An environmentally friendly permeable concrete and its preparation method

Abstract

This invention belongs to the field of building materials technology, specifically relating to an environmentally friendly permeable concrete and its preparation method. The environmentally friendly permeable concrete, by weight, comprises 200-300 parts cement, 100-200 parts medium sand, 50-150 parts aggregate, 3.5-5 parts modified bamboo leaf fiber, 8-15 parts carboxylated nitrile butadiene latex, 3-4 parts silane coupling agent, and 100-200 parts water. The modified bamboo leaf fiber undergoes surface modification via a siloxane polymer. The modified bamboo leaf fiber, silane coupling agent, and carboxylated nitrile butadiene latex exhibit good compatibility, enhancing the compressive strength, splitting tensile strength, and permeability coefficient of the environmentally friendly permeable concrete.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to an environmentally friendly permeable concrete and its preparation method. Background Technology

[0002] Concrete, typically referring to cement as a binder, sand and gravel as aggregates, and water mixed in a specific ratio, is widely used in civil engineering. With the advancement of urban green and environmental protection concepts, the idea of ​​planting vegetation on river or reservoir embankments has been proposed for the first time in urban planning. However, traditional concrete lacks permeability and cannot continuously irrigate the vegetation planted on ecological embankments through the seepage of small amounts of river or reservoir water. Therefore, it cannot be used as a building material for ecological river embankments, which contradicts the current advocacy of green urbanization.

[0003] Bamboo leaf fiber is inexpensive and has good recyclability, making its application in concrete consistent with the national advocacy for green environmental protection. Bamboo leaf fiber has good air permeability, which helps improve the permeability of environmentally friendly permeable concrete. According to the article "Experimental Study on Workability and Mechanical Properties of Bamboo Leaf Fiber Concrete" (published in *Concrete and Cement Products*, 2021, Vol. 1, pp. 54-56), bamboo leaf fiber has strong wear resistance and toughness, which helps improve the splitting tensile strength and flexural strength of environmentally friendly permeable concrete. However, adding bamboo leaf fiber reduces the compressive strength of environmentally friendly permeable concrete. Summary of the Invention

[0004] To address the problem that existing environmentally friendly permeable concrete with added bamboo leaf fiber struggles to simultaneously achieve high permeability, splitting tensile strength, and compressive strength, this application provides an environmentally friendly permeable concrete and its preparation method.

[0005] Firstly, this application provides an environmentally friendly permeable concrete.

[0006] An environmentally friendly permeable concrete, by weight, comprises 200-300 parts cement, 100-200 parts medium sand, 50-150 parts aggregate, 3.5-5 parts modified bamboo leaf fiber, 8-15 parts carboxylated nitrile latex, 3-5 parts silane coupling agent and 100-200 parts water.

[0007] The modified bamboo leaf fiber is surface-modified using a siloxane polymer.

[0008] By adopting the above technical solutions, modified bamboo leaf fibers are added to improve the permeability of concrete. Siloxane polymers are used to modify bamboo leaf fibers, enhancing their dispersion in environmentally friendly permeable concrete, allowing them to better exert their water absorption effect. The siloxane groups on the surface of the modified bamboo fibers can be linked to the network structure of the environmentally friendly permeable concrete through silane coupling agents, resulting in a synergistic effect when the concrete is subjected to external forces. Carboxylated nitrile latex improves the toughness of the environmentally friendly permeable concrete. Under external forces, the modified bamboo fibers, with their good toughness, exhibit a relatively matched strain with the concrete, reducing the internal stress on the modified bamboo fibers. This allows the modified bamboo leaf fibers, silane coupling agents, and carboxylated nitrile latex to be used in combination, enhancing the compressive strength, splitting tensile strength, and permeability coefficient of the environmentally friendly permeable concrete.

[0009] Preferably, the preparation process of the modified bamboo leaf fiber is as follows:

[0010] Mixture A is formed by mixing 3-5 parts by weight of vinyl silicone oil, 0.8-1.4 parts by weight of hydrogen-containing silicone oil, 1-1.4 parts by weight of terminal hydrogen silicone oil, and 0.0006-0.001 parts by weight of platinum coordinated with divinyltetramethylsiloxane as a thermal catalyst under stirring at 400-800 rpm.

[0011] 0.43-1.0 parts by weight of sodium alginate and 35-85 parts by weight of 10 wt% NaOH solution are mixed and heated to 60-70℃ and stirred for 20-30 min. Then, 21.6-50.7 parts by weight of bamboo leaf fiber are added, the temperature is raised to 80-85℃, the mixture is stirred and reacted for 1 h, and then cooled to prepare the pretreated mixture.

