210 results about "Cement based composites" patented technology

The invention relates to an ionic redox couple thermoelectric cement-based composite material, the composite material comprises a cement matrix and redox couples, and the redox couples exist in pores of the cement matrix; wherein the redox pairs are K4 [Fe (CN) 6] and K3 [Fe (CN) 6], and the porosity of the cement matrix is 25%-50%. According to the invention, the migration of ions in a cement matrix is regulated and controlled by introducing the redox couple, so that a relatively high Seebeck coefficient, conductivity and power factor are achieved while good mechanical properties are maintained, and the thermoelectric conversion efficiency is remarkably improved. Besides, the composite material can drive electrode reaction through temperature difference to generate a closed current loop, stable current output is achieved, and the problem of current output of a traditional ionic thermoelectric material is solved.

The invention relates to the field of cement-based composite materials, and particularly discloses a high-performance self-compacting high-crack-resistance fiber-reinforced cement-based composite material and a preparation method thereof.The cement-based composite material is prepared from cement, fly ash microspheres, silica fume, a modified geopolymer, sand, fine stone, polypropylene fibers, an expanding agent, an additive and water; wherein the additive at least comprises welan gum; the preparation method comprises the following steps: mixing and stirring the cement, the fly ash beads, the silica fume, the sand, the fine stone and the modified geopolymer, and adding the expanding agent to prepare a primary mixture; and mixing the admixture with water, adding the primary mixture, then adding the polypropylene fiber, stirring and mixing, then adding the rest admixture, and stirring to obtain the product. The cement-based composite material has the characteristics that the prepared cement-based composite material has better fluidity and better segregation resistance and crack resistance, and the cement-based composite material can be applied to the fields of non-dismantling bottom die floor support plate bottom plates, foundation support grouting reinforcement, section increasing method reinforcement, quick pavement repair and the like.

The invention relates to a marine environment mass concrete construction and crack repairing method, which comprises the following steps: in a mass concrete construction stage, carrying out aggregate precooling, carrying out layered intermittent pouring by using the precooled aggregate, and carrying out cooling treatment at the same time, so that the internal and external temperature difference is controlled within 20 DEG C; if cracks appear on the mass concrete, a polymer modified cement-based composite material is prepared for repairing, the polymer modified cement-based composite material comprises composite gel, a macromolecular tackifier and aggregate, the composite gel is based on 60%-70% of Portland cement, and 5%-8% of nano silicon powder and 10%-15% of fly ash are doped; the macromolecular adhesive comprises 0.5%-1.2% of polyacrylamide or 2%-3% of epoxy resin emulsion. When the scheme is used for repairing marine mass buildings, the overall viscosity of concrete can be improved, the internal and external temperature difference of the concrete is reduced, and the overall impermeability of the concrete repairing material is improved.

The invention relates to a photovoltaic heat dissipation enhanced radiation refrigeration cement-based composite material as well as a preparation method and application thereof. The composite material comprises white Portland cement, radiation refrigeration particles and water, the radiation refrigeration particles comprise alpha aluminum oxide and barium sulfate, the mass fraction of the radiation refrigeration particles relative to the total solid content in the composite material is 30%-60%, and the mass ratio of the alpha aluminum oxide to the barium sulfate is 1: 1-2: 1; the average particle size of the radiation refrigeration particles is 0.3-10 [mu] m; the mass fraction of the white Portland cement relative to the total solid content in the composite material is 40-70%. Compared with the prior art, the reflectivity and emissivity of the material are improved, efficient photovoltaic thermal management is achieved, meanwhile, the material has the advantages of being low in cost, simple in process, high in stability and the like, development of the building photovoltaic integrated technology is expected to be promoted, and the energy utilization efficiency is improved.

