High-pervious concrete and preparation method thereof

Abstract

The invention relates to the technical field of concrete, and particularly discloses high-pervious concrete and a preparation method thereof. The invention relates to high-permeability concrete, which is prepared from the following raw materials in parts by weight: 200 to 400 parts of cement, 80 to 130 parts of mineral powder, 40 to 60 parts of fly ash, 900 to 1200 parts of bluestone, 300 to 600 parts of cucurbitite, 45 to 72 parts of modified microcrystalline cellulose, 25 to 40 parts of modified polypropylene fiber, 80 to 110 parts of water and 20 to 23 parts of additives. The preparation method comprises the following steps: S1, uniformly mixing the cement, the mineral powder, the fly ash, the bluestone and the melon-like stone to obtain a mixed material; and S2, adding the modified microcrystalline cellulose, the modified polypropylene fiber, the additive and the water into the mixed material obtained in the step S1, and uniformly stirring and mixing to obtain the high-pervious concrete. The high-pervious concrete prepared by the invention is high in strength and excellent in pervious performance.

Description

Technical Field

[0001] The present application relates to the field of concrete technology, and in particular to a highly permeable concrete and a preparation method thereof. Background Art

[0002] Permeable concrete, also known as porous concrete or sandless concrete, is breathable, water-permeable and lightweight. It has good water permeability and can avoid the problem of water accumulation on the road. It is a porous lightweight concrete made of aggregate, cement, reinforcing agent, and water. Permeable concrete uses coarse aggregate as the skeleton and does not contain fine aggregate. Cement paste is wrapped on the surface of coarse aggregate particles to form a honeycomb concrete material with water permeability.

[0003] However, due to the lack of fine aggregate filling in permeable concrete, the coarse aggregate has a larger particle size and a smaller specific surface area. The connection area of ​​the coarse aggregate connected by cement is smaller, and the connection force is reduced, resulting in low connection stability of the coarse aggregate. In addition, there is no fine aggregate in the pores to share the load, which makes the compressive strength of the permeable concrete low.

[0004] Therefore, the water permeability of permeable concrete is inversely proportional to its strength. The higher the strength, the greater the density and the worse the water permeability. On the contrary, the better the water permeability, the lower the density, resulting in worse concrete strength. How to balance the water permeability and strength of permeable concrete is an urgent problem to be solved. Summary of the invention

[0005] In order to solve at least one of the above technical problems and develop a concrete with good permeability and material strength, the present application provides a highly permeable concrete and a preparation method thereof.

[0006] On the one hand, the present application provides a highly permeable concrete, comprising the following raw materials in parts by weight: 200-400 parts of cement, 80-130 parts of mineral powder, 40-60 parts of fly ash, 900-1200 parts of bluestone, 300-600 parts of guamite, 45-72 parts of modified microcrystalline cellulose, 25-40 parts of modified polypropylene fiber, 80-110 parts of water, and 20-23 parts of admixture.

[0007] By adopting the above technical scheme, the highly permeable concrete in this application effectively improves the strength of concrete while ensuring water permeability through the use of reasonable material ratios and additives. Specifically, the use of bluestone and melon stone with larger particle sizes can form a larger porosity, thereby ensuring that the concrete has good water permeability. The incorporation of modified microcrystalline cellulose can make the working performance and water permeability of permeable concrete more balanced, make the concrete structure more compact and stable, and can also enhance the cement hydration reaction to a certain extent. Modified polypropylene fiber can also form a microscopic network structure in concrete, increase the toughness of concrete, and prevent the expansion of microcracks.

[0008] Optionally, the preparation method of the modified microcrystalline cellulose comprises the following steps: A1. Take microcrystalline cellulose, add 15% NaOH solution and stir evenly; A2, add tetraethylene pentamine, mix and stir for 5-8 minutes, add epichlorohydrin and continue stirring to cross-link to form a solid; A3. Wash the cross-linked solid with water, dry it at 95-100° C. to constant weight, and grind it through a 150-mesh sieve to obtain the modified microcrystalline cellulose.

[0009] By adopting the above technical scheme, the cellulose chains in the microcrystalline cellulose contain a large number of hydroxyl groups, and the Cl on the epichlorohydrin can react not only with the hydroxyl groups in the microcrystalline cellulose, but also with the amino groups on the tetraethylene pentamine. The epoxy group at the other end of the epichlorohydrin can also react with the amino group of the tetraethylene pentamine, so that the epichlorohydrin plays a cross-linking role, and the microcrystalline cellulose and the small molecule amine are grafted and modified on the surface of the microcrystalline cellulose through bridging cross-linking to obtain modified microcrystalline cellulose. The surface of the microcrystalline cellulose is covered by the solid amine product, and a certain amount of amino and hydroxyl groups appear on the surface, and the hydrophilicity is improved.