[0012] The pH of the pretreated mixture was adjusted to 5-6 with dilute acid, and then 1.3-3.2 parts by weight of polyoxyethylene alkylamine and mixture A were added. The mixture was heated to 80-90℃ and stirred for 2 hours. After filtration, washing and drying, modified bamboo leaf fiber was obtained.

[0013] Preferably, the hydrogen-containing silicone oil is at least one of hydrogen-containing silicone oil I, hydrogen-containing silicone oil II, and hydrogen-containing silicone oil III, and the structural formulas of hydrogen-containing silicone oil I, hydrogen-containing silicone oil II, and hydrogen-containing silicone oil III are shown below:

[0014]

[0015] Chemical formula 1, structural formula of hydrogen-containing silicone oil I;

[0016]

[0017] Chemical formula 2, structural formula of hydrogen-containing silicone oil II;

[0018]

[0019] Chemical formula 3, the structural formula of hydrogen-containing silicone oil III;

[0020] In chemical formula 1, n is an integer ≥ 0 and m is an integer ≥ 1; in chemical formula 2, x is an integer ≥ 1 and y is an integer ≥ 3.

[0021] By adopting the above technical solution, modified bamboo leaf fiber is prepared. The siloxane polymer forms a network structure on the surface of the modified bamboo leaf fiber, which makes the modified bamboo leaf fiber, silane coupling agent and carboxylated nitrile latex produce a better synergistic effect, enhancing the compressive strength, splitting tensile strength and permeability coefficient of environmentally friendly permeable concrete.

[0022] Preferably, the mass ratio of the bamboo leaf fiber to the mixture A is (4.5-6.5):1.

[0023] By adopting the above technical solution and optimizing the mass ratio of bamboo leaf fiber to mixture A, the modified bamboo leaf fiber prepared has both good synergy and good dispersibility in environmentally friendly permeable concrete, thereby enhancing the compressive strength, splitting tensile strength and permeability coefficient of environmentally friendly permeable concrete.

[0024] When the mass ratio of bamboo leaf fiber to mixture A is small, the siloxane polymer over-modifies the bamboo leaf fiber, reducing its hydrophilicity and resulting in poor dispersibility in the slurry of the permeable concrete. This leads to a decrease in the enhancement effect on the compressive strength, splitting tensile strength, and permeability coefficient of the permeable concrete. Conversely, when the mass ratio of bamboo leaf fiber to mixture A is large, there is less siloxane polymer on the surface of the bamboo leaf fiber, resulting in insufficient modification of the bamboo leaf fiber and a poor enhancement effect on the compressive strength, splitting tensile strength, and permeability coefficient of the permeable concrete.

[0025] Preferably, the molar ratio of hydroxyl groups to vinyl groups in the mixture A is (0.82-0.91):1, and the environmentally friendly permeable concrete further includes 4-8 parts by weight of hydrogen-containing silicone oil microcapsules.

[0026] By adopting the above technical solution and optimizing the molar ratio of siloxane groups to vinyl groups in mixture A, unreacted vinyl groups are present in the siloxane polymer. The vinyl groups can react with the hydrogen-containing silicone oil released from the hydrogen-containing silicone oil microcapsules to form a network structure, which connects the siloxane polymer and carboxylated nitrile latex into a whole. This further enhances the synergistic effect between the modified bamboo leaf fiber and other raw materials of environmentally friendly permeable concrete, thereby increasing the compressive strength and splitting tensile strength of the environmentally friendly permeable concrete.

[0027] Preferably, the preparation process of the hydrogen-containing silicone oil microcapsules is as follows:

[0028] A polyvinyl alcohol solution is prepared by adding a nonionic surfactant with a mass concentration of 2%-3% to an aqueous solution of polyvinyl alcohol at 40-50℃ and stirring the mixture.

[0029] Adding hydrogen-containing silicone oil to 5%-8% of polylactic acid dichloromethane primary emulsion yields a hydrogen-containing silicone oil emulsion with a mass concentration of 7%-10%.

[0030] Hydrogen-containing silicone oil emulsion, polyvinyl alcohol solution, and 3-6% isopropanol aqueous solution were mixed at a mass ratio of 1:1:1 and ultrasonically emulsified for 30-40 minutes. Then, the mixture was stirred at 85-90℃ for 2 hours, followed by centrifugation and washing of the product with distilled water to prepare hydrogen-containing silicone oil microcapsules.

[0031] By adopting the above technical solution, stable hydrogen-containing silicone oil microcapsules were prepared. During the curing process of environmentally friendly permeable concrete, the wall material of the hydrogen-containing silicone oil microcapsules hydrolyzes and / or degrades under the heat and water released during the curing process. The hydrogen-containing silicone oil microcapsules release hydrogen-containing silicone oil, which reacts well with carboxylated nitrile latex and modified bamboo leaf fiber, further enhancing the compressive strength and splitting tensile strength of the environmentally friendly permeable concrete.

