A kind of permeable pavement material for sponge city and preparation method thereof

Abstract

The invention discloses a permeable pavement material for sponge city and a preparation method thereof, and relates to the technical field of permeable building materials. The permeable pavement material is made of the following components by weight: 60-80 parts of coarse aggregate, 20-40 parts of fine aggregate, 30-50 parts of Portland cement, 10-30 parts of slag, 10-20 parts of fly ash, 10-20 parts of filler, 5-15 parts of modified polypropylene fiber, 0.5-3 parts of water reducer, and 20-30 parts of water. The permeable pavement material of the invention not only realizes the recycling of resources, but also forms a continuous pore structure and a stable skeleton system through the optimized ratio of each component and the reinforcement effect of the modified polypropylene fiber, has excellent permeability, high mechanical strength and freeze-thaw resistance, and meets the technical requirements of sponge city construction.

Description

Technical Field

[0001] The invention relates to the technical field of permeable building materials, and in particular to a permeable pavement material for sponge cities and a preparation method thereof. Background Art

[0002] In recent years, with the acceleration of urbanization, the large increase in impermeable roads has led to increasingly prominent environmental problems such as frequent urban waterlogging, continuous decline in groundwater levels, and intensified heat island effects. As a new urban construction concept, sponge city emphasizes solving urban water environment problems through ecological means.

[0003] Permeable pavement material is one of the most important technical measures in the construction of sponge cities, with good water permeability, water retention and water purification functions. Among them, permeable concrete has become the most promising permeable pavement material due to its excellent permeability, good mechanical properties and low cost. Permeable concrete is a new type of concrete material with continuous pores, which is prepared by specific mix ratio and process with cement as the main cementitious material, coarse aggregate, a small amount of fine aggregate as the main raw materials.

[0004] At the same time, my country produces a large amount of construction waste and industrial waste every year, of which the annual production of construction waste exceeds 2 billion tons, and the annual output of industrial waste such as slag is about 400 million tons. The treatment and resource utilization of these wastes have become an environmental problem that needs to be solved urgently. Among them, abandoned granite has good physical and mechanical properties and can be used as high-quality aggregate after reasonable processing; and blast furnace slag has potential hydraulic hardness, and its chemical composition mainly includes CaO, SiO2 and Al2O3, etc. After grinding, it can react with cement to improve the strength and durability of concrete. The rational use of these industrial wastes can not only reduce the cost of building materials, but also significantly reduce environmental pollution and realize the recycling of resources.

[0005] However, currently, traditional closed pavement materials such as asphalt concrete and cement concrete are commonly used in urban roads, squares, sidewalks, etc. Although these materials have high strength and durability, their impermeability prevents rainwater from infiltrating in time, which not only increases the burden on the municipal drainage system, but also causes problems such as road waterlogging and traffic safety hazards.

[0006] The existing permeable concrete pavement materials mainly have the following technical defects:

[0007] 1. The contradiction between strength and permeability: Improving the strength of a material often reduces its permeability. How to ensure sufficient permeability while meeting the bearing capacity requirements is an important challenge;

[0008] 2. Insufficient durability: Due to its porous structure, existing permeable pavement materials are prone to durability problems such as cracking and damage;

[0009] 3. Poor frost resistance: In cold regions, the freeze-thaw cycle of water in the pores can cause material damage;

[0010] 4. Easy to clog: During use, fine particles can easily clog the pores and affect the water permeability.

[0011] CN112441774A discloses a nano-enhanced water-permeable material, a water-permeable floor tile and a water-permeable pavement. The nano-enhanced water-permeable material of the present invention comprises the following raw materials in parts by weight: 70-100 parts of aggregate; 6-10 parts of active molecular sieve powder; 8-15 parts of nano calcium carbonate; 5-8 parts of nano titanium dioxide; 2-4 parts of defoamer; 5-8 parts of water reducer; 40-60 parts of high-strength toughening agent; 35-50 parts of high-strength binder; and 4-8 parts of holmium oxide. The nano-enhanced water-permeable material of the present invention has a reasonable ratio between the components, and the water permeability coefficient, compressive strength, flexural strength and wear resistance of the obtained water-permeable material are far superior to those of ordinary water-permeable materials.