The invention belongs to the technical field of building materials, and provides a cement-based composite material with an organic-inorganic interpenetrating structure and a preparation method of the cement-based composite material. According to the preparation method disclosed by the invention, the monomer and the polymer containing the active group are introduced, the in-situ polymer formed by the monomer through in-situ polymerization and the polymer containing the active group form a double-network polymer, a single-network structure is refined, and the single-network structure and a cement hydration reaction product which is synchronously performed form an organic-inorganic interpenetrating structure; the interaction between double networks and the cement-based material is enhanced, meanwhile, the microstructure is optimized, the mechanical property of the single polymer modified cement-based material can be improved, the compressive strength is improved, and the breaking strength is further enhanced; the prepared cement-based composite material with the organic-inorganic interpenetrating structure has excellent breaking strength and compressive strength.

The invention discloses a design method of a high-ductility cement-based composite material, which comprises the following steps: S1, carrying out mix proportion design by using Box-Behnken in a response surface method, and designing a three-factor three-response test, the three factors being a water-binder ratio, a sand-binder ratio and a fiber mixing amount; s2, mixing and proportioning the materials according to the three factors in S1, and preparing to obtain the high-ductility cement-based composite material, s3, maintaining the high-ductility cement-based composite material obtained in the S2, and testing the three-response mechanical properties in the S1, wherein the three responses are compressive strength Y1, breaking strength Y2 and equivalent bending toughness Y3; and S4, analyzing the influence of the interaction of the three factors in the S1 on the three responses in the S3, establishing a response surface model equation through variance analysis verification, and verifying and optimizing a result to obtain an optimal mix proportion. A Box-Behnke method in RSM is adopted to establish a regression model with the water-binder ratio, the sand-binder ratio and the fiber mixing amount as influence factors and the compressive strength, the breaking strength and the equivalent bending toughness as response values.

The invention discloses an interface enhanced composite shear wall based on a high-ductility cement-based material. The high-ductility cement-based composite materials are formed in edge constraint areas on the two sides of the shear wall, and the common concrete is formed in a core area in the middle of the shear wall. The interface separation net is a high-strength ribbed non-dismantling formwork net and is vertically arranged at the junction of the edge constraint area and the core area, the section of the interface separation net is in a periodic concave-convex wave shape or a stepped shape, and a macroscopic mechanical meshing interface is formed. The interface seaming ribs are U-shaped ribs and are horizontally arranged at the positions of the inter-rib slurry penetrating nets of the interface separation net in a penetrating mode, one ends of the interface seaming ribs are anchored to the edge constraint area common steel bars, and the other ends of the interface seaming ribs extend into the core area and are connected with longitudinal and transverse rib cross joints of the composite material grid ribs in a hooked mode; the problems of rigidity mutation and slippage of the heterogeneous material interface are solved by utilizing the geometric occlusion effect of the interface separation net and the anchoring effect of the deep bolt pins and joints of the interface sewing ribs, cooperative work of a high-ductility material and common concrete is achieved, and good anti-seismic performance is achieved.

The invention discloses a microcapsule phase change cement material, which is prepared by compounding a microcapsule with phase change performance and a cement matrix, the microcapsule is of a core-shell structure, the raw materials of the shell are melamine, urea and formaldehyde, the raw material of the core material is octadecane, and Tween 80 and lauryl sodium sulfate are used as emulsifiers. The preparation method comprises the following steps: 1, preparing an MUF resin prepolymer; 2, preparing a core material O / W emulsion; 3, polymerization reaction of the microcapsules; and 4, preparing the microcapsule phase change cement material. When the composite material is used as a cement-based composite material, the melting temperature ranges from 25 DEG C to 29 DEG C, the crystallization temperature ranges from 19 DEG C to 23 DEG C, the melting enthalpy ranges from 13.47 J / g to 29.78 J / g when the mixing amount is 10%-30%, the crystallization enthalpy ranges from 12.94 J / g to 28.41 J / g, and the coating efficiency is 67.5%. The initial decomposition temperature ranges from 386.13 DEG C to 390.96 DEG C, the finishing temperature ranges from 399.49 DEG C to 406.42 DEG C, and the maximum degradation temperature ranges from 438.78 DEG C to 443.64 DEG C; the heat conductivity coefficient is 0.3216 to 0.3949, and is improved by 39.4 percent compared with that of standard cement.

