Preparation method of impermeable concrete

Abstract

The invention discloses a preparation method of impermeable concrete, and relates to the field of concrete. The preparation method of the impervious concrete comprises the following steps: step 1, adding 70-85 parts by weight of cement, 20-30 parts by weight of red mud, 240-330 parts by weight of coarse aggregate, 180-230 parts by weight of fine aggregate and 44-51 parts by weight of water into a stirrer, and uniformly stirring to obtain a primary mixture; 2, uniformly mixing 9-13 parts of fly ash and 4-8 parts of bagasse ash to obtain premixed powder, adding the premixed powder into the primary mixture, mixing, then adding 3-6 parts of coconut fiber, uniformly mixing, finally adding 1-2 parts of a water reducing agent, and uniformly mixing to obtain a mixed material; and step 3, the mixture is subjected to pouring, curing and demolding, and the impervious concrete is prepared. The red mud is used for replacing part of cement, and the fly ash, bagasse ash and coconut fiber are added for compounding and synergism, so that the impermeability of the concrete is improved, and the compressive strength and durability of the concrete are improved.

Description

Technical Field

[0001] The present invention relates to the field of concrete, and particularly to a preparation method of impermeable concrete. Background Art

[0002] Concrete is one of the most important engineering materials in modern times. It is an artificial stone made by mixing cementitious materials, aggregates, water, admixtures, and blending materials in a certain proportion through stirring. Concrete has rich raw materials, low price, simple production process, and at the same time has the advantages of high compressive strength and good durability, and is widely used in various construction projects.

[0003] With the development of construction projects, people's requirements for concrete are getting higher and higher. Among them, the durability of concrete is closely related to its impermeability. If the impermeability performance is insufficient, harmful substances from the outside will enter the interior of the concrete through the pores of the concrete with water, damaging the internal structure of the concrete, causing cracking of the concrete protective layer. At the same time, the free water inside the concrete increases, resulting in a significant decline in the freeze-thaw resistance performance and affecting the durability of the concrete.

[0004] In related technologies, in order to improve the impermeability of concrete, the method of applying waterproof coatings on the surface of concrete is often used. However, the waterproof coating will age after being used in the actual environment for a period of time, resulting in a reduction in waterproof performance. Therefore, it is of great significance to improve the original formula of concrete and improve its impermeability. Summary of the Invention

[0005] In order to improve the impermeability of concrete, the present application provides a preparation method of impermeable concrete.

[0006] The preparation method of impermeable concrete provided by the present application adopts the following technical scheme: A preparation method of impermeable concrete includes the following steps: Step 1: Add 70 - 85 parts of cement, 20 - 30 parts of red mud, 240 - 330 parts of coarse aggregate, 180 - 230 parts of fine aggregate, and 44 - 51 parts of water by weight into a mixer, and stir evenly to obtain a preliminary mixture. Step 2: Mix 9 - 13 parts of fly ash and 4 - 8 parts of bagasse ash evenly to obtain a premixed powder. Add the premixed powder into the preliminary mixture and mix. Then add 3 - 6 parts of coconut shell fiber and mix evenly. Finally, add 1 - 2 parts of water reducer and mix evenly to obtain a mixture. Step 3: Subject the mixture to pouring, curing, and demolding to obtain impermeable concrete.

[0007] By adopting the above technical solution, red mud is selected to replace part of the cement. The hydration reaction activity of red mud is weaker than that of cement, which can reduce the internal pores generated by hydration heat. At the same time, the unreacted red mud particles are filled in the voids, and combined with the strong water absorption of red mud particles, it is beneficial to improve the impermeability. Fly ash and bagasse ash are used synergistically as mineral admixtures, which is beneficial to improve the compressive strength and fluidity of concrete. In addition, the compactness of the concrete structure is improved, the number of pores in the concrete is reduced, and the impermeability is increased. Fly ash and bagasse ash can make up for the adverse effects of the use of red mud on the strength of concrete, while the alkalinity of red mud can stimulate the reaction activity of fly ash and bagasse ash, playing a synergistic role.

