A reinforcing agent for maintenance-free permeable concrete and its preparation method and application

Abstract

The present invention relates to the technical field of permeable concrete, and in particular to a reinforcing agent for maintenance-free permeable concrete, a preparation method thereof, and an application thereof. The reinforcing agent for maintenance-free permeable concrete comprises the following raw materials in percentage by weight: 57.5-64% of a cement hydration accelerator, 35.8-42% of a sulfonated melamine water reducer, and 0.2-0.5% of a defoamer; the cement hydration accelerator comprises modified nano-hydrated calcium silicate, triethanolamine, and diethanol monoisopropanolamine in a mass ratio of 10:0.5-1.3:0.1-0.5; the modified nano-hydrated calcium silicate is a silane coupling agent-modified nano-hydrated calcium silicate or dopamine-modified nano-hydrated calcium silicate; and the reinforcing agent for maintenance-free permeable concrete is prepared by combining the cement hydration accelerator with the sulfonated melamine water reducer. The reinforcing agent can effectively improve the compressive strength and flexural strength of the maintenance-free permeable concrete, while having good water permeability and strong freeze-thaw resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of permeable concrete, and in particular to a reinforcing agent for maintenance-free permeable concrete, a preparation method thereof, and an application thereof. Background Art

[0002] The difficulty in constructing and maintaining permeable pavement is a common technical challenge that urgently needs to be researched and resolved. Typically, after permeable concrete is poured and set, construction workers water it and cover it with a film for curing. However, due to the high permeability of concrete, the curing water penetrates deeply into the foundation through the concrete's interconnected pores, and the film can only be used to maintain a certain humidity. Consequently, conventional curing methods are not only inefficient but also labor-intensive.

[0003] Therefore, developing maintenance-free permeable concrete technology has important engineering application value, simplifying the construction and maintenance procedures of permeable pavements, saving water, and solving the maintenance issues of permeable concrete in water-scarce areas. One of the key technologies for this maintenance-free technology is the development of suitable reinforcing agents, which effectively accelerate the hydration and hardening process of cement and are crucial for improving the quality of permeable pavement projects. Summary of the Invention

[0004] The purpose of the present invention is to provide a reinforcing agent for maintenance-free permeable concrete, a preparation method and application thereof, and a reinforcing agent for maintenance-free permeable concrete is prepared by combining a cement hydration accelerator with a sulfonated melamine water reducer. The reinforcing agent can effectively promote the compressive strength and flexural strength of the maintenance-free permeable concrete, while having good permeability and strong freeze-thaw resistance.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0006] A reinforcing agent for maintenance-free permeable concrete comprises the following raw materials in percentage by weight: 57.5-64% of a cement hydration accelerator, 35.8-42% of a sulfonated melamine water reducer, and 0.2-0.5% of a defoamer; the cement hydration accelerator comprises modified nano-hydrated calcium silicate, triethanolamine, and diethanol monoisopropanolamine in a mass ratio of 10:0.5-1.3:0.1-0.5; and the modified nano-hydrated calcium silicate is silane coupling agent-modified nano-hydrated calcium silicate or dopamine-modified nano-hydrated calcium silicate.

[0007] Preferably, the mass ratio of the modified nano-calcium silicate hydrate, triethanolamine, and diethanol monoisopropanolamine is 10:0.9-1:0.4-0.5.

[0008] Preferably, the preparation method of the silane coupling agent modified nano-hydrated calcium silicate comprises the following steps: mixing anhydrous ethanol and deionized water in a volume ratio of 3-3.5:1 to obtain an ethanol / water mixture; taking 100 parts of the ethanol / water mixture, adding 1.8-3 parts of a silane coupling agent, stirring thoroughly, adjusting the pH value to 4.5-5, then adding 5-9 parts of nano-hydrated calcium silicate, stirring and ultrasonically dispersing for 2-3 hours, then heating to 60-65° C. and stirring for 2-3 hours, then filtering, washing, and drying to obtain the product;

[0009] The preparation method of the dopamine-modified nano-hydrated calcium silicate comprises the following steps: placing 3.5-5 parts of the nano-hydrated calcium silicate in 100 parts of a dopamine hydrochloride solution with a concentration of 2-2.5 g / L, adjusting the pH value to 8-8.5, then stirring and ultrasonically dispersing for 10-15 hours, then heating to 50-55° C. and stirring for 3-5 hours, then filtering, washing, and drying to obtain the product.