The invention discloses a lightweight heat-insulation cement-based composite material, and relates to the technical field of cement-based composite materials, the lightweight heat-insulation cement-based composite material comprises the following material components by weight: 40-60 parts of a cement matrix, 20-35 parts of a lightweight aggregate, 5-12 parts of a polymer modifier, and 0.5-0.3 part of a functional additive, the cement matrix is sulphoaluminate cement or Portland cement, and the functional additive is a water-based composite material. The lightweight aggregate comprises hollow glass beads with the particle size of 0.1-0.5 mm, expanded perlite with the particle size of 0.5-2 mm and surface modified aerogel particles, the aerogel particles are silicon dioxide aerogel or silicon carbide aerogel, the surface area of the aerogel particles is 700-600 m / g, the pore diameter of the aerogel particles is 40-50 nm, the polymer modifier is acrylate-styrene copolymer emulsion, and the particle size of the polymer modifier is 1-10 m / g. The solid content of the acrylate-styrene copolymer emulsion is 50-45%, the glass transition temperature of the acrylate-styrene copolymer emulsion is-10 DEG C to 15 DEG C, and the functional additive comprises a cellulose ether thickener, a polycarboxylate superplasticizer and a nano aluminum oxide dispersion liquid.

The invention provides a cement-based composite material based on a bionic structure and a preparation method thereof, and belongs to the field of building materials.The cement-based composite material comprises a plurality of cement slurry layers and a plurality of non-metal continuous fiber layers which are alternately stacked layer by layer; steel fibers are mixed in the cement slurry layers, and the steel fibers in the same cement slurry layer are arranged in the same direction; the non-metal continuous fibers in each non-metal continuous fiber layer are arranged in the same direction; and the projection included angle theta between the steel fibers in any cement slurry layer and the nonmetal continuous fibers in the adjacent nonmetal continuous fiber layer meets the following condition: 5 degrees is greater than or equal to theta. A discontinuous fiber stacking structure is improved, a rigid discontinuous steel fiber and flexible non-metal continuous fiber alternate stacking structure is adopted, and a bionic structure is formed through precise pouring forming, so that the cement-based composite material has ultrahigh tensile strength and strain performance.

The invention discloses a high-elastic-modulus and high-ductility cement-based composite material for assembly type component joint connection and a preparation method thereof.According to the scheme, the composite material is prepared from, by mass, 500-700 parts of cement, 360-504 parts of granulated blast furnace slag, 120-168 parts of fly ash, 120-168 parts of silica fume, 323-462 parts of quartz sand and 377-539 parts of iron ore sand. The concrete is prepared from the following components in parts by weight: 176 to 246 parts of water, 14 to 18 parts of composite fiber, 5.5 to 7.5 parts of a water reducing agent, 30 to 42 parts of an expanding agent, 5 to 7 parts of a binder, 0.5 to 0.7 part of a retarder, 1 to 1.4 parts of a deflocculating agent, 0.15 to 0.21 part of a defoaming agent and 0.5 to 0.7 part of a rheological agent. Furthermore, a corresponding step-by-step stirring preparation process is matched, so that the accurate regulation and control of the material performance are effectively realized. According to the invention, the problems of poor working performance, low tensile strength, insufficient elastic modulus and the like of the traditional high-ductility concrete (ECC) in assembly type component node connection can be solved, and the strict requirements of assembly type nodes on strength, construction and deformation performance can be met.

The invention discloses a microorganism-nano synergistically reinforced cement-based composite material for self-repairing concrete cracks, which realizes the self-repairing and performance improvement of the cracks through the synergistic effect of bacillus pseudofirmus, carbon nanotubes, nano magnesium oxide and red mud. The material has the following characteristics: bacillus pseudofirmus is used as a microbial remediation agent, and dormant spores are activated when meeting water and oxygen and then are subjected to a series of biochemical reactions to induce calcium carbonate precipitation products so as to effectively fill microcracks; the carbon nano tube network structure not only enhances the mechanical property of the concrete, but also can provide a channel for directional deposition of a repairing substance; the nano magnesium oxide compensates shrinkage stress through hydration reaction, and meanwhile, a proper alkaline environment is maintained to guarantee microbial activity; the industrial waste red mud is used for replacing part of cement, so that carbon emission is reduced, and microorganisms are fixed by utilizing the porous characteristic of the red mud.

