A kind of highway permeable crack-resistant concrete and preparation method thereof

Abstract

The present invention discloses a water-permeable, crack-resistant concrete for roads and a preparation method thereof, relating to the technical field of concrete. The preparation method comprises the following steps: placing coarse aggregate, fine aggregate, and porous ceramics into a mixer and stirring uniformly to obtain a premix; adding cement to the premix and continuing to stir uniformly to obtain a dry mix; adding polypropylene fiber, carbon fiber chopped strands, and a water reducer into water and stirring uniformly to obtain a suspension; adding the suspension into the dry mix and stirring uniformly to obtain the water-permeable, crack-resistant concrete for roads. The concrete prepared by the present invention exhibits excellent water permeability and crack resistance.

Description

Technical Field

[0001] The invention relates to the technical field of concrete, in particular to a road permeable and crack-resistant concrete and a preparation method thereof. Background Art

[0002] With the booming development of the transportation industry and the ever-expanding scale of highway construction, increasingly stringent requirements are being placed on concrete performance. Traditional, conventional concrete, thanks to its high strength and durability, has long been the primary material for highway construction and widely used in various highway projects. However, as public awareness of highway performance and safety grows, the drawbacks of traditional concrete are becoming increasingly prominent.

[0003] Traditional concrete structures are dense and almost impermeable. During rainfall, surface water cannot penetrate the ground quickly enough, and large amounts of water accumulate on the road surface, easily forming a water film. This not only reduces friction between the tires and the road surface, leading to dangerous situations such as skidding and loss of control, seriously threatening driving safety, but also, long-term water accumulation gradually seeps into the roadbed, increasing the moisture content of the subgrade soil and reducing its strength and stability. This can lead to roadbed subsidence, potholes, and other road surface problems, significantly shortening the lifespan of the highway and significantly increasing the cost and frequency of subsequent maintenance.

[0004] Furthermore, traditional concrete lacks crack resistance. During highway use, roads are subject to a variety of factors, including temperature fluctuations, repeated vehicle loads, and concrete shrinkage. Drastic temperature fluctuations generate internal stresses in the concrete due to thermal expansion and contraction; frequent vehicle loads induce fatigue stress within the concrete; and concrete shrinkage during the hardening process also contributes to internal stresses. Once these stresses exceed the concrete's tensile strength, they initiate cracks within the concrete. The appearance of cracks not only undermines the integrity of the concrete structure and reduces its bearing capacity, but also seriously impacts the normal use and durability of the highway.

[0005] While some permeable concrete products are currently available on the market, they have, to some extent, addressed road surface drainage issues, allowing rainwater to quickly seep into the ground, reducing road surface waterlogging and improving driving safety. However, these types of permeable concrete generally suffer from low strength and poor crack resistance, making them unable to withstand the long-term, repeated effects of heavy traffic and unable to meet the growing traffic volumes and heavy vehicle traffic demands of modern highways. While some crack-resistant concretes offer improved crack resistance, they sacrifice permeability, failing to fundamentally address the impact of surface waterlogging on road performance and driving safety. Summary of the Invention

[0006] The present invention aims to provide a road permeable and crack-resistant concrete and its preparation method to solve the technical problem of the above-mentioned background art that the water permeability and crack resistance of concrete cannot be achieved at the same time. The concrete prepared by the present invention has excellent water permeability and crack resistance.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A permeable and crack-resistant highway concrete comprising the following components in parts by weight:

[0009] 120-160 parts of cement, 300-400 parts of coarse aggregate, 40-60 parts of fine aggregate, 30-50 parts of porous ceramic composite material, 10-15 parts of polypropylene fiber, 5-10 parts of carbon fiber chopped strands, 2-5 parts of water reducer, and 30-60 parts of water.

[0010] In the technical solution of the present invention, cement is used as the cementitious material, and coarse aggregate is combined with porous ceramic composite materials to construct a continuous pore structure, providing channels for rainwater infiltration and giving concrete excellent water permeability. At the same time, the porous ceramic composite material can enhance the concrete skeleton strength and optimize the pore distribution, thereby improving the overall mechanical properties while ensuring water permeability. Polypropylene fiber and carbon fiber chopped strands form a multi-scale toughening network. Polypropylene fiber can effectively inhibit the formation of shrinkage cracks in the plastic stage of concrete and block the propagation of macro cracks during crack development. Carbon fiber chopped strands, with their high strength and high elastic modulus, disperse stress in stress concentration areas through a bridging effect, inhibiting the further development of micro cracks. The combined effect of the two significantly improves the crack resistance and toughness of concrete. Fine aggregate fills the gaps between coarse aggregate and forms a dense transition zone with the cement paste, strengthening the interfacial bonding between aggregate and paste. The water reducer can optimize the cement hydration reaction, reduce the water-cement ratio, reduce harmful pores within the concrete, and improve the overall density and durability.

[0011] Preferably, the coarse aggregate is a mixture of recycled aggregate and natural crushed stone.

[0012] Preferably, the fine aggregate is quartz sand or river sand.

[0013] Preferably, the preparation method of the porous ceramsite composite material comprises the following steps:

[0014] S1, using tetraethyl orthosilicate as a raw material to prepare nano-silica sol, immersing lightweight porous ceramsite in the nano-silica sol, and performing vacuum treatment and calcination to obtain SiO2-ceramic composite particles;

[0015] S2, using polyvinyl alcohol and methacryloyloxyethyltrimethylammonium chloride as raw materials, under the action of an initiator, grafting methacryloyloxyethyltrimethylammonium chloride onto polyvinyl alcohol to obtain positively charged polyvinyl alcohol;

[0016] S3, grafting positively charged polyvinyl alcohol onto SiO2-ceramic composite particles to obtain PVA-grafted SiO2-ceramic composite particles;

[0017] S4. Electrostatic adsorption is used to combine graphene oxide on the surface of PVA-grafted SiO2-ceramsite composite particles to obtain a porous ceramsite composite material.

