A high-permeability concrete admixture and permeable concrete

Abstract

The present invention relates to the technical field of building materials, and discloses a high-permeability concrete admixture and permeable concrete. The permeable concrete admixture of the present invention comprises the following raw materials in parts by weight: 25-35 parts of acrylic resin, 5-10 parts of modified polypropylene fiber, 15-25 parts of water reducer, 7-10 parts of kaolin, and 15-25 parts of reinforcing filler; it uses acrylic resin as the adhesive structure and adds functional additives to improve the compressive performance, impermeability performance and water permeability performance of the permeable concrete; among them, the introduction of the reinforcing filler improves the compressive strength and impermeability performance of the matrix, and the modified polypropylene fiber can cooperate with the reinforcing filler to improve the water permeability, compressive property and impermeability of the matrix, thereby improving the service life of the permeable concrete.

Description

Technical Field

[0001] The present invention relates to the technical field of building materials, and particularly relates to a high-permeability concrete admixture and permeable concrete. Background Art

[0002] Permeable concrete is an important part of sponge city construction, aiming to improve urban water resource management, environmental quality and urban sustainability. Concrete itself has relatively large pores, allowing water to enter from the upper surface and flow out from the lower surface. Laying permeable concrete pavements in cities has the following advantages: it can effectively replenish groundwater, alleviate flood disasters, provide a good travel environment and mitigate the heat island effect. However, permeable concrete hardens quickly during construction, with poor fluidity, low flexural strength, poor toughness, low water permeability and poor impermeability. Coupled with the effects of rain erosion and manhole constraints during later use, stress concentration occurs inside the permeable concrete, and the pores penetrate and expand with each other, ultimately reducing the service life.

[0003] Among these problems, the poor toughness of permeable concrete itself is the most prominent. On the premise of ensuring excellent permeability of permeable concrete, it is very necessary to conduct research on improving the strength and toughness of permeable concrete. Therefore, the method of adding admixtures can be adopted to improve the compressive strength, water permeability coefficient, impermeability, frost resistance and other properties of permeable concrete, ultimately increasing the service life of permeable concrete. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a high-permeability concrete admixture and permeable concrete.

[0005] The object of the present invention can be achieved by the following technical solutions:

[0006] A high-permeability concrete admixture, comprising the following raw materials in parts by weight: 25 - 35 parts of acrylic resin, 5 - 10 parts of modified polypropylene fiber, 15 - 25 parts of water reducer, 7 - 10 parts of kaolin, 15 - 25 parts of reinforcing filler;

[0007] The water reducer is composed of tris(1-methylethyl)naphthalenesulfonic acid sodium and 2,6-di-tert-butylnaphthalenesulfonic acid sodium mixed in a mass ratio of 1:1 - 3;

[0008] The reinforcing filler is prepared by the following steps:

[0009] Step A1: Disperse vinyltrimethoxysilane in an ethanol solution (the volume ratio of ethanol to deionized water is 9:1), adjust the pH to 8 - 9, add halloysite nanotubes and ultrasonicate for 10 - 20 min, stir and react for 2 - 3 h, then centrifuge, wash and dry to obtain surface-treated halloysite;

[0010] Step A2: Mix the surface-treated halloysite, isopropyl alcohol solution of chloroplatinic acid, and toluene evenly, displace with nitrogen three times, slowly add hydrogen-containing silicone oil under nitrogen conditions, and heat up to 80 - 90 °C for reaction for 1.5 - 2.5 h, then perform vacuum distillation, washing, and drying to obtain the reinforcing filler;

[0011] Further, in step A1, the dosage ratio of vinyltrimethoxysilane, ethanol solution, and halloysite nanotubes is 0.4 - 1 g : 20 mL : 1 - 3 g;

[0012] Further, in step A2, the dosage ratio of surface-treated halloysite, isopropyl alcohol solution of chloroplatinic acid, toluene, and hydrogen-containing silicone oil is 1 - 3 g : 5 - 10 g : 50 mL : 0.5 - 2 g, and the mass ratio of chloroplatinic acid to isopropyl alcohol in the isopropyl alcohol solution of chloroplatinic acid is 0.05 - 0.1 : 100.

