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CN-122010468-A - Full-time-period low-shrinkage ultra-high-performance concrete and preparation method thereof

CN122010468ACN 122010468 ACN122010468 ACN 122010468ACN-122010468-A

Abstract

The invention belongs to the technical field of concrete, in particular to full-time-period low-shrinkage ultra-high-performance concrete and a preparation method thereof, wherein 900-1110 parts of quartz sand, 600-700 parts of cement, 100-200 parts of silica fume, 200-250 parts of fly ash microbeads, 80-120 parts of steel fibers, 20-40 parts of montmorillonite modified shrinkage-reducing water reducer, 5-10 parts of polyvinyl alcohol fibers, 30-50 parts of composite expansion agent and 300-400 parts of water are added.

Inventors

  • MING YANG
  • LIU JIANZE
  • LI LING
  • SHAO SHIFENG
  • HU CHENG
  • XIANG WEIHENG
  • LI QING
  • ZHENG QUANXING
  • ZHU XUEQIN

Assignees

  • 桂林理工大学

Dates

Publication Date
20260512
Application Date
20251231

Claims (10)

  1. 1. The full-time low-shrinkage ultra-high-performance concrete is characterized by comprising the following components: 900-1110 parts of quartz sand, 600-700 parts of cement, 100-200 parts of silica fume, 200-250 parts of fly ash microbeads, 80-120 parts of steel fibers, 20-40 parts of montmorillonite modified reduced water reducer, 5-10 parts of polyvinyl alcohol fibers, 30-50 parts of composite expanding agent and 300-400 parts of water.
  2. 2. The full-time low-shrinkage ultra-high performance concrete of claim 1, wherein the length of the polyvinyl alcohol fiber is 6-12mm, the breaking strength is more than or equal to 1200MPa, and the alkali resistance is more than or equal to 95%.
  3. 3. The full-time low-shrinkage ultra-high performance concrete of claim 1, wherein the specific surface area of the fly ash microbeads is more than or equal to 1500m 2 /kg, the bulk density is 300-500kg/m 3 , and the particle size is 1-30 μm.
  4. 4. A full-time low shrinkage ultra-high performance concrete according to claim 1, wherein said silica sand has a particle size of less than 3mm and said silica fume has a silica fume content of not less than 30% and a particle size of less than 1. Mu.m.
  5. 5. A full-time low shrinkage ultra-high performance concrete according to claim 1, wherein said steel fibers have a diameter of 0.3-0.7mm and a length of 5-15mm.
  6. 6. A full-time low shrinkage ultra-high performance concrete according to claim 1, wherein: The composite expanding agent consists of, by weight, 2-8 parts of azo compounds, 20-30 parts of magnesium oxide, 10-30 parts of calcium oxide, 30-50 parts of calcium aluminate-calcium sulfoaluminate cement clinker, 5-10 parts of pre-absorbed spherical sodium polyacrylate and 5-10 parts of core-shell structure polyacrylamide resin/kaolin composite spheres.
  7. 7. The full-time low shrinkage ultra-high performance concrete according to claim 6, wherein said magnesia is obtained by low temperature calcination at 600-800 ℃.
  8. 8. The full-time low-shrinkage ultra-high-performance concrete of claim 1, wherein the montmorillonite modified shrinkage-reducing water reducer is prepared by the following method: (1) Sequentially adding methoxy polyethylene glycol, diethylene glycol monomethyl ether, methylol acrylamide and methacrylic acid with the molar ratio of 1:0.15:0.1:3 into a reaction kettle, stirring at 40-45 ℃ to obtain a mixed material A, and continuously removing water in the reaction kettle by vacuumizing in the reaction process; (2) Adding hydroquinone accounting for 0.05wt% of the total material weight and concentrated sulfuric acid accounting for 0.6wt% into the mixed material A in sequence, and continuously heating to 120 ℃ for reaction for 6 hours to obtain an esterification product B; (3) The temperature of the reactant is reduced to 60 ℃ and water is added to dilute the reactant; (4) Dissolving ammonium persulfate accounting for 0.15wt% of the total material weight in water to prepare a dropping material C with the concentration of 8wt%, uniformly dropping the dropping material C into a reaction kettle, keeping the temperature for 3 hours after finishing the adding, cooling, and adding 35wt% sodium hydroxide solution to adjust the pH value to 6.0-6.8 to obtain the shrinkage-reducing water reducer; (5) Preparing the shrinkage-reducing water reducer prepared in the step (4) into an aqueous solution with the mass concentration of 20-40wt%, adding montmorillonite powder into the aqueous solution, performing ultrasonic treatment for 2-6h, and performing sealed preservation for 24-48h at 20-35 ℃ to obtain the montmorillonite modified shrinkage-reducing agent.
  9. 9. The full-time low shrinkage ultra-high performance concrete according to claim 8, wherein the solid-to-liquid ratio of the shrinkage-reducing agent aqueous solution to the montmorillonite powder in the step (5) is 5:1, and the solid-to-liquid ratio of the shrinkage-reducing water reducer aqueous solution to the montmorillonite powder in the step (5) is 5:1.
  10. 10. The method for preparing the full-time low-shrinkage ultra-high performance concrete according to any one of claims 1 to 9, which is characterized by comprising the following steps of (1) pouring 900 to 1110 parts of quartz sand, 600 to 700 parts of cement, 100 to 200 parts of silica fume, 200 to 250 parts of fly ash microbeads, 80 to 120 parts of steel fibers and 5 to 10 parts of polyvinyl alcohol fibers into a stirrer, setting the stirring speed to be 60 to 80r/min, and stirring for 5 to 10min to obtain premix A; (2) And (3) adding 20-40 parts of montmorillonite modified shrinkage-reducing water reducer, 30-50 parts of composite expansion agent and 300-400 parts of water into the premix A prepared in the step (1), and continuously stirring for 5-10min to obtain the full-time low-shrinkage ultra-high-performance concrete.

