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CN-121974624-A - Cement-based composite material based on multistage toughening and intelligent repair and preparation method thereof

CN121974624ACN 121974624 ACN121974624 ACN 121974624ACN-121974624-A

Abstract

The invention belongs to the technical field of building materials, and discloses a cement-based composite material based on multistage toughening and intelligent repair and a preparation method thereof, wherein the cement-based composite material comprises, by mass, 400-500 parts of ordinary Portland cement, 50-100 parts of mineral powder, 20-60 parts of nano metakaolin, 15-35 parts of epoxy modified redispersible emulsion powder, 1-5 parts of pre-water-absorbing SAP microspheres, 0.5-1.5 parts of PP fibers, 0.5-1.5 parts of PVA fibers, 800-900 parts of machine-made sand, 1-3 parts of surface-treated shape memory alloy short fibers, 3-8 parts of elastic polymer microspheres, and the mass ratio of additive comprising geopolymer prefabricated liquid, water reducer, defoamer and retarder to the finished product dry powder, geopolymer prefabricated liquid, mixing water, water reducer, defoamer and retarder is 100 (25-28) (8-10) (1-3) (0.5-2). Compared with the existing materials, the cement-based composite material provided by the invention has the characteristics of high toughness, impact resistance and low shrinkage, and simultaneously has an internal repairing function.

Inventors

  • SHI CHEN
  • GUO KEYU
  • LI XIAOJUAN
  • HE TINGSHU
  • LIU XIGUANG

Assignees

  • 西安建筑科技大学

Dates

Publication Date
20260505
Application Date
20260127

Claims (10)