The invention discloses a lightweight high-strength high-toughness cement-based composite material and a preparation method thereof. The composite material is prepared from the following components in parts by mass: 1000 parts of a cementing material, 200-400 parts of fine aggregate, 150-250 parts of water, 10-30 parts of a water reducing agent, 14-23 parts of synthetic fiber and 10-30 parts of silicon dioxide aerogel. The preparation method comprises the following steps: mixing and stirring 1000 parts of the cementing material, 200-400 parts of the fine aggregate and 10-30 parts of the silicon dioxide aerogel to obtain a dry material, then adding 10-30 parts of the water reducing agent and 150-250 parts of the water into the dry material, mixing and stirring to obtain neat paste, and finally adding 14-23 parts of the synthetic fiber into the neat paste while stirring, and mixing and stirring to obtain slurry. The light-weight, high-strength and high-toughness cement-based composite material is few in component variety, simple in preparation method, low in volume weight, high in strength and large in ultimate tensile strain, and the problems that a traditional light-weight and high-toughness cement-based material is large in light-weight aggregate mixing amount, low in strength, poor in ductility and stability and the like are solved; and the method has a wide application prospect in infrastructures such as high-rise building structure facades and large-span bridge structure pavement layers.

The invention discloses an artificial biological reef for naturally repairing coral, a system and a preparation method. The artificial biological reef body comprises a main body structure made of a cement-based composite material, and at least one hollow cavity is formed in the main body structure; the ecological through holes penetrate through the wall thickness of the main body structure and are used for promoting water flow exchange and marine organism channels; the biological affinity surface layer is arranged on the surface of the main body structure, is made of cement-based materials mixed with seaweed extracts and has rough textures so as to promote attachment of coral larvae; and a reinforcing framework formed by a corrosion-resistant fiber reinforced material embedded in the main body structure improves the overall structural strength and impact resistance. The system comprises a plurality of reefs, special connecting pieces and a foundation stabilizing platform, and can be combined into an array for simulating a natural reef space structure. The preparation method comprises the steps of seaweed extract preparation, bioactive slurry preparation, assembly prefabrication, integrated pouring forming, maintenance and function integration, and preparation of the eco-friendly, stable-structure and multifunctional artificial reef is achieved.

The invention provides a high-strength and high-ductility damage self-repairing cement-based composite material based on spiral memory alloy fibers and a preparation method of the high-strength and high-ductility damage self-repairing cement-based composite material, and belongs to the technical field of underwater engineering concrete structures. According to the invention, the matrix mix proportion of the cement-based composite material and the hybrid reinforcement effect of the three fibers on the matrix are redesigned, so that the tensile strain capacity is also remarkably improved while the strength of the UHPSC is improved, and the deformation ductility and the cumulative energy dissipation capacity of the cement-based composite material are further remarkably enhanced; as the spiral superelastic SMA fibers have self-resetting capacity, restoring force can be provided for the unloaded cement-based composite material, tensile cracks of the cement-based composite material are promoted to be automatically closed or the width of residual cracks of the cement-based composite material is obviously reduced, and on the basis, the self-healing capacity of an incompletely hydrated cementing material in the cement-based composite material is matched, so that the self-healing performance of the cement-based composite material is improved. And the UHPSC material can present a good damage self-repairing effect.

The present invention provides a high-ductility cement-based composite material, which comprises, by weight, 20-30 parts of Portland cement, 25-45 parts of fly ash, 10-20 parts of mineral powder, 1-2 parts of PP fiber, 0.5-1 part of a polycarboxylic acid high-performance water reducer, 1-10 parts of 40-70 mesh quartz sand, 5-10 parts of 70-100 mesh quartz sand, 0.1-0.5 parts of polyacrylamide, and 15-20 parts of water. The modified PP fiber is PP fiber modified by nano-calcium carbonate, nano-silicon dioxide, and a coupling agent. The preparation method comprises the following steps: respectively weighing Portland cement, fly ash, mineral powder, quartz sand, and polyacrylamide, dry-mixing them in proportion to obtain a dry mix; then adding the polycarboxylic acid high-performance water reducer and water to the dry mix in at least two portions and stirring them; and finally adding the modified PP fiber and continuing to stir to obtain the cement-based composite material. The cement-based composite material has excellent mechanical properties, can improve the strength and durability of the structure, and has high ductility and high strength.