[0008] The addition of coconut shell fibers is beneficial to improving the tensile strength and durability of concrete. The plastic shrinkage of the concrete added with coconut shell fibers is reduced, the generation and expansion of cracks are inhibited, and at the same time, the concrete is strengthened. Fly ash and bagasse ash increase the workability of concrete and are beneficial to the dispersion of coconut shell fibers in the concrete matrix. Therefore, through the synergy of each component, the impermeability of the concrete is improved, and the mechanical properties and durability are enhanced.

[0009] Further, the coconut shell fibers selected are modified coconut shell fibers, and the modified coconut shell fibers are prepared through the following steps: Place 8 - 12 parts of coconut shell fibers in a sodium hydroxide solution with a mass concentration of 3 - 7%, and perform hydrothermal treatment at a temperature of 110 - 120°C for 4 - 6 hours, then wash, filter by suction, and dry to obtain pretreated coconut shell fibers; Mix the pretreated coconut shell fibers with a mixed solution of 70 - 90 parts of anhydrous ethanol and water with a volume ratio of 9:1, add 3 - 4 parts of ammonia water with a mass concentration of 25 - 30%, mix and stir, continuously drop 4 - 5 parts of tetraethyl orthosilicate, react at 30 - 35°C for 2 - 2.5 hours, filter by suction, wash, and dry to obtain modified coconut shell fibers.

[0010] By adopting the above technical solution, lignin, pectin, wax, etc. on the surface of coconut shell fibers are removed by sodium hydroxide treatment, increasing the roughness and strength of coconut shell fibers. Nano - silica is in - situ grown on the surface of coconut shell fibers. The nano - silica undergoes a secondary reaction with calcium hydroxide in the cement, refining the crystal grains, making the concrete structure more dense, and improving the interfacial bonding strength between coconut shell fibers and the cement matrix, thus improving the strength and impermeability of the concrete.

[0011] Further, the bagasse ash is pretreated before being mixed with fly ash, and the pretreatment steps are as follows: First, calcine the bagasse ash in a three - dimensional high - temperature furnace at 600 - 800°C for 2 - 3 hours, naturally cool it to room temperature, pulverize it with a high - speed pulverizer, and pass through a 300 - mesh sieve to obtain the pretreated bagasse ash.

[0012] By adopting the above technical solution, through the steps of calcination, pulverization, and sieving, the reaction activity of the pretreated bagasse ash is enhanced, the size and porosity of the bagasse ash are reduced, so that the pretreated bagasse ash can improve the structure inside the concrete. The high fineness can fill the gaps between the cement and the aggregate, improving the compressive strength and impermeability of the concrete.

[0013] Furthermore, the fine aggregate is selected as medium sand with a fineness modulus of 2.6 - 2.8.

[0014] By adopting the above technical solution, medium sand as the fine aggregate has good gelling properties, resulting in good performance of the concrete.

[0015] Furthermore, the fine aggregate contains expanded perlite with a particle size of 0.1 - 0.15 mm, and the expanded perlite accounts for 5% - 8% of the weight of the fine aggregate.

[0016] By adopting the above technical solution, by adding expanded perlite with a smaller particle size to the medium sand to fill the micropores, the expanded perlite has good water absorption and pore structure, and at the same time has good heat preservation performance, which has a positive effect on the impermeability and heat preservation of the concrete.

[0017] Furthermore, the cement is selected as Portland cement with a strength grade not lower than 42.5 MPa.

[0018] Furthermore, the particle size of the red mud is 25 - 30 mesh.

[0019] By adopting the above technical solution, controlling the particle size of the red mud is beneficial to the dispersion of red mud particles in the cement matrix, making the comprehensive performance of the concrete excellent.

[0020] Furthermore, the coarse aggregate is selected as continuous graded gravel with a size of 5 - 20 mm.