[0010] Preferably, the preparation method of the sulfonated melamine water reducer comprises the following steps:

[0011] Melamine, urea, salicylic acid and formaldehyde solution are mixed and subjected to hydroxymethylation reaction to obtain a hydroxymethylated solution, and then aminosulfonic acid is added to the solution to carry out a sulfonation reaction. After the sulfonation reaction is completed, an acidic polycondensation reaction and an alkaline reforming reaction are sequentially carried out to prepare the sulfonated melamine water reducer.

[0012] Preferably, the molar ratio of melamine, formaldehyde, urea, salicylic acid and aminosulfonic acid is 1:4.6-5:1.0-1.3:0.08-0.11:0.75-0.9.

[0013] More preferably, the molar ratio of melamine, formaldehyde, urea, salicylic acid and aminosulfonic acid is 1:4.9:1.2:0.105:0.82.

[0014] Preferably, the defoaming agent is polydimethylsiloxane.

[0015] As a general inventive concept, the present invention provides a method for preparing the above-mentioned reinforcing agent for maintenance-free permeable concrete, comprising the following steps:

[0016] S1: Ultrasonic dispersion of modified nano-hydrated calcium silicate, triethanolamine, and diethanol monoisopropanolamine for 1-1.5 hours while stirring to obtain a cement hydration accelerator;

[0017] S2: Add sulfonated melamine water reducer to cement hydration accelerator, mix well, then add defoamer and mix thoroughly to obtain the product.

[0018] As a general inventive concept, the present invention provides an application of a reinforcing agent for curing-free permeable concrete in the preparation of permeable concrete. Specifically, the reinforcing agent for curing-free permeable concrete is added to the permeable concrete in an amount of 2.8-4.5% of the mass of cement; the water-cement ratio of the curing-free permeable concrete is 0.3-0.34.

[0019] Preferably, EVA emulsion is added into the maintenance-free permeable concrete in an amount of 1.5-2.7% by weight of cement.

[0020] The beneficial effects of the present invention are:

[0021] 1, adopt modified nanometer calcium silicate hydrate, triethanolamine, diethanol monoisopropanolamine composite after as the cement hydration accelerator in reinforcing agent among the present invention, wherein modified nanometer calcium silicate hydrate can provide nucleation site for CSH gel growth, reduce nucleation barrier, can accelerate hydration product to form, accelerate the coagulation and the hardening rate of cement paste, on this basis, coordinate to add triethanolamine, triethanolamine molecule can be adsorbed on cement particle surface, make cement better contact with water, and can strengthen peptization dispersion effect, catalysis cement hydration, coordinate with nanometer calcium silicate hydrate, can better promote cement hydration faster. Further, add appropriate diethanol monoisopropanolamine, can promote the dispersion of cement particles, and make hydration more uniform, thereby strengthen the cement hydration promotion effect of cement hydration accelerator. Cement hydration accelerator of the present invention can effectively accelerate cement hydration hardening process, makes the early strength and the mid-and-late strength of permeable concrete obviously increase.

[0022] The modified nano-calcium silicate hydrate used in this invention is either silane coupling agent-modified nano-calcium silicate hydrate or dopamine-modified nano-calcium silicate hydrate. Compared to nano-calcium silicate hydrate, dopamine-modified nano-calcium silicate hydrate has higher dispersibility in cement, resulting in more uniform crystal nucleation and stronger cement hydration. Compared to silane coupling agent-modified nano-calcium silicate hydrate, dopamine-modified nano-calcium silicate hydrate is more effective in accelerating the hydration and hardening of permeable concrete and improving its early strength.