The invention relates to a nanofiber cement-based composite material suitable for 3D printing. The nanofiber cement-based composite material comprises the following raw materials in parts by weight: 45-50 parts of cement, 8-12 parts of silica fume, 6-10 parts of fly ash, 5-8 parts of sand, 3-5 parts of PVA, 3-5 parts of a polycarboxylate superplasticizer, 3-5 parts of floating beads and 30-35 parts of water. According to the cement-based composite material disclosed by the invention, the cement, the silica fume, the fly ash and other raw materials are matched with the modifier doped with the crystal whiskers and the effect supplement based on nano SiO modification, and the prepared cement-based composite material has excellent mechanical properties and coordinated improvement of fluidity through blending, coordination and common synergism of the raw materials.

The application provides a cement-based composite material and a preparation method thereof, and belongs to the technical field of composite material preparation.The application comprises the following steps: step one, preparing heat-conducting and enhanced phase change energy storage microcapsules with uniform and controllable particle sizes; step two, preparing heat-conducting and enhanced phase change energy storage microcapsules with controllable wall thicknesses; and step three, preparing a phase change energy storage cement-based composite material test piece.The application prepares heat-conducting and enhanced phase change energy storage microcapsules with uniform and controllable particle sizes through a microfluidic chip, controls the wall thicknesses of the microcapsules through a layer-by-layer self-assembly method, and finally adds the heat-conducting and enhanced phase change energy storage microcapsules with controllable wall thicknesses into a cement paste, so that the microcapsules are dispersed in the cement paste, and a phase change energy storage cement-based composite material with good heat regulation capacity is prepared.

This invention relates to the field of cement technology, specifically to a fiber-reinforced high-strength cement pole and its preparation method. The pole comprises a steel wire skeleton and a conical annular pole body covering its outer circumference. The pole body is formed by centrifugal molding and curing of a cement-based composite material containing interfacially pre-complexed basalt chopped fibers. The interfacially pre-complexed basalt chopped fibers are obtained sequentially through alkaline activation, silane-nano silica treatment, polycarboxylate segment grafting, and calcium ion pre-complexation, and are added to the slurry after the cementitious material is initially moistened and before the aggregate is added. This method improves the dispersibility and interfacial bonding stability of the basalt chopped fibers in a low water-cement ratio cement matrix, thereby enhancing the pole's compressive, tensile, crack, shrinkage, and freeze-thaw resistance.

The present invention discloses a method for preparing a solid electrolyte using sludge from a sand and gravel processing system. The main steps of the method are: drying and crushing the sludge from the sand and gravel processing system for pretreatment, adding silicate cement and a conductive material to the pretreated sludge, mixing them evenly, and calcining the mixture at a high temperature of 750-850°C for 1-2 hours under a nitrogen protection environment to obtain an electrolyte material; the conductive material is conductive charcoal powder or carbonized kitchen waste compost powder. The prepared electrolyte material can be further used to prepare a solid-state supercapacitor or a solid-state battery. This capacitor can be used as a wall tile, floor tile, or pavement tile, and can be combined with renewable energy to form an energy storage capacitor and a wireless charging device. The present invention not only realizes the resource utilization of solid waste from sand and gravel processing system sludge, but also realizes the multifunctional application of cement-based composite materials.

