottom layer of slurry. S7. Spray the slurry again to obtain a reinforced layer.

[0129] By adopting the above technical solution, this invention introduces the system concept of building skin into the field of building structure for the first time, endowing building structures with active, intelligent, and life-like characteristics, while realizing structural enhancement (high strength and ultra-toughness), damage self-healing (crack repair), durability improvement (barrier and corrosion resistance), and carbon negative emissions (active carbon sequestration). Thus, it can endow existing buildings with the capabilities of earthquake protection, self-repair, metabolic carbon sequestration, and conductive sensing. Simultaneously, using a semi-automated process, it can form a building "bionic skin" reinforcement layer that is highly compatible with complex substrates, has uniform thickness, and controllable fiber distribution and orientation. Through alternating operations of "spraying-laying mesh-re-spraying," the fiber mesh can be completely embedded within the composite material, forming a "sandwich" structure, which is beneficial for improving the interfacial bonding strength between the fiber mesh and the slurry, avoiding phenomena such as displacement and wrinkling of the fiber mesh caused by slurry flow or its own weight; it eliminates the quality fluctuations caused by manual pressing and troweling construction methods, which is conducive to large-scale promotion and application.

[0130] In some embodiments, the establishment of the substrate surface model in step S1 specifically includes: performing coordinate registration, noise removal, and surface reconstruction on the scanning results to extract the substrate information.

[0131] Furthermore, the information includes at least one of boundary information, curvature information, and corner information.

[0132] In some embodiments, the step S2 of generating a spraying scheme based on the model specifically includes: dividing the substrate surface into several sub-regions with simple geometric features and no risk of collision based on the model, and generating a spraying scheme by combining equidistant cross-sectional lines and a path planning algorithm based on three-dimensional topology.

[0133] Furthermore, the spraying scheme includes at least one of the following: spraying trajectory, nozzle posture, and material output rate.

[0134] In some embodiments, the application method further includes surface treatment of the substrate prior to spraying.

[0135] In some embodiments, the weaving in step S5 is performed by machine weaving.

[0136] In some embodiments, step S5, which involves weaving an optical fiber sensing array into the fiber fabric web, specifically includes: using the fiber fabric web as the load-bearing warp and / or weft yarns, using optical fibers as functional yarns, and introducing optical fibers as auxiliary warp and / or weft yarns into the fabric structure, so that the optical fiber sensing array is set inside the fiber fabric web, thereby obtaining an integrated fiber fabric web with sensing function.

[0137] According to an embodiment of the present invention, the application method employs an automated spraying system based on a multi-degree-of-freedom robotic arm for construction, while the fiber fabric mesh is laid manually.

[0138] Therefore, by combining "automatic spraying of slurry by robotic arms" with "precise laying of fiber mesh by manual labor," the automated spraying of slurry by robotic arms achieves rapid, uniform, and continuous application, overcoming the shortcomings of low efficiency and uneven thickness in manual spraying. Precise laying by manual labor ensures accurate positioning, flat spreading, and reliable overlapping of the fiber mesh, avoiding the problem of insufficient laying accuracy of robotic arms at complex boundaries. The two complement each other, improving construction efficiency while ensuring the quality of the finished product.

[0139] In some embodiments, the application method further includes a curing process after the reinforcement layer is obtained.

[0140] Furthermore, the maintenance treatment specifically includes: using a spray system mounted on a robotic arm or manually covering the area with damp burlap for moisturizing and maintenance, for a duration of not less than 7 days.

[0141] The present invention will be explained below with reference to embodiments. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0142] Example 1 like Figure 2 As shown, this embodiment takes a typical earthen structure residential building in an 8-degree seismic fortification zone as the building to be reinforced. The building is a single-story structure with a wall area of ​​195m², and the structural design is carried out according to the seismic requirements of an 8-degree seismic fortification zone.

[0143] A carbon-fixing, self-healing cement-based composite material, comprising the following components: The active magnesium oxide cement matrix is ​​a mixture of active magnesium oxide (effective content > 95%), water and sodium hexametaphosphate (Na(PO3)6) in a mass ratio of 1:0.65:0.02, with a water-cement ratio of 0.6. After 7 days of room temperature curing, the average compressive strength of the cement matrix can reach 50.2 MPa. The PVA fiber is a nano-SiO2 modified PVA fiber with a length of 12 mm, a diameter of 39 μm, a tensile strength of 720 MPa, an elastic modulus of 22 GPa, and a density of 1.8 g / cm³. 3 The dosage is 2 vt%; the preparation method of the nano-SiO2 modified PVA fiber includes: ultrasonicating nano-SiO2 in a mixed solution of toluene and water for 30 min, then immersing PVA fiber in the mixed solution at 90°C for 2 h to carry out hydrolysis and condensation reaction, forming a SiO2 nano-coating in situ on the surface of the PVA fiber, and obtaining nano-SiO2 modified PVA fiber.

