Grass-planting concrete admixture and application thereof

Abstract

The application belongs to the technical field of concrete admixtures, and particularly relates to a grass-planting concrete admixture and application thereof. The grass-planting concrete admixture comprises the following raw materials in parts by weight: silica fume 80-86 parts, water reducing agent 2-4 parts, accelerator 5-10 parts, adjusting agent 1-2 parts, and reinforcing agent 2-4 parts; the reinforcing agent is prepared by mixing polyacrylamide, EVA emulsion and sodium gluconate at a mass ratio of 1:1:2. The grass-planting concrete admixture is used for preparing concrete, which can effectively improve the strength of the grass-planting concrete, the compressive strength of which is more than 15 MPa, and promote the growth of plants, guarantee the porosity and provide an excellent living environment for the growth of plants, and effectively solve the problems of the prior art.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of concrete admixtures, and particularly relates to a grass-growing concrete admixture and application thereof. BACKGROUND

[0002] The vegetation-type porous concrete is a new type of environment-friendly building material with a continuous large-pore structure and capable of allowing plants to grow in the pores thereof, and the plant root systems can penetrate into the soil layer through the pores in the concrete and continuously absorb nutrients in the soil. With the increasing application of the grass-growing concrete and the rapid development of the research on the structural performance, how to ensure the ecological effect while improving the strength thereof has become a problem to be solved.

[0003] The general concrete admixture is mainly used for improving the strength and comprehensive performance of the concrete, and the vegetation-type concrete admixture is different from the ordinary concrete. In addition, the grass-growing concrete is generally prepared by using a low water-cement ratio to ensure the strength, and the incomplete wrapping of the slurry under the low water-cement ratio easily leads to material waste, which is also an important problem faced by the grass-growing concrete. Therefore, it is urgent to develop a concrete admixture which can be efficiently utilized and simultaneously consider the strength of the grass-growing concrete and the growth demand of the plants. SUMMARY

[0004] In view of the defects of the prior art, the application provides a grass-growing concrete admixture and application thereof. The grass-growing concrete admixture used for preparing the grass-growing concrete can effectively improve the strength of the grass-growing concrete, the compressive strength of which is greater than 15 MPa, promote the growth of the plants, ensure the porosity and provide an excellent living environment for the growth of the plants, and effectively solve the defects of the prior art.

[0005] To achieve the above object, the application provides a grass-growing concrete admixture, which comprises the following raw materials in parts by weight: silica fume 80-86 parts, water reducing agent 2-4 parts, accelerator 5-10 parts, adjusting agent 1-2 parts and reinforcing agent 2-4 parts.

[0006] The reinforcing agent is a mixture of polyacrylamide, EVA emulsion and sodium gluconate in a mass ratio of 1:1:2.

[0007] Silica ash is produced by a large amount of volatile SiO2 and Si gas in the smelting of ferrosilicon and industrial silicon (metallic silicon) in the furnace, the gas is discharged and rapidly oxidized and condensed to form, which can generate secondary hydration with calcium hydroxide generated by the "ash effect" and hydration, and can fill the pores of cementitious materials to improve the density. The admixture takes silica ash as the main raw material, which can improve the density and strength of the concrete by using its characteristics; by adding water reducing agent, mainly used to maintain the low water-cement ratio of grass planting concrete, reduce the water consumption of cement; by adding regulator to adjust the consistency and density of the concrete; by adding accelerator to improve the initial hydration speed of cement; by adding enhancer to accelerate the early hydration of cement, form voids on its surface, and finally use fluorosilane soaking to form certain groups in the voids and on the surface, promote the formation of more hydrated calcium silicate, finally through the mutual cooperation of each component, improve the strength of grass planting concrete and meet the growth needs of plants.

[0008] Further, in the above technical solution, the grass planting concrete admixture comprises the following raw materials by weight: 84 parts of silica ash, 3 parts of water reducing agent, 8.5 parts of accelerator, 1.5 parts of regulator, and 3 parts of enhancer.