[0023] 2. The sulfonated melamine water-reducing agent prepared by the method of the present invention is a sulfonated melamine-salicylic acid-urea-formaldehyde resin, which can effectively promote the mutual dispersion of cement particles and the disintegration of the flocculated structure, release the water in the encapsulated part to participate in the flow, and significantly enhance the fluidity of permeable concrete. It has a good effect when combined with a cement hydration accelerator, thereby promoting hydration.

[0024] 3. The present invention combines cement hydration accelerator with sulfonated melamine water reducer to prepare a reinforcing agent for maintenance-free permeable concrete, which can effectively promote the early, middle and late compressive strength and flexural strength of maintenance-free permeable concrete, while also having good permeability and strong freeze-thaw resistance.

[0025] 4. When the above-mentioned reinforcing agent is used to prepare maintenance-free permeable concrete, the amount of the reinforcing agent added to the water concrete is limited to 2.8-4.5% of the cement mass, the water-cement ratio of the maintenance-free permeable concrete is 0.3-0.34, and 1.5-2.7% of the cement mass of EVA emulsion is added to the concrete, which can effectively reduce the evaporation of capillary water and increase the relative humidity of the permeable concrete, thereby achieving the purpose of maintenance-free. DETAILED DESCRIPTION

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0027] The raw material nano calcium silicate hydrate used in the preparation of the modifier nano calcium silicate hydrate in the embodiment of the present invention is homemade nano calcium silicate hydrate. The preparation method is as follows: dilute the polycarboxylate water reducer with deionized water to obtain a polycarboxylate water reducer solution with a mass fraction of 3.5%, then take 100 parts of the polycarboxylate water reducer solution and place it in a reaction tank, adjust the pH value to 11.5 with NaOH solution, heat to 60°C under nitrogen protection, and add 20% calcium nitrate solution and 20% calcium nitrate solution to the reaction tank while stirring. The sodium silicate solution is 15%, the ratio of the total molar amount of calcium salt added to the reactor to the total molar amount of silicon salt added is 1.3:1, the mass ratio of the total mass of the calcium nitrate solution and the sodium silicate solution to the polycarboxylate water-reducing agent solution is 1:2.3, the dropping time is 6 hours, and after the dropwise addition is completed, the reaction is continued by stirring and heat preservation for 24 hours. During this process, the pH value of the reaction system is controlled at 11.5±0.3 using NaOH solution and dilute nitric acid solution, and then cooled to room temperature, centrifuged, washed and dried to obtain nano-hydrated calcium silicate.

[0028] The polycarboxylate water reducer was purchased from Nanjing Bermuda Biotechnology Co., Ltd., 530P type polycarboxylate water reducer.

[0029] In the following embodiments of the present invention, BASF FoamStar SI 2210 polydimethylsiloxane defoamer is used as the defoamer.

[0030] Example 1:

[0031] (1) Preparation of silane coupling agent modified nano-hydrated calcium silicate

[0032] Anhydrous ethanol and deionized water are mixed in a volume ratio of 3.5:1 to obtain an ethanol / water mixture; 2.5 parts of silane coupling agent KH570 are added to 100 parts of the ethanol / water mixture, and after sufficient stirring, the pH value is adjusted to 5, and then 8 parts of nano-calcium silicate hydrate are added, and ultrasonic dispersion is carried out while stirring for 3 hours, and then the temperature is raised to 65°C and stirred for 2.5 hours, and then filtered, washed, and dried to obtain silane coupling agent-modified nano-calcium silicate hydrate.

[0033] (2) Preparation of sulfonated melamine water reducer

[0034] 1) Hydroxymethylation reaction: Melamine, salicylic acid, urea, and 37% formaldehyde solution were added to a reaction apparatus; after stirring, the pH of the system was adjusted to 9 with NaOH solution, and the temperature was raised to 65°C and kept at this temperature for 95 minutes to mix the solution A.

[0035] 2) Sulfonation reaction: Add sulfamic acid to mixed solution A, adjust the pH value of the system to 12 with NaOH solution, then heat to 80°C and keep the temperature to react for 3.5 hours to obtain mixed solution B;

[0036] The molar ratio of melamine, formaldehyde, urea, salicylic acid and aminosulfonic acid is 1:5:1.0:0.09:0.8.