[0032] Preferably, the silane coupling agent is one of γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, phenylamino-silane, triaminosilane, γ-mercaptopropyltrimethoxysilane, γ-ureapropyltrimethoxysilane, γ-ureapropyltrihexyloxysilane, γ-methacryloyloxypropyltrimethoxysilane, and γ-glycidyl ether propyltrimethoxysilane.

[0033] By adopting the above technical solution and adding silane coupling agent, it is beneficial to improve the compatibility between organic matter and inorganic fillers in environmentally friendly permeable concrete, so that carboxylated nitrile latex is more evenly dispersed and mixed in environmentally friendly permeable concrete; adding silane coupling agent is beneficial to the formation of network structure in environmentally friendly permeable concrete, thereby enhancing the compressive strength and splitting tensile strength of environmentally friendly permeable concrete.

[0034] Preferably, the environmentally friendly permeable concrete further includes 1-3 parts by weight of a water-reducing agent.

[0035] By adopting the above technical solutions, the fluidity and strength of concrete can be improved.

[0036] Preferably, the environmentally friendly permeable concrete further includes 1-3 parts by weight of a stabilizer.

[0037] By adopting the above technical solutions, the fluidity of concrete can be improved, its compressive strength and splitting tensile strength can be increased, and its crack resistance can be enhanced.

[0038] Preferably, the aggregate has a particle size of 3-12 mm; the medium sand has a particle size of 0.16-2.5 mm.

[0039] By adopting the above technical solutions and optimizing the particle size of aggregates and medium sand, environmentally friendly permeable concrete can have better compressive strength, splitting tensile strength and permeability.

[0040] On the other hand, this application provides a method for preparing environmentally friendly permeable concrete.

[0041] A method for preparing environmentally friendly permeable concrete, the method is as follows:

[0042] (1) Under normal temperature conditions, water, carboxylated nitrile latex and silane coupling agent are added to cement under stirring conditions of 150-250 r / min to prepare a premix.

[0043] (2) Under normal temperature conditions, medium sand, aggregate, and modified bamboo leaf fiber are added to the premix at a stirring rate of 150-250 r / min to prepare the slurry for environmentally friendly permeable concrete.

[0044] (3) Under normal temperature conditions, the slurry of environmentally friendly permeable concrete is stirred at a speed of 150-250 r / min; after being stirred evenly, the slurry of environmentally friendly permeable concrete is laid and cured to form environmentally friendly permeable concrete.

[0045] By adopting the above technical solution, the environmentally friendly permeable concrete prepared has good compressive strength, splitting tensile strength and permeability.

[0046] In summary, this application has the following beneficial effects:

[0047] 1. Modified bamboo leaf fiber, silane coupling agent and carboxylated nitrile latex are used in combination in environmentally friendly permeable concrete to enhance the compressive strength, splitting tensile strength and permeability coefficient of environmentally friendly permeable concrete.

[0048] 2. In the preparation process of modified bamboo leaf fiber, the molar ratio of silane-hydrogen groups to vinyl groups in mixture A is (0.82-0.91):1; and hydrogen-containing silicone oil microcapsules are used in environmentally friendly permeable concrete. Vinyl groups can be connected to carboxylated nitrile latex through the hydrogen-containing silicone oil in the hydrogen-containing silicone oil microcapsules to form a whole, further enhancing the compressive strength and splitting tensile strength of environmentally friendly permeable concrete.

[0049] 3. The wall material of the hydrogen-containing silicone oil microcapsules is made of polylactic acid and polyvinyl alcohol. Under the heat and water released during the curing of environmentally friendly permeable concrete, the wall material of the hydrogen-containing silicone oil microcapsules undergoes hydrolysis and / or degradation. The hydrogen-containing silicone oil microcapsules release hydrogen-containing silicone oil, which reacts well with carboxylated nitrile latex and modified bamboo leaf fiber, thereby enhancing the compressive strength and splitting tensile strength of the environmentally friendly permeable concrete. Detailed Implementation

[0050] raw material

[0051] Cement (PO42.5), vinyl silicone oil (viscosity 10000 mPa·s, vinyl content 0.37 mmol / g), hydrogen-containing silicone oil (silicone oil containing side hydrogen and terminal hydrogen, viscosity 100 mPa·s, hydrogen content 1.1 mmol / g), terminal hydrogen silicone oil (viscosity 1000 mPa·s, hydrogen content 0.1 mmol / g), bamboo leaf fiber (length 0.15-0.18 mm, water solubility 10:1), bentonite (200 mesh, sieve residue <1%), calcium lignosulfonate (lignin content 50-65%) Water-insoluble matter: 0.5-1.5%, reducing matter: 5-13%), sodium alginate (model: food grade), polylactic acid (model: 4032D, powder, glass transition temperature: 50-60℃), polyvinyl alcohol (model: BP-17, MW molecular weight approximately 85,000), chitosan (MW average molecular weight 320,000, degree of substitution 95%), β-cyclodextrin (total sugar ≥86.5%), styrene-acrylic emulsion (content ≥48%, room temperature viscosity: 200S), carboxylated nitrile butadiene latex (solid content ≥44%, room temperature viscosity 200S).