[0009] Further, in the above technical solution, the water reducing agent is a polycarboxylic acid superplasticizer. In this technical solution, the polycarboxylic acid superplasticizer is used to maintain the low water-cement ratio of grass planting concrete, so that the cement hydration reaction can occur with the least amount of water, and the dosage is low and the reduction rate is high.

[0010] Further, in the above technical solution, the accelerator is white crystalline powder calcium nitrate, and the content of calcium nitrate is not less than 50%. Calcium nitrate is a water-soluble substance, which can increase the concentration of calcium ions in water after being added to the cement mixture, promote the hydration reaction of tricalcium silicate, dicalcium silicate and tricalcium aluminate to proceed in the positive direction, and improve the initial hydration speed of cement; at the same time, calcium nitrate can provide certain nutrients for grass as a base fertilizer.

[0011] Further, in the above technical solution, the regulator is hydroxypropyl methyl cellulose with a viscosity of not less than 200,000. Hydroxypropyl methyl cellulose can be used as a water retaining agent, a coagulant, an enhancer, etc., which can adjust the consistency of concrete during the molding process, improve the wrapping property of grass planting concrete cementitious material to coarse aggregate, make the cementitious material and aggregate form a group, reduce the adhesion of the material to the inner wall of the mixer, and improve the material utilization rate; at the same time, hydroxypropyl methyl cellulose can also improve the distribution of hydration product crystals, make the AFt crystals columnar and uniformly distributed, have more lap joints between each other, and have a more dense structure to improve the strength.

[0012] Further, in the technical scheme, the polyacrylamide is an ionic white particle; the EVA emulsion is an ethylene-vinyl acetate copolymer emulsion; and the sodium gluconate has a content of more than 98%.

[0013] The polyacrylamide (PAM) is a linear organic polymer, which can make suspended substances flocculate through electric neutralization, bridging adsorption, and can also play a role in adhesion through mechanical, physical and chemical effects; the EVA emulsion is a kind of binder, which has good adhesion properties, aging resistance, light resistance and saponification resistance, and can improve the water resistance, aging resistance and acid and alkali resistance of concrete; the sodium gluconate is an organic substance, which can increase the plasticity and strength of concrete as a water reducing agent and a retarder, and has a retarding effect, i.e. delaying the initial and final setting time of concrete; in the technical scheme, the reinforcing agent composed of polyacrylamide, EVA emulsion and sodium gluconate is used to accelerate the early hydration of cement, reduce the generation of calcium hydroxide which is not conducive to strength, and generate more hydrated calcium silicate, while enhancing the water resistance, aging resistance and the like of cement.

[0014] Further, in the technical scheme, the silica ash is 800-mesh ultra-fine silica ash with a SiO2 content of not less than 60%. In the technical scheme, the ultra-fine silica ash is selected to fill the voids between cement particles, and to generate gel with hydration products, thereby improving the compressive strength, durability, water retention and impact resistance of concrete.

[0015] The application further provides a use of the additive in the preparation of grass-planting concrete, and a preparation method of the grass-planting concrete.

[0016] S1. Put the coarse aggregate into a mixer, add 1 / 5 of the total water amount, and stir for 1-5 min to wet the surface layer of the coarse aggregate;

[0017] S2. Mix and stir the cement, sand, silica ash, accelerator and regulator for not less than 2 min until completely uniform to obtain a mixture;

[0018] S3. Dissolve the reinforcing agent and water reducing agent in 1 / 5 of the total water amount, and stir for 1-5 min to obtain a mixed solution;

[0019] S4. Add half of the mixture obtained in S2 into the mixer in S1, and add 2 / 5 of the total water amount, and stir for 2-6 min;

[0020] S5. Add the remaining mixture obtained in S2 and the mixed solution prepared in S3 into the mixer in S4, and add the remaining water, and stir for 3-10 min to obtain the grass-planting concrete.

