Anti-crack concrete material

Abstract

The invention discloses an anti-crack concrete material, and relates to the technical field of concrete. When the anti-crack concrete material is prepared, a polyurethane prepolymer sequentially reacts with 4, 4 '-dihydroxyazobenzene and furfuryl alcohol to prepare a furan-terminated polyurethane prepolymer, and then the furan-terminated polyurethane prepolymer reacts with 1, 4-dimaleimide-2, 3-butanediol to prepare modified polyurethane; reacting the carboxylated carbon nanotube with thionyl chloride to prepare an acylating chlorinated carbon nanotube; sodium alginate, sunflower seed oil and a calcium chloride aqueous solution are subjected to a reaction, and self-repairing microcapsules are prepared; and mixing the coarse aggregate, the fine aggregate, the matrix asphalt, the modified polyurethane, the acyl chloride carbon nanotubes, the mineral powder and the self-repairing microcapsules to prepare the anti-crack concrete material. The anti-crack concrete material prepared by the invention has good low-temperature crack resistance, self-repairing performance, ultraviolet aging resistance and waterproof performance.

Description

Technical Field

[0001] This invention relates to the field of concrete technology, specifically to a crack-resistant concrete material. Background Technology

[0002] Low-temperature cracking is one of the most common defects in asphalt pavements. The main reason is that under the combined action of low temperature and traffic load, the tensile stress in the pavement exceeds the ultimate tensile strength of the asphalt concrete itself, which leads to cracks in the pavement. This severely reduces the continuity, smoothness and driving comfort of the asphalt pavement, and seriously affects the service life of the asphalt pavement.

[0003] Asphalt is a material whose viscoelasticity changes with temperature. After a rest period, some microcracks in asphalt pavements will disappear automatically, and its strength and modulus will recover to a certain extent, extending its service life. This is mainly because the wetting, diffusion, and bonding between asphalt molecules at the fracture interface of asphalt concrete close the internal cracks in the asphalt mastic. However, the service conditions of asphalt pavements result in short rest periods, and the service temperature of the pavement is below the softening point of asphalt, making it impossible to heal cracks. Improving the self-healing performance of asphalt pavements is also beneficial for controlling the cracking problem of asphalt pavements. Therefore, this invention prepares a crack-resistant concrete material with good low-temperature crack resistance and self-healing properties. Summary of the Invention

[0004] The purpose of this invention is to provide a crack-resistant concrete material to solve the problems existing in the prior art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A crack-resistant concrete material is prepared by mixing coarse aggregate, fine aggregate, matrix asphalt, modified polyurethane, acyl chloride carbon nanotubes, mineral powder, and self-healing microcapsules.

[0006] The modified polyurethane is prepared by reacting a polyurethane prepolymer sequentially with 4,4'-dihydroxyazobenzene and furfuryl alcohol to obtain a furan-terminated polyurethane prepolymer, which is then reacted with 1,4-dimaleimide-2,3-butanediol.

[0007] The acyl chloride carbon nanotubes are prepared by reacting carboxylated carbon nanotubes with thionyl chloride.

[0008] The self-healing microcapsules are prepared by reacting sodium alginate, sunflower seed oil, and calcium chloride aqueous solution.

[0009] As an optimization, the preparation method of the crack-resistant concrete material is as follows: (1) The furan-terminated polyurethane prepolymer and 1,4-dimaleimide-2,3-butanediol were mixed evenly at a molar ratio of furan group to 1:(0.5~0.52). The mixture was stirred at 55~65℃ and 200~300r / min for 20~24h. N,N-dimethylformamide was removed by vacuum distillation. The mixture was then dried under vacuum at 50~60℃ for 10~12h to obtain the modified polyurethane. (2) Carboxylated carbon nanotubes, thionyl chloride, and N,N-dimethylformamide are mixed evenly at a mass ratio of 1:(20~30):(0.001~0.002). The mixture is stirred at 65~75℃ and 200~300r / min for 20~24h. The mixture is then centrifuged at 8000~10000rpm for 10~12min. The precipitate is washed 3~5 times with dichloroethane and dried under vacuum at 50~60℃ for 10~12h to obtain acyl chloride carbon nanotubes. (3) Mix 2.5wt% sodium alginate aqueous solution, sunflower seed oil and Tween 80 at a mass ratio of 1:(10~20):(0.5~1) evenly, add to a high-speed shearing machine, and shear and mix at 5000~6000 rpm for 15~20 min to obtain an emulsion; add the emulsion dropwise at a rate of 5 ml / min to 3wt% calcium chloride aqueous solution at a mass of 2~3 times that of 2.5wt% sodium alginate aqueous solution, stir and react at 50~60℃ and 200~300 rpm for 4~6 h, filter and wash with deionized water 3~5 times, and dry in a ventilated environment at 20~30℃ for 20~24 h to obtain self-repairing microcapsules; (4) Mix coarse aggregate and fine aggregate evenly at a mass ratio of 1:(1.5~2), heat at 160~170℃ for 4~6h, add base asphalt at 0.15~0.2 times the mass of coarse aggregate, modified polyurethane at 0.06~0.08 times the mass of coarse aggregate, and acyl chloride carbon nanotubes at 0.0012~0.0016 times the mass of coarse aggregate, mix in an asphalt concrete mixer at 160~170℃ for 80~100s, add mineral powder at 0.3~0.4 times the mass of coarse aggregate, mix for 80~100s, add self-healing microcapsules at 0.001~0.002 times the mass of coarse aggregate, mix for 20~30s, pour into a mold to form, and obtain crack-resistant concrete material.