[0052] Preparation example of intermediate

[0053] Preparation Example 1-1: A modified bamboo leaf fiber, using raw materials as shown in Table 1, and prepared as follows:

[0054] Mixture A is formed by stirring vinyl silicone oil, hydrogen-containing silicone oil, hydrogen-terminated silicone oil and platinum coordinated with the thermal catalyst divinyltetramethylsiloxane at 800 rpm.

[0055] Sodium alginate was added to a reaction vessel containing 10 wt% NaOH solution, the temperature was raised to 70°C, and the mixture was stirred for 30 min. Then bamboo leaf fiber was added, the temperature was raised to 85°C, and the mixture was stirred for 1 h. After cooling, a pretreated mixture was prepared.

[0056] The pH of the pretreated mixture was adjusted to 6 with dilute acid, and then polyoxyethylene alkylamine and mixture A were added. The mixture was heated to 90°C and stirred for 2 hours. After filtration, washing and drying, modified bamboo leaf fiber was obtained.

[0057] Preparation Example 1-2, a modified bamboo leaf fiber, differs from Preparation Example 1-1 in the raw materials and preparation process parameters used. The raw materials are shown in Table 1, and the preparation process is as follows:

[0058] Mixture A is formed by stirring vinyl silicone oil, hydrogen-containing silicone oil, hydrogen-terminated silicone oil and platinum coordinated with the thermal catalyst divinyltetramethylsiloxane at 600 rpm.

[0059] Sodium alginate was added to a reaction vessel containing 10 wt% NaOH solution, the temperature was raised to 65°C, and the mixture was stirred for 25 min. Then bamboo leaf fiber was added, the temperature was raised to 83°C, and the mixture was stirred for 1 h. After cooling, a pretreated mixture was prepared.

[0060] The pH of the pretreated mixture was adjusted to 5.5 with dilute acid, and then polyoxyethylene alkylamine and mixture A were added. The mixture was heated to 85°C and stirred for 2 hours. After filtration, washing and drying, modified bamboo leaf fiber was obtained.

[0061] Preparation Examples 1-3, a modified bamboo leaf fiber, differ from Preparation Example 1-1 in the raw materials and preparation process parameters used. The raw materials are shown in Table 1, and the preparation process is as follows:

[0062] Mixture A is formed by stirring vinyl silicone oil, hydrogen-containing silicone oil, hydrogen-terminated silicone oil and platinum coordinated with the thermal catalyst divinyltetramethylsiloxane at 400 rpm.

[0063] Sodium alginate was added to a reaction vessel containing 10 wt% NaOH solution, the temperature was raised to 60°C, and the mixture was stirred for 20 min. Then bamboo leaf fiber was added, the temperature was raised to 80°C, and the mixture was stirred for 1 h. After cooling, a pretreated mixture was prepared.

[0064] The pH of the pretreated mixture was adjusted to 5 with dilute acid, and then polyoxyethylene alkylamine and mixture A were added. The mixture was heated to 80°C and stirred for 2 hours. After filtration, washing and drying, modified bamboo leaf fiber was obtained.

[0065] Table 1. List of raw material quality and type used in the modified bamboo leaf fibers of Preparation Examples 1-1 to 1-3

[0066]

[0067] Preparation Examples 1-4, a modified bamboo leaf fiber, differs from Preparation Example 1-1 in that, while maintaining the same molar ratio of silane groups to vinyl groups, hydrogen-containing silicone oil is used instead of terminal hydrogen silicone oil.

[0068] Preparation Examples 1-5, a modified bamboo leaf fiber, differs from Preparation Example 1-1 in that, while maintaining the same molar ratio of silane groups to vinyl groups, terminal hydrogen silicone oil is used instead of hydrogen-containing silicone oil.

[0069] Preparation Examples 1-6: A modified bamboo leaf fiber, which differs from Preparation Example 1-1 in that it does not use terminal hydrogen silicone oil, and the molar ratio of silane groups to vinyl groups is 0.79:1; the bamboo leaf fiber used is 28 kg of bamboo leaf fiber, and the mass ratio of bamboo leaf fiber to mixed liquid A is 7.3:1.