[0012] Domestic and foreign studies have shown that the performance of permeable concrete mainly depends on its mix design and raw material selection. Permeable concrete is usually required to have a porosity of 15-25% to ensure good permeability; at the same time, it is also necessary to ensure that the 28-day compressive strength is not less than 20MPa to meet the use requirements. However, these two indicators often restrict each other. How to improve strength while ensuring permeability is the focus and difficulty of current research.

[0013] Therefore, there is an urgent need to develop a permeable pavement material with a reasonable mix ratio and excellent performance, which must not only ensure good permeability, but also have sufficient strength and durability, while also making full use of recycled resources such as construction waste and industrial waste to achieve the unity of economic and environmental benefits. Summary of the invention

[0014] In order to address the deficiencies in the prior art, the purpose of the present invention is to provide a permeable pavement material for sponge cities and a preparation method thereof. The permeable pavement material of the present invention not only realizes the recycling of resources, but also forms a continuous pore structure and a stable skeleton system through the optimized ratio of each component and the reinforcement effect of modified polypropylene fiber. It has excellent permeability, high mechanical strength and anti-freeze-thaw performance, and meets the technical requirements of sponge city construction.

[0015] In order to achieve the above object, the present invention adopts the following technical solution:

[0016] A permeable pavement material for sponge cities is made of the following components by weight: 60-80 parts of coarse aggregate, 20-40 parts of fine aggregate, 30-50 parts of Portland cement, 10-30 parts of slag, 10-20 parts of fly ash, 10-20 parts of filler, 5-15 parts of modified polypropylene fiber, 0.5-3 parts of water reducer and 20-30 parts of water.

[0017] Preferably, the method for preparing the modified polypropylene fiber comprises the following steps:

[0018] (1) dispersing polypropylene fiber in xylene, continuously introducing nitrogen, dissolving BPO and hydroquinone in propionitrile, slowly adding them dropwise into the reaction system, heating and refluxing to react, filtering, washing and drying the product to obtain nitrile fiber;

[0019] Nitrilation process: BPO undergoes homolysis under heating conditions to generate benzoyloxy free radicals, which are then decarboxylated to obtain phenyl free radicals. These free radicals attack the CH bonds on the PP molecular chain to form macromolecular free radicals. Propylonitrile molecules are grafted onto the PP molecular chain through addition reactions initiated by free radicals. Hydroquinone acts as an inhibitor to terminate excessive free radical reactions by providing hydrogen atoms. Finally, nitrile functional groups are introduced into the PP molecular chain.

[0020] Preferably, in step (1), the usage ratio of polypropylene fiber, xylene, BPO, hydroquinone and propionitrile is 10 g: 80-100 mL: 0.3-1.2 g: 3-10 mg: 30-50 mL.

[0021] Preferably, in step (1), the reflux reaction conditions are heating to 60-90° C. and reflux reaction for 2-8 hours; and washing with ethanol and acetone alternately for 3-5 times.

[0022] (2) dispersing the nitrile fiber in DMF, continuously introducing nitrogen, adding benzidine disulfonic acid and anhydrous AlCl3, stirring to react, filtering, washing, and drying the product to obtain the sulfonated fiber;

[0023] Sulfonation process: Under the catalysis of Lewis acid of anhydrous AlCl3, the nitrile group is first activated by coordination with AlCl3 to increase its electrophilicity. The amino group of benzidine disulfonic acid acts as a nucleophilic reagent to attack the activated nitrile carbon atom, and after the addition-proton transfer process, an imine intermediate is formed, and finally an imine structure containing a sulfonic acid group is introduced into the PP molecular chain.

[0024] Preferably, in step (2), the usage ratio of nitrile fiber, DMF, benzidine disulfonic acid, and anhydrous AlCl3 is 10g: 100-120mL: 20-30g: 1-3g.