[0010] As an optimization, the preparation method of the furan-terminated polyurethane prepolymer in step (1) is as follows: Under a nitrogen atmosphere, the polyurethane prepolymer and 4,4'-dihydroxyazobenzene are mixed evenly at a molar ratio of isocyanate group to hydroxyl group of 1:(0.5~0.6). The mixture is stirred at 80~90℃ and 200~300r / min for 2~3h. After sampling to confirm that the reaction is complete, furfuryl alcohol is added at a molar ratio of isocyanate group to hydroxyl group of 1:(1~1.02). The mixture is stirred at 55~65℃ and 200~300r / min for 1.5~2h to obtain the furan-terminated polyurethane prepolymer.

[0011] As an optimization, the preparation method of carboxylated carbon nanotubes in step (2) is as follows: carbon nanotubes and 35wt% nitric acid aqueous solution are mixed evenly at a mass ratio of 1:(50~60), stirred for 10~12 min at room temperature, heated to 75~85℃, stirred for 3~5 h at 200~300 r / min, cooled to room temperature, allowed to stand, the lower layer of liquid is taken out, diluted and washed with deionized water until the pH value is 7, centrifuged at 8000~10000 rpm for 10~12 min, the obtained precipitate is washed with deionized water 3~5 times, and vacuum dried at 50~60℃ for 10~12 h to obtain carboxylated carbon nanotubes.

[0012] As an optimization, the preparation method of the polyurethane prepolymer is as follows: Under a nitrogen atmosphere, isophorone diisocyanate, hydroxyl-terminated methyl-3,3,3-trifluoropropyl (siloxane and polysiloxane), and polytetrahydrofuran glycol are mixed evenly at a molar ratio of isocyanate group to hydroxyl group of 1:(0.6~0.7). Then, 0.006~0.008 times the mass of isophorone diisocyanate dibutyltin dilaurate and 15~20 times the mass of isophorone diisocyanate N,N-dimethylformamide are added. The mixture is stirred at 80~90℃ and 200~300 r / min for 6~8 h to obtain the polyurethane prepolymer.

[0013] As an optimization, the mass ratio of the hydroxyl-terminated methyl-3,3,3-trifluoropropyl (siloxane and polysiloxane) to polytetrahydrofurandiol is 1:(1.5~2).

[0014] As an optimization, the carbon nanotubes have a diameter of 20~40nm and a length of 1~2μm, and were purchased from Shanghai Yuanye Biotechnology Co., Ltd.

[0015] As an optimization, the hydroxyl-terminated methyl-3,3,3-trifluoropropyl (siloxane and polysiloxane) was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0016] As an optimization, the coarse aggregate is basalt with a particle size of 2.36mm to 16mm; the fine aggregate is basalt with a particle size of 0.075mm to 2.36mm; and the mineral powder is lime powder with a particle size of less than 0.075mm.

[0017] As an optimization, the base asphalt is 70# asphalt.

[0018] Compared with the prior art, the beneficial effects achieved by the present invention are: In preparing crack-resistant concrete materials, this invention involves reacting isophorone diisocyanate, hydroxyl-terminated methyl-3,3,3-trifluoropropyl (siloxane and polysiloxane), and polytetrahydrofurandiol to obtain a polyurethane prepolymer; reacting the polyurethane prepolymer sequentially with 4,4'-dihydroxyazobenzene and furfuryl alcohol to obtain a furan-terminated polyurethane prepolymer; reacting the furan-terminated polyurethane prepolymer with 1,4-dimaleimide-2,3-butanediol to obtain a modified polyurethane; reacting carbon nanotubes with nitric acid aqueous solution to obtain carboxylated carbon nanotubes; reacting the carboxylated carbon nanotubes with thionyl chloride to obtain acyl chloride carbon nanotubes; reacting sodium alginate, sunflower seed oil, and calcium chloride aqueous solution to obtain self-healing microcapsules; and mixing coarse aggregate, fine aggregate, matrix asphalt, modified polyurethane, acyl chloride carbon nanotubes, mineral powder, and self-healing microcapsules to obtain the crack-resistant concrete material.

[0019] First, a polyurethane prepolymer was prepared by reacting isophorone diisocyanate, hydroxyl-terminated methyl-3,3,3-trifluoropropyl (siloxane and polysiloxane), and polytetrahydrofuran diol. A fluorine-containing polysiloxane was then introduced onto the polyurethane. The main chain of the polysiloxane consists of Si-O-Si bonds, which are longer than those of C-C and CO-C bonds. Consequently, the polysiloxane molecular chain exhibits excellent flexibility. Therefore, the introduction of polysiloxane can improve the flexibility of the material at low temperatures, thereby improving the low-temperature crack resistance of crack-resistant concrete. Simultaneously, the introduction of fluorine can reduce the surface energy of the material and enhance its hydrophobic properties, thus improving the waterproof performance of the crack-resistant concrete. A furan-terminated polyurethane prepolymer was prepared by reacting a polyurethane prepolymer sequentially with 4,4'-dihydroxyazobenzene and furfuryl alcohol. The furan-terminated polyurethane prepolymer was then reacted with 1,4-dimaleimide-2,3-butanediol to prepare a modified polyurethane. The polyurethane prepolymer was then reacted with 4,4'-dihydroxyazobenzene to introduce azophenyl groups onto the polyurethane. These azophenyl groups can absorb ultraviolet light and consume energy through a reversible cis-trans isomerization reaction, thereby improving the UV aging resistance of the crack-resistant concrete material. Further reaction with furfuryl alcohol introduced furan groups onto the polyurethane. These furan groups can undergo a thermally reversible Diels-Alder reaction with 1,4-dimaleimide-2,3-butanediol, improving the self-healing properties of the crack-resistant concrete material.

