Porous concrete as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of concrete, and particularly relates to porous concrete as well as a preparation method and application thereof. The porous concrete is prepared from the following raw materials in parts by mass: 100 parts of Portland cement, 5 to 15 parts of silica fume, 140 to 160 parts of gravel, 10 to 20 parts of steel slag, 30 to 50 parts of sand, 0.8 to 1.5 parts of polycarboxylic acid water reducing agent, 8 to 15 parts of mixed resin, 0.3 to 0.8 part of water repellent, 0.9 to 1.2 parts of modified polypropylene fiber and 45 to 60 parts of water. The porous concrete disclosed by the invention is high in compressive strength, good in water permeability and strong in durability, and is particularly suitable for road engineering in high and cold, high-humidity and heavy traffic areas in China.

Description

Technical Field

[0001] This invention belongs to the field of concrete technology, specifically relating to porous concrete, its preparation method, and its application. Background Technology

[0002] In high-altitude, high-humidity, and heavy-load traffic areas of my country (such as the three northeastern provinces, eastern Inner Mongolia, and the eastern edge of the Qinghai-Tibet Plateau), road engineering has long faced the dual challenges of extreme climate and complex traffic loads. These regions generally have the following typical environmental characteristics: low average annual temperature, long and severe winters, and large diurnal temperature variations; relatively concentrated and high-intensity annual rainfall, with significant surface runoff during the rainy season; and some road sections bear the burden of a large number of heavy vehicles, resulting in heavy traffic loads and high traffic volumes. Under these harsh service conditions, the requirements for concrete materials are even higher.

[0003] Specifically, for the aforementioned application scenarios, extremely stringent comprehensive performance requirements are imposed on road concrete materials: compressive strength must reach a high level to withstand frequent heavy vehicle traffic and prevent premature fatigue failure of the structural layers; permeability should be maintained within a high range to ensure rapid drainage of surface water during heavy rainfall, reduce driving safety hazards caused by the water film effect, and alleviate urban flooding; abrasion resistance must be excellent to resist repeated tire friction and gravel impact, preventing surface aggregate detachment and pore structure damage; freeze-thaw resistance is particularly critical, requiring structural integrity and functional stability after hundreds of freeze-thaw cycles to prevent erosion, cracking, and other defects caused by water-saturated pores freezing and expanding.

[0004] However, existing permeable concrete technologies generally suffer from the contradiction of difficulty in synergistically optimizing strength, permeability, and durability: increasing porosity can enhance permeability, but often sacrifices mechanical strength and frost resistance; while increasing the amount of cementitious materials to improve strength can easily lead to pore blockage and decreased permeability.

[0005] Chinese Patent CN117700188B discloses a self-cleaning, fiber-reinforced, internally hydrophobic, anti-skid, and wear-resistant porous concrete pavement material. This material is composed of silicate cement, modified waste tire rubber powder, modified lignin, modified polyvinyl alcohol fiber, fly ash, coarse aggregate crushed stone, graded coarse quartz sand, graded fine quartz sand, aluminum powder, quicklime powder, calcium polyacrylate, sodium isopropyl naphthalene sulfonate, calcium lignin sulfonate, polyether-modified heptamethyltrisiloxane, and water. Although existing technologies have attempted to improve performance by introducing modified polymers or adding mineral admixtures, the long-term performance of existing porous concrete under conditions of extreme cold, heavy rainfall, and heavy traffic coupling remains unsatisfactory.

[0006] Comprehensive utilization of solid waste holds significant strategic importance and practical value in the resource recycling industry. By transforming waste generated from industry, agriculture, and daily life into renewable resources or high-value-added products, the pressure of increasingly scarce primary resources is effectively alleviated, and the over-exploitation of natural resources is reduced. The standardized and high-value utilization of solid waste significantly reduces the environmental pollution risks associated with landfilling and incineration, improving the quality of the ecological environment. In the steel smelting process, steel slag, as one of the main solid by-products, is produced in enormous quantities annually. If not effectively treated, it not only occupies a large amount of land resources but may also cause potential pollution to soil, water bodies, and the ecological environment.