This invention provides an ultra-high ductility cement-based composite material for marine engineering and its preparation method. The ultra-high ductility cement-based composite material comprises, by weight, the following raw materials: 250-500 parts cement clinker, 400-600 parts fly ash, 200-300 parts mineral powder, 100-150 parts silica fume, 160-240 parts metakaolin, 600-900 parts quartz sand, 10-20 parts organic synthetic fiber, 20-30 parts organic rust inhibitor, 180-240 parts water, and 1-8 parts water-reducing agent. The organic rust inhibitor provided by this invention can inhibit steel corrosion and chloride ion intrusion into concrete through the dual effects of binding chloride ions and forming a passivation film, thereby improving concrete durability. By controlling the mix proportions of the four mineral admixtures and the dosage of the synthetic fiber component, the concrete can better balance high strength, high ductility, high durability, high flowability, and excellent resistance to deformation.

This invention discloses a testing device and method for tensile deformation of fiber-reinforced cementitious materials, belonging to the field of engineering material testing technology. The testing device mainly includes three parts: a support frame, a lever system, and a specimen mounting system. The main steps of the testing method include: lifting the lever to unload; installing the specimen mounting system, slowly releasing the lever and finely adjusting the position of the tensile specimen to reduce eccentricity and achieve preloading; repeatedly lifting and unloading the lever, and finely adjusting the centering tensile clamp and the tensile specimen; installing the displacement sensor and zeroing it in the unloaded state; adjusting the weight of the lever according to the real-time display value of the force sensor to complete the suspension and precise loading of the tensile specimen. This method applies tensile force to the cement-based composite material through the lever mechanism and performs arbitrary crack propagation evaluation based on the micro-cracks in the cement-based material using digital image processing, which can quantitatively characterize the creep deformation and crack propagation process of cement-based composite materials under continuous tensile load.

The invention relates to the technical field of cement-based composite materials, in particular to a basalt fiber reinforced cement-based composite material and a preparation method thereof. The basalt fiber reinforced cement-based composite material is prepared from the following raw materials in parts by weight: 300 to 400 parts of fine aggregate, 200 to 300 parts of sulphoaluminate cement, 80 to 120 parts of water, 40 to 60 parts of filler, 30 to 40 parts of powder, 30 to 40 parts of silica fume and 1 to 3 parts of water reducing agent. According to the preparation method, nano-cellulose is prepared after corbicula fluminea is treated, the nano-cellulose can be filled in the material to play a role in enhancing toughness, and meanwhile, the porosity of a material interface transition area can be reduced by mixing and adding the phytic acid modified starch and utilizing the complexing effect of phosphate groups of the phytic acid modified starch; further, all the component materials are combined more uniformly, stress transfer among all the component materials is smoother, and the effect of improving the strength performance of the cement-based composite material is achieved.

Disclosed are compositions containing carbonation-cured cementitious materials and a polyanionic polymer, and methods of making thereof. The carbonation-cured cementitious materials contain calcium silicates and the polyanionic polymer can constitute between about 0.01 wt.% and about 10 wt.% of the compositions, or between about 0.01 wt.% and about 10 wt.% of the calcium silicates. Containing the disclosed compositions have (i) increased compressive strength, (ii) increased flexural strength, (iii) increased carbon dioxide sequestration capabilities, (iv) increased calcite content, (v) reduced total pore area, or a combination of (i)-(v) when compared to a composition made from similar materials that are not carbonation-cured and / or not supplemented with the polyanionic polymer.

The invention relates to the field of bridge damping, in particular to a near-fault bridge anti-seismic toughness improving device and a test method thereof.The bridge comprises T-beams, a cover beam, a diaphragm plate between every two adjacent T-beams and an ECC column located between the two T-beams; two pairs of SMA disc spring devices are arranged on the ECC column body, one pair of SMA disc spring devices are arranged towards the T beam, and the other pair of SMA disc spring devices are arranged towards the transverse partition plate; the SMA disc spring devices are used for enabling the T beams to recover to the initial positions through the recovery characteristic of the SMA disc spring devices after relative displacement of the bridge in the transverse bridge direction occurs, and the ECC column is arranged between the two T beams of the bridge, so that the T beams can be recovered to the initial positions. The limit tensile strain of the ECC (fiber cement-based composite material) material can reach more than 200 times that of the traditional concrete, and the ECC material is accompanied by the multi-crack cracking phenomenon of fine cracks, so that the strain hardening characteristic of a similar metal material under the tensile effect is formed, and the structural deformation caused by earthquakes can be effectively dealt with.