[0021] Further, in the technical scheme, the dosage of the additive in the concrete is 5%-8% of the cement dosage in the concrete.

[0022] Further, in the technical scheme, the mass ratio of the coarse aggregate, cement, sand and water is 74:15:7:5. The mix proportion of the concrete is obtained by the volume method according to the coarse aggregate density, target porosity, water-cement ratio, cement-sand ratio and other parameters.

[0023] The present application has the following beneficial effects:

[0024] (1) The additive of the present application can not only ensure the porosity, but also efficiently improve the strength of the grass-planting concrete, so as to meet the requirements of the strength and durability of the grass-planting concrete as the river bank protection against erosion and corrosion.

[0025] (2) The additive of the present application, together with the calcium nitrate as the accelerator, can promote the cement hydration reaction and increase the nitrogen fertilizer for the plant growth, so as to meet the plant growth requirements and facilitate the root system to extend and develop in the concrete pores.

[0026] (3) The additive of the present application is added one by one during the preparation of the grass-planting concrete, so that the raw materials can fully play their roles, and the adjusting agent can make the cementing material and the aggregate form a group, thereby reducing the material sticking to the inner wall of the mixer and improving the material utilization rate. DETAILED DESCRIPTION

[0027] The experimental methods in the following examples are all conventional methods unless otherwise specified. The raw materials involved in the following examples are all ordinary commercially available products and can be purchased in the market. The present application will be further described in detail in combination with the examples:

[0028] Example 1

[0029] The additive for the grass-planting concrete comprises the following raw materials by weight: 84 parts of silica fume, 3 parts of water reducing agent, 8.5 parts of accelerator, 1.5 parts of adjusting agent and 3 parts of reinforcing agent.

[0030] The water reducing agent is a polycarboxylic acid high-efficiency water reducing agent; the accelerator is white crystalline powder calcium nitrate with a content of not less than 50%; the adjusting agent is hydroxypropyl methylcellulose with a viscosity of 200,000; the reinforcing agent is a mixture of polyacrylamide, EVA emulsion and sodium gluconate at a mass ratio of 1:1:2; and the silica fume is 800-mesh ultra-fine silica fume with a SiO2 content of not less than 60%.

[0031] A method for preparing the grass-planting concrete by using the above additive, wherein the additive for the grass-planting concrete is added in an amount of 6.8% of the cement dosage, and the method comprises the following steps:

[0032] S1. Put the coarse aggregate into a mixer, add 1 / 5 of the total water amount, and stir for 3 min to wet the surface of the coarse aggregate;

[0033] S2. Mix and stir the cement, sand, silica fume, accelerator, and regulator for no less than 2 min until completely uniform to obtain a mixture;

[0034] S3. Dissolve the reinforcing agent and water reducing agent in 1 / 5 of the total water amount, and stir thoroughly for 3 min to obtain a mixed solution;

[0035] S4. Add half of the mixture obtained in S2 to the mixer in S1, and add 2 / 5 of the total water amount, and stir for 4 min;

[0036] S5. Add the remaining mixture obtained in S2 and the mixed solution prepared in S3 to the mixer in S4, and add the remaining water, and stir for 5 min to obtain the product.

[0037] The mass ratio of the coarse aggregate, cement, sand, and water is 74:15:7:5.

[0038] Example 2

[0039] A grass-planting concrete additive, comprising the following raw materials by weight: 80 parts of silica fume, 2 parts of water reducing agent, 5 parts of accelerator, 1 part of regulator, and 4 parts of reinforcing agent;

[0040] The water reducing agent is a polycarboxylic acid superplasticizer; the accelerator is white crystalline powder calcium nitrate with a content of no less than 50%; the regulator is hydroxypropyl methylcellulose with a viscosity of 200,000; the reinforcing agent is a mixture of polyacrylamide, EVA emulsion, and sodium gluconate in a mass ratio of 1:1:2; and the silica fume is 800-mesh ultra-fine silica fume with a SiO2 content of no less than 60%.