[0037] 3) Acidic polycondensation reaction: The temperature of the mixed solution B was lowered to 60° C., and the pH value of the system was adjusted to 3.5 with HCl solution. After the reaction was kept at this temperature for 75 minutes, a mixed solution C was obtained.

[0038] 4) Alkaline reforming reaction: The temperature of the mixed solution C was raised to 85° C., and the pH value of the system was adjusted to 9 with NaOH solution. The mixture was kept at this temperature for 90 minutes to obtain the product.

[0039] (3) Preparation of reinforcing agent for maintenance-free permeable concrete

[0040] The reinforcing agent for curing-free permeable concrete includes the following raw materials by weight: 62% cement hydration accelerator, 37.7% sulfonated melamine water reducer, and 0.3% defoamer. The cement hydration accelerator is composed of silane coupling agent-modified nano-hydrated calcium silicate, triethanolamine, and diethanol monoisopropanolamine in a mass ratio of 10:1:0.5.

[0041] The preparation method is as follows:

[0042] S1: Silane coupling agent modified nano-hydrated calcium silicate, triethanolamine, and diethanol monoisopropanolamine were ultrasonically dispersed with stirring for 1.5 hours to obtain a cement hydration accelerator;

[0043] S2: Add sulfonated melamine water reducer to cement hydration accelerator, mix well, then add defoamer and mix thoroughly to obtain the product.

[0044] Example 2:

[0045] (1) Preparation of silane coupling agent modified nano-hydrated calcium silicate

[0046] Anhydrous ethanol and deionized water are mixed in a volume ratio of 3:1 to obtain an ethanol / water mixture; 1.8 parts of a silane coupling agent KH570 are added to 100 parts of the ethanol / water mixture, and after sufficient stirring, the pH value is adjusted to 5, and then 5 parts of nano-hydrated calcium silicate are added, and ultrasonic dispersion is performed while stirring for 3 hours, and then the temperature is raised to 65°C and stirred for 3 hours, and then filtered, washed, and dried to obtain silane coupling agent-modified nano-hydrated calcium silicate.

[0047] (2) Preparation of sulfonated melamine water reducer

[0048] 1) Hydroxymethylation reaction: Melamine, salicylic acid, urea, and 37% formaldehyde solution were added to a reaction apparatus; after stirring, the pH of the system was adjusted to 8.5 with NaOH solution, and the temperature was raised to 68° C. and the reaction was carried out at this temperature for 90 minutes to mix the solution A.

[0049] 2) Sulfonation reaction: Add sulfamic acid to mixed solution A, adjust the pH value of the system to 11.5 with NaOH solution, then heat to 85°C and keep the temperature for 3 hours to obtain mixed solution B;

[0050] The molar ratio of melamine, formaldehyde, urea, salicylic acid and aminosulfonic acid is 1:4.8:1.2:0.08:0.75.

[0051] 3) Acidic polycondensation reaction: The temperature of the mixed solution B was lowered to 55° C., and the pH value of the system was adjusted to 3 with HCl solution. After the reaction was kept warm for 70 minutes, a mixed solution C was obtained.

[0052] 4) Alkaline reforming reaction: The temperature of the mixed solution C was raised to 80° C., and the pH value of the system was adjusted to 8.5 with NaOH solution. The mixture was kept at this temperature for 80 minutes to obtain the product.

[0053] (3) Preparation of reinforcing agent for maintenance-free permeable concrete

[0054] The reinforcing agent for curing-free permeable concrete contains the following raw materials by weight: 57.5% cement hydration accelerator, 42% sulfonated melamine water reducer, and 0.5% defoamer. The cement hydration accelerator is composed of silane coupling agent-modified nano-hydrated calcium silicate, triethanolamine, and diethanol monoisopropanolamine in a mass ratio of 10:0.5:0.3.

[0055] The preparation method is the same as that of Example 1.