[0018] In the technical solution of the present invention, lightweight porous ceramsite is used as the basic skeleton. Lightweight porous ceramsite itself has abundant pores and has certain water permeability, but its mechanical strength is poor. If used alone, it is easy to cause structural damage due to external forces, affecting the water permeability stability. To this end, the present invention uses tetraethyl orthosilicate as raw material, prepares nano-silica sol by sol-gel method, immerses lightweight porous ceramsite in it, combines with vacuum treatment to allow the sol to fully penetrate the ceramsite pores, and then calcines to form SiO2-ceramsite composite particles. Silica combines with ceramsite to fill the pore defects of ceramsite, strengthen the structure, significantly improve the strength of ceramsite, and enhance the stability of water permeability channel.

[0019] However, in practical applications, it has been found that long-term exposure to wastewater and other environments can easily lead to contaminants clogging the pores of lightweight, porous ceramsite composite particles, leading to reduced permeability and poor durability. To further address this issue, the present invention first grafts methacryloyloxyethyltrimethylammonium chloride onto polyvinyl alcohol (PVA), producing positively charged PVA to improve the uniformity of subsequent graphene oxide bonding. The positively charged PVA is then grafted onto SiO2-ceramsite composite particles, imparting a positive surface charge. Graphene oxide (which has a negative surface charge) is then uniformly bonded to the surface of the PVA-grafted SiO2-ceramsite composite particles using electrostatic adsorption. The presence of oxygen-containing functional groups (such as carboxyl groups) on the surface of graphene oxide, on the one hand, utilizes electrostatic repulsion to prevent contaminants of similar charge from approaching and attaching to the pores. On the other hand, its unique lamellar structure and surface properties impart self-cleaning capabilities to the material. Even if a small amount of contaminant adheres, it can be detached by water flow, maintaining the pores of the ceramsite unobstructed and ensuring stable permeability, resulting in long-term, efficient, and permeable concrete.

[0020] In addition, positively charged polyvinyl alcohol is grafted onto the surface of the SiO2-ceramic composite particles. Since positively charged polyvinyl alcohol molecules contain a large number of hydrophilic groups (hydroxyl groups), the grafting imparts stronger hydrophilicity to the composite particles. When exposed to water, they can quickly absorb and guide water flow, accelerating water penetration into the pores of the ceramic and concrete system, and enhancing water permeability.

[0021] Preferably, in step S1, the lightweight porous ceramsite has a particle size of 5 to 10 mm, an average pore size of 40 to 50 μm, and an open porosity of ≥50%.

[0022] Preferably, in step S1, the calcination temperature is 450-500° C., and the calcination time is 2-3 hours.

[0023] Preferably, in step S3, the method for grafting positively charged polyvinyl alcohol onto the SiO2-ceramic composite particles is to first graft an epoxy silane coupling agent onto the SiO2-ceramic composite particles, and then utilize a ring-opening reaction to graft the positively charged polyvinyl alcohol onto the SiO2-ceramic composite particles.

[0024] Preferably, in step S4, the mass ratio of the PVA grafted SiO2-ceramsite composite particles to graphene oxide is 20:1-3.

[0025] Preferably, the porous ceramsite composite material is subjected to a gamma-aminopropyltriethoxysilane grafting modification treatment, comprising the following steps:

[0026] dispersing the porous ceramsite composite material in an ethanol / water mixture to obtain a porous ceramsite composite material dispersion;

[0027] The γ-aminopropyltriethoxysilane hydrolyzate is added dropwise to the porous ceramsite composite material dispersion, and under heating conditions, the carboxyl groups on the porous ceramsite composite material and the amino groups on the γ-aminopropyltriethoxysilane undergo condensation reaction, and the product is obtained through centrifugal separation, washing and drying.

[0028] The present invention team found that the compatibility between porous ceramsite composite materials and cement hydration products is poor, which leads to the formation of weak areas at the interface between the two, resulting in a decrease in the anti-cracking performance of cement, which is unexpected by the present invention team. In order to solve this problem, the present invention grafts γ-aminopropyltriethoxysilane on the surface of porous ceramsite composite materials, such as Figure 1 This is a surface SEM image of the modified porous ceramsite composite material prepared in the present invention. After the hydrolysis of γ-aminopropyltriethoxysilane, the silanol groups generated form ionic bonds with calcium ions on the surface of the cement mineral, enhancing the interfacial bonding force between the porous ceramsite composite material and the concrete matrix, thereby preventing the concrete from deteriorating in its crack resistance.

[0029] A method for preparing permeable and crack-resistant concrete for roads comprises the following steps:

[0030] Putting coarse aggregate, fine aggregate and porous ceramic into a mixer and stirring them evenly to obtain a premix;

[0031] Add cement to the premix and continue stirring to obtain a dry mix;

[0032] Add polypropylene fiber, carbon fiber chopped strands and a water reducer into water and stir evenly to obtain a suspension;

[0033] The suspension is added into the dry mix and stirred evenly to obtain the permeable and crack-resistant highway concrete.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. A permeable channel is constructed with coarse aggregate and porous ceramic composite materials, and a toughening network is formed with polypropylene fiber and carbon fiber chopped strands. While ensuring rapid infiltration of rainwater, it effectively inhibits the generation and expansion of cracks, solving the problem that traditional concrete cannot achieve both permeability and crack resistance.

[0036] 2. To address the problems of easy clogging and poor durability of permeable concrete pores, the present invention modifies the porous ceramsite composite material by grafting positively charged polyvinyl alcohol and coating it with graphene oxide. It utilizes electrostatic repulsion and self-cleaning effects to prevent pollutants from adhering to the pores, ensuring long-term unobstructed permeable channels and extending the service life of the concrete.