[0010] The present application uses modified microcrystalline cellulose to make the working performance and water permeability of permeable concrete more balanced, and to make the concrete structure more compact and stable. Modified microcrystalline cellulose can improve the cohesiveness and water retention of cement paste, inhibit the occurrence of slurry flow and pore blocking, and stabilize the skeleton and paste structure performance of permeable concrete, thereby improving the effective porosity and water permeability coefficient. Modified microcrystalline cellulose can also enhance the hydration reaction to a certain extent, effectively prevent the early compressive strength from decreasing due to fly ash, and may improve the later strength of permeable concrete. In terms of mechanical strength, it can form complementary advantages with fly ash to make the performance of permeable concrete even better.

[0011] Optionally, in step A1, the usage ratio of the NaOH solution to microcrystalline cellulose is (8-12) mL:1 g.

[0012] Optionally, the weight ratio of microcrystalline cellulose, tetraethylenepentamine and epichlorohydrin is 1:(5-7):(8-10).

[0013] Optionally, the preparation method of the modified polypropylene fiber comprises the following steps: soaking the polypropylene fiber in a 4% NaOH solution for 4-5 hours, taking it out, washing it with water, and then soaking it in a styrene-acrylic emulsion for 40-50 minutes with stirring, and drying it to obtain the modified polypropylene fiber.

[0014] By adopting the above technical solution, the present application uses styrene acrylic emulsion to coat and modify the modified polypropylene fiber, which can enhance the uniformity of the dispersion of the polypropylene fiber in concrete, increase the bonding force between the polypropylene fiber and the concrete matrix, and thus improve the strength of the concrete structure. The modified polypropylene fiber can more effectively control early shrinkage cracks and reduce microcracks inside the concrete, thereby improving the durability of the concrete.

[0015] Optionally, the weight ratio of the modified microcrystalline cellulose to the modified polypropylene fiber is (1.5-2):1.

[0016] Optionally, the weight ratio of the modified microcrystalline cellulose to the modified polypropylene fiber is 1.8:1.

[0017] Optionally, the total weight of the modified microcrystalline cellulose and the modified polypropylene fiber accounts for 4.0-5.3% of the total weight of the raw materials of the highly permeable concrete.

[0018] By adopting the above technical solution, when the dosage of modified microcrystalline cellulose is too high, the amount of water absorbed by the permeable concrete in the initial stage of hydration will increase, which will increase the viscosity of the cement paste during the mixing process. The cementitious material introduces more bubbles that cannot be discharged to form pores, which reduces the density of the slurry and the strength of the permeable concrete. When the dosage of modified polypropylene fiber is too high, it will increase the viscosity of the concrete, making it more difficult to pour. Too many fibers will also clog the pores and affect the permeability of the concrete. Therefore, the present application controls the weight ratio between modified microcrystalline cellulose and modified polypropylene fiber, as well as the weight of the two and their proportion in the total weight of concrete raw materials, to ensure that the permeable concrete has a higher strength while ensuring the permeability of the permeable concrete.

[0019] Optionally, the admixture is a polycarboxylic acid high-efficiency water reducer.

[0020] In a second aspect, the present application provides a method for preparing the above-mentioned highly permeable concrete, comprising the following steps: S1, mixing cement, mineral powder, fly ash, bluestone and melon stone uniformly to obtain a mixed material; S2. Add modified microcrystalline cellulose, modified polypropylene fiber, admixture and water to the mixture obtained in step S1, stir and mix evenly to obtain the highly permeable concrete.

[0021] By adopting the above technical solution, the preparation method of highly permeable concrete provided by the present application can achieve uniform mixing and effective dispersion of raw materials. At the same time, the method is simple to operate, highly controllable, suitable for industrial production, and has broad application prospects.

[0022] In summary, the present invention includes at least one of the following beneficial technical effects: 1. The highly permeable concrete in this application effectively improves the strength of concrete while ensuring water permeability through the use of reasonable material ratios and additives. Specifically, the use of bluestone and melon stone with larger particle sizes can form a larger porosity, thereby ensuring that the concrete has good water permeability. The addition of modified microcrystalline cellulose can make the working performance and water permeability of permeable concrete more balanced, make the concrete structure more compact and stable, and enhance the cement hydration reaction to a certain extent. Modified polypropylene fiber can also form a microscopic network structure in concrete, increase the toughness of concrete, and prevent the expansion of microcracks.