[0013] The modified polypropylene fiber is prepared by the following steps:

[0014] Step B1: Disperse morpholineethanesulfonic acid-hydrate in deionized water, adjust the pH to 6, then add 0.3 mol / L sodium chloride solution and mix evenly, denoted as the buffer solution; Disperse sodium alginate in the buffer solution, sequentially add EDC (1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride) and NHS (N-hydroxysuccinimide), stir for 15 min, then add allylamine hydrochloride (AH) and react for 12 - 24 h, then add ethanol and stir, filter, dry, and then redisperse the product in deionized water at a concentration of 1% (w / v), dialyze for 2 days, and freeze-dry to obtain AH-sodium alginate;

[0015] Step B2: Disperse trimethylolpropane triglycidyl ether and tetrabutylammonium bromide in N,N-dimethylformamide, then add AH-sodium alginate, react under nitrogen at 80 - 90 °C for 1 - 2 h, add tetrahydrofuran and stir for 15 min, filter, wash, and dry to obtain the modified sodium alginate;

[0016] Step B3: Mix polypropylene and polyvinylpyrrolidone evenly, then extrude, pelletize, and dry through a twin-screw extruder, perform melt spinning, collect the polypropylene fiber, wash the polypropylene fiber with ethanol at a bath ratio of 1 : 10, and then wash with water at 60 - 80 °C for 1 - 2 h, and dry to obtain the pretreated polypropylene fiber;

[0017] Step B4: Stir and mix acetone, modified sodium alginate, and benzophenone, add the pretreated polypropylene fiber and impregnate for 8 - 14 h, then irradiate with ultraviolet light at 320 nm for 2 - 3 h, collect the product, wash, and dry to obtain the modified polypropylene fiber;

[0018] Further, the dosage ratio of sodium alginate, buffer solution, EDC, NHS, allylamine hydrochloride and ethanol in step B1 is 1 g: 100 mL: 0.02 mol: 0.01 mol: 0.005 - 0.02 mol: 200 mL;

[0019] Further, the dosage ratio of morpholineethanesulfonic acid-hydrate, deionized water and sodium chloride solution in the buffer solution in step B1 is 0.01 mol: 90 mL: 10 mL;

[0020] Further, the dosage ratio of trimethylolpropane triglycidyl ether, tetrabutylammonium bromide, N,N-dimethylformamide, AH-sodium alginate and tetrahydrofuran in step B2 is 0.01 - 0.02 mol: 0.0005 - 0.0015 mol: 100 mL: 1 - 3 g: 100 mL;

[0021] Further, the molar ratio of polypropylene and polyvinylpyrrolidone in step B3 is 5 - 10: 0.5 - 2;

[0022] Further, the mass ratio of acetone, modified sodium alginate, benzophenone and pretreated polypropylene fibers in step B4 is 50: 2 - 5: 0.5 - 2: 5 - 12.

[0023] In a second aspect, the present invention also provides a permeable concrete made from the above-mentioned high-permeability concrete admixture, which is prepared from the following raw materials in parts by weight: 30 - 60 parts of cement, 80 - 120 parts of stones, 8 - 16 parts of high-permeability concrete admixture, and 15 - 25 parts of water;

[0024] Further, the cement is P.O42.5 ordinary Portland cement.

[0025] Advantages of the present invention:

[0026] The permeable concrete admixture of the present invention uses acrylic resin as the adhesive structure and adds functional additives to improve the compressive performance, impermeability performance and water permeability performance of the permeable concrete; among them, the introduction of the reinforcing filler improves the compressive strength and impermeability performance of the matrix, and the modified polypropylene fiber can cooperate with the reinforcing filler to improve the water permeability, compressive property and impermeability of the matrix, thereby improving the service life of the permeable concrete.

[0027] In the reinforcing filler, the halloysite nanotubes are first modified with a coupling agent so that the surface contains a double bond structure, and then the double bond structure on the surface is used to react with the active hydrogen in the hydrogen-containing silicone oil to obtain the reinforcing filler. The introduction of reinforcing fillers can significantly improve the compressive strength and impermeability of permeable concrete. This is because the halloysite nanotubes have excellent mechanical properties and can work together with modified polypropylene fibers to coordinate the deformation of the matrix, thereby enhancing the toughness of the concrete and inhibiting the expansion of cracks. The network structure formed by the two in the cement base makes the concrete have a crack-resistant effect; at the same time, the presence of silicone oil also improves the impermeability of the matrix. This is because the hydrophobic silicone oil forms a hydrophobic film on the surface of the bonding layer that wraps the stone, allowing water to quickly pass through the pores without penetrating into the concrete, improving the impermeability of the concrete and thus increasing its service life.

