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CN-121974598-A - Shrinkage-resistant reinforcing agent for fluidized soil and preparation method thereof

CN121974598ACN 121974598 ACN121974598 ACN 121974598ACN-121974598-A

Abstract

The invention relates to the technical field of backfill materials, in particular to an anti-shrinkage reinforcing agent for fluidized soil and a preparation method thereof. Firstly, preparing an oil-in-water emulsion and a modified urea formaldehyde prepolymer, then dripping the modified urea formaldehyde prepolymer into the oil-in-water emulsion, introducing tetraethoxysilane to construct an organic-inorganic interpenetrating network shell layer, introducing aluminum nitrate and tetraethoxysilane to carry out surface mineralization modification under an alkaline condition, and finally, carrying out impregnation treatment by polyether modified polysiloxane to obtain the shrinkage-resistant reinforcing agent, thereby solving the problems of easy failure and weak interface bonding of microcapsules in a high-alkaline environment of a geopolymer, and remarkably improving the long-term volume stability, impermeability and mechanical strength of the geopolymer fluidized soil, and being suitable for the engineering fields of roadbed backfilling, underground cavity filling and the like.

Inventors

  • JI HAIXIA
  • CHEN FENG
  • CHEN XINGXING

Assignees

  • 安徽华仕纳米科技有限公司

Dates

Publication Date
20260505
Application Date
20260128

Claims (10)

  1. 1. The preparation method of the shrinkage-resistant reinforcing agent for the fluidized soil is characterized by comprising the following steps of: s1, uniformly mixing n-octyl triethoxysilane and liquid paraffin to form an oil phase suspension; S2, dissolving sodium dodecyl benzene sulfonate in deionized water to form aqueous phase dispersion liquid; S3, adding the oil phase suspension into the aqueous phase dispersion, and emulsifying to form an oil-in-water emulsion; S4, mixing urea, formaldehyde aqueous solution and gallic acid for condensation reaction, and then adding gamma-aminopropyl triethoxysilane for continuous reaction to obtain modified urea formaldehyde prepolymer solution; S5, dripping the modified urea formaldehyde prepolymer solution into an oil-in-water emulsion, adding tetraethoxysilane for in-situ coating, then adding gamma-aminopropyl triethoxysilane for grafting, then adding aluminum nitrate solution for reaction, finally adding tetraethoxysilane and hexadecyl trimethyl ammonium bromide, and separating and washing to obtain a wet product; s6, dispersing wet products in polyether modified polysiloxane aqueous solution for impregnation treatment to obtain the shrinkage-resistant reinforcing agent for the fluidized soil; In the step S4, the dosage ratio of urea, formaldehyde aqueous solution, gallic acid and gamma-aminopropyl triethoxysilane is 8-12g:21.6-32.4g:0.8-1.2 g; the dosage ratio of the modified urea formaldehyde prepolymer solution, the oil-in-water emulsion, the tetraethoxysilane, the gamma-aminopropyl triethoxysilane, the aluminum nitrate solution and the hexadecyl trimethyl ammonium bromide in the step S5 is 30-45g:150-250g:6.4-9.6g:0.8-1.2g:8-12mL:0.8-1.2g.
  2. 2. The preparation method according to claim 1, wherein the dosage ratio of n-octyl triethoxysilane to liquid paraffin in the step S1 is 6-10 g/3.75-6.25 g.
  3. 3. The method according to claim 1, wherein the oil phase suspension and the aqueous phase dispersion are used in a ratio of 10-18g to 150-250g in step S3.
  4. 4. The method according to claim 1, wherein the adding in step S3 is dripping, and the dripping speed is 4-6mL/min.
  5. 5. The method according to claim 1, wherein the temperature of the condensation reaction in step S4 is 70 to 80 ℃ for 1 to 2 hours.
  6. 6. The preparation method according to claim 1, wherein the mass fraction of the aluminum nitrate solution in the step S5 is 2wt%.
  7. 7. The method according to claim 1, wherein the in-situ coating in step S5 is performed at a reaction temperature of 45-55 ℃ for a reaction time of 1.5-2.5h.
  8. 8. The method according to claim 1, wherein in step S5, the system is heated to 55-65 ℃ after the addition of the aluminum nitrate solution, and the temperature is maintained for 0.8-1.2 hours.
  9. 9. The method according to claim 1, wherein the wet product and the aqueous polyether-modified polysiloxane solution are used in the amount ratio of 40 to 50 g/200 ml in step S6.
  10. 10. Shrink-resistant reinforcing agent for fluidized soil, characterized in that it is obtained according to the preparation method of any one of claims 1 to 9.