[0025] Preferably, in step (2), the stirring reaction conditions are: stirring the reaction at 50-80° C. for 4-12 hours; washing with deionized water for 3-5 times, and then washing with methanol for 2-4 times.

[0026] (3) Disperse the sulfonated fiber in tetrahydrofuran, continuously introduce nitrogen, add 3-mercaptopropyltriethoxysilane, cool the system, slowly add n-butyl lithium in n-hexane solution, stir the reaction in the dark, cool the reaction solution, filter, wash and dry the product to obtain modified polypropylene fiber.

[0027] Silane grafting modification: First, n-butyl lithium, as a strong base, captures the proton of the thiol group to generate a more active thiolate anion. This more nucleophilic thiolate attacks the carbon-nitrogen double bond of the imine, resulting in a Michael-type addition reaction. The reaction is carried out under anhydrous conditions, avoiding the hydrolysis of the silane group and ensuring the selectivity of the reaction. Finally, a structure containing a silane group is grafted onto the PP molecular chain, completing the modification process.

[0028] Preferably, in step (3), the dosage ratio of sulfonated fiber, tetrahydrofuran, 3-mercaptopropyltriethoxysilane, and n-butyl lithium in n-hexane solution is 10 g: 100-120 mL: 10-20 g: 5-12 mL; and the concentration of n-butyl lithium in n-hexane solution is 1.6 M.

[0029] Preferably, in step (3), the system is cooled to 0-5°C, and the reaction is stirred in the dark at 30-45°C for 4-8h; the reaction solution is cooled to 0-5°C, anhydrous methanol is added for quenching; and the reaction solution is washed with anhydrous tetrahydrofuran for 3-5 times.

[0030] Preferably, the coarse aggregate is granite waste stone with a particle size of 5-10 mm; the fine aggregate is machine-made sand with a fineness modulus of 2.2-2.7.

[0031] Preferably, the slag is ground granulated blast furnace slag with a specific surface area of ​​≥410m 2 / kg, the main chemical composition content is: CaO ≥ 38.6%, SiO2 ≥ 36.9%, Al2O3 ≤ 12.3%.

[0032] Preferably, the filler is one or more of calcium carbonate, talc, aluminum oxide, quartz powder, magnesium oxide, aluminum hydroxide, silica powder, titanium dioxide, and kaolin with a particle size of 10 to 500 μm.

[0033] The present invention also claims protection for a method for preparing the permeable pavement material for sponge cities, comprising the following steps: first adding silicate cement, slag, fly ash, filler, and modified polypropylene fiber into a mixer and stirring for 60 to 90 seconds, then adding a water reducer and water and heating to 40 to 55°C and continuing to stir for 60 to 90 seconds, and finally adding coarse aggregate and fine aggregate and continuing to stir for 120 to 150 seconds to obtain the permeable pavement material for sponge cities.

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

[0035] 1. The present invention provides a permeable pavement material for sponge city, which has good overall performance by optimizing the proportion of each component: the coarse aggregate is made of granite waste stone, which has high strength and good compressive resistance, and improves resource utilization; the fine aggregate is made of machine-made sand with a suitable fineness modulus, which forms the best gradation with the coarse aggregate to improve the density of the material; silicate cement is used as the main cementitious material to provide basic strength, while the addition of slag and fly ash not only reduces the cost, but also improves the later strength and durability through volcanic ash reaction; the addition of fillers optimizes the void structure and improves the working performance of the material; the addition of modified polypropylene fiber, through its excellent interface bonding performance and three-dimensional network reinforcement, significantly improves the crack resistance and impact resistance of the material and enhances the stability of the overall structure. The synergistic effect of each component makes the material have good permeability, strength and durability, meeting the requirements of sponge city construction.