The application discloses a kind of unbound post-tensioned prestressed fabricated column foot and post-earthquake rapid repair method, belong to building structure seismic and fabricated steel structure technical field.The column foot includes base plate, steel column, friction layer, strain hardening cement-based composite sleeve, vertical prestressed steel bar and cover plate;The friction layer uses block type structure, and is spliced by several friction layer monomers;Vertical prestressed steel bar is threaded through strain hardening cement-based composite sleeve and cover plate, and is fixed cover plate and applies prestress to vertical prestressed steel bar by disc spring group and anchor nut being set to its top end, realizes the unification of " high seismic, easy construction, fast repair ".The application also discloses the post-earthquake rapid repair method of the column foot, including post-earthquake evaluation, elastic self-resetting, installing temporary support, in-situ jacking, lateral replacement, resetting tensioning and the like steps, using unbound characteristics, without lifting off steel column can be completed in 3-4 hours friction layer replacement.

The invention relates to the use of glass fibre reinforced (GRP) composite pipe waste as filler material in both asphalt concrete and cement based composites. Significant ecological and product performance benefits are provided by using the material produced during the cutting and production processes of GRP pipes in mixtures as filler material by wet or drying and sieving through sieves of desired sizes.

The invention discloses a cement-based composite material and a preparation method thereof, and relates to the technical field of composite materials, and the cement-based composite material comprises the following components in parts by mass: 400-500 parts of cement, 150-200 parts of water, 0.5-1.0 part of a water reducing agent and 0.12-1.2 parts of magnetic graphene; the invention also provides a preparation method of the cement-based composite material. The preparation method comprises the following steps: S1, preparing the components according to the amount; s2, uniformly mixing water, a water reducing agent and the magnetic graphene, and performing ultrasonic dispersion for 10-30 minutes to form a magnetic graphene dispersion liquid; and S3, uniformly mixing and stirring the magnetic graphene dispersion liquid obtained in S2 and cement, putting the mixture into a standard mold, and then putting the standard mold into a uniform magnetic field generator for directional treatment to obtain the cement-based composite material.

The invention relates to the technical field of bridge pier repair, and particularly discloses a high-toughness corrosion-resistant ultrathin cement-based composite material for bridge pier reinforcement and a prefabricated assembled pile casing prepared from the high-toughness corrosion-resistant ultrathin cement-based composite material. The cement-based composite material is prepared from the following components in parts by weight: 20 to 30 parts of ordinary Portland cement, 10 to 20 parts of fly ash, 10 to 20 parts of mineral powder, 5 to 10 parts of silica fume, 25 to 45 parts of quartz sand, 1 to 2 parts of copper-plated steel fiber, 0.1 to 0.5 part of POM fiber, 10 to 15 parts of styrene-butadiene emulsion, 3 to 8 parts of phosphorus and aluminum co-doped nano silicon dioxide, 1 to 5 parts of modified rubber particles, 1 to 2 parts of polycarboxylic acid high-performance water reducing agent and 16 to 20 parts of water. On the basis of phosphorus and aluminum co-doped nano silicon dioxide and modified rubber particles, a high-toughness and corrosion-resistant cement-based composite material suitable for the ultrathin prefabricated pile casing is developed, so that the pile casing has the characteristics of small dead weight, good toughness and large design freedom degree, and has a better reinforcing effect on a concrete bridge lower structure with durability damage.

The application discloses an ultra-early-strength high-anti-cracking cement-based composite material and a preparation method thereof, and belongs to the technical field of building materials. The cement-based composite material comprises cement, aggregate, fiber, water reducing agent, early-strength agent, composite expansion agent, admixture and retarder. The composite expansion agent comprises expansion agent A and coated expansion agent B. The tensile strength of the coating layer of the coated expansion agent B is 1.5-2.0 MPa, and the elongation at break is 5-10%. The cement-based composite material effectively solves the problem of early cracking of ultra-early-strength cement and has high anti-cracking performance.