Highly durable anti-cracking impermeable concrete and method for preparing the same

Abstract

The application relates to the technical field of concrete, in particular to high-durability anti-cracking anti-seepage concrete and a preparation method thereof. The preparation method of the high-durability anti-cracking anti-seepage concrete comprises the following steps: preparing a bacteria-loaded porous powder; preparing modified sisal fibers; preparing modified graphene-polyethylene fibers; and preparing concrete. The bacteria-loaded porous powder with high activity, alkali resistance and long-acting stability is successfully prepared by precisely controlling the culture, sporulation and loading process of bacillus pasteurii, and after being mixed into the concrete, the dormant spores in the bacteria-loaded porous powder quickly recover after water is encountered in the concrete cracks, branchy and needle-shaped calcite-type calcium carbonate crystals are generated through a microbial-induced calcium carbonate precipitation reaction, the seepage channels are cut off by actively filling and bridging the capillary pores and micro-cracks in the concrete, and the anti-seepage reliability and durability of the concrete are greatly improved.

Description

Technical Field

[0001] This invention relates to the field of concrete technology, specifically to a high-durability, crack-resistant, and impermeable concrete and its preparation method. Background Technology

[0002] As the most widely used building material in engineering construction, concrete must possess excellent durability, crack resistance, and impermeability in harsh service environments such as underground engineering, water conservancy projects, and marine structures to resist structural damage caused by factors such as moisture erosion, chemical corrosion, and temperature shrinkage.

[0003] In existing technologies, the main hydration products of traditional silicate cement are hydrated calcium silicate gel, calcium hydroxide, and ettringite. The hydration reaction is accompanied by significant chemical shrinkage and autogenous shrinkage, with concentrated heat release and a noticeable temperature rise. In the early plastic stage after concrete pouring, the evaporation rate of internal free water is much higher than the internal bleeding water replenishment rate, leading to rapid water loss in the matrix and uneven shrinkage tensile stress. Without effective restraint, this easily results in plastic cracks. After entering the hardening stage, continuous loss of internal capillary water triggers drying shrinkage, while the elastic modulus of the cement paste rapidly increases, making it difficult to relax and release shrinkage stress, further inducing through-type drying shrinkage cracks. Simultaneously, the silicate cement matrix contains numerous interconnected capillaries after hydration, and the transition zone between aggregate and paste is loose and porous with low overall density, providing natural channels for water penetration and resulting in insufficient impermeability. Consequently, its durability is poor, making it difficult to meet the long-term, harsh service requirements of underground, water conservancy, and marine engineering applications.

[0004] Therefore, it is necessary to propose a high-durability, crack-resistant, and impermeable concrete and its preparation method to extend its service life. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a high-durability, crack-resistant, and impermeable concrete and its preparation method.

[0006] This invention provides a method for preparing high-durability, crack-resistant, and impermeable concrete, comprising the following steps: S1: Preparation of bacteria-loaded porous powder S1.1: Inoculate Bacillus pasteurellii onto nutrient agar slant and incubate at 30-32℃ for 20-24 hours. Then, pick a single colony and inoculate it into nutrient broth. Incubate at 30-32℃ and 180r / min for 18-20 hours to obtain seed culture. S1.2: Inoculate the above seed culture at a volume ratio of 2% into the sporulation medium and culture at 30-32℃ and 180 rpm for 48-72 h on a shaker. Then transfer to centrifuge tubes and centrifuge at 5000-6000 rpm and 4℃ for 10-20 min. Discard the supernatant, resuspend the precipitate in 0.9% sterile physiological saline, and centrifuge and wash 2-3 times again. Finally, resuspend in sterile physiological saline, add urea and calcium lactate, and mix thoroughly to obtain a concentration of 10. 9 -10 10 CFU / mL Bacillus pasteurellium spore suspension; S1.3: Place diatomaceous earth in a muffle furnace and calcine at 400-500℃ for 1-2 hours. After cooling, pass it through a 200-mesh sieve. Then add it to the above Bacillus pasteurellii spore suspension at a ratio of 1g:(3-5)mL. Shake and adsorb at 100-120rpm for 2-4 hours. Let it stand for 30-40 minutes to adsorb. Then filter and vacuum dry at 30℃ for 12-24 hours to obtain bacteria-loaded porous powder.