[0037] 3. Use γ-aminopropyltriethoxysilane to graft modify the porous ceramsite composite material to form chemical bonds on the surface of the porous ceramsite composite material, thereby enhancing its interfacial bonding with the concrete matrix and avoiding the decrease in anti-cracking performance due to weak interface. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is an SEM image of the modified porous ceramsite composite material prepared in the present invention. DETAILED DESCRIPTION

[0039] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the implementation regulations described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. In the specific embodiment, the cement is silicate cement PO 42.5; the recycled aggregate specification is a continuous gradation of particle size 5 to 20 mm; the natural crushed stone is limestone crushed stone with a continuous gradation of particle size 5 to 20 mm; the river sand fineness modulus is 2.3 to 3.0; the water reducer is a naphthalene-based high-efficiency water reducer, model FDN-1; the polypropylene fiber length is 6 to 12 mm; the carbon fiber chopped strands are 3 to 6 mm long; the lightweight porous ceramsite: particle size 5 to 10 mm, average pore size 40 to 50 μm, open porosity ≥ 50%.

[0040] Example 1

[0041] A permeable and crack-resistant highway concrete comprising the following components in parts by weight:

[0042] 150 parts of cement (Portland cement PO 42.5), 380 parts of coarse aggregate (mass ratio of recycled aggregate to natural crushed stone = 2:1), 55 parts of fine aggregate (river sand), 45 parts of modified porous ceramic composite material, 14 parts of polypropylene fiber, 8 parts of carbon fiber chopped strands, 4 parts of water reducer, and 55 parts of water.

[0043] The preparation method of the modified porous ceramsite composite material comprises the following steps:

[0044] Step 1: Measure 20 mL of ethyl orthosilicate and 40 mL of anhydrous ethanol and add them to a beaker. Place it on a magnetic stirrer and stir at 300 rpm for 10 minutes. Mix 8 mL of deionized water and 1.0 mL of concentrated hydrochloric acid, then slowly drip the mixture into the above mixture. Continue stirring for 2 hours to obtain a nanosilica sol.

[0045] Weigh 20g of lightweight porous ceramsite, ultrasonically clean it three times with deionized water, and then dry it in a 60°C forced air drying oven for 24 hours. Place the dried ceramsite in a vacuum drying oven, pour in 30mL of nanosilica sol, and evacuate to -0.09MPa for 30 minutes to allow the sol to fully penetrate the pores of the ceramsite. After slowly releasing the pressure, continue soaking for 2 hours. Remove the ceramsite, dry it at room temperature for 12 hours, place it in a muffle furnace, heat it to 480°C at a heating rate of 5°C / min, calcine it for 2.5 hours, and cool it naturally to obtain SiO2-ceramic composite particles.

[0046] Step 2: Weigh 10 g of polyvinyl alcohol (PVA), add 200 mL of deionized water, stir in a 90°C oil bath for 2 hours until completely dissolved, and cool to 60°C to obtain a PVA solution; weigh 3 g of methacryloyloxyethyltrimethylammonium chloride (DMC), add 50 mL of deionized water to dissolve, and obtain a DMC solution.

[0047] The DMC solution was poured into the PVA solution, and 0.1 g of ammonium persulfate (APS) was added as an initiator. Under nitrogen protection, the mixture was stirred at 200 rpm in a 60°C oil bath for 8 hours to graft DMC onto the PVA to obtain a positively charged polyvinyl alcohol solution.

[0048] Step 3: Disperse 10 g of SiO2-ceramic composite particles in 100 mL of ethanol / water (volume ratio 9:1) mixture, add 5 mL of KH-560, adjust the pH to 4-5 (using 0.1 M acetic acid), stir and hydrolyze at 60 ° C for 40 minutes, then heat to 80 ° C for 2 hours, and centrifuge and wash to obtain epoxy SiO2-ceramic composite particles.

[0049] The epoxy-SiO2-ceramic composite particles were added to an 8% aqueous solution containing 10 g of PVA (the pH was pre-adjusted to 8-9 with NaOH), and 0.1 g of tetramethylethylenediamine (TEMED) was added to catalyze the ring-opening of the epoxy group. The reaction was stirred at 70 ° C for 4 hours to allow the hydroxyl groups of PVA to undergo a ring-opening reaction with the epoxy groups. Finally, the PVA-grafted SiO2-ceramic composite particles were obtained by centrifugation and drying.

[0050] Step 4: Weigh 1.3 g of graphene oxide powder, add 300 mL of deionized water, and ultrasonically disperse for 2 hours (power 300 W) to obtain a uniform graphene oxide dispersion. Adjust the pH of the dispersion to 8-9.

[0051] Weigh 10g of PVA-grafted SiO2-ceramic composite particles and add them to the graphene oxide dispersion. Stir at 150 rpm at room temperature for 12 hours to allow the graphene oxide to evenly adhere to the particle surface through electrostatic adsorption. After the reaction, filter and separate the particles, wash three times with deionized water, and dry them in a vacuum oven at 60°C for 24 hours to obtain a porous ceramic composite material.

[0052] Step 5: Disperse 10 g of the porous ceramsite composite material in 300 mL of an ethanol / water mixture (ethanol to water volume ratio of 9:1), and ultrasonically disperse for 30 minutes to obtain a uniform dispersion.

[0053] 5 mL of γ-aminopropyltriethoxysilane (APTES), 20 mL of ethanol, and 5 mL of water were mixed and stirred for hydrolysis at room temperature for 60 minutes to obtain an APTES hydrolyzate.

[0054] The APTES hydrolyzate was slowly added dropwise to the porous ceramsite composite dispersion. The pH was adjusted to 4-5 (using 0.1M acetic acid). The mixture was stirred in an oil bath at 60°C for 3 hours. After the reaction, the mixture was centrifuged (4000 rpm for 10 minutes), washed three times with ethanol, and dried in a vacuum oven at 60°C for 24 hours to obtain the modified porous ceramsite composite.