[0021] Furthermore, the water reducer is selected from one or more of naphthalene-based superplasticizer, polycarboxylate superplasticizer, and melamine superplasticizer.

[0022] Furthermore, the length range of the coconut shell fiber is 8 - 20 mm, and the diameter range is 0.1 - 0.5 mm.

[0023] By adopting the above technical solution, controlling the length and diameter of the coconut shell fiber makes the compatibility between the coconut shell fiber and the cement matrix good, and the comprehensive performance is better.

[0024] In summary, the present application has the following beneficial effects: 1. Select red mud to replace part of the cement. The hydration reaction activity of red mud is weaker than that of cement, which can reduce the internal pores generated by hydration heat. At the same time, the unreacted red mud particles fill the voids. Coupled with the strong water absorption of red mud particles, it is beneficial to improve the impermeability. Fly ash and bagasse ash are used synergistically as mineral admixtures, which is beneficial to improve the compressive strength and fluidity of concrete. In addition, it improves the compactness of the concrete structure, reduces the number of pores in the concrete, and increases the impermeability. Fly ash and bagasse ash can compensate for the adverse effects of the use of red mud on the strength of concrete, while the alkalinity of red mud can stimulate the reaction activity of fly ash and bagasse ash, playing a synergistic role.

[0025] The addition of coconut shell fiber is beneficial to improve the tensile strength and durability of concrete. The plastic shrinkage of the concrete added with coconut shell fiber is reduced, the generation and expansion of cracks are inhibited, and at the same time, the concrete is strengthened. Fly ash and bagasse ash increase the workability of the concrete and are beneficial to the dispersion of coconut shell fiber in the concrete matrix. Therefore, through the synergy of each component, the impermeability of the concrete is improved, and the mechanical properties and durability are enhanced.

[0026] 2. Remove lignin, pectin, wax, etc. on the surface of coconut shell fiber by sodium hydroxide treatment to increase the roughness and strength of coconut shell fiber. In-situ growth of nano-silica on the surface of coconut shell fiber. Nano-silica undergoes a secondary reaction with calcium hydroxide in cement, refining the crystal grains, making the concrete structure more compact, and improving the interfacial bonding strength between coconut shell fiber and cement matrix, thus improving the strength and impermeability of the concrete. Specific implementation mode

[0027] The following further elaborates on this application in combination with Examples 1-10 and Comparative Examples 1-3.

[0028] The cement is purchased from Shandong Zhenxing Cement Co., Ltd., and it is Portland cement of grade P.O42.5.

[0029] The fine aggregate is selected as medium sand with a mud content <2% and a fineness modulus of 2.7.

[0030] The coarse aggregate is selected as continuously graded gravel of 5-20mm, and limestone gravel with a density of 2450 kg / m 3 is selected.

[0031] The fly ash is selected from Taiyue (Mining) Co., Ltd. and is Class I fly ash.

[0032] The red mud is selected as the industrial waste of the alumina plant. After calcination and sieving, red mud particles are obtained, and the particle size is 25-30 mesh.

[0033] The expanded perlite is selected from Xinyang Pingqiao Perlite Factory and has a particle size of 0.1-0.15mm.

[0034] The bagasse ash is the bagasse ash directly obtained from the boilers of sugar factories.

[0035] The length range of the coconut shell fibers is 8 - 20 mm, the diameter range is 0.1 - 0.5 mm, and the water absorption rate is 130%.

[0036] Preparation Examples Preparation Example 1 Preparation of Modified Coconut Shell Fibers Place 8 kg of coconut shell fibers in 30 kg of a sodium hydroxide solution with a mass concentration of 3%, conduct hydrothermal treatment at a temperature of 120°C for 6 h, then wash, filter by suction, and dry to obtain pretreated coconut shell fibers; Mix the pretreated coconut shell fibers with 70 kg of a mixed solution of anhydrous ethanol and water with a volume ratio of 9:1, add 3 kg of ammonia water with a mass concentration of 25%, mix and stir, continuously drop 4 kg of tetraethyl orthosilicate, react at 30°C for 2 h, filter by suction, wash, and dry to obtain modified coconut shell fibers.