[0056] Example 3:

[0057] (1) Preparation of silane coupling agent modified nano-hydrated calcium silicate

[0058] Anhydrous ethanol and deionized water are mixed in a volume ratio of 3.5:1 to obtain an ethanol / water mixture; 3 parts of silane coupling agent KH570 are added to 100 parts of the ethanol / water mixture, and after sufficient stirring, the pH value is adjusted to 4.5, and then 9 parts of nano-hydrated calcium silicate are added, and ultrasonic dispersion is carried out while stirring for 2 hours, and then the temperature is raised to 60°C and stirred for 2 hours, and then filtered, washed, and dried to obtain silane coupling agent-modified nano-hydrated calcium silicate.

[0059] (2) Preparation of sulfonated melamine water reducer

[0060] 1) Hydroxymethylation reaction: Melamine, salicylic acid, urea, and 37% formaldehyde solution were added to a reaction apparatus; after stirring, the pH of the system was adjusted to 8.5 with NaOH solution, and then the temperature was raised to 70°C and kept at this temperature for 80 minutes to mix the solution A.

[0061] 2) Sulfonation reaction: Add sulfamic acid to mixed solution A, adjust the pH value of the system to 11.5 with NaOH solution, then heat to 80°C and keep the temperature for 4 hours to obtain mixed solution B;

[0062] The molar ratio of melamine, formaldehyde, urea, salicylic acid and aminosulfonic acid is 1:4.6:1.3:0.11:0.9.

[0063] 3) Acidic polycondensation reaction: The temperature of the mixed solution B was lowered to 58° C., and the pH value of the system was adjusted to 3 with HCl solution. After the reaction was kept warm for 80 minutes, a mixed solution C was obtained.

[0064] 4) Alkaline reforming reaction: The temperature of the mixed solution C was raised to 82° C., and the pH value of the system was adjusted to 8.5 with NaOH solution. The mixture was kept at this temperature for 85 minutes to obtain the product.

[0065] (3) Preparation of reinforcing agent for maintenance-free permeable concrete

[0066] The reinforcing agent for curing-free permeable concrete contains the following raw materials by weight: 64% cement hydration accelerator, 35.8% sulfonated melamine water reducer, and 0.2% defoamer. The cement hydration accelerator is composed of silane coupling agent-modified nano-hydrated calcium silicate, triethanolamine, and diethanol monoisopropanolamine in a mass ratio of 10:1.3:0.1.

[0067] The preparation method is the same as that of Example 1.

[0068] Example 4:

[0069] A reinforcing agent for maintenance-free permeable concrete is prepared. Unlike Example 3, the silane coupling agent-modified nano-calcium silicate hydrate is replaced by dopamine-modified nano-calcium silicate hydrate. The preparation method of dopamine-modified nano-calcium silicate hydrate comprises the following steps: placing 5 parts of nano-calcium silicate hydrate in 100 parts of a 2.5 g / L dopamine hydrochloride solution, adjusting the pH value to 8.5, and then ultrasonically dispersing with stirring for 10 hours, then heating to 50°C and stirring for 5 hours, and then filtering, washing, and drying to obtain the product.

[0070] Example 5:

[0071] A reinforcing agent for maintenance-free permeable concrete is prepared. Unlike Example 3, the silane coupling agent-modified nano-hydrated calcium silicate is replaced by dopamine-modified nano-hydrated calcium silicate. The preparation method of dopamine-modified nano-hydrated calcium silicate comprises the following steps: placing 3.5 parts of nano-hydrated calcium silicate in 100 parts of a 2 g / L dopamine hydrochloride solution, adjusting the pH value to 8, and then ultrasonically dispersing with stirring for 15 hours, then heating to 55°C and stirring for 3 hours, and then filtering, washing, and drying to obtain the product.

[0072] Example 6:

[0073] A reinforcing agent for maintenance-free permeable concrete was prepared. The difference from Example 5 was that in the cement hydration accelerator, the mass ratio of dopamine-modified nano-hydrated calcium silicate, triethanolamine, and diethanol monoisopropanolamine was 10:1:0.4.