[0007] Therefore, the objective of this invention is to develop a high-efficiency porous concrete that can effectively improve the application scenarios of steel slag. Summary of the Invention

[0008] The purpose of this invention is to provide a porous concrete, its preparation method, and its application.

[0009] To achieve the above objectives, the present invention provides the following technical solution: A porous concrete comprises the following raw materials in parts by weight: 100 parts silicate cement, 5-15 parts silica fume, 140-160 parts crushed stone, 10-20 parts steel slag, 30-50 parts sand, 0.8-1.5 parts polycarboxylate superplasticizer, 8-15 parts mixed resin, 0.3-0.8 parts water-repellent agent, 0.9-1.2 parts modified polypropylene fiber, and 45-60 parts water.

[0010] Preferably, the mixed resin includes acrylate emulsion, ethylene-vinyl acetate copolymer emulsion, and styrene-acrylic polymer emulsion.

[0011] Preferably, the mixed resin comprises an acrylate emulsion, an ethylene-vinyl acetate copolymer emulsion, and a styrene-acrylic polymer emulsion in a mass ratio of 1:(0.4-0.6):(1.3-1.5).

[0012] This invention improves the freeze-thaw resistance of porous concrete by adding a mixed resin, and further enhances compressive strength when the three emulsions are blended in a specific ratio. The analysis reveals that the mixed resin forms a composite polymer network structure within the concrete. The resulting polymer film not only tightly encapsulates cement hydration products and aggregate surfaces, effectively bridging and filling microcracks, but its elastic deformation capacity also buffers and disperses the expansion stress generated by freeze-thaw cycles, preventing crack propagation. This synergistic effect significantly improves the durability and freeze-thaw resistance of the concrete.

[0013] Preferably, the method for preparing the modified polypropylene fiber includes the following steps: (1) Polypropylene, polypropylene grafted with glycidyl methacrylate, styrene-ethylene / butene-styrene grafted with maleic anhydride, and ethylene-acrylate-maleic anhydride terpolymer were mixed evenly and then extruded and granulated by a twin-screw extruder to obtain modified masterbatch. (2) The modified masterbatch is melt-spun and then cut to obtain modified polypropylene fibers.

[0014] In the system of this invention, directly adding polypropylene fibers does not produce ideal synergistic effects with the mixed resin. The inventors, by adding modified polypropylene fibers to porous concrete, achieve a better synergistic effect with the mixed resin, improving the compressive strength and wear resistance of the porous concrete. This is because the modified polypropylene fibers interact with the active components in the mixed resin through their unique surface functional groups, forming a strong interfacial bridge; simultaneously, a synergistic reinforcement system is formed where the modified polypropylene fibers can better bear the load and the resin can better transfer stress. When the concrete is under pressure or wear, this system can effectively inhibit the initiation and propagation of microcracks and distribute stress more evenly, thereby significantly improving the compressive strength and wear resistance of the material.

[0015] Preferably, the hydrophobic agent is a silane powder hydrophobic agent.

[0016] Preferably, the crushed stone comprises limestone, granite and basalt in a mass ratio of (0.3-0.5):(0.8-1.0):(1.4-1.5).

[0017] The particle size of limestone is 9.5-16.0 mm, with an average particle size of 11.5-13.0 mm; the particle size of granite is 4.7-8.5 mm, with an average particle size of 5.5-7.0 mm; and the particle size of basalt is 1.3-4.5 mm, with an average particle size of 2.0-3.5 mm.

[0018] Preferably, all sand particles can pass through a 4.75mm sieve, with a 0.15mm sieve aperture of 2-4%; the fineness modulus is 2.3-3.0.