[0144] The hollow plant fiber is made of hollow sisal fiber, with a length of 15 mm, a diameter of 200 μm, a tensile strength of 350 MPa, an elastic modulus of 3.2 GPa, and a density of 1.5 g / cm³. 3 The dosage is 2 vt% The fiber fabric mesh is made of alkali-resistant glass fiber impregnated with PVC resin, with an areal density of 400 g / m². 2 The unidirectional yarn fineness is 5280 tex, the unidirectional tensile strength is 1337 MPa, the breaking force is 130 kN / m, the elastic modulus is 55 GPa, and the mesh size is 25mm×25mm.

[0145] The method for applying the composite material includes: (1) System Deployment and Planning. A six-degree-of-freedom industrial robotic arm was deployed at the construction site, and an end effector with integrated spraying function was installed and connected to the slurry supply system. A three-dimensional laser scanner was used to scan the entire wall surface to generate a high-precision point cloud model. The model was imported into the control system software, and the thickness of the cement-based composite reinforcement layer was set (6mm for the bottom layer and two cover layers). The software automatically planned the movement path of the robotic arm, the attitude angle of the nozzle, the spraying speed, and the laying trajectory of the fiber mesh.

[0146] (2) Surface treatment of the structure. The robotic arm replaces the high-pressure water jet or polishing head and automatically roughens and cleans the existing structural surface along the planned path, removing loose layers and dirt, fully wetting it, and forming a solid, clean bonding surface with micro-roughness.

[0147] (3) Preparation of integrated fiber fabric web. Using fiber fabric web as the load-bearing warp and / or weft yarn, and optical fiber as the functional yarn, the optical fiber is introduced into the fabric structure as auxiliary warp and / or weft yarn by means of machine weaving, so that the optical fiber sensing array is set inside the fiber fabric web, thereby obtaining an integrated fiber fabric web with sensing function.

[0148] (4) Semi-automated layered construction. The robotic arm switches to the slurry supply system, and the operator starts the automated spraying program. The robotic arm moves along the predetermined trajectory, and the special nozzle sprays the freshly mixed composite material slurry evenly onto the interface agent under constant pressure, forming a dense and uniform base layer of about 6 mm thick. While the base slurry still has good plasticity (usually within 30 minutes after spraying), 2-3 construction workers cooperate to unfold the pre-cut integrated fiber fabric mesh (15m×15m mesh) according to the wall size and lay it tightly against the bottom of the board. The workers gently roll it with a scraper or roller to ensure that the mesh is completely embedded in the wet slurry, ensuring no wrinkles, no arching, and no visible voids. The robotic arm is started again, and it sprays a cover layer of slurry about 6 mm thick on the laid fiber mesh along a path staggered from the base layer, completely wrapping the fiber mesh. This is repeated twice to form a total thickness of about 20 mm and a total volume of about 3.9 m³. 3 The overall reinforcement layer can be finished by using a scraper assembly attached to a robotic arm or by manual finishing.

[0149] (5) Integrated curing. After construction is completed, the reinforcement layer is immediately moisturized by using a spray system mounted on a robotic arm or by manually covering it with wet burlap for a period of not less than 7 days. After curing, the reinforcement layer enters the natural carbonization and service stage, and its carbon fixation and self-healing functions are activated.

[0150] The mechanical properties of the composite material were tested according to standard T / CECS 997-2022, "Technical Specification for High-Toughness Concrete-Reinforced Masonry Structures". The tests showed that the composite material has a tensile strength of 11.3 MPa, a maximum tensile strain of 2.03%, a maximum crack width of 65 μm, an equivalent flexural strength of 15.1 MPa, and an equivalent flexural toughness of 177.9 kJ / m. 3 It is evident that the glass fiber mesh and PVA fiber exhibit a good synergistic effect due to the high deformation performance and low elastic modulus, allowing the crack control performance of PVA fiber and the high ductility advantage of glass fiber mesh to be fully utilized simultaneously.

[0151] According to standards GB 50003-2011 "Code for Design of Masonry Structures" and GB50608-2010 "Technical Specification for Application of Fiber Reinforced Composite Materials in Construction Engineering", the ultimate shear bearing capacity of the unreinforced soil structure before and after reinforcement was tested and verified. The ultimate shear bearing capacity of the unreinforced soil structure was 575 kN. After reinforcement with the aforementioned composite material, the ultimate shear bearing capacity of the soil structure was 4709 kN, which is higher than the standard value of 4108 kN for seismic action at an 8-degree intensity, and thus meets the seismic fortification requirements of an 8-degree intensity.