[0074] Example 7:

[0075] A reinforcing agent for maintenance-free permeable concrete was prepared. Different from Example 5, in the cement hydration accelerator, the mass ratio of dopamine-modified nano-hydrated calcium silicate, triethanolamine, and diethanol monoisopropanolamine was 10:0.9:0.5.

[0076] Example 8:

[0077] The preparation of a reinforcing agent for maintenance-free permeable concrete is different from Example 7 in that when preparing the sulfonated melamine water reducer, the molar ratio of melamine, formaldehyde, urea, salicylic acid, and aminosulfonic acid is 1:4.9:1.2:0.105:0.82.

[0078] Comparative Example 1:

[0079] The difference from Example 3 is that the cement hydration accelerator is composed of silane coupling agent modified nano-hydrated calcium silicate, triethanolamine, and diethanol monoisopropanolamine in a mass ratio of 10:0.3:1.

[0080] Comparative Example 2:

[0081] The difference from Example 3 is that the cement hydration accelerator is composed of nano-calcium silicate hydrate, triethanolamine, and diethanol monoisopropanolamine in a mass ratio of 10:1.3:0.1.

[0082] Comparative Example 3:

[0083] The difference from Example 3 is that the cement hydration accelerator is composed of nano-calcium silicate hydrate and triethanolamine in a mass ratio of 10:1.3.

[0084] Comparative Example 4:

[0085] Different from Example 3, when preparing the sulfonated melamine water reducer, the molar ratio of melamine, formaldehyde, urea, salicylic acid and aminosulfonic acid is 1:3.5:2:0.2:0.8.

[0086] Example 9:

[0087] The invention discloses a maintenance-free permeable concrete, which comprises the following raw materials in parts by weight: 750 parts of coarse aggregate, 220 parts of 42.5-grade ordinary Portland cement, 5 parts of EVA emulsion, 70 parts of water, and a reinforcing agent for the maintenance-free permeable concrete in an amount of 3.8% by weight of cement; wherein the coarse aggregate is crushed stone, and the particle size of the coarse aggregate is 5-10 mm.

[0088] For the maintenance-free permeable concrete in Example 9, the reinforcing agents in Examples 1-8 and Comparative Examples 1-4 were used to prepare the maintenance-free permeable concrete, and the concrete preparation method was as follows: first, the cement, coarse aggregate, and EVA emulsion were evenly mixed, and then 2 / 3 of the formula amount of water was added. After stirring for 50 seconds, the reinforcing agent for maintenance-free permeable concrete was added and stirred for 100 seconds. Then, the remaining water was added, and the material was stirred for 150 seconds to obtain maintenance-free permeable concrete slurry.

[0089] Curing-free concrete specimens were prepared using the aforementioned curing-free permeable concrete slurry and placed in a conventional environment (temperature of 20-28°C and humidity of 40-65%) for curing-free concrete. The compressive and flexural strengths of the curing-free concrete were tested in accordance with GB / T50081, "Standard for Test Methods of Mechanical Properties of Ordinary Concrete." The specimen dimensions for the compressive strength test were 150 mm × 150 mm × 150 mm, and the specimen dimensions for the flexural strength test were 150 mm × 150 mm × 450 mm. The specific test results are shown in Table 1.

[0090] Table 1 Test results of compressive strength and flexural strength of curing-free permeable concrete

[0091]

[0092] The test data from Examples 1-8 in Table 1 demonstrate that the reinforcing agent of the present invention effectively improves the early strength of curing-free concrete and exhibits excellent mid- to late-stage strength. A comparison of Example 3 with Comparative Examples 1-4 demonstrates that the composition ratio of the cement hydration accelerator affects its concrete reinforcing effect, and that its effectiveness is significantly diminished if the nano-hydrated calcium silicate is not modified. Furthermore, the molar ratio of melamine, formaldehyde, urea, salicylic acid, and sulfamic acid in the preparation of the sulfonated melamine water-reducing agent also significantly influences the performance of the reinforcing agent.