[0037] Preparation Example 2 Preparation of Modified Coconut Shell Fibers Place 12 kg of coconut shell fibers in 45 kg of a sodium hydroxide solution with a mass concentration of 7%, conduct hydrothermal treatment at a temperature of 110°C for 4 h, then wash, filter by suction, and dry to obtain pretreated coconut shell fibers; Mix the pretreated coconut shell fibers with 90 kg of a mixed solution of anhydrous ethanol and water with a volume ratio of 9:1, add 4 kg of ammonia water with a mass concentration of 25%, mix and stir, continuously drop 5 kg of tetraethyl orthosilicate, react at 35°C for 2.5 h, filter by suction, wash, and dry to obtain modified coconut shell fibers.

[0038] Preparation Example 3 Preparation of Modified Coconut Shell Fibers Place 10 kg of coconut shell fibers in 35 kg of a sodium hydroxide solution with a mass concentration of 4%, conduct hydrothermal treatment at a temperature of 115°C for 5 h, then wash, filter by suction, and dry to obtain pretreated coconut shell fibers; Mix the pretreated coconut shell fibers with 80 kg of a mixed solution of anhydrous ethanol and water with a volume ratio of 9:1, add 3.5 kg of ammonia water with a mass concentration of 25%, mix and stir, continuously drop 4.5 kg of tetraethyl orthosilicate, react at 32°C for 2.5 h, filter by suction, wash, and dry to obtain modified coconut shell fibers. Examples

[0039] Example 1 An impermeable concrete, comprising the following raw materials: 70 kg of cement, 20 kg of red mud, 240 kg of coarse aggregate, 180 kg of fine aggregate, 44 parts of water, 9 kg of fly ash, 4 kg of bagasse ash, 3 kg of coconut shell fiber, 1 kg of water reducing agent. The polycarboxylate superplasticizer of Xingbang Building Materials is selected, and the brand is PC-1050.

[0040] The preparation method of the impermeable concrete includes the following steps: Step 1: Add cement, red mud, coarse aggregate, fine aggregate and water into a mixer according to weight parts, and stir for 6 min until evenly mixed to obtain a preliminary mixture. Step 2: Pretreat the bagasse ash. The pretreatment steps are as follows: First, calcine the bagasse ash in a three-dimensional high-temperature furnace at 600 °C for 3 h, take out the bagasse ash, wait for it to cool naturally to room temperature, grind the bagasse ash with a high-speed powder mill, and pass through a 300-mesh sieve to obtain the pretreated bagasse ash. Mix the fly ash and the pretreated bagasse ash evenly to obtain a premixed powder. Add the premixed powder to the preliminary mixture and stir for 2 min, then add the coconut shell fiber and stir for 3 min, and finally add the water reducing agent and stir for 1 min to mix evenly to obtain a mixture. Step 3: Pour the mixture into a standard mold, gently vibrate and compact it to form a slurry, put the formed concrete test block into a constant temperature room at 20 °C, cure for 24 hours, demold, and obtain the impermeable concrete.

[0041] Example 2 An impermeable concrete, comprising the following raw materials: 85 kg of cement, 30 kg of red mud, 330 kg of coarse aggregate, 230 kg of fine aggregate, 51 parts of water, 13 kg of fly ash, 8 kg of bagasse ash, 6 kg of coconut shell fiber, 2 kg of water reducing agent. The naphthalene series water reducing agent of Jinan Yucai Chemical Industry is selected.