[0020] Secondly, carboxylated carbon nanotubes were prepared by reacting carbon nanotubes with nitric acid aqueous solution; acyl chloride carbon nanotubes were prepared by reacting carboxylated carbon nanotubes with thionyl chloride. Nanomaterials have excellent surface and size effects, which can prevent or reduce the propagation of cracks when asphalt is about to crack at low temperatures, thereby improving the low-temperature crack resistance of crack-resistant concrete materials. In addition, carbon nanotubes have a cavity structure that can absorb ultraviolet light, further improving the UV aging resistance of crack-resistant concrete materials. At the same time, the carbon nanotubes were modified by introducing acyl chloride groups. The acyl chloride groups can react with the hydroxyl groups on asphalt and modified polyurethane to form a cross-linked network structure, further improving the low-temperature crack resistance of crack-resistant concrete materials.

[0021] Finally, self-healing microcapsules were prepared by reacting sodium alginate, sunflower seed oil, and calcium chloride aqueous solution. The chemical composition of sunflower seed oil is extremely similar to the lightweight components of the base asphalt. Therefore, sunflower seed oil can be used as a repair agent for asphalt. Sodium alginate was used as a coating material. The alginate chain structure in the sodium alginate aqueous solution can form a network cross-linked structure when it encounters divalent calcium ions, thereby encapsulating the repair agent droplets in it to prepare self-healing microcapsules. When mixed with base asphalt and modified polyurethane, the self-healing performance of crack-resistant concrete materials was further improved. Detailed Implementation

[0022] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] Example 1 A crack-resistant concrete material, comprising the following preparation steps: (1) Under a nitrogen atmosphere, isophorone diisocyanate, hydroxyl-terminated methyl-3,3,3-trifluoropropyl (siloxane and polysiloxane), and polytetrahydrofuran diol were mixed uniformly at a molar ratio of isocyanate group to hydroxyl group of 1:0.6, wherein the mass ratio of hydroxyl-terminated methyl-3,3,3-trifluoropropyl (siloxane and polysiloxane) to polytetrahydrofuran diol was 1:1.5. Dibutyltin dilaurate (0.006 times the mass of isophorone diisocyanate) and N,N-dimethylformamide (15 times the mass of isophorone diisocyanate) were added. The mixture was stirred at 80℃ and 200 r / min for 6 h to obtain a polyurethane prepolymer. Under a nitrogen atmosphere, isophorone diisocyanate and hydroxyl group were mixed uniformly at a molar ratio of isocyanate group to hydroxyl group of 1:0.5. A polyurethane prepolymer and 4,4'-dihydroxyazobenzene were mixed evenly and stirred at 80℃ and 200 r / min for 2 h. After sampling to confirm the complete reaction, furfuryl alcohol was added at a molar ratio of isocyanate group to hydroxyl group of 1:1, and stirred at 55℃ and 200 r / min for 1.5 h to obtain a furan-terminated polyurethane prepolymer. The furan-terminated polyurethane prepolymer and 1,4-dimaleimide-2,3-butanediol were mixed evenly at a molar ratio of furan group to 1,4-dimaleimide-2,3-butanediol of 1:0.5, and stirred at 55℃ and 200 r / min for 20 h. N,N-dimethylformamide was removed by vacuum distillation, and the mixture was dried under vacuum at 50℃ for 10 h to obtain a modified polyurethane. (2) Carbon nanotubes and 35wt% nitric acid aqueous solution are mixed evenly at a mass ratio of 1:50. Stir at room temperature for 10 min, heat to 75℃, stir at 200 r / min for 3 h, cool to room temperature, let stand, take the lower layer liquid, dilute and wash with deionized water until pH value is 7, centrifuge at 8000 rpm for 10 min, wash the precipitate with deionized water 3 times, and vacuum dry at 50℃ for 10 h to obtain carboxylated carbon nanotubes; carboxylated carbon nanotubes, thionyl chloride and N,N-dimethylformamide are mixed evenly at a mass ratio of 1:20:0.001, stirred at 65℃, 200 r / min for 20 h, centrifuge at 8000 rpm for 10 min, wash the precipitate with dichloroethane 3 times, and vacuum dry at 50℃ for 10 h to obtain acyl chloride carbon nanotubes; (3) Mix 2.5wt% sodium alginate aqueous solution, sunflower seed oil and Tween 80 at a mass ratio of 1:10:0.5, add to a high-speed shearing machine, and shear and mix at 5000 rpm for 15 min to obtain an emulsion; add the emulsion dropwise at a rate of 5 ml / min to a 3wt% calcium chloride aqueous solution with a mass of 2 times that of the 2.5wt% sodium alginate aqueous solution, stir and react at 50℃ and 200 rpm for 4 h, filter and wash with deionized water 3 times, and air dry at 20℃ for 20 h to obtain self-repairing microcapsules; (4) Mix coarse aggregate and fine aggregate evenly at a mass ratio of 1:1.5, heat at 160℃ for 4 hours, add base asphalt at 0.15 times the mass of coarse aggregate, modified polyurethane at 0.06 times the mass of coarse aggregate, and acyl chloride carbon nanotubes at 0.0012 times the mass of coarse aggregate, mix in an asphalt concrete mixer at 160℃ for 80 seconds, add mineral powder at 0.3 times the mass of coarse aggregate, mix for 80 seconds, add self-healing microcapsules at 0.001 times the mass of coarse aggregate, mix for 20 seconds, pour into a mold to form, and obtain crack-resistant concrete material.

