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CN-121974606-A - Self-compacting concrete and preparation method thereof

CN121974606ACN 121974606 ACN121974606 ACN 121974606ACN-121974606-A

Abstract

The application discloses self-compacting concrete and a preparation method thereof, and relates to the technical field of concrete. The modified water reducer is prepared from hydroxyl-containing monomer I, double bond-containing acyl chloride monomer II, unsaturated polyether monomer III and double bond-containing monomer IV according to the mass ratio of (0.5-1.5) to (9-12) to (1), and through esterification reaction and double bond addition polymerization, a polymer is prepared, and hydroxyl, carboxyl and polyether side chains are simultaneously introduced into the polymer molecular chain. The water reducer has the advantages that through the synergistic effect of stable hydrogen bond adsorption, steric hindrance and electrostatic repulsion, the compressive strength of concrete is improved, the slump is reduced, the balance between ultra-long retarding and high-strength development is realized, and the comprehensive performance is excellent.

Inventors

  • HUANG YAO
  • HU CHUNLEI

Assignees

  • 上海春祥混凝土有限公司

Dates

Publication Date
20260505
Application Date
20260204

Claims (10)

  1. 1. The self-compacting concrete is characterized by comprising, by weight, 320-360 parts of cement, 65-85 parts of fly ash, 90-100 parts of mineral powder, 170-200 parts of water, 620-650 parts of sand, 930-970 parts of stone and 6-10 parts of a modified water reducing agent, wherein the modified water reducing agent comprises a hydroxyl-containing monomer I, a double bond-containing acyl chloride monomer II, an unsaturated polyether monomer III and a double bond-containing monomer IV, and the mass ratio of the hydroxyl-containing monomer I to the double bond-containing acyl chloride monomer II to the unsaturated polyether monomer III to the double bond-containing monomer IV is (0.5-1.5): 1 (9-12): 1.
  2. 2. The self-compacting concrete of claim 1, wherein the hydroxyl-containing monomer one is any one of sorbitol, beta-cyclodextrin, trehalose.
  3. 3. The self-compacting concrete according to claim 1, wherein the acyl chloride monomer II containing double bond is any one of acryloyl chloride and 3-butoxyacryloyl chloride, and the unsaturated polyether monomer III is any one of isobutylether and isopentylether.
  4. 4. The self-compacting concrete of claim 1, wherein the monomer four containing a double bond is any one of crotonic acid and itaconic acid.
  5. 5. The self-compacting concrete of claim 1, wherein the preparation method of the modified water reducer comprises the following steps: S1, dissolving a monomer I containing hydroxyl into a first solvent, adding a deacidification agent, stirring in an ice bath, introducing inert gas, adding an organic solution of an acyl chloride monomer II containing double bonds, keeping stirring in the ice bath, stirring at normal temperature, filtering to remove impurities, distilling a filtrate obtained by filtering, precipitating, washing, drying and grinding to obtain an intermediate; S2, dissolving an unsaturated polyether monomer III in a second solvent to obtain an unsaturated polyether monomer solution, mixing a monomer IV containing double bonds with the intermediate prepared in the step S1 to obtain a first monomer, mixing a reducing agent and a chain transfer agent to obtain a second monomer, adding the first monomer and the second monomer into the unsaturated polyether monomer solution under heating, stirring, preserving heat, and adjusting pH to be neutral to obtain the modified water reducer.
  6. 6. The self-compacting concrete of claim 5, wherein the ice bath temperature in step S1 is-4-0 ℃.
  7. 7. The self-compacting concrete of claim 5, wherein the deacidification agent in step S1 is any one of triethylamine and tri-n-butylamine.
  8. 8. The self-compacting concrete of claim 5, wherein the heating temperature in step S2 is 40-60 ℃.
  9. 9. The self-compacting concrete of claim 5, wherein the stirring rate in step S2 is 300-600rpm and the stirring time is 3-4.5 hours.
  10. 10. A method of preparing self-compacting concrete according to any one of claims 1 to 9, comprising the steps of: Mixing cement, fly ash, mineral powder, water and a modified water reducing agent, adding sand and stone, and uniformly stirring to obtain the self-compacting concrete.