[0007] S2: Preparation of modified sisal fiber Sisal fibers were treated with sodium hydroxide solution and sulfuric acid solution respectively, then surface-modified with KH550, and then modified with silica to obtain modified sisal fibers. S3: Preparation of modified graphene-polyethylene fibers After dispersing graphene oxide in deionized water, KH560 and plasma-treated polyethylene fibers are added to react and then thermo-cured to obtain modified graphene-polyethylene fibers. S4: Concrete preparation Add crushed stone to a mixer, then add sulfoaluminate cement, slag powder, fly ash and anhydrous gypsum, dry mix for 3-5 minutes, then add the above-mentioned bacterial porous powder, polycarboxylate superplasticizer and 80% water, mix for 3-5 minutes, then add the remaining water, the above-mentioned modified sisal fiber and the above-mentioned modified graphene-polyethylene fiber, and continue mixing for 6-8 minutes to obtain concrete.

[0008] Furthermore, S2 includes the following steps: S2.1: Immerse sisal fibers in a 5wt% sodium hydroxide solution, let them stand for 18-20 hours, then remove them, wash them until neutral, and dry them. Then immerse them in a 5wt% sulfuric acid solution, let them stand for 6-8 hours, then remove them, wash them until neutral, and dry them to obtain pretreated sisal fibers. S2.2: Immerse the above pretreated sisal fibers in 2.5 vol% KH550 ethanol solution at a ratio of 1 g: (8-10) mL, shake at a constant temperature of 30°C for 2-3 h, then remove and dry at 80-90°C for 3-4 h to obtain surface-modified sisal fibers. S2.3: Add nano-silica to deionized water at a ratio of 1g:(40-50)mL, disperse ultrasonically for 30-40min, then add the above surface-modified sisal fiber at a ratio of 1g:(10-20)mL, stir at a constant temperature of 40-50℃ for 3-4h, remove and dry to obtain modified sisal fiber.

[0009] Furthermore, S3 includes the following steps: S3.1: Add graphene oxide and sodium dodecylbenzenesulfonate to deionized water at a ratio of (4-5) g: 1 g: (1.8-2.2) L, and ultrasonically disperse for 40-50 min to obtain a graphene oxide dispersion; S3.2: Add silane coupling agent KH560 to the above graphene oxide dispersion, stir evenly, adjust the pH to 4.5 with acetic acid, then add plasma-treated polyethylene fiber at a ratio of 1g:(20-30)mL, sonicate for 20-30min, stir and react for 3-4h, take it out, pre-dry at 80-90℃ for 1-2h, then heat-cur at 110-120℃ for 4-5h, then wash with ethanol and dry to obtain modified graphene-polyethylene fiber.

[0010] Furthermore, the nutrient agar consists of: 10 g / L peptone, 3 g / L beef extract, 5 g / L sodium chloride, and 20 g / L agar, with a pH of 7-7.4.

[0011] Furthermore, the nutrient broth contains: 10 g / L peptone, 3 g / L beef extract, 5 g / L sodium chloride, and has a pH of 7-7.4.

[0012] Furthermore, the sporulation medium consisted of: 5 g / L peptone, 1.5 g / L beef extract, 5 g / L sodium chloride, 5 g / L urea, 0.01 g / L manganese sulfate, and 0.1 g / L calcium chloride, with a pH of 7.1-7.3.

[0013] Furthermore, the urea concentration in the Bacillus pasteurellium spore suspension was 0.6 mol / L and the calcium lactate concentration was 0.4 mol / L.

[0014] Furthermore, the amount of silane coupling agent KH560 added is 2.5-3% of the volume of the graphene oxide dispersion.

[0015] Furthermore, by weight, the raw material composition of concrete is as follows: 85-100 parts sulfoaluminate cement, 16-20 parts slag powder, 8-12 parts fly ash, 4-6 parts anhydrous gypsum, 250-290 parts crushed stone, 2.5-3.5 parts bacterial-loaded porous powder, 1.1-1.3 parts modified sisal fiber, 1-2 parts modified graphene-polyethylene fiber, 1-1.4 parts polycarboxylate superplasticizer, and 38-44 parts water.

[0016] A high-durability, crack-resistant, and impermeable concrete, which is prepared by any of the above-described methods for preparing high-durability, crack-resistant, and impermeable concrete.