[0024] Example 2 A crack-resistant concrete material, comprising the following preparation steps: (1) Under a nitrogen atmosphere, isophorone diisocyanate, hydroxyl-terminated methyl-3,3,3-trifluoropropyl (siloxane and polysiloxane), and polytetrahydrofuran diol were mixed evenly at a molar ratio of isocyanate group to hydroxyl group of 1:0.65, wherein the mass ratio of hydroxyl-terminated methyl-3,3,3-trifluoropropyl (siloxane and polysiloxane) to polytetrahydrofuran diol was 1:1.8. Dibutyltin dilaurate (0.007 times the mass of isophorone diisocyanate) and N,N-dimethylformamide (18 times the mass of isophorone diisocyanate) were added. The mixture was stirred at 85°C and 250 r / min for 7 h to obtain a polyurethane prepolymer. Under a nitrogen atmosphere, isophorone diisocyanate and hydroxyl group of 1:0.55 were mixed evenly. A polyurethane prepolymer and 4,4'-dihydroxyazobenzene were mixed evenly and stirred at 85°C and 250 r / min for 2.5 h. After confirming the complete reaction by sampling, furfuryl alcohol was added at a molar ratio of isocyanate group to hydroxyl group of 1:1.01, and the mixture was stirred at 60°C and 250 r / min for 1.8 h to obtain a furan-terminated polyurethane prepolymer. A furan-terminated polyurethane prepolymer and 1,4-dimaleimide-2,3-butanediol were mixed evenly at a molar ratio of furan group to 1,4-dimaleimide-2,3-butanediol of 1:0.51, and stirred at 60°C and 250 r / min for 22 h. N,N-dimethylformamide was removed by vacuum distillation, and the mixture was dried under vacuum at 55°C for 11 h to obtain a modified polyurethane. (2) Carbon nanotubes and 35wt% nitric acid aqueous solution were mixed evenly at a mass ratio of 1:55. The mixture was stirred at room temperature for 11 min, heated to 80℃, stirred at 250 r / min for 4 h, cooled to room temperature, and allowed to stand. The lower layer of liquid was taken out, diluted and washed with deionized water until the pH value was 7. The mixture was then centrifuged at 9000 rpm for 11 min. The precipitate was washed with deionized water 4 times and dried under vacuum at 55℃ for 11 h to obtain carboxylated carbon nanotubes. Carboxylated carbon nanotubes, thionyl chloride and N,N-dimethylformamide were mixed evenly at a mass ratio of 1:25:0.0015. The mixture was stirred at 70℃ for 250 r / min for 22 h, centrifuged at 9000 rpm for 11 min, and the precipitate was washed with dichloroethane 4 times and dried under vacuum at 55℃ for 11 h to obtain acyl chloride carbon nanotubes. (3) Mix 2.5wt% sodium alginate aqueous solution, sunflower seed oil and Tween 80 at a mass ratio of 1:15:0.8, add to a high-speed shearing machine, and shear and mix at 5500 rpm for 18 min to obtain an emulsion; add the emulsion dropwise at a rate of 5 ml / min to a 3wt% calcium chloride aqueous solution that is 2.5 times the mass of the 2.5wt% sodium alginate aqueous solution, stir and react at 55℃ and 250 rpm for 5 h, filter and wash with deionized water 4 times, and air dry at 25℃ for 22 h to obtain self-repairing microcapsules; (4) Mix coarse aggregate and fine aggregate evenly at a mass ratio of 1:1.8, heat at 165℃ for 5 hours, add base asphalt at 0.18 times the mass of coarse aggregate, modified polyurethane at 0.07 times the mass of coarse aggregate, and acyl chloride carbon nanotubes at 0.0014 times the mass of coarse aggregate, mix in an asphalt concrete mixer at 165℃ for 90 seconds, add mineral powder at 0.35 times the mass of coarse aggregate, mix for 90 seconds, add self-healing microcapsules at 0.0015 times the mass of coarse aggregate, mix for 25 seconds, pour into a mold to form, and obtain crack-resistant concrete material.

[0025] Example 3 A crack-resistant concrete material, comprising the following preparation steps: (1) Under a nitrogen atmosphere, isophorone diisocyanate, hydroxyl-terminated methyl-3,3,3-trifluoropropyl (siloxane and polysiloxane), and polytetrahydrofuran diol were mixed evenly at a molar ratio of isocyanate group to hydroxyl group of 1:0.7, wherein the mass ratio of hydroxyl-terminated methyl-3,3,3-trifluoropropyl (siloxane and polysiloxane) and polytetrahydrofuran diol was 1:2. Dibutyltin dilaurate (0.008 times the mass of isophorone diisocyanate) and N,N-dimethylformamide (20 times the mass of isophorone diisocyanate) were added. The mixture was stirred at 90℃ and 300 r / min for 8 h to obtain a polyurethane prepolymer. Under a nitrogen atmosphere, isophorone diisocyanate and hydroxyl group were mixed at a molar ratio of 1:0.6. A polyurethane prepolymer and 4,4'-dihydroxyazobenzene were mixed evenly and stirred at 90℃ and 300 r / min for 3 h. After sampling to confirm the complete reaction, furfuryl alcohol was added at a molar ratio of isocyanate group to hydroxyl group of 1:1.02, and stirred at 65℃ and 300 r / min for 2 h to obtain a furan-terminated polyurethane prepolymer. The furan-terminated polyurethane prepolymer and 1,4-dimaleimide-2,3-butanediol were mixed evenly at a molar ratio of furan group to 1,4-dimaleimide-2,3-butanediol of 1:0.52, and stirred at 65℃ and 300 r / min for 24 h. N,N-dimethylformamide was removed by vacuum distillation, and the mixture was dried under vacuum at 60℃ for 12 h to obtain a modified polyurethane. (2) Carbon nanotubes and 35wt% nitric acid aqueous solution were mixed evenly at a mass ratio of 1:60. The mixture was stirred at room temperature for 12 min, heated to 85℃, stirred at 300 r / min for 5 h, cooled to room temperature, and allowed to stand. The lower layer of liquid was taken out, diluted and washed with deionized water until the pH value was 7. The mixture was then centrifuged at 10000 rpm for 12 min. The precipitate was washed with deionized water 5 times and dried under vacuum at 60℃ for 12 h to obtain carboxylated carbon nanotubes. Carboxylated carbon nanotubes, thionyl chloride and N,N-dimethylformamide were mixed evenly at a mass ratio of 1:30:0.002. The mixture was stirred at 75℃, stirred at 300 r / min for 24 h, centrifuged at 10000 rpm for 12 min, and the precipitate was washed with dichloroethane 5 times and dried under vacuum at 60℃ for 12 h to obtain acyl chloride carbon nanotubes. (3) Mix 2.5wt% sodium alginate aqueous solution, sunflower seed oil and Tween 80 at a mass ratio of 1:20:1, add to a high-speed shearing machine, and shear and mix at 6000 rpm for 20 min to obtain an emulsion; add the emulsion dropwise at a rate of 5 ml / min to a 3wt% calcium chloride aqueous solution with a mass of 3 times that of the 2.5wt% sodium alginate aqueous solution, stir and react at 60℃ and 300 rpm for 6 h, filter and wash with deionized water 5 times, and dry in a ventilated environment at 30℃ for 24 h to obtain self-repairing microcapsules; (4) Mix coarse aggregate and fine aggregate evenly at a mass ratio of 1:2, heat at 170℃ for 6 hours, add base asphalt at 0.2 times the mass of coarse aggregate, modified polyurethane at 0.08 times the mass of coarse aggregate, and acyl chloride carbon nanotubes at 0.0016 times the mass of coarse aggregate, mix in an asphalt concrete mixer at 170℃ for 100 seconds, add mineral powder at 0.4 times the mass of coarse aggregate, mix for 100 seconds, add self-healing microcapsules at 0.002 times the mass of coarse aggregate, mix for 30 seconds, pour into a mold to form, and obtain crack-resistant concrete material.