[0055] A method for preparing permeable and crack-resistant concrete for roads comprises the following steps:

[0056] The coarse aggregate, fine aggregate and modified porous ceramic were put into a mixer and stirred at 80 rpm for 3 minutes to mix the aggregates evenly to obtain a premix;

[0057] Add cement to the premix and continue mixing for 5 minutes to form a uniform dry mix;

[0058] Add polypropylene fiber, carbon fiber chopped strands and water reducer into water and stir for 10 minutes to disperse them uniformly to obtain a suspension;

[0059] The suspension was added to the dry mix and stirred at a rotation speed of 100 rpm for 8 minutes to obtain permeable and crack-resistant highway concrete.

[0060] Example 2

[0061] A permeable and crack-resistant highway concrete comprising the following components in parts by weight:

[0062] Cement (Portland cement PO 42.5) 130 parts, coarse aggregate (mass ratio of recycled aggregate to natural crushed stone = 2:1) 320 parts, fine aggregate (river sand) 45 parts, modified porous ceramic composite material 35 parts, polypropylene fiber 12 parts, carbon fiber chopped strands 6 parts, water reducer 3 parts, water 40 parts.

[0063] The preparation method of the modified porous ceramsite composite material comprises the following steps:

[0064] Step 1: Measure 20 mL of ethyl orthosilicate and 40 mL of anhydrous ethanol and add them to a beaker. Place it on a magnetic stirrer and stir at 300 rpm for 10 minutes. Mix 8 mL of deionized water and 1.0 mL of concentrated hydrochloric acid, then slowly drip the mixture into the above mixture. Continue stirring for 2 hours to obtain a nanosilica sol.

[0065] Weigh 20g of lightweight porous ceramsite, ultrasonically clean it three times with deionized water, and then dry it in a 60°C forced air drying oven for 24 hours. Place the dried ceramsite in a vacuum drying oven, pour in 30mL of nanosilica sol, and evacuate to -0.09MPa for 30 minutes to allow the sol to fully penetrate the pores of the ceramsite. After slowly releasing the pressure, continue soaking for 2 hours. Remove the ceramsite, dry it at room temperature for 12 hours, place it in a muffle furnace, heat it to 480°C at a heating rate of 5°C / min, calcine it for 2.5 hours, and cool it naturally to obtain SiO2-ceramic composite particles.

[0066] Step 2: Weigh 10 g of polyvinyl alcohol (PVA), add 200 mL of deionized water, stir in a 90°C oil bath for 2 hours until completely dissolved, and cool to 60°C to obtain a PVA solution; weigh 3 g of methacryloyloxyethyltrimethylammonium chloride (DMC), add 50 mL of deionized water to dissolve, and obtain a DMC solution.

[0067] The DMC solution was poured into the PVA solution, and 0.1 g of ammonium persulfate (APS) was added as an initiator. Under nitrogen protection, the mixture was stirred at 200 rpm in a 60°C oil bath for 8 hours to graft DMC onto the PVA to obtain a positively charged polyvinyl alcohol solution.

[0068] Step 3: Disperse 10 g of SiO2-ceramic composite particles in 100 mL of ethanol / water (volume ratio 9:1) mixture, add 5 mL of KH-560, adjust the pH to 4-5 (using 0.1 M acetic acid), stir and hydrolyze at 60 ° C for 40 minutes, then heat to 80 ° C for 2 hours, and centrifuge and wash to obtain epoxy SiO2-ceramic composite particles.

[0069] The epoxy-SiO2-ceramic composite particles were added to an 8% aqueous solution containing 10 g of PVA (the pH was pre-adjusted to 8-9 with NaOH), and 0.1 g of tetramethylethylenediamine (TEMED) was added to catalyze the ring-opening of the epoxy group. The reaction was stirred at 70 ° C for 4 hours to allow the hydroxyl groups of PVA to undergo a ring-opening reaction with the epoxy groups. Finally, the PVA-grafted SiO2-ceramic composite particles were obtained by centrifugation and drying.

[0070] Step 4: Weigh 0.8 g of graphene oxide powder, add 300 mL of deionized water, and ultrasonically disperse for 2 hours (power 300 W) to obtain a uniform graphene oxide dispersion. Adjust the pH of the dispersion to 8-9.

[0071] Weigh 10g of PVA-grafted SiO2-ceramic composite particles and add them to the graphene oxide dispersion. Stir at 150 rpm at room temperature for 12 hours to allow the graphene oxide to evenly adhere to the particle surface through electrostatic adsorption. After the reaction, filter and separate the particles, wash three times with deionized water, and dry them in a vacuum oven at 60°C for 24 hours to obtain a porous ceramic composite material.

[0072] Step 5: Disperse 10 g of the porous ceramsite composite material in 300 mL of an ethanol / water mixture (ethanol to water volume ratio of 9:1), and ultrasonically disperse for 30 minutes to obtain a uniform dispersion.

[0073] 5 mL of γ-aminopropyltriethoxysilane (APTES), 20 mL of ethanol, and 5 mL of water were mixed and stirred for hydrolysis at room temperature for 60 minutes to obtain an APTES hydrolyzate.

[0074] The APTES hydrolyzate was slowly added dropwise to the porous ceramsite composite dispersion. The pH was adjusted to 4-5 (using 0.1M acetic acid). The mixture was stirred in an oil bath at 60°C for 3 hours. After the reaction, the mixture was centrifuged (4000 rpm for 10 minutes), washed three times with ethanol, and dried in a vacuum oven at 60°C for 24 hours to obtain the modified porous ceramsite composite.

[0075] A method for preparing permeable and crack-resistant concrete for roads comprises the following steps:

[0076] The coarse aggregate, fine aggregate and modified porous ceramic were put into a mixer and stirred at 80 rpm for 3 minutes to mix the aggregates evenly to obtain a premix;

[0077] Add cement to the premix and continue mixing for 5 minutes to form a uniform dry mix;

[0078] Add polypropylene fiber, carbon fiber chopped strands and water reducer into water and stir for 10 minutes to disperse them uniformly to obtain a suspension;

[0079] The suspension was added to the dry mix and stirred at a rotation speed of 100 rpm for 8 minutes to obtain permeable and crack-resistant highway concrete.