[0017] The present invention has the following advantages: 1. In this invention, by precisely controlling the cultivation, spore production, and loading processes of Bacillus pasteurellii, a highly active, alkali-resistant, and long-lasting stable porous powder loaded with bacteria was successfully prepared. When this powder is incorporated into concrete, the dormant spores in the porous powder rapidly reactivate upon contact with water in concrete cracks. Through a microbial-induced calcium carbonate precipitation reaction, dendritic and needle-shaped calcite-type calcium carbonate crystals are generated, which can actively fill and bridge the capillaries and microcracks inside the concrete, cutting off seepage channels. At the same time, the generated calcium carbonate crystals can refine the internal pore structure of the concrete, reduce porosity and permeability coefficient, and improve the density of the concrete from the structural root. Moreover, this self-healing process can be triggered multiple times, achieving long-term maintenance of the concrete's seepage prevention performance. This solves the technical pain points of traditional concrete seepage prevention materials, such as easy aging, short seepage prevention life, and easy secondary leakage, significantly improving the seepage prevention reliability and durability of concrete.

[0018] 2. In this invention, the modified sisal fibers have a large diameter, high elongation, and excellent flexibility. After modification with nano-silica, they bond tightly to the cement matrix, effectively inhibiting plastic shrinkage cracks and drying shrinkage cracks during the plastic and early hardening stages of concrete. Simultaneously, they bridge and prevent crack propagation at both macro and meso scales, consuming crack propagation energy. Modified graphene... Polyethylene fibers are characterized by their fine diameter, high strength, and high elastic modulus. The graphene coating on their surface enables strong interfacial bonding with the matrix, precisely capturing and confining micro-cracks within concrete, preventing them from developing into macro-cracks. Simultaneously, the nano-reinforcing effect of graphene refines the matrix's pore structure and reduces matrix defects, thereby minimizing the initiation factors of cracks. The combined use of these two materials achieves macro-crack reduction. Mesoscopic Microscopic, multi-scale, full-coverage crack prevention, with flexible fibers and high-strength, high-modulus fibers forming a rigid-flexible synergistic complement, not only absorbs early shrinkage stress and inhibits large-scale cracking through modified sisal fibers, but also utilizes modified graphene... Polyethylene fibers constrain the development of micro-defects and enhance the crack resistance of the matrix. At the same time, both types of modified fibers have excellent alkali resistance and good compatibility with sulfoaluminate cement matrix. They can synergistically exert the superimposed effects of stress dispersion, crack bridging, and defect repair, blocking the cracking path from crack initiation to propagation and significantly improving the overall crack resistance of concrete. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating the preparation method of high-durability, crack-resistant, and impermeable concrete used in embodiments of the present invention. Detailed Implementation

[0020] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this invention.

[0021] Example 1: A method for preparing high-durability, crack-resistant, and impermeable concrete, such as... Figure 1 As shown, it includes the following steps: S1: Preparation of bacteria-loaded porous powder S1.1: Bacillus pasteurellii was inoculated onto a nutrient agar slant and incubated at 30°C for 20 hours. Single colonies were then picked and inoculated into nutrient broth and incubated at 30°C and 180 rpm for 18 hours to obtain a seed culture. The nutrient agar consisted of 10 g / L peptone, 3 g / L beef extract, 5 g / L sodium chloride, and 20 g / L agar, with a pH of 7. The nutrient broth consisted of 10 g / L peptone, 3 g / L beef extract, and 5 g / L sodium chloride, with a pH of 7. S1.2: Inoculate the above seed culture at a volume ratio of 2% into the sporulation medium and culture at 30℃ and 180 rpm for 48 h on a shaker. Then transfer to a centrifuge tube and centrifuge at 5000 rpm and 4℃ for 10 min. Discard the supernatant, resuspend the precipitate in 0.9% sterile physiological saline, centrifuge and wash twice more, and finally resuspend in sterile physiological saline. Add urea and calcium lactate, mix thoroughly, and obtain a concentration of 10. 9 CFU / mL Bacillus pasteurellis spore suspension, wherein the sporulation medium consisted of: 5 g / L peptone, 1.5 g / L beef extract, 5 g / L sodium chloride, 5 g / L urea, 0.01 g / L manganese sulfate, 0.1 g / L calcium chloride, and pH 7.1; the urea concentration in the Bacillus pasteurellis spore suspension was 0.6 mol / L and the calcium lactate concentration was 0.4 mol / L. S1.3: Diatomaceous earth was placed in a muffle furnace and calcined at 400℃ for 1 hour. After cooling, it was passed through a 200-mesh sieve and then added to the above Bacillus pasteurellii spore suspension at a ratio of 1 g: 3 mL. The mixture was shaken at 100 rpm for 2 hours for adsorption, and then allowed to stand for 30 minutes for adsorption. After filtration and low-temperature vacuum drying at 30℃ for 12 hours, the bacteria-loaded porous powder was obtained.