[0019] The method for preparing porous concrete includes the following steps: (1) Mix the crushed stone, steel slag, and sand evenly, add the modified polypropylene fiber, mix evenly, and then add the premixed cement, silica fume, and water-repellent agent. Stir evenly to obtain the mixture. (2) Mix the polycarboxylate superplasticizer and some water evenly to obtain a superplasticizer mixture. Mix the mixed resin and the remaining water evenly to obtain a resin mixture. First add the superplasticizer mixture to the mixture and stir evenly. Then add the resin mixture and stir evenly.

[0020] An application of porous concrete.

[0021] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: 1. The porous concrete of the present invention has excellent comprehensive performance, high compressive strength, high permeability, good wear resistance and high freeze-thaw resistance. These properties are superior to existing products and are more suitable for road engineering in cold, humid and heavy traffic areas in my country.

[0022] 2. This invention improves the freeze-thaw resistance of porous concrete by adding mixed resin, and can also improve compressive strength when mixed in a specific ratio.

[0023] 3. By adding modified polypropylene fibers to porous concrete, the present invention can produce a better synergistic effect with the mixed resin, thereby improving the compressive strength and wear resistance of porous concrete.

[0024] 4. This invention obtains a highly permeable material by using graded crushed stone while ensuring permeability, and also improves the wear resistance of porous concrete. Detailed Implementation

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] All raw materials used in the following embodiments of the present invention are commercially available products: Polypropylene, mineral-filled modified PP, type 30A. Guangdong Jushi Chemical Co., Ltd.

[0027] Polypropylene grafted with glycidyl methacrylate, PP-g-GMA, brand LyondellBasell, model PX2250, supplier Dongguan Suda Plastic Raw Materials Co., Ltd.

[0028] Styrene-ethylene / butene-styrene grafted maleic anhydride, SEBS-g-MAH, Kraton, USA, FG1901, FG1901.

[0029] Ethylene-acrylate-maleic anhydride terpolymer, SK Lotader 4403 (Korea), Shanghai Anping International Trade Co., Ltd.

[0030] Silyl-based powdered water-repellent agent, model: Elastane Seal81. Supplier: Nanjing Yaojie Energy Saving Technology Co., Ltd.

[0031] Acrylic emulsion, model: Dow PRIMALTR407. Supplier: Shanghai Zhenlishi Network Technology Co., Ltd.

[0032] Ethylene-vinyl acetate coemulsion, Jinan Quanchi New Materials Co., Ltd.

[0033] Styrene-acrylic polymer emulsion, Dow PRIMAL™ AS-398, supplied by Shandong Maikenm Chemical Co., Ltd.

[0034] Polycarboxylate superplasticizer, Weifang Ruiguang Chemical Co., Ltd., high-performance polycarboxylate superplasticizer.

[0035] Sand: All sand particles can pass through a 4.75mm sieve, with a 3% pass rate for 0.15mm sieve openings, and a fineness modulus of 2.5.

[0036] The particle size of steel slag is 5-10mm. According to standards such as "Technical Specification for Application of Steel Slag Mixture in Highway Engineering", the autoclaving expansion rate of steel slag is 0.26% and the metallic iron content is 0.8wt%. Example

[0037] This embodiment provides a porous concrete comprising the following raw materials in parts by weight: 100 parts ordinary Portland cement 52.5R, 10 parts silica fume, 150 parts crushed stone, 16 parts steel slag, 40 parts sand, 1.2 parts polycarboxylate superplasticizer, 12 parts mixed resin, 0.5 parts silane powder water-repellent agent, 1.0 part modified polypropylene fiber, and 57 parts water.