[0080] Example 3

[0081] A permeable and crack-resistant highway concrete comprising the following components in parts by weight:

[0082] 140 parts of cement (Portland cement PO 42.5), 350 parts of coarse aggregate (mass ratio of recycled aggregate to natural crushed stone = 2:1), 50 parts of fine aggregate (river sand), 40 parts of modified porous ceramic composite material, 13 parts of polypropylene fiber, 7 parts of carbon fiber chopped strands, 3.5 parts of water reducer, and 45 parts of water.

[0083] The preparation method of the modified porous ceramsite composite material comprises the following steps:

[0084] Step 1: Measure 20 mL of ethyl orthosilicate and 40 mL of anhydrous ethanol and add them to a beaker. Place it on a magnetic stirrer and stir at 300 rpm for 10 minutes. Mix 8 mL of deionized water and 1.0 mL of concentrated hydrochloric acid, then slowly drip the mixture into the above mixture. Continue stirring for 2 hours to obtain a nanosilica sol.

[0085] Weigh 20g of lightweight porous ceramsite, ultrasonically clean it three times with deionized water, and then dry it in a 60°C forced air drying oven for 24 hours. Place the dried ceramsite in a vacuum drying oven, pour in 30mL of nanosilica sol, and evacuate to -0.09MPa for 30 minutes to allow the sol to fully penetrate the pores of the ceramsite. After slowly releasing the pressure, continue soaking for 2 hours. Remove the ceramsite, dry it at room temperature for 12 hours, place it in a muffle furnace, heat it to 480°C at a heating rate of 5°C / min, calcine it for 2.5 hours, and cool it naturally to obtain SiO2-ceramic composite particles.

[0086] Step 2: Weigh 10 g of polyvinyl alcohol (PVA), add 200 mL of deionized water, stir in a 90°C oil bath for 2 hours until completely dissolved, and cool to 60°C to obtain a PVA solution; weigh 3 g of methacryloyloxyethyltrimethylammonium chloride (DMC), add 50 mL of deionized water to dissolve, and obtain a DMC solution.

[0087] The DMC solution was poured into the PVA solution, and 0.1 g of ammonium persulfate (APS) was added as an initiator. Under nitrogen protection, the mixture was stirred at 200 rpm in a 60°C oil bath for 8 hours to graft DMC onto the PVA to obtain a positively charged polyvinyl alcohol solution.

[0088] Step 3: Disperse 10 g of SiO2-ceramic composite particles in 100 mL of ethanol / water (volume ratio 9:1) mixture, add 5 mL of KH-560, adjust the pH to 4-5 (using 0.1 M acetic acid), stir and hydrolyze at 60 ° C for 40 minutes, then heat to 80 ° C for 2 hours, and centrifuge and wash to obtain epoxy SiO2-ceramic composite particles.

[0089] The epoxy-SiO2-ceramic composite particles were added to an 8% aqueous solution containing 10 g of PVA (the pH was pre-adjusted to 8-9 with NaOH), and 0.1 g of tetramethylethylenediamine (TEMED) was added to catalyze the ring-opening of the epoxy group. The reaction was stirred at 70 ° C for 4 hours to allow the hydroxyl groups of PVA to undergo a ring-opening reaction with the epoxy groups. Finally, the PVA-grafted SiO2-ceramic composite particles were obtained by centrifugation and drying.

[0090] Step 4: Weigh 1.0 g of graphene oxide powder, add 300 mL of deionized water, and ultrasonically disperse for 2 hours (power 300 W) to obtain a uniform graphene oxide dispersion. Adjust the pH of the dispersion to 8-9.

[0091] Weigh 10g of PVA-grafted SiO2-ceramic composite particles and add them to the graphene oxide dispersion. Stir at 150 rpm at room temperature for 12 hours to allow the graphene oxide to evenly adhere to the particle surface through electrostatic adsorption. After the reaction, filter and separate the particles, wash three times with deionized water, and dry them in a vacuum oven at 60°C for 24 hours to obtain a porous ceramic composite material.

[0092] Step 5: Disperse 10 g of the porous ceramsite composite material in 300 mL of an ethanol / water mixture (ethanol to water volume ratio of 9:1), and ultrasonically disperse for 30 minutes to obtain a uniform dispersion.

[0093] 5 mL of γ-aminopropyltriethoxysilane (APTES), 20 mL of ethanol, and 5 mL of water were mixed and stirred for hydrolysis at room temperature for 60 minutes to obtain an APTES hydrolyzate.

[0094] The APTES hydrolyzate was slowly added dropwise to the porous ceramsite composite dispersion. The pH was adjusted to 4-5 (using 0.1M acetic acid). The mixture was stirred in an oil bath at 60°C for 3 hours. After the reaction, the mixture was centrifuged (4000 rpm for 10 minutes), washed three times with ethanol, and dried in a vacuum oven at 60°C for 24 hours to obtain the modified porous ceramsite composite.

[0095] A method for preparing permeable and crack-resistant concrete for roads comprises the following steps:

[0096] The coarse aggregate, fine aggregate and modified porous ceramic were put into a mixer and stirred at 80 rpm for 3 minutes to mix the aggregates evenly to obtain a premix;

[0097] Add cement to the premix and continue mixing for 5 minutes to form a uniform dry mix;

[0098] Add polypropylene fiber, carbon fiber chopped strands and water reducer into water and stir for 10 minutes to disperse them uniformly to obtain a suspension;

[0099] The suspension was added to the dry mix and stirred at a rotation speed of 100 rpm for 8 minutes to obtain permeable and crack-resistant highway concrete.

[0100] Example 4

[0101] A permeable and crack-resistant highway concrete comprising the following components in parts by weight:

[0102] 160 parts of cement (Portland cement PO 42.5), 400 parts of coarse aggregate (mass ratio of recycled aggregate to natural crushed stone = 2:1), 60 parts of fine aggregate (river sand), 50 parts of modified porous ceramic composite material, 15 parts of polypropylene fiber, 10 parts of carbon fiber chopped strands, 5 parts of water reducer, and 60 parts of water.