[0022] S2: Preparation of modified sisal fiber S2.1: Immerse sisal fibers in a 5wt% sodium hydroxide solution, let them stand for 18 hours, then remove them, wash them until neutral, and dry them. Then immerse them in a 5wt% sulfuric acid solution, let them stand for 6 hours, then remove them, wash them until neutral, and dry them to obtain pretreated sisal fibers. S2.2: Immerse the pretreated sisal fibers in 2.5 vol% KH550 ethanol solution at a ratio of 1 g: 8 mL, shake at a constant temperature of 30 °C for 2 h, then remove and dry at 80 °C for 3 h to obtain surface-modified sisal fibers. S2.3: Add nano-silica to deionized water at a ratio of 1g:40mL, ultrasonically disperse for 30min, then add the above surface-modified sisal fiber at a ratio of 1g:10mL, stir at a constant temperature of 40℃ for 3h, remove and dry to obtain modified sisal fiber; S3: Preparation of modified graphene-polyethylene fibers S3.1: Add graphene oxide and sodium dodecylbenzenesulfonate to deionized water at a ratio of 4g:1g:1.8L, and ultrasonically disperse for 40min to obtain a graphene oxide dispersion; S3.2: Add silane coupling agent KH560 to the above graphene oxide dispersion, stir evenly, adjust the pH to 4.5 with acetic acid, then add plasma-treated polyethylene fiber at a ratio of 1g:20mL, sonicate for 20min, stir and react for 3h, remove, pre-dry at 80℃ for 1h, then heat-cur at 110℃ for 4h, then wash with ethanol and dry to obtain modified graphene-polyethylene fiber, wherein the amount of silane coupling agent KH560 added is 2.5% of the volume of graphene oxide dispersion; S4: Concrete preparation Add crushed stone to a mixer, then add sulfoaluminate cement, slag powder, fly ash, and anhydrous gypsum, and dry mix for 3 minutes. Then add the above-mentioned bacteria-loaded porous powder, polycarboxylate superplasticizer, and 80% water, and mix for 3 minutes. After that, add the remaining water, the above-mentioned modified sisal fiber, and the above-mentioned modified graphene-polyethylene fiber, and continue mixing for 6 minutes to obtain concrete. The raw material composition of the concrete, by weight, is: 85 parts sulfoaluminate cement, 16 parts slag powder, 8 parts fly ash, 4 parts anhydrous gypsum, 250 parts crushed stone, 2.5 parts bacteria-loaded porous powder, 1.1 parts modified sisal fiber, 1 part modified graphene-polyethylene fiber, 1 part polycarboxylate superplasticizer, and 38 parts water.

[0023] Example 2: A method for preparing high-durability, crack-resistant, and impermeable concrete, such as... Figure 1 As shown, it includes the following steps: S1: Preparation of bacteria-loaded porous powder S1.1: Bacillus pasteurellii was inoculated onto a nutrient agar slant and incubated at 31°C for 22 hours. Single colonies were then picked and inoculated into nutrient broth and incubated at 31°C and 180 rpm for 19 hours to obtain a seed culture. The nutrient agar consisted of 10 g / L peptone, 3 g / L beef extract, 5 g / L sodium chloride, and 20 g / L agar, with a pH of 7.2. The nutrient broth consisted of 10 g / L peptone, 3 g / L beef extract, and 5 g / L sodium chloride, with a pH of 7.2. S1.2: Inoculate the above seed culture at a volume ratio of 2% into the sporulation medium and culture at 31℃ and 180 rpm for 60 h on a shaker. Then transfer to a centrifuge tube and centrifuge at 5500 rpm and 4℃ for 15 min. Discard the supernatant, resuspend the precipitate in 0.9% sterile physiological saline, centrifuge and wash twice more, and finally resuspend in sterile physiological saline. Add urea and calcium lactate, mix thoroughly, and obtain a concentration of 10. 9 CFU / mL Bacillus pasteurellis spore suspension, wherein the sporulation medium consisted of: 5 g / L peptone, 1.5 g / L beef extract, 5 g / L sodium chloride, 5 g / L urea, 0.01 g / L manganese sulfate, 0.1 g / L calcium chloride, and pH 7.2; the urea concentration in the Bacillus pasteurellis spore suspension was 0.6 mol / L and the calcium lactate concentration was 0.4 mol / L. S1.3: Diatomaceous earth was placed in a muffle furnace and calcined at 450℃ for 1.5h. After cooling, it was passed through a 200-mesh sieve and then added to the above Bacillus pasteurellis spore suspension at a ratio of 1g:4mL. The mixture was shaken at 110rpm for 3h and then allowed to stand for 35min for adsorption. After filtration and low-temperature vacuum drying at 30℃ for 18h, the bacteria-loaded porous powder was obtained.