[0023] 2. The method for preparing highly permeable concrete provided in this application can achieve uniform mixing and effective dispersion of raw materials. At the same time, the method is simple to operate, highly controllable, suitable for industrial production, and has broad application prospects. DETAILED DESCRIPTION

[0024] The present application is further described in detail below with reference to the embodiments. Specific embodiments

[0025] Preparation Example 1 Preparation Example 1 This preparation example provides a modified polypropylene fiber, and the preparation method includes the following steps: putting a polypropylene fiber with a length of 12-18 mm into a NaOH solution with a mass fraction of 4% for 4.5 hours, taking it out, washing it with water, and then putting it into a styrene-acrylic emulsion and stirring and soaking it for 45 minutes, and drying it to obtain the modified polypropylene fiber.

[0026] Preparation Example 2-4 Preparation Example 2 This preparation example provides a modified microcrystalline cellulose, and the preparation method comprises the following steps: A1. Take microcrystalline cellulose, add 15% NaOH solution and stir evenly; A2, add tetraethylene pentamine, mix and stir for 5 minutes, add epichlorohydrin and continue stirring to crosslink to form a solid; A3. The cross-linked solid was washed with water, dried at 95° C. to constant weight, and then crushed through a 150-mesh sieve to obtain the modified microcrystalline cellulose.

[0027] In step A1, the ratio of NaOH solution to microcrystalline cellulose is 8 mL:1 g; The weight ratio of microcrystalline cellulose, tetraethylenepentamine and epichlorohydrin is 1:5:8.

[0028] Preparation Example 3 The difference between this preparation example and preparation example 2 is that the preparation method of modified microcrystalline cellulose in this preparation example comprises the following steps: A1, taking microcrystalline cellulose, adding a 15% by mass NaOH solution and stirring evenly; A2, add tetraethylene pentamine, mix and stir for 7 minutes, add epichlorohydrin and continue stirring to cross-link to form a solid; A3. The cross-linked solid was washed with water, dried at 98° C. to constant weight, and then crushed through a 150-mesh sieve to obtain the modified microcrystalline cellulose.

[0029] In step A1, the dosage ratio of the NaOH solution to microcrystalline cellulose is 10 mL: 1 g.

[0030] The weight ratio of microcrystalline cellulose, tetraethylenepentamine and epichlorohydrin is 1:6:9.

[0031] Preparation Example 4 The difference between this preparation example and preparation example 2 is that the preparation method of modified microcrystalline cellulose in this preparation example comprises the following steps: A1, taking microcrystalline cellulose, adding a 15% by mass NaOH solution and stirring evenly; A2, add tetraethylene pentamine, mix and stir for 8 minutes, add epichlorohydrin and continue stirring to cross-link to form a solid; A3. The cross-linked solid was washed with water, dried at 100° C. to constant weight, and then crushed through a 150-mesh sieve to obtain the modified microcrystalline cellulose.

[0032] In step A1, the dosage ratio of the NaOH solution to microcrystalline cellulose is 12 mL: 1 g.

[0033] The weight ratio of microcrystalline cellulose, tetraethylenepentamine and epichlorohydrin is 1:7:10.

[0034] Example 1 The present embodiment provides a highly permeable concrete, which includes the following raw materials by weight: 400 parts of cement, 130 parts of mineral powder, 60 parts of fly ash, 1200 parts of bluestone, 300 parts of melon stone, 63 parts of modified microcrystalline cellulose, 35 parts of modified polypropylene fiber, 110 parts of water, and 23 parts of admixture.

[0035] The preparation method of the highly permeable concrete in this preparation example comprises the following steps: S1, mixing cement, mineral powder, fly ash, bluestone and melon stone uniformly to obtain a mixed material; S2. Add modified microcrystalline cellulose, modified polypropylene fiber, admixture and water to the mixture obtained in step S1, stir and mix evenly to obtain the highly permeable concrete.

[0036] The modified polypropylene fiber used in this example is prepared by Preparation Example 1, the modified microcrystalline cellulose is prepared by Preparation Example 2, the admixture is a polycarboxylic acid high-efficiency water reducer, and the particle size of the bluestone is 10±2 mm.

[0037] Embodiment 2-4 Example 2 The difference between this embodiment and embodiment 1 is that when preparing highly permeable concrete, the total weight of modified microcrystalline cellulose and polypropylene fiber is 98 parts, and the weight ratio of modified microcrystalline cellulose to polypropylene fiber is 1.5:1.