[0103] The preparation method of the modified porous ceramsite composite material comprises the following steps:

[0104] Step 1: Measure 20 mL of ethyl orthosilicate and 40 mL of anhydrous ethanol and add them to a beaker. Place it on a magnetic stirrer and stir at 300 rpm for 10 minutes. Mix 8 mL of deionized water and 1.0 mL of concentrated hydrochloric acid, then slowly drip the mixture into the above mixture. Continue stirring for 2 hours to obtain a nanosilica sol.

[0105] Weigh 20g of lightweight porous ceramsite, ultrasonically clean it three times with deionized water, and then dry it in a 60°C forced air drying oven for 24 hours. Place the dried ceramsite in a vacuum drying oven, add 30mL of nanosilica sol, and evacuate to -0.09MPa for 30 minutes to allow the sol to fully penetrate the pores of the ceramsite. After slowly releasing the pressure, continue soaking for 2 hours. Remove the ceramsite, air-dry it at room temperature for 12 hours, place it in a muffle furnace, heat it to 500°C at a heating rate of 5°C / min, calcine it for 3 hours, and cool it naturally to obtain SiO2-ceramic composite particles.

[0106] Step 2: Weigh 10 g of polyvinyl alcohol (PVA), add 200 mL of deionized water, stir in a 90°C oil bath for 2 hours until completely dissolved, and cool to 60°C to obtain a PVA solution; weigh 3 g of methacryloyloxyethyltrimethylammonium chloride (DMC), add 50 mL of deionized water to dissolve, and obtain a DMC solution.

[0107] The DMC solution was poured into the PVA solution, and 0.1 g of ammonium persulfate (APS) was added as an initiator. Under nitrogen protection, the mixture was stirred at 200 rpm in a 60°C oil bath for 8 hours to graft DMC onto the PVA to obtain a positively charged polyvinyl alcohol solution.

[0108] Step 3: Disperse 10 g of SiO2-ceramic composite particles in 100 mL of ethanol / water (volume ratio 9:1) mixture, add 5 mL of KH-560, adjust the pH to 4-5 (using 0.1 M acetic acid), stir and hydrolyze at 60 ° C for 40 minutes, then heat to 80 ° C for 2 hours, and centrifuge and wash to obtain epoxy SiO2-ceramic composite particles.

[0109] The epoxy-SiO2-ceramic composite particles were added to an 8% aqueous solution containing 10 g of PVA (the pH was pre-adjusted to 8-9 with NaOH), and 0.1 g of tetramethylethylenediamine (TEMED) was added to catalyze the ring-opening of the epoxy group. The reaction was stirred at 70 ° C for 4 hours to allow the hydroxyl groups of PVA to undergo a ring-opening reaction with the epoxy groups. Finally, the PVA-grafted SiO2-ceramic composite particles were obtained by centrifugation and drying.

[0110] Step 4: Weigh 1.5 g of graphene oxide powder, add 300 mL of deionized water, and ultrasonically disperse for 2 hours (power 300 W) to obtain a uniform graphene oxide dispersion. Adjust the pH of the dispersion to 8-9.

[0111] Weigh 10g of PVA-grafted SiO2-ceramic composite particles and add them to the graphene oxide dispersion. Stir at 150 rpm at room temperature for 12 hours to allow the graphene oxide to evenly adhere to the particle surface through electrostatic adsorption. After the reaction, filter and separate the particles, wash three times with deionized water, and dry them in a vacuum oven at 60°C for 24 hours to obtain a porous ceramic composite material.

[0112] Step 5: Disperse 10 g of the porous ceramsite composite material in 300 mL of an ethanol / water mixture (ethanol to water volume ratio of 9:1), and ultrasonically disperse for 30 minutes to obtain a uniform dispersion.

[0113] 5 mL of γ-aminopropyltriethoxysilane (APTES), 20 mL of ethanol, and 5 mL of water were mixed and stirred for hydrolysis at room temperature for 60 minutes to obtain an APTES hydrolyzate.

[0114] The APTES hydrolyzate was slowly added dropwise to the porous ceramsite composite dispersion. The pH was adjusted to 4-5 (using 0.1M acetic acid). The mixture was stirred in an oil bath at 60°C for 3 hours. After the reaction, the mixture was centrifuged (4000 rpm for 10 minutes), washed three times with ethanol, and dried in a vacuum oven at 60°C for 24 hours to obtain the modified porous ceramsite composite.

[0115] A method for preparing permeable and crack-resistant concrete for roads comprises the following steps:

[0116] The coarse aggregate, fine aggregate and modified porous ceramic were put into a mixer and stirred at 80 rpm for 3 minutes to mix the aggregates evenly to obtain a premix;

[0117] Add cement to the premix and continue mixing for 5 minutes to form a uniform dry mix;

[0118] Add polypropylene fiber, carbon fiber chopped strands and water reducer into water and stir for 10 minutes to disperse them uniformly to obtain a suspension;

[0119] The suspension was added to the dry mix and stirred at a rotation speed of 100 rpm for 8 minutes to obtain permeable and crack-resistant highway concrete.

[0120] Example 5

[0121] A permeable and crack-resistant highway concrete comprising the following components in parts by weight:

[0122] 120 parts of cement (Portland cement PO 42.5), 300 parts of coarse aggregate (mass ratio of recycled aggregate to natural crushed stone = 2:1), 40 parts of fine aggregate (river sand), 30 parts of modified porous ceramic composite material, 10 parts of polypropylene fiber, 5 parts of carbon fiber chopped strands, 2 parts of water reducer, and 30 parts of water.