[0042] The preparation method of the impermeable concrete includes the following steps: Step 1: Add cement, red mud, coarse aggregate, fine aggregate and water into a mixer according to weight parts, and stir for 10 min until evenly mixed to obtain a preliminary mixture. Step 2: Pretreat the bagasse ash. The pretreatment steps are as follows: First, calcine the bagasse ash in a three-dimensional high-temperature furnace at 800 °C for 2 h, take out the bagasse ash, wait for it to cool naturally to room temperature, grind the bagasse ash with a high-speed powder mill, and pass through a 300-mesh sieve to obtain the pretreated bagasse ash. Mix the fly ash and the pretreated bagasse ash evenly to obtain a premixed powder. Add the premixed powder to the preliminary mixture and stir for 4 min, then add the coconut shell fiber and stir for 6 min, and finally add the water reducing agent and stir for 2 min to mix evenly to obtain a mixture. Step 3: Pour the mixture into a standard mold, gently vibrate and compact it to form the slurry, place the formed concrete test block in a constant temperature room at 20°C, cure for 24 hours, demold, and obtain the impermeable concrete.

[0043] Example 3 An impermeable concrete, comprising the following raw materials: 80 kg of cement, 25 kg of red mud, 310 kg of coarse aggregate, 200 kg of fine aggregate, 48 parts of water, 12 kg of fly ash, 6 kg of bagasse ash, 4 kg of coconut shell fiber, 1.5 kg of water reducing agent, and the polycarboxylic high-performance water reducing agent of Shanghai Hengchuang Chemical Industry is selected, with the brand number of Sika 540P.

[0044] The preparation method of the impermeable concrete comprises the following steps: Step 1: Add cement, red mud, coarse aggregate, fine aggregate and water into a mixer according to parts by weight, stir for 8 min until evenly mixed, and obtain a preliminary mixture; Step 2: Pretreat the bagasse ash, and the pretreatment steps are as follows: First, calcine the bagasse ash in a three-dimensional high-temperature furnace at 700°C for 2.5 h, take out the bagasse ash, wait for it to cool naturally to room temperature, grind the bagasse ash with a high-speed pulverizer, and pass through a 300-mesh sieve to obtain the pretreated bagasse ash; Mix the fly ash and the pretreated bagasse ash evenly to obtain a preliminary mixed powder, add the preliminary mixed powder into the preliminary mixture and stir for 3 min, then add the coconut shell fiber and stir for 5 min, and finally add the water reducing agent and stir for 1 min to mix evenly to obtain a mixture; Step 3: Pour the mixture into a standard mold, gently vibrate and compact it to form the slurry, place the formed concrete test block in a constant temperature room at 20°C, cure for 24 hours, demold, and obtain the impermeable concrete.

[0045] Example 4 The difference between the impermeable concrete of this example and that of Example 1 is that: the bagasse ash in this example is not pretreated and is directly mixed with the fly ash.

[0046] Example 5 The difference between the impermeable concrete of this example and that of Example 1 is that: the coconut shell in this example selects the modified coconut shell fiber prepared in Preparation Example 1.

[0047] Example 6 The difference between the impermeable concrete of this example and that of Example 1 is that: the coconut shell in this example selects the modified coconut shell fiber prepared in Preparation Example 2.

[0048] Example 7 The difference between the impermeable concrete of this example and that of Example 1 is that the coconut shell in this example is the modified coconut shell fiber prepared in Preparation Example 3.

[0049] Example 8 The difference between the impermeable concrete of this example and that of Example 1 is that the fine aggregate in this example contains expanded perlite, and the expanded perlite accounts for 5% of the weight of the fine aggregate. That is, 171 kg of medium sand and 9 kg of expanded perlite are selected in the fine aggregate.

[0050] Example 9 The difference between the impermeable concrete of this example and that of Example 1 is that the fine aggregate in this example contains expanded perlite, and the expanded perlite accounts for 8% of the weight of the fine aggregate. That is, 165.6 kg of medium sand and 14.4 kg of expanded perlite are selected in the fine aggregate.

[0051] Example 10 The difference between the impermeable concrete of this example and that of Example 1 is that the coconut shell in this example is the modified coconut shell fiber prepared in Preparation Example 3. The fine aggregate in this example contains expanded perlite, and the expanded perlite accounts for 5% of the weight of the fine aggregate. That is, 171 kg of medium sand and 9 kg of expanded perlite are selected in the fine aggregate.