[0024] S2: Preparation of modified sisal fiber S2.1: Immerse sisal fibers in a 5 wt% sodium hydroxide solution, let them stand for 19 hours, then remove them, wash them until neutral, and dry them. Then immerse them in a 5 wt% sulfuric acid solution, let them stand for 7 hours, then remove them, wash them until neutral, and dry them to obtain pretreated sisal fibers. S2.2: Immerse the pretreated sisal fibers in a 2.5 vol% KH550 ethanol solution at a ratio of 1 g: 9 mL, shake at a constant temperature of 30 °C for 2.5 h, then remove and dry at 85 °C for 3.5 h to obtain surface-modified sisal fibers. S2.3: Add nano-silica to deionized water at a ratio of 1g:45mL, ultrasonically disperse for 35min, then add the above surface-modified sisal fiber at a ratio of 1g:15mL, stir at a constant temperature of 45℃ for 3.5h, take it out and dry it to obtain modified sisal fiber; S3: Preparation of modified graphene-polyethylene fibers S3.1: Add graphene oxide and sodium dodecylbenzenesulfonate to deionized water at a ratio of 4.5g:1g:2L, and ultrasonically disperse for 45min to obtain a graphene oxide dispersion; S3.2: Add silane coupling agent KH560 to the above graphene oxide dispersion, stir evenly, adjust the pH to 4.5 with acetic acid, then add plasma-treated polyethylene fiber at a ratio of 1g:25mL, sonicate for 25min, stir and react for 3.5h, remove, pre-dry at 85℃ for 1.5h, then heat-cur at 115℃ for 4.5h, then wash with ethanol and dry to obtain modified graphene-polyethylene fiber, wherein the amount of silane coupling agent KH560 added is 2.8% of the volume of graphene oxide dispersion; S4: Concrete preparation Crushed stone is added to a mixer, followed by sulfoaluminate cement, slag powder, fly ash, and anhydrous gypsum. The mixture is dry-mixed for 4 minutes. Then, the aforementioned bacteria-loaded porous powder, polycarboxylate superplasticizer, and 80% water are added and mixed for another 4 minutes. The remaining water, the aforementioned modified sisal fiber, and the aforementioned modified graphene-polyethylene fiber are added, and the mixture is mixed for another 7 minutes to obtain concrete. The concrete composition, by weight, is: 95 parts sulfoaluminate cement, 18 parts slag powder, 10 parts fly ash, 5 parts anhydrous gypsum, 270 parts crushed stone, 3 parts bacteria-loaded porous powder, 1.2 parts modified sisal fiber, 1.5 parts modified graphene-polyethylene fiber, 1.2 parts polycarboxylate superplasticizer, and 41 parts water.

[0025] Example 3: A method for preparing high-durability, crack-resistant, and impermeable concrete, such as... Figure 1 As shown, it includes the following steps: S1: Preparation of bacteria-loaded porous powder S1.1: Bacillus pasteurellii was inoculated onto a nutrient agar slant and incubated at 32℃ for 24 hours. Single colonies were then picked and inoculated into nutrient broth and incubated at 32℃ and 180 r / min for 20 hours to obtain a seed culture. The nutrient agar consisted of 10 g / L peptone, 3 g / L beef extract, 5 g / L sodium chloride, and 20 g / L agar, with a pH of 7.4. The nutrient broth consisted of 10 g / L peptone, 3 g / L beef extract, and 5 g / L sodium chloride, with a pH of 7.4. S1.2: Inoculate the above seed culture at a volume ratio of 2% into the sporulation medium and culture at 32℃ and 180 rpm for 72 h on a shaker. Then transfer to a centrifuge tube and centrifuge at 6000 rpm and 4℃ for 10-20 min. Discard the supernatant, resuspend the precipitate in 0.9% sterile physiological saline, centrifuge and wash three times again, and finally resuspend in sterile physiological saline. Add urea and calcium lactate, mix thoroughly, and obtain a concentration of 10. 10CFU / mL Bacillus pasteurellis spore suspension, wherein the sporulation medium consisted of: 5 g / L peptone, 1.5 g / L beef extract, 5 g / L sodium chloride, 5 g / L urea, 0.01 g / L manganese sulfate, 0.1 g / L calcium chloride, and pH 7.3; the urea concentration in the Bacillus pasteurellis spore suspension was 0.6 mol / L and the calcium lactate concentration was 0.4 mol / L. S1.3: Diatomaceous earth was placed in a muffle furnace and calcined at 500℃ for 2 hours. After cooling, it was passed through a 200-mesh sieve and then added to the above Bacillus pasteurellii spore suspension at a ratio of 1g:5mL. The mixture was shaken at 120rpm for 4 hours for adsorption, and then allowed to stand for 40 minutes for adsorption. After filtration and low-temperature vacuum drying at 30℃ for 24 hours, the bacteria-loaded porous powder was obtained.