Description

Full-time-period low-shrinkage ultra-high-performance concrete and preparation method thereof Technical Field The invention belongs to the technical field of concrete, and particularly relates to full-time low-shrinkage ultra-high-performance concrete and a preparation method thereof. Background Ultra-High Performance Concrete (UHPC) is a novel cement-based composite material with Ultra-high strength, high toughness and high durability. Compared with common concrete, the ultra-high performance concrete has excellent mechanical property, durability and penetration explosion resistance, for example, under the same penetration condition, the penetration depth and pit opening damage of the ultra-high performance concrete are far smaller than those of the common concrete. However, the ultra-high performance concrete still has some defects to be solved, namely, the performance of the ultra-high performance concrete is complicated by the influence factors of raw materials, the preparation process involves a large number of materials and the amount of the materials is large, and the preparation process and the performance of the ultra-high performance concrete are complicated. The consumption of the cementing material is large, the water gel ratio is low, the hydration of the cementing material is insufficient, the ultra-low water gel ratio and the early shrinkage of the high cement consumption are large. This condition can negatively impact the volume stability and durability of ultra-high performance concrete. Therefore, how to reduce the shrinkage of the ultra-high performance concrete in the whole period while improving the mechanical properties of the ultra-high performance concrete is a problem which needs to be solved currently. Disclosure of Invention The invention aims to provide full-time low-shrinkage ultra-high-performance concrete and a preparation method thereof, so as to solve the problems in the background technology. In order to achieve the aim, the invention provides the technical scheme that the full-time low-shrinkage ultra-high-performance concrete comprises the following components: 900-1110 parts of quartz sand, 600-700 parts of cement, 100-200 parts of silica fume, 200-250 parts of fly ash microbeads, 80-120 parts of steel fibers, 20-40 parts of montmorillonite modified reduced water reducer, 5-10 parts of polyvinyl alcohol fibers, 30-50 parts of composite expanding agent and 300-400 parts of water. Further, the length of the polyvinyl alcohol fiber is 6-12mm, the breaking strength is more than or equal to 1200MPa, and the alkali resistance is more than or equal to 95%. Further, the specific surface area of the fly ash micro-beads is more than or equal to 1500m 2/kg, the bulk density is 300-500kg/m 3, the particle size is 1-30 mu m, the fly ash micro-beads can improve the fluidity, and the silica fume can increase the compactness of UHPC and improve the impermeability. Further, the particle size of the quartz sand is smaller than 3mm, and the silica fume with the particle size smaller than 1 μm accounts for not less than 30 percent. Further, the diameter of the steel fiber is 0.3-0.7mm, and the length is 5-15mm. The steel fiber and the polyvinyl alcohol fiber are used as reinforcing and toughening materials and are inserted into the cementing material in a disordered way, so that the effects of crack resistance and stress transmission are achieved. The montmorillonite modified shrinkage-inhibiting water reducer has better water reducing and enhancing effects, plays roles in adjusting setting time and improving slurry fluidity retention, and can reduce the surface tension of a slurry liquid phase, thereby reducing cracking. The steel fiber and the polyvinyl alcohol fiber cooperate with the composite toughening system, so that early microcrack of UHPC (ultra high pressure polyethylene) can be reduced, particularly the generation of cracks during plastic process is reduced, the risk of later stage crack generation is indirectly reduced, and the steel fiber can provide enough tensile strength for UHPC, and further reduce the risk of cracking. Further, the composite expanding agent consists of, by weight, 2-8 parts of azo compounds, 20-30 parts of magnesium oxide, 10-30 parts of calcium oxide, 30-50 parts of calcium aluminate-calcium sulfoaluminate cement clinker, 5-10 parts of spherical sodium polyacrylate after pre-water absorption and 5-10 parts of core-shell structure polyacrylamide resin/kaolin composite spheres; Further, the magnesium oxide is obtained by low-temperature calcination at 600-800 ℃. The MgO expanding agent has a delayed micro-expansion effect and mainly acts on the late-mid expansion, the direct driving force of the expansion of the MgO expanding agent is derived from the swelling force and the crystallization pressure of Mg (OH) 2 crystals, the Mg (OH) 2 crystals are tiny in the early stage of hydration, the main factors of the expansion of the slurry are the water absorption