[0038] The method for preparing the modified polypropylene fiber includes the following steps: (1) According to the weight parts, 85 parts of polypropylene, 8 parts of polypropylene grafted with glycidyl methacrylate PP-g-GMA, 5 parts of styrene-ethylene / butene-styrene grafted with maleic anhydride SEBS-g-MAH, and 2 parts of ethylene-acrylate-maleic anhydride terpolymer were mixed evenly and then extruded and granulated through a twin-screw extruder. The temperature settings were: Zone 1: 170℃; Zone 2: 180℃; Zone 3: 185℃; Zone 4: 175℃; and the screw speed was 250 rpm to obtain the modified masterbatch. (2) The modified masterbatch was melt-spun under the following conditions: spinning temperature of 195℃ and spinning speed of 1500m / min; the drawing process was as follows: first-stage cold drawing: 25℃ and drawing ratio of 3.0; second-stage hot drawing: temperature of 105℃ and drawing ratio of 1.8; heat setting temperature of 120℃ and winding speed of 2800m / min, to obtain long fibers with a diameter of 38.6μm, which were then cut to obtain modified polypropylene fibers with a length of 6mm.

[0039] The mixed resin comprises an acrylate emulsion, an ethylene-vinyl acetate copolymer emulsion, and a styrene-acrylic polymer emulsion in a mass ratio of 1:0.5:1.4.

[0040] The crushed stone comprises limestone, granite, and basalt in a mass ratio of 0.4:1.0:1.4. The limestone has a particle size of 9.5-16.0 mm and an average particle size of 12.4 mm; the granite has a particle size of 4.7-8.5 mm and an average particle size of 6.3 mm; and the basalt has a particle size of 1.3-4.5 mm and an average particle size of 2.7 mm.

[0041] The method for preparing the porous concrete includes the following steps: (1) Mix the crushed stone, steel slag, and sand evenly, add the modified polypropylene fiber, mix evenly, and then add the premixed cement, silica fume, and water-repellent agent. Stir evenly to obtain the mixture. (2) Mix the polycarboxylate superplasticizer and 1 / 3 of the water evenly to obtain a superplasticizer mixture. Mix the resin with the remaining 2 / 3 of the water evenly to obtain a resin mixture. First add the superplasticizer mixture to the mixture and stir evenly. Then add the resin mixture and stir evenly. Example

[0042] This embodiment provides a porous concrete comprising the following raw materials in parts by weight: 100 parts ordinary Portland cement 52.5R, 8 parts silica fume, 160 parts crushed stone, 10 parts steel slag, 50 parts sand, 0.8 parts polycarboxylate superplasticizer, 15 parts mixed resin, 0.3 parts silane powder water-repellent agent, 1.2 parts modified polypropylene fiber, and 45 parts water.

[0043] The method for preparing the modified polypropylene fiber includes the following steps: (1) 85 parts by weight of polypropylene, 8 parts by weight of polypropylene grafted with glycidyl methacrylate PP-g-GMA, 5 parts by weight of styrene-ethylene / butene-styrene grafted with maleic anhydride SEBS-g-MAH, and 2 parts by weight of ethylene-acrylate-maleic anhydride terpolymer were mixed evenly and then extruded and granulated by twin-screw extruder. The temperature settings were: Zone 1: 170℃; Zone 2: 180℃; Zone 3: 185℃; Zone 4: 175℃; and the screw speed was 250 rpm to obtain modified masterbatch. (2) The modified masterbatch was melt-spun under the following conditions: spinning temperature of 195℃ and spinning speed of 1500m / min; the drawing process was as follows: first-stage cold drawing: 25℃ and drawing ratio of 3.0; second-stage hot drawing: temperature of 105℃ and drawing ratio of 1.8; heat setting temperature of 120℃ and winding speed of 2800m / min, to obtain long fibers with a diameter of 38.6μm, which were then cut to obtain modified polypropylene fibers with a length of 6mm.

[0044] The mixed resin includes an acrylate emulsion, an ethylene-vinyl acetate copolymer emulsion, and a styrene-acrylic polymer emulsion in a mass ratio of 1:0.4:1.5.

[0045] The crushed stone comprises limestone, granite, and basalt in a mass ratio of 0.3:1.0:1.4. The limestone has a particle size of 9.5-16.0 mm and an average particle size of 12.4 mm; the granite has a particle size of 4.7-8.5 mm and an average particle size of 6.3 mm; and the basalt has a particle size of 1.3-4.5 mm and an average particle size of 2.7 mm.