[0026] S2: Preparation of modified sisal fiber S2.1: Immerse sisal fibers in a 5wt% sodium hydroxide solution, let them stand for 20 hours, then remove them, wash them until neutral, and dry them. Then immerse them in a 5wt% sulfuric acid solution, let them stand for 8 hours, then remove them, wash them until neutral, and dry them to obtain pretreated sisal fibers. S2.2: Immerse the pretreated sisal fiber in 2.5 vol% KH550 ethanol solution at a ratio of 1 g: 10 mL, shake at a constant temperature of 30 °C for 3 h, then remove and dry at 90 °C for 4 h to obtain surface-modified sisal fiber. S2.3: Add nano-silica to deionized water at a ratio of 1g:50mL, disperse ultrasonically for 40min, then add the above surface-modified sisal fiber at a ratio of 1g:20mL, stir at a constant temperature of 50℃ for 4h, take it out and dry it to obtain modified sisal fiber; S3: Preparation of modified graphene-polyethylene fibers S3.1: Add graphene oxide and sodium dodecylbenzenesulfonate to deionized water at a ratio of 5g:1g:2.2L, and disperse by ultrasonication for 50min to obtain a graphene oxide dispersion; S3.2: Add silane coupling agent KH560 to the above graphene oxide dispersion, stir evenly, adjust the pH to 4.5 with acetic acid, then add plasma-treated polyethylene fiber at a ratio of 1g:30mL, sonicate for 30min, stir and react for 4h, remove, pre-dry at 90℃ for 2h, then heat-cur at 120℃ for 5h, then wash with ethanol and dry to obtain modified graphene-polyethylene fiber, wherein the amount of silane coupling agent KH560 added is 3% of the volume of graphene oxide dispersion; S4: Concrete preparation Add crushed stone to a mixer, then add sulfoaluminate cement, slag powder, fly ash, and anhydrous gypsum, and dry mix for 5 minutes. Then add the above-mentioned bacteria-loaded porous powder, polycarboxylate superplasticizer, and 80% water, and mix for 5 minutes. After that, add the remaining water, the above-mentioned modified sisal fiber, and the above-mentioned modified graphene-polyethylene fiber, and continue mixing for 8 minutes to obtain concrete. The raw material composition of the concrete, by weight, is: 100 parts sulfoaluminate cement, 20 parts slag powder, 12 parts fly ash, 6 parts anhydrous gypsum, 290 parts crushed stone, 3.5 parts bacteria-loaded porous powder, 1.3 parts modified sisal fiber, 2 parts modified graphene-polyethylene fiber, 1.4 parts polycarboxylate superplasticizer, and 44 parts water.

[0027] Comparative Example 1 differs from Example 1 in that the bacterial-loaded porous powder in step S4 is removed.

[0028] Comparative Example 2 differs from Example 1 in that the modified graphene-polyethylene fiber in step S4 is replaced with an equal amount of modified sisal fiber.

[0029] Comparative Example 3 differs from Example 1 in that the modified sisal fiber in step S4 is replaced with an equal amount of modified graphene-polyethylene fiber.

[0030] Test example: Test 1: The concrete prepared in Examples 1-3 and Comparative Example 1 was poured into Φ100mm×50mm disc specimens. After standard curing for 28 days, constant water pressure permeability test was carried out. Each group was tested 3 times and the average value was taken. The results are shown in Table 1.

