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CN-121717594-B - Polymer-based anti-cracking concrete and preparation method thereof

CN121717594BCN 121717594 BCN121717594 BCN 121717594BCN-121717594-B

Abstract

The invention discloses polymer-based anti-cracking concrete and a preparation method thereof, and relates to the technical field of concrete. The invention relates to a preparation method of polymer-based anti-cracking concrete, which comprises the steps of reacting caffeic acid with glycidyl methacrylate to prepare a chain extender, sequentially reacting isophorone diisocyanate with polyethylene glycol and the chain extender to prepare polyurethane, then reacting with mercaptopropyl trimethoxy silane to prepare modified polyurethane, reacting carboxylated cellulose nanofibers with 4-amino-2, 6-tetramethylpiperidine to prepare pre-modified nanocellulose, reacting with isocyanatopropyl triethoxysilane to prepare modified nanocellulose, uniformly mixing fine aggregate, coarse aggregate, cement, fly ash, modified polyurethane, modified nanocellulose, water, a water reducing agent and a defoaming agent, pouring into a mold for vibrating, standing, demolding and curing to prepare the polymer-based anti-cracking concrete. The polymer-based anti-cracking concrete prepared by the invention has good anti-cracking and anti-aging properties.

Inventors

  • ZHU YAN
  • CHEN JIAJIA
  • HE LIANG

Assignees

  • 南通职业大学

Dates

Publication Date
20260508
Application Date
20260225

Claims (10)