[0036] 2. The present invention provides a modified polypropylene fiber, firstly introducing polar nitrile groups on the fiber surface by nitrilization, which form hydrogen bonds with cement paste and react with Ca 2+ Ionic coordination significantly improves the hydrophilicity and dispersibility of the fiber and enhances its compatibility with the cement matrix. Subsequently, the hydrophilicity and activity of the fiber surface are further improved by sulfonation, and the interfacial bonding force is enhanced. At the same time, the introduced sulfonic acid group and amino group can also improve the flow properties of the slurry and the microstructure of the concrete. Finally, silane grafting is used to introduce silane groups with bonding ability while maintaining the hydrophilicity of the fiber. The Si-OH groups formed after hydrolysis can form chemical bonds with cement hydration products (CSH gel), thereby achieving chemical anchoring of the fiber and the matrix. The modified fiber can form a three-dimensional network structure in the material, share the tensile stress generated by external loads, and play a role similar to "rebar". At the same time, a strong interface bond is formed between the modified fiber and the aggregate, which significantly improves the crack resistance, impact resistance, and fatigue resistance of the composite material. Especially in the freeze-thaw cycle, the modified fiber can not only effectively release the expansion stress generated by water freezing, but also reduce the peeling damage of the hydration product due to its strong interface bonding with the matrix, thereby improving the overall mechanical properties and durability of the material. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with embodiments. Of course, the specific embodiments described here are only used to explain the present invention and are not used to limit the present invention.

[0038] Unless otherwise specified, the chemical reagents and materials in the present invention are purchased from commercial sources or synthesized from raw materials purchased from commercial sources.

[0039] Polypropylene fibers were purchased from Jinan Shunjie Engineering Materials Co., Ltd., with lengths ranging from 3 to 19 mm;

[0040] The polycarboxylate water reducer was purchased from Sumitomo, Japan, with the brand name Carbomer HV-501;

[0041] Fly ash was purchased from Shijiazhuang Chilin Mineral Products Co., Ltd. with a density of 2.45 kg / m 3 .

[0042] A method for preparing a permeable pavement material for a sponge city comprises the following steps:

[0043] (1) Disperse 10 g of polypropylene fiber in 80-100 mL of xylene, continuously introduce nitrogen, dissolve 0.3-1.2 g of BPO and 3-10 mg of hydroquinone in 30-50 mL of propionitrile, slowly add them dropwise to the reaction system, heat to 60-90 °C and reflux for 2-8 h, filter the product, wash it with ethanol and acetone alternately for 3-5 times, and dry it to obtain nitrile fiber;

[0044] (2) Disperse 10 g of nitrile fiber in 100-120 mL of DMF, continuously introduce nitrogen, add 20-30 g of diphenylamine disulfonic acid and 1-3 g of anhydrous AlCl3, stir and react at 50-80 °C for 4-12 h, filter the product, wash with deionized water for 3-5 times, then wash with methanol for 2-4 times, and dry to obtain sulfonated fiber;

[0045] (3) Disperse 10 g of sulfonated fiber in 100-120 mL of tetrahydrofuran, continue to introduce nitrogen, add 10-20 g of 3-mercaptopropyltriethoxysilane, cool the system to 0-5 °C, slowly add 5-12 mL of 1.6 M n-butyl lithium n-hexane solution, stir and react at 30-45 °C in the dark for 4-8 h, cool the reaction solution to 0-5 °C, add anhydrous methanol to quench, filter the product, wash with anhydrous tetrahydrofuran 3-5 times, and dry to obtain modified polypropylene fiber;

[0046] (4) First, 30-50 parts of silicate cement, 10-30 parts of slag, 10-20 parts of fly ash, 10-20 parts of filler, and 5-15 parts of modified polypropylene fiber are added into a mixer and stirred for 60-90 seconds. Subsequently, 0.5-3 parts of a water reducer and 20-30 parts of water are added and heated to 40-55° C. and stirred for 60-90 seconds. Finally, 60-80 parts of coarse aggregate and 20-40 parts of fine aggregate are added and stirred for 120-150 seconds to obtain the permeable pavement material for sponge city.