[0152] Comparative Example 1 like Figure 3As shown, this comparative example is based on Example 1, differing only in that: a traditional reinforced concrete (wire mesh) cement mortar surface layer is used for reinforcement. Due to the protective layer requirement for the reinforcing mesh, the thickness of the reinforced surface layer is 60mm, with a total volume of approximately 11.7m³. 3 The reinforcement ratio is 1.2%.

[0153] Test Example 1 The carbon emissions of the reinforced layers described in Example 1 and Comparative Example 1 were calculated according to standard GB / T 51366-2019, "Standard for Calculation of Carbon Emissions from Buildings". The emission factor method was used, and the service life was calculated as 50 years. The full life-cycle carbon emission calculation results are as follows: (1) Carbon emissions during the raw material production stage: E1 = Σ(M i ×F i ), where M i F represents the amount (kg) of the i-th raw material. i Let be the carbon emission factor (kg CO2 / kg) of the i-th raw material.

[0154] Raw material usage and carbon emissions in Example 1: The carbon emission factor of activated magnesium oxide cement (MgO recovered from waste magnesium oxychloride cement MOC-based waste) is 0.49 kg CO2 / kg, with a usage of 8.58 tons and carbon emissions of 4204 kg CO2; the carbon emission factor of sisal fiber is 0.1 kg CO2 / kg (plant fiber is a renewable material with low energy consumption in the production process), with a usage of 117 kg and carbon emissions of 11.7 kg CO2; the carbon emission factor of PVA fiber is 2.8 kg CO2 / kg, with a usage of 140 kg and carbon emissions of 392 kg CO2; the carbon emission factor of glass fiber woven mesh is 2.39 kg CO2 / kg, with a usage of 156 kg (0.4 kg / m²). 2 ×390m 2 E1 = 5041.2 kg CO2, with carbon emissions of 433.5 kg CO2.

[0155] Comparative Example 1: Raw material usage and carbon emissions: The total weight of the reinforced cement mortar was 29.25 tons; of which, the carbon emission factor of cement was 0.9 kg CO2 / kg, the usage was 11.11 t, and the carbon emissions were 9999 kg CO2; the carbon emission factor of steel bars was 2.3 kg CO2 / kg, the usage was 1102 kg, and the carbon emissions were 2534.6 kg CO2; the carbon emission factor of sand was 0.01 kg CO2 / kg, the usage was 14 t, and the carbon emissions were 140 kg CO2; E1' = 12673.6 kg CO2.

[0156] (2) Carbon emissions during construction phase (E2): Carbon emissions from transportation E 22 =Σ(Qk ×D k ×F k ), where Q k Let D be the transport volume (t) of the k-th material. k F represents the transport distance (km). k The carbon emission factor of the transportation vehicle (kg CO2 / (t·km)).

[0157] The construction efficiency and transportation distance of the two schemes are similar, so the energy consumption during the construction phase is related to the amount of materials used. The carbon emission during the construction phase of Example 1 is E2 = 500 kg CO2, and the carbon emission during the construction phase of Comparative Example 1 is E2' = 1500 kg CO2.

[0158] (3) Carbon emissions during operation and use (E3): Carbon sequestration negative carbon emissions E 32 =-(F seq ×M), where F seq M represents the carbon fixation factor per unit mass of Example 1 (kg CO2 / kg), and M represents the total mass of the reinforcement layer (kg).

[0159] The carbon fixation factor of the reinforced layer described in Example 1 was determined using the acid dissolution weight loss method. Specifically, the sample cured with carbon dioxide was pulverized and added to an acid solution and stirred, causing the carbonate components in the sample to react with the acid and release carbon dioxide gas. By comparing the mass change of the system before and after the reaction, and subtracting the mass change caused by factors such as water evaporation in the blank control, the amount of carbon dioxide released by the sample could be obtained, and the carbon fixation factor could be calculated.

[0160] Measurements showed that the carbon fixation factor of Example 1 was 0.45 kg CO2 / kg, and the total carbon fixation amount was E3 = 3861 kg CO2. Considering long-term service conditions, the limiting carbon fixation factor of Example 1 was 1.1 kg CO2 / kg, and the total carbon fixation amount was E3 = 9438 kg CO2. The scheme of Comparative Example 1 had no carbon fixation effect, E3' = 0.