[0031] Table 1: Test results of permeability coefficient and seepage height

[0032] As shown in Table 1, the concrete prepared in Comparative Example 1 without the addition of the bacterial-loaded porous powder had a higher permeability coefficient and seepage height than that in Example 1. This demonstrates that by precisely controlling the cultivation, spore production, and loading process of Bacillus pasteurellii, a highly active, alkali-resistant, and long-lasting stable bacterial-loaded porous powder was successfully prepared. When incorporated into concrete, the dormant spores in the bacterial-loaded porous powder rapidly reactivate upon contact with water in concrete cracks. Through microbial-induced calcium carbonate precipitation, dendritic and needle-shaped calcite-type calcium carbonate crystals are generated, which can actively fill and bridge the capillaries and microcracks inside the concrete, cutting off seepage channels. At the same time, the generated calcium carbonate crystals can refine the internal pore structure of the concrete, reduce porosity and permeability coefficient, and improve the density of the concrete from the structural root. Moreover, this self-healing process can be triggered multiple times, achieving long-term maintenance of the concrete's seepage prevention performance. This solves the technical pain points of traditional concrete seepage prevention materials, such as easy aging, short seepage prevention life, and easy secondary leakage, significantly improving the seepage prevention reliability and durability of concrete.

[0033] Test 2: The concrete prepared in Examples 1-3 and Comparative Examples 2-3 was poured into flat crack-resistant molds of 600mm×600mm×100mm. Then, early plastic cracking tests were conducted in accordance with GB / T 50082-2024 to test its early plastic cracking performance at 24h. Each group was tested in parallel 3 times, and the average value was taken. The results are shown in Table 2.

[0034] Table 2: Test results of early plastic cracking

[0035] As shown in Table 2, in Comparative Examples 2 and 3, when only single modified sisal fiber or single modified graphene-polyethylene fiber was added, the total 24-hour crack length and total crack area of ​​the concrete were significantly higher than those in Example 1. This demonstrates that modified sisal fiber and modified graphene... Polyethylene fiber can achieve macroscopic Mesoscopic Microscopic, multi-scale, full-coverage crack prevention, with flexible fibers and high-strength, high-modulus fibers forming a rigid-flexible synergistic complement, not only absorbs early shrinkage stress and inhibits large-scale cracking through modified sisal fibers, but also utilizes modified graphene... Polyethylene fibers constrain the development of micro-defects and enhance the crack resistance of the matrix. At the same time, both types of modified fibers have excellent alkali resistance and good compatibility with sulfoaluminate cement matrix. They can synergistically exert the superimposed effects of stress dispersion, crack bridging, and defect repair, blocking the cracking path from crack initiation to propagation and significantly improving the overall crack resistance of concrete.

[0036] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims. Parts not described in detail in this specification are prior art known to those skilled in the art.

Claims

1. A method for preparing high-durability, crack-resistant, and impermeable concrete, characterized in that, Includes the following steps: S1: Preparation of bacteria-loaded porous powder S1.1: Inoculate Bacillus pasteurellii onto nutrient agar slant and incubate at 30-32℃ for 20-24 hours. Then, pick a single colony and inoculate it into nutrient broth. Incubate at 30-32℃ and 180r / min for 18-20 hours to obtain seed culture. S1.2: Inoculate the above seed culture at a volume ratio of 2% into the sporulation medium and culture at 30-32℃ and 180 rpm for 48-72 h on a shaker. Then transfer to centrifuge tubes and centrifuge at 5000-6000 rpm and 4℃ for 10-20 min. Discard the supernatant, resuspend the precipitate in 0.9% sterile physiological saline, and centrifuge and wash 2-3 times again. Finally, resuspend in sterile physiological saline, add urea and calcium lactate, and mix thoroughly to obtain a concentration of 10. 9 -10 10 CFU / mL Bacillus pasteurellium spore suspension; S1.3: Place diatomaceous earth in a muffle furnace and calcine at 400-500℃ for 1-2 hours. After cooling, pass it through a 200-mesh sieve. Then add it to the above Bacillus pasteurellii spore suspension at a ratio of 1g:(3-5)mL. Shake and adsorb at 100-120rpm for 2-4 hours. Let it stand for 30-40 minutes to adsorb. Then filter and vacuum dry at 30℃ for 12-24 hours to obtain bacteria-loaded porous powder. S2: Preparation of modified sisal fiber Sisal fibers were treated with sodium hydroxide solution and sulfuric acid solution respectively, then surface-modified with KH550, and then modified with silica to obtain modified sisal fibers. S3: Preparation of modified graphene-polyethylene fibers After dispersing graphene oxide in deionized water, KH560 and plasma-treated polyethylene fibers are added to react and then thermo-cured to obtain modified graphene-polyethylene fibers. S4: Concrete preparation Add crushed stone to a mixer, then add sulfoaluminate cement, slag powder, fly ash and anhydrous gypsum, dry mix for 3-5 minutes, then add the above-mentioned bacterial porous powder, polycarboxylate superplasticizer and 80% water, mix for 3-5 minutes, then add the remaining water, the above-mentioned modified sisal fiber and the above-mentioned modified graphene-polyethylene fiber, and continue mixing for 6-8 minutes to obtain concrete.