Description

Self-compacting concrete and preparation method thereof Technical Field The application relates to the technical field of concrete, in particular to self-compacting concrete and a preparation method thereof. Background With the acceleration of the urban process, the development of the underground space advances to deep and complicated, and the foundation pit support is used as a core link of underground engineering, so that the requirements on safety, economy and efficiency are increasingly severe. Under the multiple driving of urban underground traffic demand upgrading, construction cost control and severe environmental complexity, the traditional support mode is difficult to meet the modern engineering demands, and the bored pile becomes one of the mainstream substitution technologies by virtue of unique advantages. The technology is characterized in that the post construction piles are meshed and embedded with the pile forming part to form a continuous pile wall with soil retaining and waterproof functions, and the technology is widely applied to foundation pit engineering of dense urban building groups and complex geological conditions due to the characteristics of strong adaptability, economy, environmental protection and the like. However, the construction characteristics of the bored pile set special requirements on concrete are that the pile body concrete needs to be poured at two sides to realize tight engagement water stop when the bored pile is bored later, so that the concrete is required to ensure the later bearing strength, long setting time and low early strength and is ensured to be in an operable state when being cut. In the existing method, although the initial setting time of the concrete can be prolonged by adding retarder, excessive retarder is easy to cause strength reduction and poor hardening, the conventional retarder system has short gel time and is difficult to meet the requirement of ultra-long setting, meanwhile, the concrete is compact depending on vibration, the defects of honeycombs, pitting surfaces and the like are easy to occur in a complex supporting structure, and the supporting integrity and the waterproof effect are influenced. Under the condition, the self-compacting concrete can automatically fill the templates and wrap the reinforcing steel bars without vibrating and realize the compacting property, so that the self-compacting concrete becomes an ideal material for solving the construction problem of the bored pile. The self-compaction function is realized by optimizing a cementing material system, aggregate grading and additive combination, and meanwhile, the setting time and strength development can be regulated and controlled as required, so that a reliable material scheme is provided for complex foundation pit support. Taking subway transfer stations in a core area of a certain city as an example of deep foundation pit engineering, when commercial prosperous sections exist at the place, surrounding high-rise residential buildings and traffic thoroughfares at the periphery, underground pipelines are dense, foundation pit excavation depth is deep, and geology presents a multilayer complex structure. Because the construction is positioned in the urban sensitive area, noise, vibration and stratum settlement are required to be strictly controlled, the bored pile is selected as a supporting structure, the self-compacting concrete is faced with big test in the process that the engineering pile has large pile diameter, long pile body and dense reinforcement cage arrangement, the concrete is required to be filled into all corners of the pile body under the condition of no vibration, and particularly, the concrete is required to smoothly pass through the gaps of the reinforcement cage and wrap the reinforcement, so that the aggregate segregation and slurry-bone separation in the flowing process must be avoided. Meanwhile, the foundation pit has large depth and complex geology, pore walls collapse easily when pore formation occurs, good volume stability needs to be kept for a long time after concrete pouring, and the requirements of construction fluidity are met and gravity layering segregation is resisted. In addition, the number of engineering support piles is large, the working procedures are crossed frequently, the construction interval between the pre-cast piles and the post-cast piles is up to 72 hours, concrete needs to be kept in a cuttable state within 72 hours, and meanwhile later strength development cannot be influenced, so that the integral bearing and waterproof effects of the occluding piles are guaranteed. Disclosure of Invention The application aims to provide self-compacting concrete which has an excellent dispersing effect, can improve slump resistance of the concrete, has a good retarding effect, and can be suitable for concrete working conditions with complex environments. In a first aspect, the self-compacting concrete and the preparation method there