[0028] In the modified polypropylene fiber, the amino group in allylamine is firstly reacted with sodium alginate activated by EDC and NHS to obtain AH-sodium alginate containing a double bond structure; then the epoxy group in trimethylolpropane triglycidyl ether is reacted with the hydroxyl group in AH-sodium alginate to obtain modified sodium alginate containing double bonds and epoxy structures; then a water-soluble polymer is mixed with polypropylene and spun to obtain polypropylene fiber, which is then washed with high temperature water to obtain pre-treated polypropylene fiber; finally, the modified sodium alginate is grafted onto the pre-treated polypropylene fiber by ultraviolet irradiation to obtain modified polypropylene fiber. The introduction of modified polypropylene fiber can improve the crack resistance, impermeability and water permeability of permeable concrete; among them, the water-soluble polymer in the pre-treated polypropylene fiber is dissolved by high-temperature water washing, so that the fiber forms a porous structure, changes the smooth surface characteristics of the fiber, and makes the fiber surface rough. The bonding effect between the rough surface and the cement base can increase the toughness of the concrete, improve the crack resistance and impermeability of the concrete, and at the same time, the porous structure can also improve the water permeability of the concrete; the epoxy group contained can undergo cross-linking, curing and filling with cement hydrates, thereby improving the stability and compressive resistance of the permeable concrete structure; in addition, the large number of hydrophilic groups contained in sodium alginate, such as carboxyl and hydroxyl, have certain water absorption properties, which improves the water permeability of the concrete. At the same time, the adhesion of sodium alginate enhances the friction between the internal particles of the concrete, thereby improving the strength of the concrete, and further enhancing the durability and service life of the permeable concrete. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. 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.

[0030] Example 1

[0031] The reinforcing filler is prepared by the following steps:

[0032] Step A1: Disperse 0.4 g of vinyltrimethoxysilane in 20 mL of an ethanol solution (volume ratio of ethanol to deionized water is 9:1), adjust the pH to 8, add 1 g of halloysite nanotubes, ultrasonicate for 10 min, stir and react for 2 h, then centrifuge, wash, and dry to obtain surface-treated halloysite;

[0033] Step A2: Mix 1 g of the surface-treated halloysite, 5 g of chloroplatinic acid isopropanol solution, and 50 mL of toluene evenly, displace with nitrogen three times, slowly add 0.5 g of hydrogen-containing silicone oil under nitrogen conditions, and raise the temperature to 80 °C for reaction for 1.5 h, then perform vacuum distillation, wash, and dry to obtain the reinforcing filler. The mass ratio of chloroplatinic acid to isopropanol in the chloroplatinic acid isopropanol solution is 0.05:100.

[0034] The modified polypropylene fiber is prepared by the following steps:

[0035] Step B1: Disperse 0.01 mol of morpholineethanesulfonic acid hydrate in 90 mL of deionized water, adjust the pH to 6, then add 10 mL of 0.3 mol / L sodium chloride solution and mix evenly, denoted as the buffer solution; Disperse 1 g of sodium alginate in 100 mL of the buffer solution, successively add 0.02 mol of EDC and 0.01 mol of NHS, stir for 15 min, then add 0.005 mol of allylamine hydrochloride (AH) and react for 12 h, then add 200 mL of ethanol and stir, filter, and dry. Then redisperse the product in deionized water at a concentration of 1% (w / v), dialyze for 2 days, and freeze-dry to obtain AH-sodium alginate;

[0036] Step B2: Disperse 0.01 mol of trimethylolpropane triglycidyl ether and 0.0005 mol of tetrabutylammonium bromide in 100 mL of N,N-dimethylformamide, then add 1 g of AH-sodium alginate, react at 80 °C under nitrogen for 1 h, add 100 mL of tetrahydrofuran and stir for 15 min, filter, wash, and dry to obtain modified sodium alginate;