[0038] Example 3 The difference between this embodiment and embodiment 1 is that, when preparing highly permeable concrete, the total weight of modified microcrystalline cellulose and polypropylene fiber is 98 parts, and the weight ratio of modified microcrystalline cellulose to polypropylene fiber is 1.7:1.

[0039] Example 4 The difference between this embodiment and embodiment 1 is that, when preparing highly permeable concrete, the total weight of modified microcrystalline cellulose and polypropylene fiber is 98 parts, and the weight ratio of modified microcrystalline cellulose to polypropylene fiber is 2:1.

[0040] Comparative Examples 1-3 Comparative Example 1 Comparative Example 1 The difference between this comparative example and Example 1 is that, when preparing highly permeable concrete, an equal amount of microcrystalline cellulose is used instead of modified microcrystalline cellulose.

[0041] Comparative Example 2 The difference between this comparative example and Example 1 is that no modified polypropylene fiber is added when preparing the highly permeable concrete.

[0042] Comparative Example 3 The difference between this comparative example and Example 1 is that no modified microcrystalline cellulose is added when preparing the highly permeable concrete.

[0043] Comparative Example 4 The difference between this comparative example and Example 1 is that modified microcrystalline cellulose and modified polypropylene fiber are not added when preparing highly permeable concrete.

[0044] Experimental testing: Compression effect: Test the compressive strength of concrete test samples according to GB / T50081; Water permeability effect: Test the water permeability coefficient of the concrete test sample according to JC / T945.

[0045] The experimental test results of Examples 1-4 and Comparative Examples 1-4 are shown in Table 1.

[0046] Table 1 - Experimental test results of Examples 1-4 and Comparative Examples 1-4 Analysis of results: The difference between Examples 2-4 and Example 1 is that, when preparing highly permeable concrete, the total weight of modified microcrystalline cellulose and modified polypropylene fiber is 98 parts, and the weight ratio of modified microcrystalline cellulose and modified polypropylene fiber is different. Combined with the experimental test results in Table 1, it can be seen that when the weight ratio of modified microcrystalline cellulose and modified polypropylene fiber is 1.8:1, the highly permeable concrete obtained has high compressive strength and strong water permeability. The difference between Comparative Example 1 and Example 1 is that, when preparing highly permeable concrete, an equal amount of microcrystalline cellulose is used instead of modified microcrystalline cellulose. Combined with the experimental test results in Table 1, it can be seen that the use of modified microcrystalline cellulose can further improve the permeability and compressive strength of concrete. The difference between Comparative Example 2 and Example 1 is that, when preparing highly permeable concrete, modified polypropylene fiber is not added. The difference between Comparative Example 3 and Example 1 is that, when preparing highly permeable concrete, modified microcrystalline cellulose is not added. The difference between Comparative Example 4 and Example 1 is that modified microcrystalline cellulose and modified polypropylene fiber are not added when preparing highly permeable concrete. Combined with the experimental test results in Table 1, it can be seen that when preparing highly permeable concrete, the compound use of modified microcrystalline cellulose and modified polypropylene fiber can better improve the comprehensive performance of the prepared highly permeable concrete.

[0047] Embodiment 5-6 The difference between Example 5-6 and Example 1 is that the weight fractions of some components are changed when preparing the highly permeable concrete. See Table 2 for the differences.

[0048] Table 2 - Differences between Examples 5-6 and Example 1 The experimental test results of Examples 5-6 are shown in Table 3.

[0049] Table 3 - Experimental test results of Examples 5-6 Result analysis: The difference between Examples 5-6 and Example 1 is that, when preparing highly permeable concrete, the weight proportions of some components are different. Combined with the experimental test results in Table 3, it can be seen that when preparing highly permeable concrete, the highly permeable concrete prepared in Example 5 has better comprehensive performance.

[0050] Embodiment 7-9 The difference between Example 7-9 and Example 5 is that when preparing highly permeable concrete, on the premise that the weight ratio of modified microcrystalline cellulose and modified polypropylene fiber is 1.8:1, the proportion of the total weight of modified microcrystalline cellulose and modified polypropylene fiber in the total weight of the highly permeable concrete raw materials is changed, and a better weight ratio is selected.

[0051] In Example 5, the total weight of the modified microcrystalline cellulose and the modified polypropylene fiber is 98 parts, and the total weight of the highly permeable concrete is 2119 parts.

[0052] Therefore, it is not difficult to conclude that in Example 5, the sum of the weights of modified microcrystalline cellulose (referred to as variable 1) and modified polypropylene fiber (referred to as variable 2) accounts for 4.6% of the total weight of raw materials of highly permeable concrete (referred to as the matrix).