[0161] (4) Carbon emissions (E4) during maintenance and repair: The reinforcement layer described in Example 1 exhibits excellent durability, requiring only one partial repair during its 50-year service life. The carbon emissions during the maintenance and repair phase are E4 = 500 kg CO2. In Comparative Example 1, due to issues such as steel reinforcement corrosion and mortar cracking, repairs are performed every 10 years, with carbon emissions during the maintenance and repair phase estimated at E4' = 2500 kg CO2. The total life-cycle carbon emissions (Etotal) of the reinforcement system are calculated as E1 + E2 + E3 + E4. Example 1: Total life-cycle carbon emissions (E) of the reinforcement system. total = 2180.2 kg CO2, Comparative Example 1 Total life cycle carbon emissions Etotal =16673.6 kg CO2, the overall carbon reduction rate of the reinforcement system in Example 1 is 86.9%. If the extreme carbon sequestration factor under long-term service is considered, the total carbon emissions of Example 1 over the entire life cycle can be reduced to -3396.8 kg CO2, achieving positive artificial carbon sequestration throughout the entire life cycle.

[0162] In the description of this specification, the references to terms such as "an embodiment," "some embodiments," "a method of implementation," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0163] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A cement-based composite material with carbon fixation, self-healing, and sensing functions, characterized in that, By volume percentage, it consists of 92-97% active magnesium oxide cement matrix, 1-4% hollow plant fiber, 1-2% PVA fiber, 0.5-3% fiber woven web and 0.05-0.1% fiber optic sensor array; The hollow plant fiber is bamboo fiber or sisal fiber; The length of the hollow plant fiber is 15~50 mm; The equivalent diameter of the hollow fiber cells in the hollow plant fiber is 5~50 μm; The length of the PVA fiber is 11~18 mm; The diameter of the PVA fiber is 39~70 μm; The tensile strength of the PVA fiber is 700~1620 MPa; The PVA fiber is a nano-SiO2 modified PVA fiber; The unidirectional yarn fineness of the fiber fabric web is 1000~8000 tex; The tensile strength of the fiber fabric web is >100 kN / m; The mesh size of the fiber fabric web is greater than or equal to 15mm × 15mm; The equivalent tensile strength of the composite material is greater than 10 MPa; The ultimate tensile strain of the composite material is greater than 1.5%; The composite material exhibits strain hardening characteristics under tensile load, with crack width within 100 μm. The composite material can achieve self-healing of cracks with a width of less than or equal to 100 μm within 10 days in a CO2-containing environment.

2. The composite material according to claim 1, characterized in that, At least one of the following conditions must be met: The activated magnesium oxide cement matrix comprises 60-70 wt% activated magnesium oxide, 30-40 wt% water, and 60.01-0.03 wt% sodium hexametaphosphate (Na(PO4)). The water-cement ratio of the active magnesium oxide cement matrix is ​​0.4~0.

6.

3. The composite material according to claim 1, characterized in that, At least one of the following conditions must be met: The outer diameter of the hollow plant fiber is 50~250 μm; The tensile strength of the hollow plant fiber is 250~450 MPa.

4. The composite material according to claim 1, characterized in that, The elastic modulus of the PVA fiber is 20~40 GPa.

5. The composite material according to claim 1, characterized in that, At least one of the following conditions must be met: The fiber fabric web includes at least one of carbon fiber web, glass fiber web, basalt fiber web or aramid fiber web; The fiber fabric web is at least one of a two-dimensional mesh structure or a three-dimensional mesh structure; The uniaxial tensile strength of the fiber fabric web is 800~2400 MPa; The elastic modulus of the fiber fabric web is 50~200 GPa; The interlayer spacing d of the fiber fabric web satisfies: 5mm < d < 10mm.

6. The composite material according to claim 1, characterized in that, The fiber optic sensing array is disposed inside the fiber optic fabric web.

7. The composite material according to any one of claims 1 to 6, characterized in that, The composite material has a carbon fixation factor greater than 0.2 g CO2 / g and a carbon absorption efficiency greater than 40 g·m. -2 ·d -1 The carbonization depth is greater than or equal to 20 mm after 28 days.

8. A method for applying the cement-based composite material as described in any one of claims 1 to 7, characterized in that, include: A three-dimensional scan of the substrate surface is performed to obtain digital scan results, and a substrate surface model is established. Based on the model, a spraying scheme is generated; The active magnesium oxide cement matrix, hollow plant fiber, and PVA fiber are mixed to obtain a slurry; The automated spraying system is activated to spray the slurry onto the substrate surface, thus obtaining the base slurry. By incorporating an optical fiber sensor array into the fiber fabric web, an integrated fiber fabric web with sensing capabilities is obtained. Before the initial setting of the bottom slurry, the integrated fiber fabric web is spread out and pressed into the surface of the bottom slurry; The slurry is sprayed again to obtain a reinforcing layer.

9. The application method according to claim 8, characterized in that, The application method employs an automated spraying system based on a multi-degree-of-freedom robotic arm for construction, while the fiber fabric mesh is laid manually.

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