[0046] The method for preparing the porous concrete includes the following steps: (1) Mix the crushed stone, steel slag, and sand evenly, add the modified polypropylene fiber, mix evenly, and then add the premixed cement, silica fume, and water-repellent agent. Stir evenly to obtain the mixture. (2) Mix the polycarboxylate superplasticizer and 1 / 3 of the water evenly to obtain a superplasticizer mixture. Mix the resin with the remaining 2 / 3 of the water evenly to obtain a resin mixture. First add the superplasticizer mixture to the mixture and stir evenly. Then add the resin mixture and stir evenly.

[0047] Comparative Example 1 The difference between this comparative example and Example 1 is that the preparation method of the modified polypropylene fiber includes the following steps: (1) 85 parts by weight of polypropylene were extruded and granulated by a twin-screw extruder. The temperature settings were: Zone 1: 170℃; Zone 2: 180℃; Zone 3: 185℃; Zone 4: 175℃; and the screw speed was 250 rpm to obtain masterbatch. (2) The masterbatch was melt-spun under the following conditions: spinning temperature was 195℃ and spinning speed was 1500m / min; the drawing process was as follows: first-stage cold drawing: 25℃ and drawing ratio 3.0; second-stage hot drawing: temperature 105℃ and drawing ratio 1.8; heat setting temperature was 120℃ and winding speed was 2800m / min, resulting in long fibers with a diameter of 38.6μm, which were then cut to obtain modified polypropylene fibers with a length of 6mm.

[0048] Comparative Example 2 The difference between this comparative example and Example 1 is that the preparation method of the modified polypropylene fiber includes the following steps: (1) Mix 85 parts of polypropylene and 8 parts of polypropylene grafted with glycidyl methacrylate PP-g-GMA according to the weight parts, and then extrude and granulate them through a twin-screw extruder. The temperature settings are: Zone 1: 170℃; Zone 2: 180℃; Zone 3: 185℃; Zone 4: 175℃; and the screw speed is 250 rpm to obtain the modified masterbatch. (2) The modified masterbatch was melt-spun under the following conditions: spinning temperature of 195℃ and spinning speed of 1500m / min; the drawing process was as follows: first-stage cold drawing: 25℃ and drawing ratio of 3.0; second-stage hot drawing: temperature of 105℃ and drawing ratio of 1.8; heat setting temperature of 120℃ and winding speed of 2800m / min, to obtain long fibers with a diameter of 38.6μm, which were then cut to obtain modified polypropylene fibers with a length of 6mm.

[0049] Comparative Example 3 The difference between this comparative example and Example 1 is that the preparation method of the modified polypropylene fiber includes the following steps: (1) Mix 85 parts of polypropylene, 8 parts of polypropylene grafted with glycidyl methacrylate PP-g-GMA, and 5 parts of styrene-ethylene / butene-styrene grafted with maleic anhydride SEBS-g-MAH according to the following weight parts, and then extrude and granulate the mixture through a twin-screw extruder. The temperature settings are: Zone 1: 170℃; Zone 2: 180℃; Zone 3: 185℃; Zone 4: 175℃; and the screw speed is 250 rpm to obtain the modified masterbatch. (2) The modified masterbatch was melt-spun under the following conditions: spinning temperature of 195℃ and spinning speed of 1500m / min; the drawing process was as follows: first-stage cold drawing: 25℃ and drawing ratio of 3.0; second-stage hot drawing: temperature of 105℃ and drawing ratio of 1.8; heat setting temperature of 120℃ and winding speed of 2800m / min, to obtain long fibers with a diameter of 38.6μm, which were then cut to obtain modified polypropylene fibers with a length of 6mm.

[0050] Comparative Example 4 The difference between this comparative example and Example 1 is that the mixed resin includes an acrylate emulsion, an ethylene-vinyl acetate copolymer emulsion, and a styrene-acrylic polymer emulsion in a mass ratio of 0.5:1.4:1.0.