[0047] The coarse aggregate is granite waste stone with a particle size of 5-10 mm; the fine aggregate is machine-made sand with a fineness modulus of 2.2-2.7; the slag is ground and granulated blast furnace slag with a specific surface area of ​​≥410m 2 / kg, the main chemical composition content is: CaO ≥ 38.6%, SiO2 ≥ 36.9%, Al2O3 ≤ 12.3%; the filler is one or more of calcium carbonate, talcum powder, alumina, quartz powder, magnesium oxide, aluminum hydroxide, silicon micropowder, titanium dioxide, and kaolin with a particle size of 10-500μm.

[0048] The present invention will be further described below through specific embodiments.

[0049] A method for preparing a permeable pavement material for a sponge city comprises the following steps:

[0050] (1) Disperse 10 g of polypropylene fiber in 100 mL of xylene, continuously introduce nitrogen, dissolve 1.2 g of BPO and 10 mg of hydroquinone in 50 mL of propionitrile, slowly add them dropwise to the reaction system, heat to 90 °C and reflux for 2 h, filter the product, wash it with ethanol and acetone alternately for 3 times, and dry it to obtain nitrile fiber;

[0051] (2) Disperse 10 g of nitrile fiber in 100 mL of DMF, continue to introduce nitrogen, add 30 g of diphenylamine disulfonic acid and 3 g of anhydrous AlCl3, stir and react at 80 °C for 4 h, filter the product, wash it 3 times with deionized water, then wash it 2 times with methanol, and dry it to obtain sulfonated fiber;

[0052] (3) Disperse 10 g of sulfonated fiber in 100 mL of tetrahydrofuran, continue to introduce nitrogen, add 20 g of 3-mercaptopropyltriethoxysilane, cool the system to 2 °C, slowly add 12 mL of 1.6 M n-butyl lithium n-hexane solution, stir and react for 4 h at 45 °C in the dark, cool the reaction solution to 2 °C, add anhydrous methanol to quench, filter the product, wash it three times with anhydrous tetrahydrofuran, and dry it to obtain modified polypropylene fiber;

[0053] (4) First, 500 g of silicate cement, 300 g of slag, 200 g of fly ash, 200 g of calcium carbonate, and 150 g of modified polypropylene fiber were added into a mixer and stirred for 75 seconds. Subsequently, 30 g of polycarboxylic acid water reducer and 300 g of water were added and heated to 50° C. and stirred for 75 seconds. Finally, 800 g of granite waste stone and 400 g of machine-made sand were added and stirred for 135 seconds to obtain the permeable pavement material for sponge city.

[0054] A method for preparing a permeable pavement material for a sponge city comprises the following steps:

[0055] (1) Disperse 10 g of polypropylene fiber in 100 mL of xylene, continuously introduce nitrogen, dissolve 1 g of BPO and 8 mg of hydroquinone in 40 mL of propionitrile, slowly add them dropwise to the reaction system, heat to 80 °C and reflux for 4 h, filter the product, wash it with ethanol and acetone alternately for 3 times, and dry it to obtain nitrile fiber;

[0056] (2) Disperse 10 g of nitrile fiber in 100 mL of DMF, continue to introduce nitrogen, add 28 g of diphenylamine disulfonic acid and 2 g of anhydrous AlCl3, stir and react at 70 °C for 6 h, filter the product, wash it 3 times with deionized water, then wash it 2 times with methanol, and dry it to obtain sulfonated fiber;

[0057] (3) Disperse 10 g of sulfonated fiber in 100 mL of tetrahydrofuran, continue to introduce nitrogen, add 18 g of 3-mercaptopropyltriethoxysilane, cool the system to 2 °C, slowly add 10 mL of 1.6 M n-butyl lithium n-hexane solution, stir and react for 6 h at 40 °C in the dark, cool the reaction solution to 2 °C, add anhydrous methanol to quench, filter the product, wash it three times with anhydrous tetrahydrofuran, and dry it to obtain modified polypropylene fiber;

[0058] (4) First, 420 g of silicate cement, 240 g of slag, 180 g of fly ash, 180 g of calcium carbonate, and 120 g of modified polypropylene fiber are added into a mixer and stirred for 75 seconds. Subsequently, 25 g of polycarboxylic acid water reducer and 260 g of water are added and heated to 50° C. and stirred for 75 seconds. Finally, 720 g of granite waste stone and 320 g of machine-made sand are added and stirred for 135 seconds to obtain the permeable pavement material for sponge city.