  1. 1. The cement-based composite material based on multistage toughening and intelligent repairing is characterized in that the raw materials comprise finished product dry powder, additive and mixing water: In the finished product dry powder, the components comprise 400-500 parts of ordinary Portland cement, 50-100 parts of mineral powder, 20-60 parts of nano metakaolin, 15-35 parts of epoxy modified redispersible latex powder, 1-5 parts of pre-water-absorbing SAP microspheres, 0.5-1.5 parts of PP fibers, 0.5-1.5 parts of PVA fibers, 800-900 parts of machine-made sand, 1-3 parts of surface-treated shape memory alloy short fibers and 3-8 parts of elastic polymer microspheres; the additive comprises a geopolymer prefabricated liquid, a water reducing agent, a defoaming agent and a retarder, wherein the mass ratio of the finished dry powder to the geopolymer prefabricated liquid to the mixing water to the water reducing agent is 100 (25-28), the mass ratio of the defoaming agent to the retarder to the water reducing agent is 8-10, the mass ratio of the defoaming agent to the retarder is 1-3, and the mass ratio of the defoaming agent to the retarder is 0.5-2.
  2. 2. The cement-based composite material based on multistage toughening and intelligent repair according to claim 1, wherein the preparation process of the geopolymer prefabricated liquid is as follows: mixing sodium silicate with the modulus of 1.2-1.8 with sodium hydroxide solution to prepare an alkali excitant, wherein the concentration of the sodium hydroxide solution is 8-12mol/L, and the mass ratio of the sodium silicate to the sodium hydroxide solution is (3-4): 1; mixing the alkali-activated agent and metakaolin powder, and aging for 30-40 hours at 25-35 ℃ to obtain the geopolymer prefabricating liquid, wherein the mass ratio of the alkali-activated agent to the metakaolin powder is (0.7-0.9): 1.
  3. 3. The cement-based composite material based on multistage toughening and intelligent repair according to claim 1, wherein the preparation process of the epoxy modified redispersible emulsion powder is as follows: dispersing the ethylene-vinyl acetate copolymer emulsion powder into a solvent to obtain a dispersion liquid A, wherein the mass ratio of the ethylene-vinyl acetate copolymer emulsion powder to the solvent is 1 (6-8), and the solvent adopts toluene or acetone; Adding an epoxy silane coupling agent and a catalyst into the dispersion liquid A, and reacting for 5-7 hours at 65-75 ℃ to obtain a reaction mixed liquid A, wherein the mass ratio of the ethylene-vinyl acetate copolymer emulsion powder to the epoxy silane coupling agent to the catalyst is 100 (5-15) (0.05-0.45), and the catalyst adopts dibutyltin dilaurate; And (3) carrying out solid-liquid separation on the reaction mixed solution A, and washing and vacuum drying a solid product to obtain the epoxy modified redispersible emulsion powder.
  4. 4. The cement-based composite material based on multistage toughening and intelligent repair according to claim 1, wherein the preparation process of the pre-water-absorbing SAP microsphere is as follows: The SAP microspheres are placed in deionized water and soaked for 3 to 4 hours, so that the SAP microspheres absorb water to swell; Separating the SAP microsphere after water absorption and swelling, and removing water on the surface to obtain the pre-water absorption SAP microsphere; The particle size of the SAP microsphere is 100-300 mu m, and the pre-water absorption capacity is 20-50 times of the self dry weight of the SAP microsphere.
  5. 5. The cement-based composite material based on multistage toughening and intelligent repair according to claim 1, wherein the preparation process of the surface-treated shape memory alloy short fiber is as follows: Immersing the shape memory alloy short fiber into mixed acid liquid of hydrofluoric acid and nitric acid, treating for 5-20 minutes at 20-40 ℃, separating the shape memory alloy short fiber, cleaning and drying to obtain the surface-treated shape memory alloy short fiber, wherein the mixed acid liquid of hydrofluoric acid and nitric acid is obtained by mixing hydrofluoric acid with the concentration of 40 wt-50 wt% and nitric acid with the concentration of 65 wt-70 wt% according to the volume ratio of 1 (2-4); Or electroplating the shape memory alloy short fiber serving as a cathode in electrolyte containing copper salt, and forming a copper plating layer on the surface of the shape memory alloy short fiber to obtain the surface-treated shape memory alloy short fiber, wherein the electrolyte containing copper salt adopts a copper sulfate solution with the concentration of 100-200g/L, and the current density is controlled to be 0.5-2A/dm 2 and the electroplating time is controlled to be 5-15 minutes during electroplating.
  6. 6. The cement-based composite material based on multistage toughening and intelligent repairing according to claim 5, wherein the shape memory alloy short fiber is nickel-titanium alloy fiber, the diameter of the nickel-titanium alloy fiber is 0.08-0.25mm, the length of the nickel-titanium alloy fiber is 8-15mm, and the austenite finish temperature is-10 ℃ to 15 ℃.
  7. 7. The cement-based composite material based on multistage toughening and intelligent repair according to claim 1, wherein the elastic polymer microsphere has a core-shell structure, a shell of the elastic polymer microsphere is cross-linked polyacrylate, a core of the elastic polymer microsphere is a liquid hydrocarbon compound, the average particle size of the elastic polymer microsphere is 30-150 mu m, the thickness of the shell is 3-15 mu m, and the liquid hydrocarbon compound comprises at least one of liquid paraffin, isoparaffin and low-molecular-weight polyolefin liquid.
  8. 8. The cement-based composite material based on multistage toughening and intelligent repairing according to claim 1, wherein the length of the PP fiber is 5-7mm, the length of the PVA fiber is 7-9mm, the ordinary Portland cement is P.O42.5 ordinary Portland cement, the mineral powder is S95 mineral powder, the water reducer is a polycarboxylate water reducer, the defoamer is an organosilicon defoamer, and the retarder is sodium gluconate.
  9. 9. The method for preparing the cement-based composite material based on multistage toughening and intelligent repairing according to any one of claims 1 to 8, which is characterized by comprising the following steps: Mixing ordinary Portland cement, mineral powder, nano metakaolin, epoxy modified redispersible emulsion powder, PP fibers, PVA fibers, machine-made sand and elastic polymer microspheres in a dry way, and uniformly mixing to obtain a first dry mixture; adding the pre-water-absorption SAP microspheres into the first dry mixed material, and uniformly mixing to obtain a second dry mixed material; adding the surface-treated shape memory alloy short fiber into the second dry blend in inert atmosphere, and uniformly mixing to obtain finished dry powder; when the cement-based composite material is used, 25-28 parts of geopolymer prefabricated liquid, 8-10 parts of mixing water, 5-10 parts of water reducer, 1-3 parts of defoamer and 0.5-2 parts of retarder are correspondingly added into every 100 parts of finished dry powder in parts by mass, and the slurry based on the cement-based composite material with multistage toughening and intelligent restoration is obtained after uniform mixing.
  10. 10. The method for preparing the cement-based composite material based on multistage toughening and intelligent repairing according to claim 9, which is characterized by comprising the following steps: Dry mixing common silicate cement, mineral powder, nano metakaolin, epoxy modified redispersible emulsion powder, PP fiber, PVA fiber, machine-made sand and elastic polymer microsphere to obtain a first dry mixture, wherein the rotation speed of the dry mixture is 28-32 revolutions per minute, and the dry mixing time is 14-16 minutes; Adding the pre-water-absorbing SAP microspheres into the first dry mixed material to obtain a second dry mixed material, wherein the mixing speed is 18-22 rpm, and the mixing time is 4-6 minutes; Adding the surface-treated shape memory alloy short fiber into the second dry blend in an inert atmosphere, and carrying out in a nitrogen atmosphere when the finished product dry powder is obtained, wherein the ambient humidity is less than 35%, the mixing rotating speed is 78-82 r/min, and the mixing time is 3-5 min; When in use, the geopolymer prefabricated liquid, the mixing water, the water reducer, the defoaming agent and the retarder are added into the finished dry powder, and then mixed for 3-5 minutes at the rotating speed of 60-120 r/min, so as to obtain the slurry of the cement-based composite material based on multistage toughening and intelligent repair.