[0093] The 28-day permeability coefficient of maintenance-free permeable concrete was tested in accordance with CJJ / T135-2009, "Technical Specification for Permeable Cement Concrete Pavement," and the 28-day freeze-thaw resistance of permeable concrete was tested in accordance with JGJT193-2009, "Concrete Durability Test and Evaluation Standard." The specific test results are shown in Table 2.

[0094] Table 2 Test results of permeability coefficient and freeze-thaw resistance of curing-free permeable concrete

[0095]

[0096] It can be seen from the test data in Table 1 that the curing-free concrete in the examples and comparative examples both have a high water permeability coefficient, but the freeze-thaw resistance of the permeable concrete in the examples is significantly better than that of the comparative examples.

[0097] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A reinforcing agent for maintenance-free permeable concrete, characterized in that: The invention comprises the following raw materials in weight percentage: 57.5-64% cement hydration accelerator, 35.8-42% sulfonated melamine water reducer, and 0.2-0.5% defoamer; the cement hydration accelerator comprises modified nano-hydrated calcium silicate, triethanolamine, and diethanol monoisopropanolamine in a mass ratio of 10:0.5-1.3:0.1-0.5, and the modified nano-hydrated calcium silicate is dopamine-modified nano-hydrated calcium silicate; and the preparation method of the dopamine-modified nano-hydrated calcium silicate comprises the following steps: placing 3.5-5 parts of nano-hydrated calcium silicate in 100 parts of a dopamine hydrochloride solution with a concentration of 2-2.5 g / L, adjusting the pH value to 8-8.5, then performing ultrasonic dispersion with stirring for 10-15 hours, then heating to 50-55°C and stirring for 3-5 hours, then filtering, washing, and drying to obtain the product.

2. The reinforcing agent for maintenance-free permeable concrete according to claim 1, characterized in that: The mass ratio of the modified nano-calcium silicate hydrate, triethanolamine and diethanol monoisopropanolamine is 10:0.9-1:0.4-0.

5.

3. The reinforcing agent for maintenance-free permeable concrete according to claim 1, characterized in that: The preparation method of the sulfonated melamine water reducer comprises the following steps: Melamine, urea, salicylic acid and formaldehyde solution are mixed and subjected to hydroxymethylation reaction to obtain a hydroxymethylated solution, and then aminosulfonic acid is added to the solution to carry out a sulfonation reaction. After the sulfonation reaction is completed, an acidic polycondensation reaction and an alkaline reforming reaction are sequentially carried out to prepare the sulfonated melamine water reducer.

4. The reinforcing agent for maintenance-free permeable concrete according to claim 3, characterized in that: The molar ratio of melamine, formaldehyde, urea, salicylic acid and aminosulfonic acid is 1:4.6-5:1.0-1.3:0.08-0.11:0.75-0.

9.

5. The reinforcing agent for maintenance-free permeable concrete according to claim 4, characterized in that: The molar ratio of melamine, formaldehyde, urea, salicylic acid and aminosulfonic acid is 1:4.9:1.2:0.105:0.

82.

6. The reinforcing agent for maintenance-free permeable concrete according to claim 1, characterized in that: The defoaming agent is polydimethylsiloxane.

7. A method for preparing a reinforcing agent for maintenance-free permeable concrete according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1: Ultrasonic dispersion of modified nano-hydrated calcium silicate, triethanolamine, and diethanol monoisopropanolamine for 1-1.5 hours while stirring to obtain a cement hydration accelerator; S2: Add sulfonated melamine water reducer to cement hydration accelerator, mix well, then add defoamer and mix thoroughly to obtain the product.

8. Use of the reinforcing agent for curing-free permeable concrete according to any one of claims 1 to 6 or the reinforcing agent for curing-free permeable concrete prepared by the preparation method according to claim 7 in the preparation of permeable concrete, characterized in that: The reinforcing agent for maintenance-free permeable concrete is added to the permeable concrete in an amount of 2.8-4.5% of the mass of cement; the water-cement ratio of the maintenance-free permeable concrete is 0.3-0.

34.

9. The use according to claim 8, characterized in that The maintenance-free permeable concrete is added with EVA emulsion in an amount of 1.5-2.7% by weight of cement.

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