[0051] Comparative Example 5 The difference between this comparative example and Example 1 is that the mixed resin includes an acrylate emulsion and a styrene-acrylic polymer emulsion in a mass ratio of 1:1.4.

[0052] Comparative Example 6 The difference between this comparative example and Example 1 is that the crushed stone is granite, the particle size of the granite is 4-10 mm, and the average particle size is 7.5 mm.

[0053] Comparative Example 7 The difference between this comparative example and Example 1 is that the product in Example 1 is from Chinese Patent CN117700188B, a self-cleaning fiber-reinforced internal hydrophobic anti-skid wear-resistant porous concrete pavement material.

[0054] Performance testing 1. Compressive strength: The compressive strength of concrete after 28 days was tested according to GB / T50081-2002; 2. Permeability coefficient: Tested according to CJJ / T135-2009; 3. Abrasion resistance: The wear amount after 28 days is tested according to T0567-2005 in JTGE30-2020; 4. Freeze-thaw resistance: Refer to GB / T50082-2024 to test the number of freeze-thaw cycles of porous concrete pavement materials, and count the maximum number of freeze-thaw cycles when cracks appear.

[0055] The results are shown in Table 1.

[0056] Table 1 Performance Test Results compressive strength (MPa) Permeability coefficient (mm / s) <![CDATA[Wear resistance kg / m 2 > Freeze-thaw resistance Example 1 52.3 8.5 0.31 223 Example 2 50.8 8.4 0.32 220 Comparative Example 1 41.9 6.8 0.55 179 Comparative Example 2 44.5 8.0 0.46 190 Comparative Example 3 46.7 8.1 0.37 201 Comparative Example 4 44.2 8.3 0.36 189 Comparative Example 5 43.1 8.2 0.38 184 Comparative Example 6 41.2 8.8 0.73 176 Comparative Example 7 43.4 8.0 0.39 185 As shown in Table 1, the porous concrete of Examples 1-2 has excellent comprehensive performance, high compressive strength, high permeability, good wear resistance, and high freeze-thaw resistance. These properties are superior to existing technology products, making it more suitable for road engineering in cold, humid, and heavy traffic areas in my country.

[0057] In Comparative Example 1, the polypropylene fibers without any modifiers have weak adhesion to the cement matrix, making it difficult to effectively transfer loads. This leads to easy failure at the fiber-matrix interface when the concrete is under stress, thus significantly reducing its compressive strength. Poor adhesion between the polypropylene fibers and the matrix means that the fibers are easily pulled out or cut during wear, making them unable to effectively resist abrasion. The stress generated by freeze-thaw cycles will preferentially initiate and propagate microcracks from this point, accelerating the erosion and damage of the concrete.

[0058] In Comparative Example 2, PP-g-GMA improved the chemical bond between the fiber and the inorganic cement matrix, but lacked the flexibility provided by SEBS-g-MAH, resulting in a reduced fiber toughening effect and lower overall strength compared to Example 1. The absence of SEBS-g-MAH led to insufficient fiber toughness, weakening its ability to absorb and disperse energy under repeated friction and impact, and reducing its wear resistance. Simultaneously, the modified polypropylene fiber-matrix interface exhibited high rigidity but insufficient toughness, which was detrimental to buffering the expansion stress generated by freeze-thaw cycles.

[0059] In Comparative Example 3, the lack of ethylene-acrylate-maleic anhydride terpolymer as a linker weakens the synergistic effect between PP-g-GMA and SEBS-g-MAH, resulting in insufficient overall fiber performance and interfacial bonding with the matrix, weakened compressive strength, and reduced abrasion resistance due to the lack of a bridging agent in the stress transfer efficiency between components. The modified polypropylene fiber prepared by this method has poor interfacial stability and its performance is weakened under long-term freeze-thaw conditions.