[0026] Comparative Example 1 The difference between the preparation steps of the crack-resistant concrete material in Comparative Example 1 and Example 2 lies in step (1). Step (1) is modified as follows: Under a nitrogen atmosphere, isophorone diisocyanate, hydroxyl-terminated methyl-3,3,3-trifluoropropyl (siloxane and polysiloxane), and polytetrahydrofuran diol are mixed evenly according to the molar ratio of isocyanate group to hydroxyl group of 1:0.65. The mass ratio of hydroxyl-terminated methyl-3,3,3-trifluoropropyl (siloxane and polysiloxane) and polytetrahydrofuran diol is 1:1.8. Dilauric acid with a mass of 0.007 times that of isophorone diisocyanate is added. Dibutyltin and N,N-dimethylformamide (18 times the mass of isophorone diisocyanate) were reacted at 85°C and 250 rpm for 7 h to obtain a polyurethane prepolymer. Under a nitrogen atmosphere, the polyurethane prepolymer and 4,4'-dihydroxyazobenzene were mixed uniformly at a molar ratio of isocyanate groups to hydroxyl groups of 1:0.55, and reacted at 85°C and 250 rpm for 2.5 h. After confirming complete reaction by sampling, furfuryl alcohol was added at a molar ratio of isocyanate groups to hydroxyl groups of 1:1.01, and the mixture was reacted at 60°C and 250 rpm for 1.8 h to obtain the modified polyurethane. The remaining steps were the same as in Example 2.

[0027] Comparative Example 2 The difference between the preparation steps of the crack-resistant concrete material in Comparative Example 2 and Example 2 lies in step (1). Step (1) is modified as follows: Under a nitrogen atmosphere, isophorone diisocyanate, hydroxyl-terminated methyl-3,3,3-trifluoropropyl (siloxane and polysiloxane), and polytetrahydrofuran diol are mixed evenly at a molar ratio of isocyanate group to hydroxyl group of 1:0.65. The mass ratio of hydroxyl-terminated methyl-3,3,3-trifluoropropyl (siloxane and polysiloxane) and polytetrahydrofuran diol is 1:1.8. Dibutyltin dilaurate (0.007 times the mass of isophorone diisocyanate) and N,N-dimethylformamide (18 times the mass of isophorone diisocyanate) are added. A polyurethane prepolymer was prepared by stirring at 250 rpm for 7 h at 5 °C. Under a nitrogen atmosphere, the polyurethane prepolymer and furfuryl alcohol were mixed uniformly at a molar ratio of isocyanate groups to hydroxyl groups of 1:1.01, and stirred at 250 rpm for 1.8 h at 60 °C to obtain a furan-terminated polyurethane prepolymer. The furan-terminated polyurethane prepolymer and 1,4-dimaleimide-2,3-butanediol were mixed uniformly at a molar ratio of furan groups to 1,4-dimaleimide-2,3-butanediol of 1:0.51, and stirred at 250 rpm for 22 h at 60 °C. N,N-dimethylformamide was removed by vacuum distillation, and the mixture was dried under vacuum at 55 °C for 11 h to obtain the modified polyurethane. The remaining steps were the same as in Example 2.