[0059] A method for preparing a permeable pavement material for a sponge city comprises the following steps:

[0060] (1) Disperse 10 g of polypropylene fiber in 100 mL of xylene, continuously introduce nitrogen, dissolve 0.7 g of BPO and 6 mg of hydroquinone in 40 mL of propionitrile, slowly add them dropwise to the reaction system, heat to 70 °C and reflux for 6 h, filter the product, wash it with ethanol and acetone alternately for 3 times, and dry it to obtain nitrile fiber;

[0061] (2) Disperse 10 g of nitrile fiber in 100 mL of DMF, continue to introduce nitrogen, add 25 g of diphenylamine disulfonic acid and 2 g of anhydrous AlCl3, stir and react at 60 °C for 10 h, filter the product, wash it 3 times with deionized water, then wash it 2 times with methanol, and dry it to obtain sulfonated fiber;

[0062] (3) Disperse 10 g of sulfonated fiber in 100 mL of tetrahydrofuran, continue to introduce nitrogen, add 12 g of 3-mercaptopropyltriethoxysilane, cool the system to 2 °C, slowly add 8 mL of 1.6 M n-butyl lithium n-hexane solution, stir and react at 35 °C in the dark for 6 h, cool the reaction solution to 2 °C, add anhydrous methanol to quench, filter the product, wash it three times with anhydrous tetrahydrofuran, and dry it to obtain modified polypropylene fiber;

[0063] (4) First, 350 g of silicate cement, 150 g of slag, 150 g of fly ash, 150 g of calcium carbonate, and 100 g of modified polypropylene fiber are added into a mixer and stirred for 75 seconds. Subsequently, 10 g of polycarboxylic acid water reducer and 250 g of water are added and heated to 50° C. and stirred for 75 seconds. Finally, 650 g of granite waste stone and 250 g of machine-made sand are added and stirred for 135 seconds to obtain the permeable pavement material for sponge city.

[0064] A method for preparing a permeable pavement material for a sponge city comprises the following steps:

[0065] (1) Disperse 10 g of polypropylene fiber in 100 mL of xylene, continuously introduce nitrogen, dissolve 0.3 g of BPO and 3 mg of hydroquinone in 30 mL of propionitrile, slowly add them dropwise to the reaction system, heat to 60 °C and reflux for 8 h, filter the product, wash it with ethanol and acetone alternately for 3 times, and dry it to obtain nitrile fiber;

[0066] (2) Disperse 10 g of nitrile fiber in 100 mL of DMF, continue to introduce nitrogen, add 20 g of benzidine disulfonic acid and 1 g of anhydrous AlCl3, stir and react at 50 °C for 12 h, filter the product, wash it 3 times with deionized water, then wash it 2 times with methanol, and dry it to obtain sulfonated fiber;

[0067] (3) Disperse 10 g of sulfonated fiber in 100 mL of tetrahydrofuran, continue to introduce nitrogen, add 10 g of 3-mercaptopropyltriethoxysilane, cool the system to 2 °C, slowly add 5 mL of 1.6 M n-butyl lithium n-hexane solution, stir and react at 30 °C in the dark for 8 h, cool the reaction solution to 2 °C, add anhydrous methanol to quench, filter the product, wash it three times with anhydrous tetrahydrofuran, and dry it to obtain modified polypropylene fiber;

[0068] (4) First, 300 g of silicate cement, 100 g of slag, 100 g of fly ash, 100 g of calcium carbonate, and 80 g of modified polypropylene fiber are added into a mixer and stirred for 75 seconds. Subsequently, 5 g of polycarboxylic acid water reducer and 200 g of water are added and heated to 50° C. and stirred for 75 seconds. Finally, 600 g of granite waste stone and 200 g of machine-made sand are added and stirred for 135 seconds to obtain the permeable pavement material for sponge city.