[0041] A method for preparing a grass-planting concrete using the above additive, which is added with the above grass-planting concrete additive in an amount of 6.8% of the cement, and comprises the following steps:

[0042] S1. Put the coarse aggregate into a mixer, add 1 / 5 of the total water amount, and stir for 1 min to wet the surface of the coarse aggregate;

[0043] S2. Mix and stir the cement, sand, silica fume, accelerator, and regulator for no less than 2 min until completely uniform to obtain a mixture;

[0044] S3. Dissolve the reinforcing agent and water reducing agent in 1 / 5 of the total water amount, and stir thoroughly for 1 min to obtain a mixed solution;

[0045] S4. Add half of the mixture obtained in S2 to the mixer of S1, and add 2 / 5 of the total water, and stir for 2 minutes;

[0046] S5. Add the remaining mixture obtained in S2 and the mixture prepared in S3 to the mixer of S4, and add the remaining water, and stir for 3 minutes.

[0047] The mass ratio of the coarse aggregate, cement, sand and water is 74:15:7:5.

[0048] Example 3

[0049] The plant grass concrete additive comprises the following raw materials in parts by weight: silica fume 86 parts, water reducing agent 4 parts, accelerator 10 parts, adjusting agent 2 parts, and reinforcing agent 2 parts.

[0050] The water reducing agent is a polycarboxylic acid high-efficiency water reducing agent; the accelerator is white crystalline powder calcium nitrate, and the content is not less than 50%; the adjusting agent is hydroxypropyl methylcellulose, and the viscosity is 200,000; the reinforcing agent is a mixture of polyacrylamide, EVA emulsion and sodium gluconate in a mass ratio of 1:1:2; and the silica fume is 800-mesh ultra-fine silica fume, and the SiO2 content is not less than 60%.

[0051] A method for preparing the plant grass concrete by using the additive comprises the following steps:

[0052] S1. Put the coarse aggregate into a mixer, add 1 / 5 of the total water, and stir for 5 minutes to wet the surface layer of the coarse aggregate;

[0053] S2. Mix and stir the cement, sand, silica fume, accelerator and adjusting agent for not less than 2 minutes until completely uniform to obtain a mixture;

[0054] S3. Dissolve the reinforcing agent and water reducing agent in 1 / 5 of the total water, and stir for 5 minutes to obtain a mixture;

[0055] S4. Add half of the mixture obtained in S2 to the mixer of S1, and add 2 / 5 of the total water, and stir for 6 minutes;

[0056] S5. Add the remaining mixture obtained in S2 and the mixture prepared in S3 to the mixer of S4, and add the remaining water, and stir for 10 minutes.

[0057] The mass ratio of the coarse aggregate, cement, sand and water is 74:15:7:5.

[0058] Comparative Example 1

[0059] A grass-planting concrete additive comprises the following raw materials in parts by weight: 86.6 parts of silica fume, 8.8 parts of an accelerator, 1.5 parts of a regulator, and 3.1 parts of a reinforcing agent.

[0060] The accelerator is white crystalline powder calcium nitrate with a content of not less than 50%; the regulator is hydroxypropyl methyl cellulose with a viscosity of 200,000; the reinforcing agent is a mixture of polyacrylamide, EVA emulsion, and sodium gluconate in a mass ratio of 1:1:2; and the silica fume is 800-mesh ultra-fine silica fume with a SiO2 content of not less than 60%.

[0061] The method for preparing the grass-planting concrete is the same as that in Example 1 except that the grass-planting concrete additive of the present comparative example is used.

[0062] Comparative Example 2

[0063] A grass-planting concrete additive comprises the following raw materials in parts by weight: 91.8 parts of silica fume, 3.3 parts of a water-reducing agent, 1.6 parts of a regulator, and 3.3 parts of a reinforcing agent.