[0123] The preparation method of the modified porous ceramsite composite material comprises the following steps:

[0124] Step 1: Measure 20 mL of ethyl orthosilicate and 40 mL of anhydrous ethanol and add them to a beaker. Place it on a magnetic stirrer and stir at 300 rpm for 10 minutes. Mix 8 mL of deionized water and 1.0 mL of concentrated hydrochloric acid, then slowly drip the mixture into the above mixture. Continue stirring for 2 hours to obtain a nanosilica sol.

[0125] Weigh 20g of lightweight porous ceramsite, ultrasonically clean it three times with deionized water, and then dry it in a 60°C forced air drying oven for 24 hours. Place the dried ceramsite in a vacuum drying oven, add 30mL of nanosilica sol, and evacuate to -0.09MPa for 30 minutes to allow the sol to fully penetrate the pores of the ceramsite. After slowly releasing the pressure, continue soaking for 2 hours. Remove the ceramsite, air-dry it at room temperature for 12 hours, place it in a muffle furnace, heat it to 450°C at a heating rate of 5°C / min, calcine it for 2 hours, and cool it naturally to obtain SiO2-ceramic composite particles.

[0126] Step 2: Weigh 10 g of polyvinyl alcohol (PVA), add 200 mL of deionized water, stir in a 90°C oil bath for 2 hours until completely dissolved, and cool to 60°C to obtain a PVA solution; weigh 3 g of methacryloyloxyethyltrimethylammonium chloride (DMC), add 50 mL of deionized water to dissolve, and obtain a DMC solution.

[0127] The DMC solution was poured into the PVA solution, and 0.1 g of ammonium persulfate (APS) was added as an initiator. Under nitrogen protection, the mixture was stirred at 200 rpm in a 60°C oil bath for 8 hours to graft DMC onto the PVA to obtain a positively charged polyvinyl alcohol solution.

[0128] Step 3: Disperse 10 g of SiO2-ceramic composite particles in 100 mL of ethanol / water (volume ratio 9:1) mixture, add 5 mL of KH-560, adjust the pH to 4-5 (using 0.1 M acetic acid), stir and hydrolyze at 60 ° C for 40 minutes, then heat to 80 ° C for 2 hours, and centrifuge and wash to obtain epoxy SiO2-ceramic composite particles.

[0129] The epoxy-SiO2-ceramic composite particles were added to an 8% aqueous solution containing 10 g of PVA (the pH was pre-adjusted to 8-9 with NaOH), and 0.1 g of tetramethylethylenediamine (TEMED) was added to catalyze the ring-opening of the epoxy group. The reaction was stirred at 70 ° C for 4 hours to allow the hydroxyl groups of PVA to undergo a ring-opening reaction with the epoxy groups. Finally, the PVA-grafted SiO2-ceramic composite particles were obtained by centrifugation and drying.

[0130] Step 4: Weigh 0.5 g of graphene oxide powder, add 300 mL of deionized water, and ultrasonically disperse for 2 hours (power 300 W) to obtain a uniform graphene oxide dispersion. Adjust the pH of the dispersion to 8-9.

[0131] Weigh 10g of PVA-grafted SiO2-ceramic composite particles and add them to the graphene oxide dispersion. Stir at 150 rpm at room temperature for 12 hours to allow the graphene oxide to evenly adhere to the particle surface through electrostatic adsorption. After the reaction, filter and separate the particles, wash three times with deionized water, and dry them in a vacuum oven at 60°C for 24 hours to obtain a porous ceramic composite material.

[0132] Step 5: Disperse 10 g of the porous ceramsite composite material in 300 mL of an ethanol / water mixture (ethanol to water volume ratio of 9:1), and ultrasonically disperse for 30 minutes to obtain a uniform dispersion.

[0133] 5 mL of γ-aminopropyltriethoxysilane (APTES), 20 mL of ethanol, and 5 mL of water were mixed and stirred for hydrolysis at room temperature for 60 minutes to obtain an APTES hydrolyzate.

[0134] The APTES hydrolyzate was slowly added dropwise to the porous ceramsite composite dispersion. The pH was adjusted to 4-5 (using 0.1M acetic acid). The mixture was stirred in an oil bath at 60°C for 3 hours. After the reaction, the mixture was centrifuged (4000 rpm for 10 minutes), washed three times with ethanol, and dried in a vacuum oven at 60°C for 24 hours to obtain the modified porous ceramsite composite.

[0135] A method for preparing permeable and crack-resistant concrete for roads comprises the following steps:

[0136] The coarse aggregate, fine aggregate and modified porous ceramic were put into a mixer and stirred at 80 rpm for 3 minutes to mix the aggregates evenly to obtain a premix;

[0137] Add cement to the premix and continue mixing for 5 minutes to form a uniform dry mix;

[0138] Add polypropylene fiber, carbon fiber chopped strands and water reducer into water and stir for 10 minutes to disperse them uniformly to obtain a suspension;

[0139] The suspension was added to the dry mix and stirred at a rotation speed of 100 rpm for 8 minutes to obtain permeable and crack-resistant highway concrete.

[0140] Comparative Example 1

[0141] The difference between Comparative Example 1 and Example 1 is that no modified porous ceramic composite material is added to the concrete.

[0142] Comparative Example 2

[0143] The difference between Comparative Example 2 and Example 1 is that step 2 is omitted during the preparation of the modified porous ceramic composite material, that is, methacryloyloxyethyltrimethylammonium chloride is not grafted onto polyvinyl alcohol.

[0144] Comparative Example 3

[0145] The difference between Comparative Example 3 and Example 1 is that Step 2 and Step 3 are omitted during the preparation of the modified porous ceramic composite material, that is, polyvinyl alcohol is not grafted onto the SiO2-ceramic composite particles.

[0146] Comparative Example 4

[0147] The difference between Comparative Example 4 and Example 1 is that Step 4 and Step 5 are omitted in the preparation process of the modified porous ceramic composite material, that is, graphene oxide is not combined with the PVA grafted SiO2-ceramic composite particles.

[0148] Comparative Example 5

[0149] The difference between Comparative Example 5 and Example 1 is that the modified porous ceramic composite material in the concrete is replaced by a porous ceramic composite material.