Description

Shrinkage-resistant reinforcing agent for fluidized soil and preparation method thereof Technical Field The invention relates to the technical field of backfill materials, in particular to an anti-shrinkage reinforcing agent for fluidized soil and a preparation method thereof. Background With the continuous improvement of the national requirements for recycling solid wastes, the technology of the geopolymer (alkali-activated cementing material) fluidized soil which takes industrial waste residues such as fly ash, slag and the like as main raw materials is widely applied to the engineering fields of roadbed backfill, underground cavity filling and the like due to the advantages of green low carbon, early strength, rapid hardening and the like. However, the geopolymer material has significant volume shrinkage problems in the hardening process, particularly high chemical shrinkage and drying shrinkage of the geopolymer material, which are extremely easy to cause microcracks in the matrix, so that engineering hidden troubles such as leakage, strength collapse and durability reduction are caused. At present, the main means for solving the shrinkage problem of the geopolymer comprises adding a shrinkage reducing agent and an internal curing agent, wherein the traditional alcohol ether shrinkage reducing agent can reduce shrinkage by reducing the surface tension of a pore solution, but often hinders the alkali-activated reaction process, and obviously reduces the early strength of the material, and the internal curing material leaves macroscopic holes in a matrix after releasing water, so that the mechanical property and the impermeability of a hardened body are seriously weakened. In recent years, phase change microcapsule or slow release microcapsule technology has been introduced into the field, in an attempt to achieve long-lasting anti-shrinkage adjustment by encapsulation of hydrophobic components or moisture. However, the existing microcapsule technology is faced with a serious technical bottleneck when being directly applied to a geopolymer fluidized soil system. Firstly, the geopolymer reaction environment has extremely strong alkalinity (the pH value is usually as high as 13-14), the pure organic shell layers such as urea-formaldehyde resin, melamine formaldehyde resin and the like are extremely easy to hydrolyze, swell and even break under the environment, so that the internal core components (such as paraffin and silane) leak out prematurely at the initial stage of stirring or coagulation and cannot exert the long-term internal curing and shrinkage resistance, secondly, the surface of the pure organic microcapsule is chemically inert, only weak physical and mechanical engagement exists between the surface of the pure organic microcapsule and an inorganic aluminosilicate matrix, the chemical bonding effect is lacking, the weak interface transition region is extremely easy to peel off under the long-term dry and wet cycle or temperature change stress, so that the microcapsule becomes a defect source in the matrix, and in addition, in order to improve the alkali resistance, the prior art tends to increase the thickness or compactness of the shell layer, but the prior art introduces a new contradiction that the excessively compact shell layer blocks the release channel of moisture or modified molecules, so that the internal curing function cannot realize the respiratory regulation, and the later strength is increased and is weak. Therefore, there is a need to develop an anti-shrinkage enhancer which is resistant to attack in a strongly alkaline environment and combines long-term volume stability with mechanical strength. Disclosure of Invention In view of the above, the invention aims to provide an anti-shrinkage reinforcing agent for fluidized soil and a preparation method thereof, so as to solve the problems that the inner curing failure is caused by easy hydrolysis of a shell layer in a strong base polymer, and long-term volume stability and mechanical strength are difficult to be compatible. Based on the above object, the invention provides a preparation method of an anti-shrinkage reinforcing agent for fluidized soil, which comprises the following steps: s1, mixing n-octyl triethoxysilane and liquid paraffin, and performing ultrasonic dispersion treatment to obtain uniform oil phase suspension; s2, dissolving sodium dodecyl benzene sulfonate in deionized water, and stirring until the solution is clear and transparent to obtain aqueous phase dispersion; s3, slowly adding the oil phase suspension into the water phase dispersion liquid under a high-speed shearing state, and carrying out high-speed shearing emulsification reaction to obtain an oil-in-water emulsion; S4, mixing urea, formaldehyde aqueous solution and gallic acid, regulating the pH value of the system to 8, carrying out condensation reaction under the condition of heating and stirring, and then adding gamma-aminopropyl triethoxysilane for c