[0053] The differences between Examples 7-9 and Example 5 are shown in Table 4.

[0054] Proportion = (variable 1 + variable 2) / total weight of matrix * 100%.

[0055] Table 4 - Differences between Examples 7-9 and Example 5 The experimental test results of Examples 7-9 are shown in Table 5.

[0056] Table 5 - Experimental test results of Examples 7-9 Results analysis: The difference between Examples 7-9 and Example 5 is that when preparing highly permeable concrete, when the proportion of modified microcrystalline cellulose (referred to as variable 1) and modified polypropylene fiber (referred to as variable 2) in highly permeable concrete (referred to as matrix) is between 4.0-5.3%, the comprehensive performance of the highly permeable concrete obtained is better. When the proportion of modified microcrystalline cellulose (referred to as variable 1) and modified polypropylene fiber (referred to as variable 2) in highly permeable concrete (referred to as matrix) is 4.6%, the comprehensive performance of the highly permeable concrete obtained is better.

[0057] Embodiment 10-11 Example 10 The difference between this embodiment and embodiment 5 is that the preparation parameters of the modified microcrystalline cellulose used in the preparation of highly permeable concrete are different. The modified microcrystalline cellulose in this embodiment is prepared by Preparation Example 3.

[0058] Embodiment 11 The difference between this embodiment and embodiment 5 is that the preparation parameters of the modified microcrystalline cellulose used in the preparation of highly permeable concrete are different. The modified microcrystalline cellulose in this embodiment is prepared by Preparation Example 4.

[0059] The experimental test results of Examples 10-11 are shown in Table 6.

[0060] Table 6 - Experimental test results of Examples 10-11 Result analysis: The difference between Examples 10-11 and Example 5 is that, when preparing highly permeable concrete, the modified microcrystalline cellulose prepared in Preparation Example 3 can better improve the comprehensive performance of the permeable concrete.

[0061] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A highly permeable concrete, characterized in that: The invention comprises the following raw materials in parts by weight: 200-400 parts of cement, 80-130 parts of mineral powder, 40-60 parts of fly ash, 900-1200 parts of bluestone, 300-600 parts of melon stone, 45-72 parts of modified microcrystalline cellulose, 25-40 parts of modified polypropylene fiber, 80-110 parts of water and 20-23 parts of admixture.

2. The highly permeable concrete according to claim 1, characterized in that: The preparation method of the modified microcrystalline cellulose comprises the following steps: A1. Take microcrystalline cellulose, add 15% NaOH solution and stir evenly; A2, add tetraethylene pentamine, mix and stir for 5-8 minutes, add epichlorohydrin and continue stirring to cross-link to form a solid; A3. Wash the cross-linked solid with water, dry it at 95-100° C. to constant weight, and grind it through a 150-mesh sieve to obtain the modified microcrystalline cellulose.

3. The highly permeable concrete according to claim 2, characterized in that: In the step A1, the dosage ratio of the NaOH solution to microcrystalline cellulose is (8-12) mL:1 g.

4. The highly permeable concrete according to claim 2, characterized in that: The weight ratio of the microcrystalline cellulose, tetraethylenepentamine and epichlorohydrin is 1:(5-7):(8-10).

5. The highly permeable concrete according to claim 1, characterized in that: The preparation method of the modified polypropylene fiber comprises the following steps: soaking the polypropylene fiber in a 4% NaOH solution for 4-5 hours, taking it out, washing it with water, and then soaking it in a styrene-acrylic emulsion for 40-50 minutes with stirring, and drying it to obtain the modified polypropylene fiber.

6. The highly permeable concrete according to claim 1, characterized in that: The weight ratio of the modified microcrystalline cellulose to the modified polypropylene fiber is (1.5-2):

1.

7. The highly permeable concrete according to claim 6, characterized in that: The weight ratio of the modified microcrystalline cellulose to the modified polypropylene fiber is 1.8:

1.

8. The highly permeable concrete according to claim 1, characterized in that: The total weight of the modified microcrystalline cellulose and the modified polypropylene fiber accounts for 4.0-5.3% of the total weight of the raw materials of the highly permeable concrete.

9. The highly permeable concrete according to claim 1, characterized in that: The admixture is a polycarboxylic acid high-efficiency water reducer.

10. A method for preparing highly permeable concrete according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1, mixing cement, mineral powder, fly ash, bluestone and melon stone uniformly to obtain a mixed material; S2. Add modified microcrystalline cellulose, modified polypropylene fiber, admixture and water to the mixture obtained in step S1, stir and mix evenly to obtain the highly permeable concrete.

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