  1. 1. The polymer-based anti-cracking concrete is characterized by being prepared by uniformly mixing fine aggregate, coarse aggregate, cement, fly ash, modified polyurethane, modified nanocellulose, water, a water reducing agent and a defoaming agent, pouring the mixture into a mould for vibrating, standing, demoulding and curing; The modified polyurethane is prepared by sequentially reacting isophorone diisocyanate with polyethylene glycol and a chain extender to prepare polyurethane, and then reacting with mercaptopropyl trimethoxy silane; The chain extender is prepared by the reaction of caffeic acid and glycidyl methacrylate; the modified nano-cellulose is prepared by reacting carboxylated cellulose nano-fibers with 4-amino-2, 6-tetramethylpiperidine to prepare pre-modified nano-cellulose and then reacting the pre-modified nano-cellulose with isocyanatopropyl triethoxysilane.
  2. 2. The polymer-based anti-crack concrete according to claim 1, wherein the carboxylated cellulose nanofibers have an average diameter of 10nm, an average length of 1000nm and a surface carboxyl content of 1.2mmol/g.
  3. 3. The polymer-based crack-resistant concrete according to claim 1, wherein said cement is p.o42.5 portland cement.
  4. 4. The polymer-based anti-crack concrete according to claim 1, wherein the water reducer is a polycarboxylate water reducer.
  5. 5. The polymer-based anti-crack concrete according to claim 1, wherein the defoamer is Dili-828m.
  6. 6. The polymer-based anti-crack concrete according to claim 1, wherein the polyethylene glycol has a weight average molecular weight of 2000.
  7. 7. A method for preparing the polymer-based anti-crack concrete according to claim 1, comprising the following preparation steps: (1) Uniformly mixing caffeic acid, glycidyl methacrylate, tetrabutylammonium bromide, 2, 6-di-tert-butyl-p-cresol and N, N-dimethylformamide, stirring and reacting for 8-10 hours at 110-120 ℃, distilling under reduced pressure, extracting, washing and drying to obtain a chain extender; (2) Uniformly mixing isophorone diisocyanate and polyethylene glycol according to the mole ratio of1 (0.6-0.7) of isocyanate groups and hydroxyl groups in a nitrogen atmosphere, adding dibutyl tin dilaurate and N, N-dimethylformamide, stirring and reacting for 3-5 hours at 80-90 ℃ to obtain a polyurethane prepolymer, uniformly mixing the polyurethane prepolymer and a chain extender according to the mole ratio of1 (1-1.02) of isocyanate groups and hydroxyl groups in the nitrogen atmosphere, stirring and reacting for 3-5 hours at 80-90 ℃ to obtain polyurethane, uniformly mixing polyurethane, mercaptopropyl trimethoxysilane and azodiisobutyronitrile under the nitrogen atmosphere, stirring and reacting for 20-24 hours at 60-70 ℃, distilling under reduced pressure, washing and drying to obtain modified polyurethane; (3) Uniformly mixing carboxylated cellulose nanofibers, 4-amino-2, 6-tetramethylpiperidine, triethylamine and dimethyl sulfoxide, stirring and reacting for 4-6 hours at 75-85 ℃, and carrying out centrifugal separation, washing and drying to obtain pre-modified nanocellulose; uniformly mixing the pre-modified nanocellulose, the propyltriethoxysilane isocyanate, the dibutyltin dilaurate and the N, N-dimethylformamide in a nitrogen atmosphere, stirring and reacting for 6-8 hours at 60-70 ℃, and carrying out centrifugal separation, washing and drying to obtain the modified nanocellulose; (4) Uniformly mixing the fine aggregate and the coarse aggregate according to the mass ratio of 1 (2.2-2.4), stirring for 1-3 min, adding cement with the mass of 1.25-1.3 times of the fine aggregate and fly ash with the mass of 1.6-1.8 times of the fine aggregate, stirring for 1-3 min, adding modified polyurethane with the mass of 0.1-0.2 times of the fine aggregate and modified nanocellulose with the mass of 0.04-0.05 times of the fine aggregate, stirring for 1-3 min, adding water with the mass of 0.3-0.4 times of the fine aggregate, a water reducing agent with the mass of 0.001-0.002 times of the fine aggregate and a defoaming agent with the mass of 0.0004-0.0005 times of the fine aggregate, stirring for 3-5 min, pouring into a die, vibrating, standing for 24h at room temperature, demolding, and curing for 28 days at normal temperature to obtain the polymer-based anti-crack concrete.
  8. 8. The preparation method of the polymer-based anti-cracking concrete according to claim 7, wherein the preparation method of the chain extender in the step (1) is characterized in that caffeic acid, glycidyl methacrylate, tetrabutylammonium bromide, 2, 6-di-tert-butyl-p-cresol and N, N-dimethylformamide are uniformly mixed according to the mass ratio of 1 (0.9-1) (0.06-0.08) (0.002-0.004) (5-10), stirred and reacted for 8-10 hours at 110-120 ℃, N-dimethylformamide is removed by reduced pressure distillation, deionized water with the mass of 4-6 times of caffeic acid is added, ethyl acetate is used for extraction for 2-4 times, an organic phase is sequentially washed with saturated sodium bicarbonate aqueous solution and deionized water for 2-4 times, anhydrous sodium sulfate with the mass of 1.2-1.4 times of caffeic acid is added, stirring is carried out for 20-40 minutes, ethyl acetate is removed by rotary evaporation, and vacuum drying is carried out on the obtained filtrate at 50-60 ℃ for 10-12 hours, so that the chain extender is obtained.
  9. 9. The preparation method of the polymer-based anti-cracking concrete is characterized in that the preparation method of the modified polyurethane in the step (2) comprises the steps of uniformly mixing isophorone diisocyanate and polyethylene glycol according to the mole ratio of isocyanate groups to hydroxyl groups of 1 (0.6-0.7) in a nitrogen atmosphere, adding dibutyltin dilaurate with the mass ratio of 0.006-0.008 times of isophorone diisocyanate, uniformly mixing isophorone diisocyanate with N, N-dimethylformamide with the mass ratio of 15-20 times of isophorone diisocyanate at 80-90 ℃ for 3-5 hours, stirring and reacting for 3-5 hours to obtain a polyurethane prepolymer, uniformly mixing polyurethane prepolymer and a chain extender according to the mole ratio of isocyanate groups to 1 (1-1.02) in a nitrogen atmosphere, stirring and reacting for 3-5 hours at 80-90 ℃, and uniformly mixing polyurethane, mercaptopropyl trimethoxysilane and azodiisobutyronitrile according to the mass ratio of 1 (0.2-0.4) (0.002-0.004), stirring and reacting for 60-70 ℃ for 3-5 hours in a nitrogen atmosphere, drying and distilling for 1-20 ℃ for 1-10 hours to obtain the polyurethane, and drying and performing vacuum-drying and washing for the polyurethane.
  10. 10. The preparation method of the polymer-based anti-cracking concrete is characterized by comprising the steps of uniformly mixing (0.2-0.3): (0.1-0.12): (10-12) of carboxylated cellulose nanofibers, 4-amino-2, 6-tetramethylpiperidine, triethylamine and dimethyl sulfoxide according to a mass ratio of 1, (0.002-0.004): (10-12), stirring and reacting for 4-6 h at 75-85 ℃, centrifugally separating and washing for 3-5 times with absolute ethyl alcohol, vacuum drying for 10-12 h at 50-60 ℃ to obtain pre-modified nanocellulose, and uniformly mixing (0.3-0.4): (10-12) of pre-modified nanocellulose, propyltriethoxysilane, dibutyltin dilaurate and N, N-dimethylformamide according to a mass ratio of 1, (0.002-0.004), stirring and reacting for 6-8 h at 60-70 ℃, centrifugally separating and washing for 5-5 times, and vacuum drying for 10-12 h at 50 ℃ to obtain the pre-modified nanocellulose.