[0052] Comparative Example Comparative Example 1 The difference between the impermeable concrete of this comparative example and that of Example 1 is that no red mud is added in this comparative example, and an equal mass of cement is used to replace the red mud.

[0053] Comparative Example 2 The difference between the impermeable concrete of this comparative example and that of Example 1 is that no bagasse ash is added in this comparative example, and an equal mass of fly ash is used to replace the bagasse ash.

[0054] Comparative Example 3 The difference between the impermeable concrete of this comparative example and that of Example 1 is that no coconut shell fiber is added in this comparative example.

[0055] Preparation of performance test samples: The concrete prepared in Examples 1-10 and Comparative Examples 1-3 was poured into standard cubic specimens with side lengths of 150 mm * 150 mm * 150 mm according to the requirements of Chapter 4 in the "Standard for Test Methods of Mechanical Properties of Ordinary Concrete" (GB / T50081-2020), and cured for 28 days.

[0056] Compressive strength: Test according to the compressive strength test in Chapter 5 of the "Standard for Test Methods of Mechanical Properties of Ordinary Concrete" (GB / T 50081-2020), and record the compressive strength (MPa).

[0057] Impermeability performance: According to the water penetration height method in Section 1, Chapter 6 of the Standard Test Method for Long-Term Performance and Durability of Ordinary Concrete (GB / T 50082-2012), the water penetration test was carried out for 24 hours, and the average water penetration height (mm) was recorded.

[0058] Table 1 As can be seen from Table 1, for the impermeable concrete prepared in Examples 1-3, compared with Comparative Example 1, red mud was selected to replace part of the cement in the raw material components. The reaction activity of red mud is lower than that of cement, which reduces the hydration reaction, resulting in a decrease in compressive strength. At the same time, the pores generated by the hydration heat are reduced, and the unreacted red mud particles accumulate in the voids, playing a role in blocking the water seepage channels. At the same time, red mud has a high water absorption rate and good water retention property. Under the condition of increasing water pressure, red mud can absorb a large amount of water and prevent water from seeping out, thus improving the impermeability performance.

[0059] Compared with Comparative Example 2, in Examples 1-3, fly ash and bagasse ash were jointly used as mineral admixtures. They improved the internal structure of the concrete. By filling the voids between cement and aggregates, the concrete became more dense. The ultra-fine particle size of bagasse ash significantly reduced the number of pores, thus improving the compressive strength and impermeability performance of the concrete.

[0060] Compared with Comparative Example 3, in Examples 1-3, coconut shell fibers were added to the raw materials. The coconut shell fibers restricted the concrete and limited the lateral expansion of the concrete when it was compressed. Therefore, the tensile strength of the concrete was slightly improved. At the same time, the coconut shell fibers could inhibit the generation of cracks and improve the impermeability performance of the concrete.

[0061] Compared with Example 1, in Example 4, bagasse ash was not pretreated. The reaction activity of bagasse ash was lower than that of Example 1, with a high porosity and large size, resulting in the insufficient exertion of the filling effect of the particle size and a decrease in mechanical properties and impermeability performance.

[0062] Compared with Example 1, in Examples 5-7, modified coconut shell fibers were selected in the raw materials, and nano-silica was coated on the coconut shell fibers to form a nano-hybrid. The nano-silica was connected to the cement matrix through chemical bonds, thus improving the interfacial bonding strength between the coconut shell fibers and the cement matrix, and making the cross-linking and compatibility of the concrete system better. At the same time, the nano-silica can react with the cement for a second time to further improve the internal structure of the concrete and enhance the compactness. Therefore, the compressive strength and impermeability performance of the concrete are improved.

[0063] In Examples 8-9, compared with Example 1, expanded perlite is added to the fine aggregate. The small particle size of the expanded perlite can fill the micropores, and at the same time, the porous structure makes the expanded perlite have good water absorption, which can further absorb the moisture in the concrete and reduce the shrinkage of the concrete during the hardening process, playing a positive role in improving the impermeability and mechanical properties of the concrete.