[0037] Step B3: Mix 5 mol of polypropylene and 0.5 mol of polyvinylpyrrolidone evenly, then extrude, granulate, and dry through a twin-screw extruder, perform melt spinning, collect the polypropylene fiber, wash the polypropylene fiber with ethanol at a bath ratio of 1:10, and then wash with water at 60 °C for 1 h, and dry to obtain the pretreated polypropylene fiber;

[0038] Step B4: Stir and mix 50 g of acetone, 2 g of modified sodium alginate, and 0.5 g of benzophenone. Add 5 g of pretreated polypropylene fibers and impregnate for 8 h. Then irradiate under ultraviolet light at 320 nm for 2 h. Collect the product, wash it, and dry it to obtain modified polypropylene fibers.

[0039] Example 2

[0040] The reinforcing filler is prepared by the following steps:

[0041] Step A1: Disperse 0.7 g of vinyltrimethoxysilane in 20 mL of an ethanol solution (the volume ratio of ethanol to deionized water is 9:1), adjust the pH to 8.5, add 2 g of halloysite nanotubes, and ultrasonicate for 15 min. Stir and react for 2.5 h, then centrifuge, wash, and dry to obtain surface-treated halloysite.

[0042] Step A2: Mix 2 g of surface-treated halloysite, 7 g of chloroplatinic acid isopropanol solution, and 50 mL of toluene evenly. Displace with nitrogen three times, slowly add 1 g of hydrogen-containing silicone oil under nitrogen conditions, and raise the temperature to 85 °C to react for 2 h. Carry out vacuum distillation, wash, and dry to obtain the reinforcing filler. The mass ratio of chloroplatinic acid to isopropanol in the chloroplatinic acid isopropanol solution is 0.07:100.

[0043] The modified polypropylene fibers are prepared by the following steps:

[0044] Step B1: Disperse 0.01 mol of morpholineethanesulfonic acid monohydrate in 90 mL of deionized water, adjust the pH to 6, then add 10 mL of 0.3 mol / L sodium chloride solution and mix evenly, denoted as the buffer solution. Disperse 1 g of sodium alginate in 100 mL of the buffer solution, sequentially add 0.02 mol of EDC and 0.01 mol of NHS, stir for 15 min, then add 0.01 mol of allylamine hydrochloride (AH) and react for 18 h. Then add 200 mL of ethanol and stir, filter by suction, and dry. Then redisperse the product in deionized water at a concentration of 1% (w / v) and dialyze for 2 days, followed by freeze-drying to obtain AH-sodium alginate.

[0045] Step B2: Disperse 0.015 mol of trimethylolpropane triglycidyl ether and 0.001 mol of tetrabutylammonium bromide in 100 mL of N,N-dimethylformamide, then add 2 g of AH-sodium alginate, and react at 85 °C under nitrogen for 1.5 h. Add 100 mL of tetrahydrofuran and stir for 15 min, filter by suction, wash, and dry to obtain modified sodium alginate.

[0046] Step B3: Mix 7 mol of polypropylene and 1 mol of polyvinylpyrrolidone evenly, then extrude, pelletize, and dry through a twin-screw extruder, perform melt spinning, collect the polypropylene fibers, wash the polypropylene fibers with ethanol at a bath ratio of 1:10, then wash with water at 70 °C for 1.5 h, and dry to obtain the pretreated polypropylene fibers;

[0047] Step B4: Stir and mix 50 g of acetone, 3.5 g of modified sodium alginate, and 1 g of benzophenone, add 9 g of the pretreated polypropylene fibers and impregnate for 11 h, then irradiate under ultraviolet light at 320 nm for 2.5 h, collect the product, wash, and dry to obtain the modified polypropylene fibers.

[0048] Example 3

[0049] The reinforcing filler is prepared by the following steps:

[0050] Step A1: Disperse 1 g of vinyltrimethoxysilane in 20 mL of an ethanol solution (the volume ratio of ethanol to deionized water is 9:1), adjust the pH to 9, add 3 g of halloysite nanotubes and ultrasonicate for 20 min, stir and react for 3 h, centrifuge, wash, and dry to obtain surface-treated halloysite;

[0051] Step A2: Mix 3 g of the surface-treated halloysite, 10 g of chloroplatinic acid isopropanol solution, and 50 mL of toluene evenly, displace with nitrogen three times, slowly add 2 g of hydrogen-containing silicone oil under nitrogen conditions, and heat up to 90 °C to react for 2.5 h, perform vacuum distillation, wash, and dry to obtain the reinforcing filler. The mass ratio of chloroplatinic acid to isopropanol in the chloroplatinic acid isopropanol solution is 0.1:100.