[0060] In Comparative Example 4, the reduced proportion of acrylate emulsion and increased proportion of EVA led to a decrease in the rigidity and an increase in the flexibility of the polymer film formed by the resin system, weakening the bond strength to the aggregate and reducing the compressive strength. The change in the mixed resin ratio affected the balance between the hardness and toughness of the polymer film, resulting in a decrease in its resistance to wear; the weakened synergistic effect of the components reduced the overall resistance of the concrete to freeze-thaw damage.

[0061] In Comparative Example 5, removing EVA from the mixed resin resulted in an EVA emulsion that provides excellent flexibility and adhesion. Its absence made the resin system too rigid and lacking in toughness, affecting stress distribution and leading to reduced strength. The absence of EVA also weakened the resin system's ability to adapt to temperature deformation and resist freeze-thaw stress.

[0062] The use of a single granite aggregate in Comparative Example 6 resulted in a decrease in compressive strength, because the mixed gradation of crushed stone in Example 1 formed a good aggregate skeleton, which can improve the mechanical strength of concrete.

[0063] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A porous concrete, characterized in that, The raw materials include the following parts by weight: 100 parts silicate cement, 5-15 parts silica fume, 140-160 parts crushed stone, 10-20 parts steel slag, 30-50 parts sand, 0.8-1.5 parts polycarboxylate superplasticizer, 8-15 parts mixed resin, 0.3-0.8 parts water repellent, 0.9-1.2 parts modified polypropylene fiber, and 45-60 parts water.

2. The porous concrete according to claim 1, characterized in that, The mixed resins include acrylate emulsions, ethylene-vinyl acetate copolymer emulsions, and styrene-acrylic polymer emulsions.

3. The porous concrete according to claim 2, characterized in that, The mixed resin includes an acrylate emulsion, an ethylene-vinyl acetate copolymer emulsion, and a styrene-acrylic polymer emulsion in a mass ratio of 1:(0.4-0.6):(1.3-1.5).

4. The porous concrete according to claim 1, characterized in that, The method for preparing the modified polypropylene fiber includes the following steps: (1) Polypropylene, polypropylene grafted with glycidyl methacrylate, styrene-ethylene / butene-styrene grafted with maleic anhydride, and ethylene-acrylate-maleic anhydride terpolymer were mixed evenly and then extruded and granulated by a twin-screw extruder to obtain modified masterbatch. (2) The modified masterbatch is melt-spun and then cut to obtain modified polypropylene fibers.

5. The porous concrete according to claim 1, characterized in that, The hydrophobic agent is a silane powder hydrophobic agent.

6. The porous concrete according to claim 1, characterized in that, The crushed stone comprises limestone, granite and basalt in a mass ratio of (0.3-0.5):(0.8-1.0):(1.4-1.5).

7. The porous concrete according to claim 6, characterized in that, The particle size of limestone is 9.5-16.0 mm, with an average particle size of 11.5-13.0 mm; the particle size of granite is 4.7-8.5 mm, with an average particle size of 5.5-7.0 mm; and the particle size of basalt is 1.3-4.5 mm, with an average particle size of 2.0-3.5 mm.

8. The porous concrete according to claim 1, characterized in that, All sand particles can pass through a 4.75mm sieve, with a 0.15mm sieve aperture of 2-4%; the fineness modulus is 2.3-3.

0.

9. A method for preparing porous concrete according to any one of claims 1-8, characterized in that, Includes the following steps: (1) Mix the crushed stone, steel slag, and sand evenly, add the modified polypropylene fiber, mix evenly, and then add the premixed cement, silica fume, and water-repellent agent. Stir evenly to obtain the mixture. (2) Mix the polycarboxylate superplasticizer and some water evenly to obtain a superplasticizer mixture. Mix the mixed resin and the remaining water evenly to obtain a resin mixture. First add the superplasticizer mixture to the mixture and stir evenly. Then add the resin mixture and stir evenly.

10. The application of porous concrete according to any one of claims 1-8 in road engineering in areas with high cold, high humidity and heavy traffic.