[0064] The water-reducing agent is a polycarboxylic acid high-efficiency water-reducing agent; the regulator is hydroxypropyl methyl cellulose with a viscosity of 200,000; the reinforcing agent is a mixture of polyacrylamide, EVA emulsion, and sodium gluconate in a mass ratio of 1:1:2; and the silica fume is 800-mesh ultra-fine silica fume with a SiO2 content of not less than 60%.

[0065] The method for preparing the grass-planting concrete is the same as that in Example 1 except that the grass-planting concrete additive of the present comparative example is used.

[0066] Comparative Example 3

[0067] A grass-planting concrete additive comprises the following raw materials in parts by weight: 85.3 parts of silica fume, 3 parts of a water-reducing agent, 8.6 parts of an accelerator, and 3 parts of a reinforcing agent.

[0068] The water-reducing agent is a polycarboxylic acid high-efficiency water-reducing agent; the accelerator is white crystalline powder calcium nitrate with a content of not less than 50%; the reinforcing agent is a mixture of polyacrylamide, EVA emulsion, and sodium gluconate in a mass ratio of 1:1:2; and the silica fume is 800-mesh ultra-fine silica fume with a SiO2 content of not less than 60%.

[0069] The method for preparing the grass-planting concrete is the same as that in Example 1 except that the grass-planting concrete additive of the present comparative example is used.

[0070] Comparative Example 4

[0071] A grass-planting concrete additive comprises the following raw materials in parts by weight: 86.6 parts of silica fume, 3.1 parts of a water-reducing agent, 8.8 parts of an accelerator, and 1.5 parts of a regulator.

[0072] The water reducing agent is a polycarboxylic acid superplasticizer; the accelerator is white crystalline powder calcium nitrate, and the content is not less than 50%; the adjusting agent is hydroxypropyl methyl cellulose, and the viscosity is 2000000; the silica ash is 800 mesh ultra-fine silica ash, and the SiO2 content is not less than 60%.

[0073] The method for preparing the grass-planting concrete uses the grass-planting concrete admixture of the present application.

[0074] Comparative Example 5

[0075] A grass-planting concrete admixture comprises the following raw materials by weight: 84 parts of silica ash, 3 parts of water reducing agent, 8.5 parts of accelerator, 1.5 parts of adjusting agent, and 3 parts of reinforcing agent.

[0076] The water reducing agent is a polycarboxylic acid superplasticizer; the accelerator is white crystalline powder calcium nitrate, and the content is not less than 50%; the adjusting agent is hydroxypropyl methyl cellulose, and the viscosity is 2000000; the reinforcing agent is a mixture of polyacrylamide, EVA emulsion, and sodium gluconate at a mass ratio of 1:1:2; and the silica ash is 800 mesh ultra-fine silica ash, and the SiO2 content is not less than 60%.

[0077] A method for preparing the grass-planting concrete using the above-mentioned admixture, and the method comprises the following steps: adding 6.8% of the grass-planting concrete admixture to cement, and then putting the coarse aggregate, cement, sand, silica ash, accelerator, adjusting agent, reinforcing agent, and water reducing agent into a mixer, and adding water, and stirring for 10 minutes to obtain the grass-planting concrete.

[0078] The mass ratio of the coarse aggregate, cement, sand, and water is 74:15:7:5.

[0079] Test Example

[0080] 1. According to the relevant standards of GB / T 50081-2019, the performance of the grass-planting concrete of Examples 1-3 and Comparative Examples 1-5, the concrete prepared by directly adding the existing admixture to the concrete raw materials, and the concrete prepared without adding the admixture (control example) is tested, and the compressive strength (7d, 28d) test results are shown in Table 1.