[0069] Comparative Example 1

[0070] A method for preparing a permeable pavement material for a sponge city comprises the following steps:

[0071] (1) Disperse 10 g of polypropylene fiber in 100 mL of xylene, continuously introduce nitrogen, dissolve 1.2 g of BPO and 10 mg of hydroquinone in 50 mL of propionitrile, slowly add them dropwise to the reaction system, heat to 90 °C and reflux for 2 h, filter the product, wash it with ethanol and acetone alternately for 3 times, and dry it to obtain nitrile fiber;

[0072] (2) Disperse 10 g of nitrile fiber in 100 mL of DMF, continue to introduce nitrogen, add 30 g of diphenylamine disulfonic acid and 3 g of anhydrous AlCl3, stir and react at 80 °C for 4 h, filter the product, wash it 3 times with deionized water, then wash it 2 times with methanol, and dry it to obtain sulfonated fiber;

[0073] (3) First, 500 g of silicate cement, 300 g of slag, 200 g of fly ash, 200 g of calcium carbonate, and 150 g of sulfonated fiber were added into a mixer and stirred for 75 seconds. Subsequently, 30 g of polycarboxylate water reducer and 300 g of water were added and heated to 50° C. and stirred for 75 seconds. Finally, 800 g of granite waste stone and 400 g of machine-made sand were added and stirred for 135 seconds to obtain the permeable pavement material for sponge city.

[0074] Comparative Example 2

[0075] A method for preparing a permeable pavement material for a sponge city comprises the following steps:

[0076] (1) Disperse 10 g of polypropylene fiber in 100 mL of xylene, continuously introduce nitrogen, dissolve 1.2 g of BPO and 10 mg of hydroquinone in 50 mL of propionitrile, slowly add them dropwise to the reaction system, heat to 90 °C and reflux for 2 h, filter the product, wash it with ethanol and acetone alternately for 3 times, and dry it to obtain nitrile fiber;

[0077] (2) First, 500 g of silicate cement, 300 g of slag, 200 g of fly ash, 200 g of calcium carbonate, and 150 g of nitrile fiber were added into a mixer and stirred for 75 seconds. Subsequently, 30 g of polycarboxylic acid water reducer and 300 g of water were added and heated to 50° C. and stirred for 75 seconds. Finally, 800 g of granite waste stone and 400 g of machine-made sand were added and stirred for 135 seconds to obtain the permeable pavement material for sponge city.

[0078] The permeable pavement materials prepared in Examples 1 to 4 and Comparative Examples 1 to 2 were made into 100 mm × 100 mm × 400 mm test pieces, cured for 28 days, and tested for compressive strength and flexural strength with reference to GB / T 50107-2010 "Standard for Testing and Evaluation of Concrete Strength"; tested for water permeability coefficient and wear resistance with reference to JC / T 2558-2020 "Permeable Concrete"; tested for porosity with reference to DB33 / T 1153-2018 "Technical Specification for Application of Permeable Concrete Pavement"; and characterized for antifreeze performance with reference to GB / T 50082-2009 "Standard for Test Methods for Long-term Performance and Durability of Ordinary Concrete" 4.2 Quick Freezing Method with reference to the maximum number of freeze-thaw cycles when the mass loss rate does not exceed 5%. Specific data are shown in Table 1.