[0070] Preparation Examples 1-7, a modified bamboo leaf fiber, differs from Preparation Example 1-1 in that 3.5 kg of terminal hydrogen silicone oil is used, and the molar ratio of hydroxyl group to vinyl group is 1.1:1; 28 kg of bamboo leaf fiber is used, and the mass ratio of bamboo leaf fiber to mixed liquid A is 3.8:1.

[0071] Preparation Examples 1-8, a modified bamboo leaf fiber, differs from Preparation Example 1-1 in that the silane coupling agent γ-aminopropyltriethoxysilane is used to replace the terminal hydrogen silicone oil, hydrogen-containing silicone oil and vinyl silicone oil in equal amounts.

[0072] Preparation Example 2-1: A hydrogen-containing silicone oil microcapsule, the preparation process is as follows:

[0073] A polyvinyl alcohol solution was prepared by adding a 2% (w / w) nonionic surfactant (dodecylphenol polyoxyethylene ether) to a 2% (w / w) aqueous solution of polyvinyl alcohol at 40°C and stirring.

[0074] Hydrogen-containing silicone oil was added to 5% of polylactic acid dichloromethane primary emulsion to obtain a hydrogen-containing silicone oil emulsion with a mass concentration of 7%.

[0075] Hydrogen-containing silicone oil emulsion, polyvinyl alcohol solution, and 3% isopropanol aqueous solution were mixed at a mass ratio of 1:1:1 and then ultrasonically emulsified at 30 kHz for 40 min. The mixture was then stirred at 85 °C for 2 h to remove the isopropanol. The mixture was then centrifuged and washed with distilled water to obtain hydrogen-containing silicone oil microcapsules.

[0076] Preparation Example 2-2: A hydrogen-containing silicone oil microcapsule, the preparation process of which is as follows:

[0077] A polyvinyl alcohol solution was prepared by adding a 2.5% (w / w) nonionic surfactant (Tween 20) to a 2.5% (w / w) aqueous solution of polyvinyl alcohol at 45°C and stirring.

[0078] Hydrogen-containing silicone oil is added to a 6% polylactic acid dichloromethane primary emulsion to obtain a hydrogen-containing silicone oil emulsion with a mass concentration of 7%-10%.

[0079] Hydrogen-containing silicone oil emulsion, polyvinyl alcohol solution, and 5% isopropanol aqueous solution were mixed in a mass ratio of 1:1:1, ultrasonically emulsified at 35 kHz for 35 min, stirred at 88 °C for 2 h to remove isopropanol, centrifuged, and washed with distilled water to finally obtain hydrogen-containing silicone oil microcapsules.

[0080] Preparation Examples 2-3: A hydrogen-containing silicone oil microcapsule, the preparation process is as follows:

[0081] A 3% (w / w) aqueous solution of polyvinyl alcohol was prepared by adding a 3% (w / w) nonionic surfactant (Tween 20) at 50°C and stirring the mixture.

[0082] Hydrogen-containing silicone oil was added to 8% of polylactic acid dichloromethane primary emulsion to obtain a hydrogen-containing silicone oil emulsion with a mass concentration of 10%.

[0083] Hydrogen-containing silicone oil emulsion, polyvinyl alcohol solution, and 6% isopropanol aqueous solution were mixed at a mass ratio of 1:1:1 and then ultrasonically emulsified at 40 kHz for 30 min. The mixture was then stirred at 90 °C for 2 h to remove the isopropanol. The mixture was then centrifuged and washed with distilled water to obtain hydrogen-containing silicone oil microcapsules.

[0084] Preparation Example 2-4, a hydrogen-containing silicone oil microcapsule, differs from Preparation Example 2-1 in that sodium hydroxide is used to replace polyvinyl alcohol in an equal amount, and chitosan is used to replace polylactic acid in an equal amount.

[0085] Preparation Example 2-5, a hydrogen-containing silicone oil microcapsule, differs from Preparation Example 2-1 in that it uses β-cyclodextrin to replace polylactic acid in equal amounts.

[0086] Preparation Example 2-6, a hydrogen-containing silicone oil microcapsule, differs from Preparation Example 2-1 in that it uses dodecylphenol polyoxyethylene ether to replace polylactic acid and polyvinyl alcohol in equal amounts.

[0087] Example

[0088] Example 1: An environmentally friendly permeable concrete, using the raw materials listed in Table 2, and its preparation process is as follows:

[0089] (1) In a cement mixer, cement is added at room temperature. Then water, carboxylated nitrile latex, hydrogen-containing silicone oil microcapsules, water-reducing agent, stabilizer and silane coupling agent are added to the cement under stirring conditions of 250 r / min. The mixture is stirred evenly to prepare a premix.