[0028] Comparative Example 3 The difference between the preparation steps of the crack-resistant concrete material in Comparative Example 3 and Example 2 lies in step (1). Step (1) is modified as follows: Under a nitrogen atmosphere, isophorone diisocyanate and polytetrahydrofuran diol are mixed evenly at a molar ratio of isocyanate group to hydroxyl group of 1:0.65. Dibutyltin dilaurate (0.007 times the mass of isophorone diisocyanate) and N,N-dimethylformamide (18 times the mass of isophorone diisocyanate) are added. The mixture is stirred at 85°C and 250 r / min for 7 h to obtain a polyurethane prepolymer. Under a nitrogen atmosphere, the polyurethane prepolymer and 4,4'-dihydroxyazo dyes are mixed at a molar ratio of isocyanate group to hydroxyl group of 1:0.55. Benzene was mixed thoroughly and stirred at 85°C and 250 rpm for 2.5 h. After confirming complete reaction by sampling, furfuryl alcohol was added at a molar ratio of isocyanate groups to hydroxyl groups of 1:1.01, and the mixture was stirred at 60°C and 250 rpm for 1.8 h to obtain a furan-terminated polyurethane prepolymer. The furan-terminated polyurethane prepolymer and 1,4-dimaleimide-2,3-butanediol were mixed thoroughly at a molar ratio of furan groups to 1,4-dimaleimide-2,3-butanediol of 1:0.51, and stirred at 60°C and 250 rpm for 22 h. N,N-dimethylformamide was removed by vacuum distillation, and the mixture was dried under vacuum at 55°C for 11 h to obtain the modified polyurethane. The remaining steps were the same as in Example 2.

[0029] Comparative Example 4 The difference between the preparation steps of the crack-resistant concrete material in Comparative Example 4 and Example 2 lies in the differences in steps (2) and (4). Step (2) is modified as follows: carbon nanotubes and 35wt% nitric acid aqueous solution are mixed evenly at a mass ratio of 1:55, stirred at room temperature for 11 min, heated to 80℃, stirred at 250 r / min for 4 h, cooled to room temperature, allowed to stand, the lower layer of liquid is taken, diluted and washed with deionized water until the pH value is 7, centrifuged at 9000 rpm for 11 min, the obtained precipitate is washed 4 times with deionized water, and vacuum dried at 55℃ for 11 h. Carboxylated carbon nanotubes were obtained; step (4) was modified as follows: coarse aggregate and fine aggregate were mixed evenly at a mass ratio of 1:1.8, heated at 165°C for 5 hours, and then 0.18 times the mass of the coarse aggregate of base asphalt, 0.07 times the mass of the coarse aggregate of modified polyurethane, and 0.0014 times the mass of the coarse aggregate of carboxylated carbon nanotubes were added. The mixture was stirred for 90 seconds in an asphalt concrete mixer at 165°C, then 0.35 times the mass of the coarse aggregate of mineral powder was added and stirred for 90 seconds. Finally, 0.0015 times the mass of the coarse aggregate of self-healing microcapsules were added and stirred for 25 seconds. The mixture was then poured into a mold to form a crack-resistant concrete material. The remaining steps were the same as in Example 2.

[0030] Comparative Example 5 The preparation steps of the crack-resistant concrete material in Comparative Example 5 differ from those in Example 2 in that step (2) is omitted, and step (4) is modified as follows: coarse aggregate and fine aggregate are mixed evenly at a mass ratio of 1:1.8, heated at 165°C for 5 hours, base asphalt (0.18 times the mass of coarse aggregate) and modified polyurethane (0.07 times the mass of coarse aggregate) are added, and the mixture is stirred for 90 seconds in an asphalt concrete mixer at 165°C. Mineral powder (0.35 times the mass of coarse aggregate) is added, and the mixture is stirred for 90 seconds. Self-healing microcapsules (0.0015 times the mass of coarse aggregate) are added, and the mixture is stirred for 25 seconds. The mixture is then poured into a mold to form the crack-resistant concrete material. The remaining steps are the same as in Example 2.

[0031] Comparative Example 6 The preparation steps of the crack-resistant concrete material in Comparative Example 6 differ from those in Example 2 in that step (3) is omitted, and step (4) is modified as follows: coarse aggregate and fine aggregate are mixed evenly at a mass ratio of 1:1.8, heated at 165°C for 5 hours, and then base asphalt (0.18 times the mass of coarse aggregate), modified polyurethane (0.07 times the mass of coarse aggregate), and acyl chloride carbon nanotubes (0.0014 times the mass of coarse aggregate) are added. The mixture is then stirred for 90 seconds in an asphalt concrete mixer at 165°C, followed by the addition of mineral powder (0.35 times the mass of coarse aggregate), and stirred for another 90 seconds. The mixture is then poured into a mold to form the crack-resistant concrete material. The remaining steps are the same as in Example 2.

[0032] Test Example 1 Low-temperature crack resistance test: The crack-resistant concrete materials obtained in the various embodiments and comparative examples were used to prepare small beam specimens with dimensions of 250mm × 30mm × 35mm. The low-temperature crack resistance of the asphalt mixture was evaluated through a low-temperature small beam bending test. The test was conducted according to the method T0715 of JTG E20-2011 "Test Procedure for Asphalt-Based Asphalt Mixtures for Highway Engineering", with a loading rate set at 50mm / min and a temperature set at -10℃. The low-temperature crack resistance of the asphalt mixture was evaluated by measuring the tensile strength of the small beam specimens under low-temperature loading.

[0033] The results are shown in Table 1.

[0034] Flexural tensile strength (MPa) Flexural tensile strength (MPa) Example 1 12.64 Comparative Example 1 9.25 Example 2 12.69 Comparative Example 2 12.59 Example 3 12.61 Comparative Example 3 8.57 Comparative Example 4 9.55 Comparative Example 5 7.34 Comparative Example 6 12.73 A comparison of the experimental data of Examples 1-3 and Comparative Examples 1-6 in Table 1 shows that the crack-resistant concrete material prepared by the present invention has good low-temperature crack resistance.

[0035] By comparison, the flexural tensile strength of Examples 1-3 is greater than that of Comparative Examples 1 and 4, indicating that the acyl chloride groups on the acyl chloride nanotubes can react with the hydroxyl groups on the asphalt and modified polyurethane to form a cross-linked network structure, which further improves the low-temperature crack resistance of the crack-resistant concrete material.