[0079] Table 1 Performance test results of permeable pavement materials for sponge cities

[0080]

[0081] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A permeable pavement material for sponge cities, characterized in that: The composition is made of the following components by weight: 60-80 parts of coarse aggregate, 20-40 parts of fine aggregate, 30-50 parts of Portland cement, 10-30 parts of slag, 10-20 parts of fly ash, 10-20 parts of filler, 5-15 parts of modified polypropylene fiber, 0.5-3 parts of water reducer, and 20-30 parts of water; The preparation method of the modified polypropylene fiber comprises the following steps: (1) dispersing polypropylene fiber in xylene, continuously introducing nitrogen, dissolving BPO and hydroquinone in propionitrile, slowly adding them dropwise into the reaction system, heating and refluxing to react, filtering, washing and drying the product to obtain nitrile fiber; (2) dispersing the nitrile fiber in DMF, continuously introducing nitrogen, adding benzidine disulfonic acid and anhydrous AlCl3, stirring to react, filtering, washing, and drying the product to obtain the sulfonated fiber; (3) Disperse the sulfonated fiber in tetrahydrofuran, continuously introduce nitrogen, add 3-mercaptopropyltriethoxysilane, cool the system, slowly add n-butyl lithium in n-hexane solution, stir the reaction in the dark, cool the reaction solution, filter, wash and dry the product to obtain modified polypropylene fiber.

2. The permeable pavement material for sponge city according to claim 1, characterized in that: In step (1), the usage ratio of polypropylene fiber, xylene, BPO, hydroquinone and propionitrile is 10 g: 80-100 mL: 0.3-1.2 g: 3-10 mg: 30-50 mL.

3. The permeable pavement material for sponge city according to claim 1, characterized in that: In step (1), the reflux reaction conditions are to heat the mixture to 60-90° C. and reflux for 2-8 hours; and wash the mixture with ethanol and acetone alternately for 3-5 times.

4. The permeable pavement material for sponge city according to claim 1, characterized in that: In step (2), the usage ratio of nitrile fiber, DMF, diphenylamine disulfonic acid, and anhydrous AlCl3 is 10g: 100-120mL: 20-30g: 1-3g.

5. The permeable pavement material for sponge city according to claim 1, characterized in that: In step (2), the stirring reaction conditions are 50-80° C. for 4-12 h; washing with deionized water for 3-5 times, and then washing with methanol for 2-4 times.

6. The permeable pavement material for sponge city according to claim 1, characterized in that: In step (3), the dosage ratio of sulfonated fiber, tetrahydrofuran, 3-mercaptopropyltriethoxysilane, and n-butyl lithium in n-hexane solution is 10 g: 100-120 mL: 10-20 g: 5-12 mL; and the concentration of n-butyl lithium in n-hexane solution is 1.6 M.

7. The permeable pavement material for sponge city according to claim 1, characterized in that: In step (3), the system is cooled to 0-5°C, and the reaction is stirred in the dark at 30-45°C for 4-8h; the reaction solution is cooled to 0-5°C, and anhydrous methanol is added to quench; and the reaction solution is washed with anhydrous tetrahydrofuran for 3-5 times.

8. The permeable pavement material for sponge city according to claim 1, characterized in that: The coarse aggregate is granite waste stone with a particle size of 5-10 mm; the fine aggregate is machine-made sand with a fineness modulus of 2.2-2.7; the slag is ground and granulated blast furnace slag with a specific surface area of ​​≥410m 2 / kg, the main chemical composition content is: CaO ≥ 38.6%, SiO2 ≥ 36.9%, Al2O3 ≤ 12.3%; the filler is one or more of calcium carbonate, talcum powder, alumina, quartz powder, magnesium oxide, aluminum hydroxide, silicon micropowder, titanium dioxide, and kaolin with a particle size of 10-500μm.

9. A method for preparing a sponge city permeable pavement material according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: firstly adding silicate cement, slag, fly ash, filler and modified polypropylene fiber into a mixer and stirring for 60 to 90 seconds, then adding a water reducer and water and heating to 40 to 55° C. and continuing stirring for 60 to 90 seconds, and finally adding coarse aggregate and fine aggregate and continuing stirring for 120 to 150 seconds to obtain the permeable pavement material for sponge cities.

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