[0052] The modified polypropylene fibers are prepared by the following steps:

[0053] Step B1: Disperse 0.01 mol of morpholineethanesulfonic acid hydrate in 90 mL of deionized water, adjust the pH to 6, then add 10 mL of 0.3 mol / L sodium chloride solution and mix evenly, denoted as the buffer solution; disperse 1 g of sodium alginate in 100 mL of the buffer solution, sequentially add 0.02 mol of EDC and 0.01 mol of NHS and stir for 15 min, then add 0.02 mol of allylamine hydrochloride (AH) and react for 24 h, then add 200 mL of ethanol and stir, filter by suction and dry, and then redisperse the product in deionized water at a concentration of 1% (w / v), dialyze for 2 days, and freeze-dry to obtain AH-sodium alginate;

[0054] Step B2: Disperse 0.02 mol of trimethylolpropane triglycidyl ether and 0.0015 mol of tetrabutylammonium bromide in 100 mL of N,N-dimethylformamide, then add 3 g of AH-sodium alginate, react under nitrogen at 90 °C for 2 h, add 100 mL of tetrahydrofuran and stir for 15 min, filter, wash, and dry to obtain modified sodium alginate;

[0055] Step B3: Mix 10 mol of polypropylene and 2 mol of polyvinylpyrrolidone evenly, then extrude, pelletize, and dry through a twin-screw extruder, perform melt spinning, collect polypropylene fibers, wash the polypropylene fibers with ethanol at a bath ratio of 1:10, and then wash with water at 80 °C for 2 h, and dry to obtain pretreated polypropylene fibers;

[0056] Step B4: Stir and mix 50 g of acetone, 5 g of modified sodium alginate, and 2 g of benzophenone, add 12 g of pretreated polypropylene fibers and impregnate for 14 h, then irradiate under ultraviolet light at 320 nm for 3 h, collect the product, wash, and dry to obtain modified polypropylene fibers.

[0057] Example 4

[0058] The preparation of a highly permeable concrete admixture includes the following steps:

[0059] Step S1: First, mix sodium tris(1-methylethyl)naphthalenesulfonate and 2,6-di-tert-butylnaphthalenesulfonate in a mass ratio of 1:1 to prepare a water-reducing agent;

[0060] Step S2: Then, weigh the raw materials by weight parts, mix 25 parts of acrylic resin, 5 parts of the modified polypropylene fibers prepared in Example 1, 15 parts of the water-reducing agent, 7 parts of kaolin, and 15 parts of the reinforcing filler prepared in Example 1 evenly by stirring to obtain a highly permeable concrete admixture.

[0061] The preparation of a permeable concrete: Weigh the raw materials by weight parts, add 30 parts of P.O42.5 ordinary Portland cement, 80 parts of gravel, 8 parts of the highly permeable concrete admixture prepared by the above method, and 15 parts of water into a mixer and stir and mix evenly to obtain it.

[0062] Example 5

[0063] The preparation of a highly permeable concrete admixture includes the following steps:

[0064] Step S1: First, mix sodium tris(1-methylethyl)naphthalenesulfonate and 2,6-di-tert-butylnaphthalenesulfonate in a mass ratio of 1:2 to prepare a water-reducing agent;

[0065] Step S2: Weigh the raw materials by parts by weight. Mix 30 parts of acrylic resin, 8 parts of the modified polypropylene fiber prepared in Example 2, 20 parts of water reducer, 8 parts of kaolin, and 20 parts of the reinforcing filler prepared in Example 2 evenly by stirring to obtain the high-permeability concrete admixture.

[0066] Preparation of permeable concrete: Weigh the raw materials by parts by weight. Add 50 parts of P.O42.5 ordinary Portland cement, 100 parts of stones, 12 parts of the high-permeability concrete admixture prepared by the above method, and 20 parts of water into a mixer and stir and mix evenly to obtain the permeable concrete.