[0081] Table 1 Compressive strength performance results

[0082]

[0083] As can be seen from the results of Table 1, the grass-planting concrete prepared by the grass-planting concrete admixture and the preparation method of the present application has a compressive strength of more than 15 MPa, while the grass-planting concrete of Comparative Examples 1-4 has no good reinforcing effect due to the lack of components, which shows that the components in the admixture of the present application are suitable and coordinated with each other, and have a significant reinforcing effect. The reinforcing effect of the admixture of the prior art is also not as good as that of the admixture of the present application. The reinforcing effect of Comparative Example 5 is also affected due to the different preparation method.

[0084] 2. The grass-planting experiment was carried out in the grass-planting concrete treated by the admixture of Example 1 of the present application, and the results are shown in Table 2.

[0085] Table 2: Comparison of the height of rye grass

[0086]

[0087] As can be seen from the results of Table 2, the height of rye grass in the grass-planting concrete using the admixture of the present application can be increased by about 10%, which is close to the height of rye grass in the soil, which shows that the admixture of the present application is beneficial to the adaptation of plants to the grass-planting concrete medium and better growth.

[0088] In summary, the present application optimizes the ingredients of the grass-planting concrete admixture and the preparation method of the grass-planting concrete, so that the grass-planting concrete admixture can not only effectively improve the strength of the grass-planting concrete, but also promote the growth of plants, and ensure the porosity while providing an excellent living environment for the growth of plants.

[0089] Finally, it should be emphasized that the above description is only the preferred embodiments of the present application, and is not intended to limit the present application. For those skilled in the art, the present application can have various changes and modifications, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A grass-planting concrete admixture, characterized in that, The raw materials include the following parts by weight: 80-86 parts silica fume, 2-4 parts water-reducing agent, 5-10 parts accelerator, 1-2 parts regulator, and 2-4 parts reinforcing agent; The reinforcing agent is composed of polyacrylamide, EVA emulsion, and sodium gluconate mixed in a mass ratio of 1:1:

2. The polyacrylamide is an ionic white granule; the EVA emulsion is an ethylene-vinyl acetate copolymer emulsion; the sodium gluconate content is greater than 98%. The silica fume is 800-mesh ultrafine silica fume, with a SiO2 content of not less than 60%. The accelerator is white crystalline powdered calcium nitrate, wherein the calcium nitrate content is not less than 50%; The regulator is hydroxypropyl methylcellulose with a viscosity of not less than 200,000. The admixture is added to concrete at a dosage of 5-8% of the cement content.

2. The grass-planting concrete admixture according to claim 1, characterized in that, The raw materials include the following parts by weight: 84 parts silica fume, 3 parts water-reducing agent, 8.5 parts accelerator, 1.5 parts regulator, and 3 parts reinforcing agent.

3. The grass-planting concrete admixture according to claim 1 or 2, characterized in that, The water-reducing agent is a polycarboxylate superplasticizer.

4. The application of the grass-planting concrete admixture according to any one of claims 1-3 in the preparation of grass-planting concrete, characterized in that, The method for preparing the grass-planted concrete includes the following steps: S1. Put the coarse aggregate into the mixer, add 1 / 5 of the total water volume, and mix for 1-5 minutes to moisten the surface of the coarse aggregate; S2. Mix cement, sand, silica fume, accelerator, and regulator for no less than 2 minutes until completely homogeneous to obtain a mixture; S3. Dissolve the reinforcing agent and water-reducing agent in 1 / 5 of the total water volume, and stir thoroughly for 1-5 minutes to obtain a mixture; S4. Add half of the mixture obtained in S2 to the mixer in S1, and add 2 / 5 of the total water volume, and mix for 2-6 minutes; S5. Add the remaining mixture obtained in S2 and the mixture prepared in S3 to the mixer in S4, and add the remaining water. Mix for 3-10 minutes to obtain the final product.

5. The application according to claim 4, characterized in that, The mass ratio of coarse aggregate, cement, sand and water is 74:15:7:5.

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