[0090] (2) Under normal temperature conditions, medium sand, aggregate, and modified bamboo leaf fiber are added to the premix at a stirring rate of 250 r / min to prepare the slurry for environmentally friendly permeable concrete.

[0091] (3) Under normal temperature conditions, the slurry of environmentally friendly permeable concrete is stirred at a speed of 250 r / min. After being stirred evenly, it is quickly spread on the construction surface and cured to form environmentally friendly permeable concrete.

[0092] Examples 2 and 3 describe an environmentally friendly permeable concrete, which differs from Example 1 in that the raw materials and mixing speed settings are different, as detailed in Table 2.

[0093] Table 2. List of raw material quality, type, and mixing speed settings used in the environmentally friendly permeable concrete of Examples 1 to 3.

[0094]

[0095]

[0096] Examples 4 to 8 are environmentally friendly permeable concretes, which differ from Example 1 in that the modified bamboo leaf fibers are prepared in Examples 1-4 to 1-8 respectively.

[0097] Examples 9 to 11 describe an environmentally friendly permeable concrete, which differs from Example 1 in that the hydrogen-containing silicone oil microcapsules are prepared in accordance with Examples 2-4 to 2-6.

[0098] Example 12, an environmentally friendly permeable concrete, differs from Example 1 in that it does not use hydrogen-containing silicone oil microcapsules.

[0099] Example 13, an environmentally friendly permeable concrete, differs from Example 1 in that it does not use hydrogen-containing silicone oil microcapsules, water-reducing agents, and stabilizers.

[0100] Comparative Example

[0101] Comparative Example 1, an environmentally friendly permeable concrete, differs from Example 13 in that it uses bamboo leaf fiber to replace the modified bamboo leaf fiber in equal amounts.

[0102] Comparative Example 2, an environmentally friendly permeable concrete, differs from Example 13 in that it uses styrene-acrylic emulsion to replace carboxylated butadiene-acrylic latex in an equal amount.

[0103] Comparative Example 3, an environmentally friendly permeable concrete, differs from Example 13 in that it does not use carboxylated nitrile latex and silane coupling agent.

[0104] Comparative Example 4, an environmentally friendly permeable concrete, differs from Example 13 in that it does not use modified bamboo leaf fiber, carboxylated nitrile latex, and silane coupling agent.

[0105] Comparative Example 5, an environmentally friendly permeable concrete, differs from Comparative Example 1 in that it does not use carboxylated nitrile latex and silane coupling agent.

[0106] Performance testing

[0107] Test 1: Compressive strength and splitting tensile strength

[0108] According to GB / T50081-2019 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete", the compressive strength and splitting tensile strength (MPa) of the test specimens were tested using a universal testing machine. The test specimens were demolded 24 hours after molding and then placed in a standard curing room for 28 days.

[0109] Experiment 2: Permeability Coefficient

[0110] The permeability coefficient (mm / s) of the test sample was tested according to GB / T25993-2010 "Instructions for Test Device of Permeability Coefficient of Standard Permeable Cement Concrete".

[0111] Test samples: Environmentally friendly permeable concrete of Examples 1-13 were used as example samples; environmentally friendly permeable concrete of Comparative Examples 1-5 were used as comparative example samples.

[0112] Test results: The test results of compressive strength, splitting tensile strength and permeability coefficient of the environmentally friendly permeable concrete of Examples 1-13 and Comparative Examples 1-5 are shown in Table 3.

[0113] Table 3 lists the test results of compressive strength, splitting tensile strength, and permeability coefficient of the environmentally friendly permeable concrete in Examples 1-13 and Comparative Examples 1-5.

[0114]

[0115]

[0116] As can be seen from Examples 1-13 and Comparative Examples 1-5, and in conjunction with Table 3,

[0117] The compressive strength, splitting tensile strength, and permeability coefficient of the environmentally friendly permeable concrete in Examples 1-13 are superior to those in Comparative Examples 1-5. This may be because the use of modified bamboo fiber in the concrete improves its permeability. Furthermore, the siloxane on the surface of the modified bamboo fiber enhances the dispersion of bamboo leaf fiber in the environmentally friendly permeable concrete, allowing the modified bamboo fiber to better exert its water absorption effect. The siloxane polymer on the surface of the modified bamboo fiber can better synergize with the silane coupling agent, enhancing the interaction between the modified bamboo fiber and other raw materials of the environmentally friendly permeable concrete. Carboxylated nitrile latex improves the toughness of the environmentally friendly permeable concrete. Under external force, the modified bamboo fiber with good toughness undergoes a relatively matched strain with the concrete, reducing the internal stress on the modified bamboo fiber. This allows the modified bamboo leaf fiber, silane coupling agent, and carboxylated nitrile latex to be used in combination, enhancing the compressive strength, splitting tensile strength, and permeability coefficient of the environmentally friendly permeable concrete.