[0064] In Example 10, compared with Example 1, both modified coconut shell fibers and expanded perlite are used, which improves the overall bonding strength and compactness of the concrete, thus fully improving the impermeability and mechanical strength of the concrete.

[0065] This specific embodiment is only an interpretation of the present application and does not limit the present application. After reading this specification, those skilled in the art can make modifications to this specific embodiment without creative contributions as needed, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A method for preparing impermeable concrete, characterized in that, It includes the following steps: Step 1: By weight, add 70 - 85 parts of cement, 20 - 30 parts of red mud, 240 - 330 parts of coarse aggregate, 180 - 230 parts of fine aggregate, and 44 - 51 parts of water into a mixer, and stir evenly to obtain a preliminary mixture; Step 2: Mix 9 - 13 parts of fly ash and 4 - 8 parts of bagasse ash evenly to obtain a premixed powder. Add the premixed powder into the preliminary mixture and mix. Then add 3 - 6 parts of coconut shell fiber and mix evenly. Finally, add 1 - 2 parts of water reducing agent and mix evenly to obtain a mixing material; Step 3: Subject the mixing material to pouring, curing, and demolding to obtain impermeable concrete.

2. The preparation method of an impermeable concrete according to claim 1, characterized in that, The coconut shell fiber is selected as modified coconut shell fiber, and the modified coconut shell fiber is prepared through the following steps: Place 8 - 12 parts of coconut shell fiber in a sodium hydroxide solution with a mass concentration of 3 - 7%, and perform hydrothermal treatment at a temperature of 110 - 120 °C for 4 - 6 h. Then wash, filter by suction, and dry to obtain pretreated coconut shell fiber; Mix the pretreated coconut shell fiber with 70 - 90 parts of a mixed solution of anhydrous ethanol and water with a volume ratio of 9:1, add 3 - 4 parts of ammonia water with a mass concentration of 25 - 30%, and mix and stir. Continuously drop 4 - 5 parts of tetraethyl orthosilicate, and react at 30 - 35 °C for 2 - 2.5 h. Filter by suction, wash, and dry to obtain modified coconut shell fiber.

3. The preparation method of an impermeable concrete according to claim 1, characterized in that, The bagasse ash is pretreated before being mixed with fly ash, and the pretreatment steps are as follows: First, calcine the bagasse ash in a three-dimensional high-temperature furnace at 600 - 800 °C for 2 - 3 h, naturally cool it to room temperature, crush it with a high-speed pulverizer, and pass through a 300-mesh sieve to obtain pretreated bagasse ash.

4. The preparation method of an impermeable concrete according to claim 1, characterized in that: The fine aggregate is selected as medium sand with a fineness modulus of 2.6 - 2.

8.

5. The preparation method of an impermeable concrete according to claim 4, characterized in that: The fine aggregate contains expanded perlite with a particle size of 0.1 - 0.15 mm, and the expanded perlite accounts for 5% - 8% of the weight of the fine aggregate.

6. The preparation method of an impermeable concrete according to claim 1, characterized in that: The cement is selected as Portland cement with a strength grade not lower than 42.5 MPa.

7. The preparation method of an impermeable concrete according to claim 6, characterized in that: The particle size of the red mud is 25 - 30 mesh.

8. The preparation method of an impermeable concrete according to claim 1, characterized in that: The coarse aggregate is selected as continuously graded gravel with a size of 5 - 20 mm.

9. The preparation method of an impermeable concrete according to claim 1, wherein: The water reducing agent is selected from one or more of naphthalene-based high-range water reducing agent, polycarboxylate high-range water reducing agent, and melamine high-range water reducing agent.

10. The preparation method of an impermeable concrete according to claim 1, characterized in that: The length range of the coconut shell fiber is 8 - 20 mm, and the diameter range is 0.1 - 0.5 mm.

Images