[0036] By comparison, the flexural tensile strength of Examples 1-3 is greater than that of Comparative Example 3, indicating that the main chain of hydroxyl-terminated methyl-3,3,3-trifluoropropyl (siloxane and polysiloxane) is composed of Si-O-Si bonds. The bond length of Si-O-Si bonds is longer than that of chemical bonds such as CC and COC. Correspondingly, the molecular chain of polysiloxane exhibits excellent flexibility. Therefore, the introduction of polysiloxane can improve the flexibility of the material at low temperatures, thereby improving the low-temperature crack resistance of crack-resistant concrete materials.

[0037] By comparison, the flexural tensile strength of Examples 1-3 is greater than that of Comparative Example 5, indicating that carbon nanotubes, as nanomaterials, have excellent surface and size effects. When asphalt cracks at low temperatures, they can prevent or reduce the propagation of cracks, thereby improving the low-temperature crack resistance of crack-resistant concrete materials.

[0038] Test Example 2 Self-healing performance test: The crack-resistant concrete materials prepared in each embodiment and comparative example were made into standard dumbbell-shaped specimens of the same size according to GB / T2568-1995 "Test Method for Tensile Properties of Resin Castings". The tensile strength M was tested. The dumbbell-shaped specimens were cut in the middle. After cutting, the cut ends were aligned and spliced. Then, they were placed in a constant temperature oven at 140℃ for repair. The tensile strength N was tested again. The self-repair efficiency was calculated as N / M×100%.

[0039] The results are shown in Table 2.

[0040] Self-repair efficiency Self-repair efficiency Example 1 92.57% Comparative Example 1 78.54% Example 2 93.01% Comparative Example 2 92.69% Example 3 92.93% Comparative Example 3 92.85% Comparative Example 4 92.53% Comparative Example 5 92.78% Comparative Example 6 80.25% A comparison of the experimental data from Examples 1-3 and Comparative Examples 1-6 in Table 2 reveals that the crack-resistant concrete material prepared by this invention has good self-healing properties.

[0041] By comparison, the self-healing efficiency of Examples 1-3 is greater than that of Comparative Example 1, indicating that the furan groups on the modified polyurethane undergo a thermally reversible Diels-Alder reaction with 1,4-dimaleimide-2,3-butanediol, thereby improving the self-healing performance of the crack-resistant concrete material.

[0042] By comparison, the self-healing efficiency of Examples 1-3 was greater than that of Comparative Example 6, indicating that the self-healing microcapsules were prepared by reacting sodium alginate, sunflower seed oil, and calcium chloride aqueous solution. The chemical composition of sunflower seed oil is extremely similar to the lightweight components of the base asphalt. Therefore, sunflower seed oil can be used as a repair agent for asphalt. Sodium alginate was used as a coating material. The alginate chain structure in the sodium alginate aqueous solution can form a network cross-linked structure after encountering divalent calcium ions, thereby encapsulating the repair agent droplets in it to prepare self-healing microcapsules. When mixed with base asphalt and modified polyurethane, the self-healing performance of crack-resistant concrete materials was further improved.

[0043] Test Example 3: UV aging resistance test: The crack-resistant concrete materials prepared in each embodiment and comparative example were made into standard dumbbell-shaped specimens of the same size according to GB / T2568-1995 "Test Method for Tensile Properties of Resin Cast Ingredients". The tensile strength X was tested, and the specimens were placed in ultraviolet light for 360 hours of ultraviolet aging. The ultraviolet strength was 21 W / m. 2 The ultraviolet temperature is 50℃, and the tensile strength Y is tested again. The performance degradation rate is calculated as 1-Y / X×100%.

[0044] The results are shown in Table 3.

[0045] performance degradation rate performance degradation rate Example 1 1.79% Comparative Example 1 1.76% Example 2 1.73% Comparative Example 2 6.53% Example 3 1.81% Comparative Example 3 1.78% Comparative Example 4 1.75% Comparative Example 5 4.62% Comparative Example 6 1.79% A comparison of the experimental data from Examples 1-3 and Comparative Examples 1-6 in Table 3 reveals that the crack-resistant concrete material prepared by this invention has good resistance to ultraviolet aging.

[0046] By comparison, the performance degradation rate of Examples 1-3 was less than that of Comparative Example 2, indicating that the reaction of polyurethane prepolymer with 4,4'-dihydroxyazobenzene introduces azophenyl groups onto the polyurethane. The azophenyl groups can absorb ultraviolet light and consume energy through a reversible cis-trans isomerization reaction, thereby improving the UV aging resistance of crack-resistant concrete materials.

[0047] By comparison, the performance degradation rate of Examples 1-3 was less than that of Comparative Example 5, indicating that carbon nanotubes have a cavity structure that can absorb ultraviolet light, further improving the UV aging resistance of crack-resistant concrete materials.

[0048] Test Example 4: Waterproof performance test: The crack-resistant concrete materials prepared in each embodiment and comparative example were made into 40mm×40mm×20mm samples. The static water contact angle of the sample surface was tested using an SZ-CAMC33 contact angle analyzer with a water droplet volume of 1.00μL and a liquid flow rate of 0.5mm / s.

[0049] The results are shown in Table 4.

[0050] Water contact angle Water contact angle Example 1 112.5° Comparative Example 1 111.9° Example 2 113.1° Comparative Example 2 112.3° Example 3 112.8° Comparative Example 3 89.7° Comparative Example 4 112.6° Comparative Example 5 112.9° Comparative Example 6 112.7° A comparison of the experimental data from Examples 1-3 and Comparative Examples 1-6 in Table 4 reveals that the crack-resistant concrete material prepared by this invention has good waterproof performance.

[0051] By comparison, the water contact angles of Examples 1-3 are greater than those of Comparative Example 3, indicating that the fluorine element on the modified polyurethane can reduce the surface energy of the material, enhance the hydrophobic properties of the material, and thus improve the waterproof performance of the crack-resistant concrete material.