[0067] Example 6

[0068] Preparation of a high-permeability concrete admixture includes the following steps:

[0069] Step S1: First, mix sodium tris(1-methylethyl)naphthalenesulfonate and sodium 2,6-di-tert-butylnaphthalenesulfonate in a mass ratio of 1:3 to prepare a water reducer;

[0070] Step S2: Then, weigh the raw materials by parts by weight. Mix 35 parts of acrylic resin, 10 parts of the modified polypropylene fiber prepared in Example 3, 25 parts of water reducer, 10 parts of kaolin, and 25 parts of the reinforcing filler prepared in Example 3 evenly by stirring to obtain the high-permeability concrete admixture.

[0071] Preparation of permeable concrete: Weigh the raw materials by parts by weight. Add 60 parts of P.O42.5 ordinary Portland cement, 120 parts of stones, 16 parts of the high-permeability concrete admixture prepared by the above method, and 25 parts of water into a mixer and stir and mix evenly to obtain the permeable concrete.

[0072] Comparative Example 1

[0073] This comparative example provides a high-permeability concrete admixture and permeable concrete. The difference from Example 6 is that halloysite nanotubes are used instead of the reinforcing filler prepared in Example 3, and the rest are the same.

[0074] Comparative Example 2

[0075] This comparative example provides a high-permeability concrete admixture and permeable concrete. The difference from Example 6 is that polypropylene fiber is used instead of the modified polypropylene fiber prepared in Example 3, and the rest are the same.

[0076] Perform performance tests on the permeable concrete prepared in Examples 4 - 6 and Comparative Examples 1 - 2: After mixing the raw material components evenly, make several permeable concrete brick specimens with dimensions of 20 cm × 20 cm × 5 cm. After natural curing for 28 days, test the performance;

[0077] Permeability coefficient: The permeability coefficient was tested with reference to the test method for permeability coefficient disclosed in Appendix C of GB / T 25993-2010 "Permeable Pavement Bricks and Pavement Panels", and the permeability coefficients of different specimens at a water temperature of 15 °C were calculated;

[0078] Compressive strength: The 28-day compressive strength (MPa) of the permeable concrete was detected in accordance with GB / T 50081-2002 "Standard Test Method for Mechanical Properties of Ordinary Concrete";

[0079] Frost resistance: The frost resistance test was carried out with reference to the frost resistance test disclosed in GB / T 4111-2013 "Test Methods for Concrete Blocks and Bricks";

[0080] The test results are shown in the following table:

[0081]

[0082] As can be seen from the above table, the permeability coefficient of the high-permeability concrete admixture prepared by the present invention and the permeable concrete prepared with this admixture is in the range of 5.5 mm / s - 6.0 mm / s, the 28-day compressive strength is in the range of 48.2 MPa - 52.1 MPa, and the average compressive strength loss rate is in the range of 0.93% - 1.16%. This indicates that the permeable concrete has the advantages of high permeability, excellent compressive performance, excellent frost resistance, good impermeability performance, and long service life, and has wide applications.

[0083] The above content is only an example and illustration of the concept of the present invention. Those skilled in the art of this technology can make various modifications or supplements to the described specific embodiments or use similar methods for substitution, as long as they do not deviate from the scope defined by the concept of the invention, they shall fall within the protection scope of the present invention.