[0150] Comparative Example 6

[0151] The difference between Comparative Example 6 and Example 1 is that polypropylene fibers and carbon fiber chopped strands are not added to the concrete.

[0152] Performance testing:

[0153] 1. Water Permeability Test: In accordance with GB / T 25993-2010, a 50mm diameter and 100mm deep hole was drilled in the center of the top surface of a 150mm×150mm×150mm concrete cube specimen that had been cured for 28 days. The specimen was then fixed to a water permeability meter and filled with water to a head height of 50mm. The time it took for the water level to drop by 20mm was recorded. The water permeability coefficient was calculated using the formula k=L×V / A×t×H, where the measured values ​​for specimen thickness L, water volume V, permeable area A, time t, and head height H were substituted. The test was repeated three times and the average value was taken. The test results are shown in Table 1.

[0154] 2. Water permeability test: Place the concrete specimen in sewage containing 10% clay particles at a rate of 10L / m 2 h flow rate circulation flushing 500L / m 2 Comparing the permeability coefficients before and after water flow, the permeability attenuation rate was calculated using the formula: attenuation rate = (k0 - k1) / k0 × 100%. Here, k0 is the initial permeability coefficient and k1 is the permeability coefficient after water flow. This was used to assess the concrete's permeability stability. The test results are shown in Table 1.

[0155] 3. Cracking resistance test: According to ASTM C1018 standard, 100mm×100mm×400mm prism specimens were prepared. After curing for 28 days, the three-point loading method was used to apply load at a rate of 0.05mm / min, and the load-deflection curve was recorded simultaneously. The 0-5δ p Area and 0-δ p The ratio of the area (δ p The toughness index I5 is calculated using the peak load-corresponding deflection. A higher I5 indicates a stronger ability of the concrete to resist crack propagation. The test results are shown in Table 1.

[0156] 4. Compressive strength test: According to GB / T 50081-2019 standard, fresh concrete was poured into 150mm×150mm×150mm cubic specimens. After standard curing for 28 days, the specimens were placed on a pressure testing machine and loaded uniformly at a rate of 0.5-0.8MPa / s until they failed. The maximum load at failure was recorded and the formula f was used to calculate the compressive strength. c =A / F (F is the failure load, A is the pressure-bearing area of ​​the specimen) to calculate the compressive strength. The result is the arithmetic mean of the three specimens, accurate to 0.1 MPa. The test results are shown in Table 1.

[0157] Table 1:

[0158]

[0159] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A road permeable crack-resistant concrete, characterized in that: Comprise the following components by weight: 120-160 parts of cement, 300-400 parts of coarse aggregate, 40-60 parts of fine aggregate, 30-50 parts of modified porous ceramsite composite material, 10-15 parts of polypropylene fiber, 5-10 parts of carbon fiber chopped strands, 2-5 parts of water reducer, and 40-50 parts of water; The preparation method of the modified porous ceramsite composite material comprises the following steps: S1, using tetraethyl orthosilicate as a raw material to prepare nano-silica sol, immersing lightweight porous ceramsite in the nano-silica sol, and performing vacuum treatment and calcination to obtain SiO2-ceramic composite particles; S2, using polyvinyl alcohol and methacryloyloxyethyltrimethylammonium chloride as raw materials, under the action of an initiator, grafting methacryloyloxyethyltrimethylammonium chloride onto polyvinyl alcohol to obtain positively charged polyvinyl alcohol; S3, grafting positively charged polyvinyl alcohol onto SiO2-ceramic composite particles to obtain PVA-grafted SiO2-ceramic composite particles; S4, using an electrostatic adsorption method to combine graphene oxide on the surface of PVA-grafted SiO2-ceramic composite particles to obtain a porous ceramic composite material; dispersing the porous ceramsite composite material in an ethanol / water mixture to obtain a porous ceramsite composite material dispersion; The hydrolyzed solution of gamma-aminopropyltriethoxysilane is added dropwise to the porous ceramsite composite material dispersion, and a condensation reaction is carried out under heating conditions. The modified porous ceramsite composite material is obtained through centrifugal separation, washing and drying.

2. The permeable and crack-resistant concrete for roads according to claim 1, characterized in that: The coarse aggregate is a mixture of recycled aggregate and natural crushed stone.

3. The permeable and crack-resistant concrete for highway according to claim 1, characterized in that: The fine aggregate is quartz sand or river sand.

4. The permeable and crack-resistant concrete for highway according to claim 1, characterized in that: In step S1, the lightweight porous ceramsite has a particle size of 5 to 10 mm, an average pore size of 40 to 50 μm, and an open porosity of ≥50%.

5. The permeable and crack-resistant concrete for highway according to claim 1, characterized in that: In the step S1, the calcination temperature is 450-500° C., and the calcination time is 2-3 hours.

6. The permeable and crack-resistant concrete for highway according to claim 1, characterized in that: In step S3, the method for grafting positively charged polyvinyl alcohol onto the SiO2-ceramic composite particles is to first graft an epoxy silane coupling agent onto the SiO2-ceramic composite particles, and then utilize a ring-opening reaction to graft the positively charged polyvinyl alcohol onto the SiO2-ceramic composite particles.

7. The permeable and crack-resistant concrete for highway according to claim 1, characterized in that: In step S4, the mass ratio of the PVA grafted SiO2-ceramsite composite particles to the graphene oxide is 20:1-3.

8. A method for preparing the permeable and crack-resistant concrete for roads according to any one of claims 1 to 7, characterized in that: The following steps are involved: Put the coarse aggregate, fine aggregate and porous ceramsite into a mixer and mix them evenly to obtain a premix; Add cement to the premix and continue stirring to obtain a dry mix; Add polypropylene fiber, carbon fiber chopped strands and a water reducer into water and stir evenly to obtain a suspension; The suspension is added into the dry mix and stirred evenly to obtain the permeable and crack-resistant highway concrete.

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