Description

Polymer-based anti-cracking concrete and preparation method thereof Technical Field The invention relates to the technical field of concrete, in particular to polymer-based anti-cracking concrete and a preparation method thereof. Background The ordinary Portland cement concrete has the characteristics of high compressive strength, easy molding, fire resistance, wear resistance, corrosion resistance, good stability and the like, but has poor cracking resistance, and in order to improve the defects, the ordinary Portland cement concrete is doped with a polymer to form polymer modified concrete, and compared with the ordinary Portland cement concrete, the ordinary Portland cement concrete has stronger water retention and cracking resistance, and the toughness, the bonding strength, the tensile strength and the durability are greatly improved. Because the polymer modified concrete has a plurality of technical advantages, the polymer modified concrete is widely applied to repairing projects such as supporting layer defect, beam surface repairing, base plate or bridge reinforcing, tunnel plugging and the like in actual engineering. However, the concrete added with the organic polymer can be aged under the action of natural factors such as solar ultraviolet rays, rainwater and the like, and the strength and the performance of the concrete are reduced, so that the application of the polymer modified concrete is limited. Therefore, the polymer-based anti-cracking concrete prepared by the invention has good anti-cracking performance and ageing resistance. Disclosure of Invention The invention aims to provide polymer-based anti-cracking concrete and a preparation method thereof, which are used for solving the problems in the prior art. In order to solve the technical problems, the invention provides the following technical scheme: The polymer-based anti-cracking concrete is prepared by uniformly mixing fine aggregate, coarse aggregate, cement, fly ash, modified polyurethane, modified nanocellulose, water, a water reducing agent and a defoaming agent, pouring the mixture into a mould for vibrating, standing, demoulding and curing. As optimization, the modified polyurethane is prepared by sequentially reacting isophorone diisocyanate with polyethylene glycol and a chain extender to prepare polyurethane, and then reacting with mercaptopropyl trimethoxy silane; preferably, the chain extender is prepared by reacting caffeic acid with glycidyl methacrylate; As optimization, the modified nano-cellulose is prepared by reacting carboxylated cellulose nano-fibers with 4-amino-2, 6-tetramethylpiperidine to prepare pre-modified nano-cellulose and then reacting with isocyanatopropyl triethoxysilane. As optimization, the average diameter of the carboxylated cellulose nanofiber is 10nm, the average length is 1000nm, and the surface carboxyl content is 1.2mmol/g, and the carboxylated cellulose nanofiber is purchased from Nanjing Xianfeng nanotechnology Co. Preferably, the cement is p.o42.5 Portland cement available from Jin Yuji east cement (tangshan) limited liability company. As optimization, the fine aggregate is natural river sand, and meets the grading requirement of the 2-region sand in GB/T14684-2022. As optimization, the fly ash is first-grade ash and is purchased from Jining Heng novel building materials limited company. As optimization, the water reducer is a polycarboxylic acid water reducer, and is purchased from Shandong Yuncheng resplendent novel building material technology Co. Preferably, the model number of the defoamer is Dili-828m. Preferably, the polyethylene glycol has a weight average molecular weight of 2000 and is available from Shanghai Michelson Biotechnology Co. The preparation method of the polymer-based anti-cracking concrete comprises the following preparation steps: (1) Uniformly mixing caffeic acid, glycidyl methacrylate, tetrabutylammonium bromide, 2, 6-di-tert-butyl-p-cresol and N, N-dimethylformamide, stirring and reacting for 8-10 hours at 110-120 ℃, distilling under reduced pressure, extracting, washing and drying to obtain a chain extender; (2) Uniformly mixing isophorone diisocyanate and polyethylene glycol according to the mole ratio of1 (0.6-0.7) of isocyanate groups and hydroxyl groups in a nitrogen atmosphere, adding dibutyl tin dilaurate and N, N-dimethylformamide, stirring and reacting for 3-5 hours at 80-90 ℃ to obtain a polyurethane prepolymer, uniformly mixing the polyurethane prepolymer and a chain extender according to the mole ratio of1 (1-1.02) of isocyanate groups and hydroxyl groups in the nitrogen atmosphere, stirring and reacting for 3-5 hours at 80-90 ℃ to obtain polyurethane, uniformly mixing polyurethane, mercaptopropyl trimethoxysilane and azodiisobutyronitrile under the nitrogen atmosphere, stirring and reacting for 20-24 hours at 60-70 ℃, distilling under reduced pressure, washing and drying to obtain modified polyurethane; (3) Uniformly mixing carboxylated cellulose nanof