Claims

1. A highly permeable concrete admixture, characterized in that: The invention comprises the following raw materials in parts by weight: 25-35 parts of acrylic resin, 5-10 parts of modified polypropylene fiber, 15-25 parts of water reducing agent, 7-10 parts of kaolin, and 15-25 parts of reinforcing filler; The water reducing agent is prepared by mixing sodium tri(1-methylethyl)naphthalenesulfonate and sodium 2,6-di-tert-butylnaphthalenesulfonate in a mass ratio of 1:1-3; The reinforcing filler is prepared by the following steps: Step A1, dispersing vinyltrimethoxysilane in an ethanol solution, adjusting the pH to 8-9, adding halloysite nanotubes, ultrasonicating for 10-20 minutes, stirring for reaction for 2-3 hours, centrifuging, washing, and drying to obtain surface-treated halloysite; Step A2, mixing the surface treated halloysite, chloroplatinic acid isopropanol solution and toluene evenly, replacing with nitrogen three times, slowly adding hydrogen-containing silicone oil under nitrogen, heating to 80-90° C. for reaction for 1.5-2.5 h, distilling under reduced pressure, washing and drying to obtain a reinforcing filler; The modified polypropylene fiber is prepared by the following steps: Step B1, dispersing morpholineethanesulfonic acid monohydrate in deionized water, adjusting the pH to 6, and then adding 0.3 mol / L sodium chloride solution to mix evenly, recorded as buffer; dispersing sodium alginate in the buffer, adding EDC and NHS in sequence and stirring for 15 minutes, then adding allylamine hydrochloride to react for 12-24 hours, then adding ethanol and stirring, filtering and drying, and then re-dispersing the product in deionized water at a concentration of 1 w / v%, dialyzing for 2 days, and freeze-drying to obtain AH-sodium alginate; Step B2, dispersing trimethylolpropane triglycidyl ether and tetrabutylammonium bromide in N,N-dimethylformamide, adding AH-sodium alginate, reacting for 1-2h under nitrogen and 80-90°C, adding tetrahydrofuran and stirring for 15min, filtering, washing and drying to obtain modified sodium alginate; Step B3, the polypropylene and polyvinyl pyrrolidone are uniformly mixed, and then extruded through a twin-screw extruder, granulated, dried, melt-spun, and polypropylene fibers are collected. The polypropylene fibers are washed with anhydrous ethanol at a bath ratio of 1:10, and then washed with water at 60-80° C. for 1-2 hours and dried to obtain pre-treated polypropylene fibers; Step B4, stir and mix acetone, modified sodium alginate and benzophenone, add pretreated polypropylene fiber and soak for 8-14 hours, then irradiate under 320nm ultraviolet light for 2-3 hours, collect the product, wash and dry to obtain modified polypropylene fiber.

2. A highly permeable concrete admixture according to claim 1, characterized in that: In step A1, the usage ratio of vinyltrimethoxysilane, ethanol solution and halloysite nanotubes is 0.4-1 g: 20 mL: 1-3 g.

3. A highly permeable concrete admixture according to claim 1, characterized in that: In step A2, the usage ratio of surface-treated halloysite, chloroplatinic acid isopropanol solution, toluene and hydrogen-containing silicone oil is 1-3 g: 5-10 g: 50 mL: 0.5-2 g, and the mass ratio of chloroplatinic acid and isopropanol in the chloroplatinic acid isopropanol solution is 0.05-0.1:

100.

4. A highly permeable concrete admixture according to claim 1, characterized in that: In step B1, the dosage ratio of sodium alginate, buffer solution, EDC, NHS, allylamine hydrochloride and ethanol is 1 g: 100 mL: 0.02 mol: 0.01 mol: 0.005-0.02 mol: 200 mL, and the dosage ratio of morpholineethanesulfonic acid monohydrate, deionized water and sodium chloride solution in the buffer solution is 0.01 mol: 90 mL: 10 mL.

5. A highly permeable concrete admixture according to claim 1, characterized in that: In step B2, the dosage ratio of trimethylolpropane triglycidyl ether, tetrabutylammonium bromide, N,N-dimethylformamide, AH-sodium alginate and tetrahydrofuran is 0.01-0.02 mol: 0.0005-0.0015 mol: 100 mL: 1-3 g: 100 mL.

6. A highly permeable concrete admixture according to claim 1, characterized in that: The molar ratio of polypropylene to polyvinyl pyrrolidone in step B3 is 5-10:0.5-2.

7. A highly permeable concrete admixture according to claim 1, characterized in that: In step B4, the mass ratio of acetone, modified sodium alginate, benzophenone and pre-treated polypropylene fiber is 50:2-5:0.5-2:5-12.

8. A permeable concrete made from the highly permeable concrete admixture according to any one of claims 1 to 7, characterized in that: The permeable concrete is prepared from the following raw materials in parts by weight: 30-60 parts of cement, 80-120 parts of gravel, 8-16 parts of highly permeable concrete admixture, and 15-25 parts of water.

9. The permeable concrete made from the highly permeable concrete admixture according to claim 8, characterized in that: The cement is P.O42.5 ordinary Portland cement.

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