2. The method for preparing high-durability, crack-resistant, and impermeable concrete according to claim 1, characterized in that, S2 includes the following steps: S2.1: Immerse sisal fibers in a 5wt% sodium hydroxide solution, let them stand for 18-20 hours, then remove them, wash them until neutral, and dry them. Then immerse them in a 5wt% sulfuric acid solution, let them stand for 6-8 hours, then remove them, wash them until neutral, and dry them to obtain pretreated sisal fibers. S2.2: Immerse the above pretreated sisal fibers in 2.5 vol% KH550 ethanol solution at a ratio of 1 g: (8-10) mL, shake at a constant temperature of 30°C for 2-3 h, then remove and dry at 80-90°C for 3-4 h to obtain surface-modified sisal fibers. S2.3: Add nano-silica to deionized water at a ratio of 1g:(40-50)mL, disperse ultrasonically for 30-40min, then add the above surface-modified sisal fiber at a ratio of 1g:(10-20)mL, stir at a constant temperature of 40-50℃ for 3-4h, remove and dry to obtain modified sisal fiber.

3. The method for preparing high-durability, crack-resistant, and impermeable concrete according to claim 2, characterized in that, S3 includes the following steps: S3.1: Add graphene oxide and sodium dodecylbenzenesulfonate to deionized water at a ratio of (4-5) g: 1 g: (1.8-2.2) L, and ultrasonically disperse for 40-50 min to obtain a graphene oxide dispersion; S3.2: Add silane coupling agent KH560 to the above graphene oxide dispersion, stir evenly, adjust the pH to 4.5 with acetic acid, then add plasma-treated polyethylene fiber at a ratio of 1g:(20-30)mL, sonicate for 20-30min, stir and react for 3-4h, take it out, pre-dry at 80-90℃ for 1-2h, then heat-cur at 110-120℃ for 4-5h, then wash with ethanol and dry to obtain modified graphene-polyethylene fiber.

4. The method for preparing high-durability, crack-resistant, and impermeable concrete according to claim 1, characterized in that, The nutrient agar consists of 10 g / L peptone, 3 g / L beef extract, 5 g / L sodium chloride, and 20 g / L agar, with a pH of 7-7.

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5. The method for preparing high-durability, crack-resistant, and impermeable concrete according to claim 1, characterized in that, The nutritious broth contains: 10g / L peptone, 3g / L beef extract, 5g / L sodium chloride, and has a pH of 7-7.

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6. The method for preparing high-durability, crack-resistant, and impermeable concrete according to claim 1, characterized in that, The sporulation medium consists of: 5 g / L peptone, 1.5 g / L beef extract, 5 g / L sodium chloride, 5 g / L urea, 0.01 g / L manganese sulfate, and 0.1 g / L calcium chloride, with a pH of 7.1-7.

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7. The method for preparing high-durability, crack-resistant, and impermeable concrete according to claim 1, characterized in that, The urea concentration in the Bacillus pasteurellium spore suspension was 0.6 mol / L and the calcium lactate concentration was 0.4 mol / L.

8. The method for preparing high-durability, crack-resistant, and impermeable concrete according to claim 3, characterized in that, The amount of silane coupling agent KH560 added is 2.5-3% of the volume of the graphene oxide dispersion.

9. The method for preparing high-durability, crack-resistant, and impermeable concrete according to claim 1, characterized in that, By weight, the raw material composition of concrete is as follows: 85-100 parts sulfoaluminate cement, 16-20 parts slag powder, 8-12 parts fly ash, 4-6 parts anhydrous gypsum, 250-290 parts crushed stone, 2.5-3.5 parts bacterial-loaded porous powder, 1.1-1.3 parts modified sisal fiber, 1-2 parts modified graphene-polyethylene fiber, 1-1.4 parts polycarboxylate superplasticizer, and 38-44 parts water.

10. A high-durability, crack-resistant, and impermeable concrete, characterized in that, It is prepared by the method for preparing high-durability, crack-resistant, and impermeable concrete as described in any one of claims 1-9.

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