Description

Cement-based composite material based on multistage toughening and intelligent repair and preparation method thereof Technical Field The invention belongs to the technical field of building materials, and particularly relates to a cement-based composite material based on multistage toughening and intelligent repair and a preparation method thereof. Background As the most main engineering building material, the cement-based material is easy to crack and damage due to load, shrinkage and environmental corrosion in the long-term service process. Timely and effective repair is important to guaranteeing structural safety and prolonging service life. However, the conventional cement-based repair material has the inherent defects of large brittleness, poor toughness, weak impact resistance and the like, and is extremely easy to fail under the working condition of strict dynamic load or deformation requirements. In addition, the drying shrinkage and temperature shrinkage of the material often cause debonding of new and old interfaces or generation of internal microcracks, and the durability of the repairing effect is seriously affected. Although toughness can be improved to some extent by incorporating common fibers, such toughening approaches have limited effectiveness and cannot impart damage self-healing or active crack resistance to the material. At present, a cement-based repairing material capable of fundamentally and synchronously solving the problems of high toughness, impact resistance, low shrinkage and inherent repairing function is not available. Therefore, developing a high-performance composite material becomes a key direction for breaking through the bottleneck of the prior art and meeting the severe engineering repair requirement. Disclosure of Invention In order to solve the technical problems, the invention aims to provide a cement-based composite material based on multistage toughening and intelligent repair and a preparation method thereof. In order to achieve the above purpose, the present invention adopts the following technical scheme: the cement-based composite material based on multistage toughening and intelligent repairing comprises the following raw materials of finished product dry powder, additive and mixing water: In the finished product dry powder, the components comprise 400-500 parts of ordinary Portland cement, 50-100 parts of mineral powder, 20-60 parts of nano metakaolin, 15-35 parts of epoxy modified redispersible latex powder, 1-5 parts of pre-water-absorbing SAP microspheres, 0.5-1.5 parts of PP fibers, 0.5-1.5 parts of PVA fibers, 800-900 parts of machine-made sand, 1-3 parts of surface-treated shape memory alloy short fibers and 3-8 parts of elastic polymer microspheres; the additive comprises a geopolymer prefabricated liquid, a water reducing agent, a defoaming agent and a retarder, wherein the mass ratio of the finished dry powder to the geopolymer prefabricated liquid to the mixing water to the water reducing agent is 100 (25-28), the mass ratio of the defoaming agent to the retarder to the water reducing agent is 8-10, the mass ratio of the defoaming agent to the retarder is 1-3, and the mass ratio of the defoaming agent to the retarder is 0.5-2. Preferably, the preparation process of the geopolymer prefabricated liquid is as follows: mixing sodium silicate with the modulus of 1.2-1.8 with sodium hydroxide solution to prepare an alkali excitant, wherein the concentration of the sodium hydroxide solution is 8-12mol/L, and the mass ratio of the sodium silicate to the sodium hydroxide solution is (3-4): 1; mixing the alkali-activated agent and metakaolin powder, and aging for 30-40 hours at 25-35 ℃ to obtain the geopolymer prefabricating liquid, wherein the mass ratio of the alkali-activated agent to the metakaolin powder is (0.7-0.9): 1. Preferably, the preparation process of the epoxy modified redispersible emulsion powder comprises the following steps: dispersing the ethylene-vinyl acetate copolymer emulsion powder into a solvent to obtain a dispersion liquid A, wherein the mass ratio of the ethylene-vinyl acetate copolymer emulsion powder to the solvent is 1 (6-8), and the solvent adopts toluene or acetone; Adding an epoxy silane coupling agent and a catalyst into the dispersion liquid A, and reacting for 5-7 hours at 65-75 ℃ to obtain a reaction mixed liquid A, wherein the mass ratio of the ethylene-vinyl acetate copolymer emulsion powder to the epoxy silane coupling agent to the catalyst is 100 (5-15) (0.05-0.45), and the catalyst adopts dibutyltin dilaurate; And (3) carrying out solid-liquid separation on the reaction mixed solution A, and washing and vacuum drying a solid product to obtain the epoxy modified redispersible emulsion powder. Preferably, the preparation process of the pre-water-absorbing SAP microsphere is as follows: The SAP microspheres are placed in deionized water and soaked for 3 to 4 hours, so that the SAP microspheres absorb water to swell; Sep