[0052] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A crack-resistant concrete material, characterized in that, The crack-resistant concrete material is prepared by mixing coarse aggregate, fine aggregate, matrix asphalt, modified polyurethane, acyl chloride carbon nanotubes, mineral powder, and self-healing microcapsules. The modified polyurethane is prepared by reacting a polyurethane prepolymer sequentially with 4,4'-dihydroxyazobenzene and furfuryl alcohol to obtain a furan-terminated polyurethane prepolymer, which is then reacted with 1,4-dimaleimide-2,3-butanediol. The acyl chloride carbon nanotubes are prepared by reacting carboxylated carbon nanotubes with thionyl chloride. The self-healing microcapsules are prepared by reacting sodium alginate, sunflower seed oil, and calcium chloride aqueous solution.

2. The crack-resistant concrete material according to claim 1, characterized in that, The method for preparing the crack-resistant concrete material is as follows: (1) The furan-terminated polyurethane prepolymer and 1,4-dimaleimide-2,3-butanediol were mixed evenly according to the molar ratio of furan group to 1: (0.5~0.52). The mixture was stirred and reacted at 55~65℃ for 20~24h. The mixture was then distilled under reduced pressure and dried to obtain the modified polyurethane. (2) Carboxylated carbon nanotubes, thionyl chloride, and N,N-dimethylformamide are mixed evenly at a mass ratio of 1:(20~30):(0.001~0.002), and stirred at 65~75℃ for 20~24h. After centrifugation, washing, and drying, acyl chloride carbon nanotubes are obtained. (3) Mix 2.5wt% sodium alginate aqueous solution, sunflower seed oil and Tween 80 at a mass ratio of 1:(10~20):(0.5~1) evenly, add to a high-speed shearing machine, and shear and mix at 5000~6000 rpm for 15~20 min to obtain an emulsion; add the emulsion dropwise at a rate of 5 ml / min to 3wt% calcium chloride aqueous solution, which is 2~3 times the mass of 2.5wt% sodium alginate aqueous solution, and stir and react at 50~60℃ for 4~6 h, filter, wash and dry to obtain self-repairing microcapsules; (4) Mix coarse aggregate and fine aggregate evenly at a mass ratio of 1:(1.5~2), heat at 160~170℃ for 4~6h, add base asphalt at 0.15~0.2 times the mass of coarse aggregate, modified polyurethane at 0.06~0.08 times the mass of coarse aggregate, and acyl chloride carbon nanotubes at 0.0012~0.0016 times the mass of coarse aggregate, mix in an asphalt concrete mixer at 160~170℃ for 80~100s, add mineral powder at 0.3~0.4 times the mass of coarse aggregate, mix for 80~100s, add self-healing microcapsules at 0.001~0.002 times the mass of coarse aggregate, mix for 20~30s, pour into a mold to form, and obtain crack-resistant concrete material.

3. The crack-resistant concrete material according to claim 2, characterized in that, The preparation method of the furan-terminated polyurethane prepolymer in step (1) is as follows: Under a nitrogen atmosphere, the polyurethane prepolymer and 4,4'-dihydroxyazobenzene are mixed evenly at a molar ratio of isocyanate group to hydroxyl group of 1:(0.5~0.6). The mixture is stirred and reacted at 80~90℃ for 2~3h. After sampling to confirm that the reaction is complete, furfuryl alcohol is added at a molar ratio of isocyanate group to hydroxyl group of 1:(1~1.02). The mixture is stirred and reacted at 55~65℃ for 1.5~2h to obtain the furan-terminated polyurethane prepolymer.

4. The crack-resistant concrete material according to claim 2, characterized in that, The preparation method of the carboxylated carbon nanotubes in step (2) is as follows: carbon nanotubes and 35wt% nitric acid aqueous solution are mixed evenly at a mass ratio of 1: (50~60), stirred for 10~12 min at room temperature, heated to 75~85℃, stirred for 3~5 h, cooled to room temperature, allowed to stand, the lower layer liquid is taken out, diluted and washed with deionized water until the pH value is 7, centrifuged, washed and dried to obtain carboxylated carbon nanotubes.

5. A crack-resistant concrete material according to claim 1 or 2, characterized in that, The coarse aggregate is basalt with a particle size of 2.36 mm to 16 mm; the fine aggregate is basalt with a particle size of 0.075 mm to 2.36 mm; and the mineral powder is lime powder with a particle size of less than 0.075 mm.

6. A crack-resistant concrete material according to claim 1 or 2, characterized in that, The base asphalt is 70# asphalt.

7. The crack-resistant concrete material according to claim 3, characterized in that, The polyurethane prepolymer is prepared as follows: Under a nitrogen atmosphere, isophorone diisocyanate, hydroxyl-terminated methyl-3,3,3-trifluoropropyl (siloxane and polysiloxane), and polytetrahydrofuran diol are mixed evenly at a molar ratio of isocyanate group to hydroxyl group of 1:(0.6~0.7). Then, 0.006~0.008 times the mass of isophorone diisocyanate dibutyltin dilaurate and 15~20 times the mass of isophorone diisocyanate N,N-dimethylformamide are added. The mixture is stirred and reacted at 80~90℃ for 6~8 hours to obtain the polyurethane prepolymer.

8. The crack-resistant concrete material according to claim 4, characterized in that, The carbon nanotubes have a diameter of 20-40 nm and a length of 1-2 μm.

9. The crack-resistant concrete material according to claim 7, characterized in that, The mass ratio of the hydroxyl-terminated methyl-3,3,3-trifluoropropyl (siloxane and polysiloxane) to polytetrahydrofurandiol is 1:(1.5~2).