[0118] The compressive strength and splitting tensile strength of the environmentally friendly permeable concrete in Example 13 are superior to those in Comparative Example 1, indicating that modified bamboo fiber has a better compatibility effect in environmentally friendly permeable concrete compared to bamboo leaf fiber. This may be because bamboo leaf fiber is lighter than water, making it prone to floating on top of the slurry in environmentally friendly permeable concrete, leading to uneven dispersion of the bamboo leaf fiber during the slurry molding process. Modified bamboo fiber forms a layer of siloxane polymer on its surface, which, on the one hand, increases the specific gravity of the bamboo fiber, resulting in more uniform dispersion of the bamboo leaf fiber in the concrete; on the other hand, when the environmentally friendly permeable concrete is subjected to external forces, the siloxane polymer increases the interaction force between the bamboo fiber and the concrete structure, weakening the force on the bamboo leaf fiber and making the stress on the bamboo leaf fiber more uniform, thereby improving the compressive strength and splitting tensile strength of the environmentally friendly permeable concrete.

[0119] Compared with the test results of Comparative Example 3, Comparative Example 4 shows that without the use of modified bamboo leaf fiber, the compressive strength of environmentally friendly permeable concrete increases, while the splitting tensile strength and permeability coefficient decrease.

[0120] The compressive strength and splitting tensile strength of the environmentally friendly permeable concrete in Example 13 are better than those in Comparative Example 2. This may be because the styrene-acrylic emulsion does not contain carbon-carbon double bonds, which weakens the interaction between the modified bamboo fiber and other raw materials of the environmentally friendly permeable concrete, resulting in a poorer synergistic effect.

[0121] The experimental results of Comparative Examples 1 and 5, and the results of Example 13 and Comparative Example 3, show that compared with bamboo leaf fiber, the environmentally friendly permeable concrete using modified bamboo leaf fiber without the use of carboxylated nitrile latex and silane coupling agent has a more significant decrease in compressive strength and splitting tensile strength. This indicates that the compatibility effect between modified bamboo leaf fiber, carboxylated nitrile latex and silane coupling agent is better than that between bamboo leaf fiber, carboxylated nitrile latex and silane coupling agent.

[0122] The compressive strength and splitting tensile strength of the environmentally friendly permeable concrete in Examples 1-3 are superior to those in Examples 4-8. This indicates that the raw materials used to prepare the siloxane polymer, including vinyl silicone oil, hydrogen-containing silicone oil, and terminal hydrogen silicone oil, as well as the preferred amounts of vinyl silicone oil, hydrogen-containing silicone oil, and terminal hydrogen silicone oil, and the preferred molar ratio of silane groups to vinyl groups, improve the compressive strength, splitting tensile strength, and permeability coefficient of the environmentally friendly permeable concrete. This may be because the use of vinyl silicone oil, hydrogen-containing silicone oil, and terminal hydrogen silicone oil not only forms a better network structure on the surface of bamboo fiber, but also allows the vinyl groups in the network structure to be linked together with the carboxylated nitrile latex through the hydrogen-containing silicone oil microcapsules, further enhancing the synergistic effect between the modified bamboo leaf fiber and other raw materials of the environmentally friendly permeable concrete, thereby increasing the compressive strength and splitting tensile strength of the environmentally friendly permeable concrete.

[0123] The compressive strength and splitting tensile strength of the environmentally friendly permeable concrete in Examples 1-3 are better than those in Examples 9-13. This may be because the wall material of the hydrogen-containing silicone oil microcapsules is made of polylactic acid and polyvinyl alcohol. During the curing process of the environmentally friendly permeable concrete, the wall material formed by the reaction of polylactic acid and polyvinyl alcohol undergoes hydrolysis and / or degradation under the action of heat and water released during the curing process. The hydrogen-containing silicone oil released by the hydrogen-containing silicone oil microcapsules can react well with carboxylated nitrile latex and modified bamboo leaf fiber, thereby enhancing the compressive strength and splitting tensile strength of the environmentally friendly permeable concrete.

[0124] When the wall material of the hydrogen-containing silicone oil microcapsules is chitosan and β-cyclodextrin, the hydrogen-containing silicone oil in the microcapsules cannot be released in time, resulting in less reaction between the hydrogen-containing silicone oil and carboxylated nitrile latex and modified bamboo leaf fiber. This leads to insufficient reinforcement of the compressive strength and splitting tensile strength of the environmentally friendly permeable concrete by the hydrogen-containing silicone oil microcapsules.

[0125] In Example 11, dodecylphenol polyoxyethylene ether was used to encapsulate hydrogen-containing silicone oil to form micelles. The interaction between dodecylphenol polyoxyethylene ether and hydrogen-containing silicone oil was weak. During long-term stirring or high-temperature processes, the micelles were prone to rupture, causing the hydrogen-containing silicone oil to be contaminated by water. This resulted in insufficient reinforcement of the compressive strength and splitting tensile strength of the environmentally friendly permeable concrete by the hydrogen-containing silicone oil microcapsules.

[0126] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. An environmentally friendly permeable concrete, characterized in that, By weight, it includes 200-300 parts cement, 100-200 parts medium sand, 50-150 parts aggregate, 3.5-5 parts modified bamboo leaf fiber, 8-15 parts carboxylated nitrile latex, 3-5 parts silane coupling agent and 100-200 parts water. The preparation process of the modified bamboo leaf fiber is as follows: Mixture A is formed by mixing 3-5 parts by weight of vinyl silicone oil, 0.8-1.4 parts by weight of hydrogen-containing silicone oil, 1-1.4 parts by weight of terminal hydrogen silicone oil, and 0.0006-0.001 parts by weight of platinum coordinated with divinyltetramethylsiloxane as a thermal catalyst under stirring at 400-800 rpm. 0.43-1.0 parts by weight of sodium alginate and 35-85 parts by weight of 10wt% NaOH solution are mixed and heated to 60-70℃ and stirred for 20-30 min. Then, 21.6-50.7 parts by weight of bamboo leaf fiber are added, the temperature is raised to 80-85℃, the mixture is stirred and reacted for 1 h, and then cooled to prepare the pretreated mixture. The pH of the pretreated mixture was adjusted to 5-6 with dilute acid, and then 1.3-3.2 parts by weight of polyoxyethylene alkylamine and mixture A were added. The mixture was heated to 80-90℃ and stirred for 2 hours. After filtration, washing and drying, modified bamboo leaf fiber was obtained. The chemical formula of the hydrogen-containing silicone oil is: ； In the chemical formula, x is an integer ≥ 1, and y is an integer ≥ 3; The mass ratio of bamboo leaf fiber to mixture A is (4.5-6.5):1; The molar ratio of hydroxyl groups to vinyl groups in the mixture A is (0.82-0.91):1, and the environmentally friendly permeable concrete also includes 4-8 parts by weight of hydrogen-containing silicone oil microcapsules. The preparation process of the hydrogen-containing silicone oil microcapsules is as follows: A polyvinyl alcohol solution is prepared by adding a nonionic surfactant with a mass concentration of 2%-3% to an aqueous solution of polyvinyl alcohol at 40-50℃ and stirring the mixture. Adding hydrogen-containing silicone oil to 5%-8% of polylactic acid dichloromethane primary emulsion yields a hydrogen-containing silicone oil emulsion with a mass concentration of 7%-10%. Hydrogen-containing silicone oil emulsion, polyvinyl alcohol solution, and 3-6% isopropanol aqueous solution were mixed at a mass ratio of 1:1:1 and ultrasonically emulsified for 30-40 minutes. Then, the mixture was stirred at 85-90℃ for 2 hours, followed by centrifugation and washing of the product with distilled water to prepare hydrogen-containing silicone oil microcapsules.

2. The environmentally friendly permeable concrete according to claim 1, characterized in that, The silane coupling agent is one of γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, phenylamino-silane, triaminosilane, γ-mercaptopropyltrimethoxysilane, γ-ureapropyltrimethoxysilane, γ-ureapropyltrihexyloxysilane, γ-methacryloyloxypropyltrimethoxysilane, and γ-glycidyl etheryltrimethoxysilane.

3. The environmentally friendly permeable concrete according to claim 1, characterized in that, The environmentally friendly permeable concrete also includes 1-3 parts by weight of water-reducing agent.

4. The environmentally friendly permeable concrete according to claim 1, characterized in that, The environmentally friendly permeable concrete also includes 1-3 parts by weight of stabilizer.

5. The environmentally friendly permeable concrete according to claim 1, characterized in that, The aggregate has a particle size of 3-12 mm; the medium sand has a particle size of 0.16-2.5 mm.

6. A method for preparing the environmentally friendly permeable concrete according to any one of claims 1-5, characterized in that, Its preparation method is as follows: (1) Under normal temperature conditions, water, carboxylated nitrile latex, hydrogen-containing silicone oil microcapsules and silane coupling agent are added to cement under stirring conditions of 150-250 r / min to prepare a premix. (2) Under normal temperature conditions, medium sand, aggregate, and modified bamboo leaf fiber are added to the premix at a stirring rate of 150-250 r / min to prepare the slurry for environmentally friendly permeable concrete. (3) Under normal temperature conditions, maintain the stirring speed of 150-250r / min to mix the slurry of environmentally friendly permeable concrete; After being mixed evenly, the slurry of the environmentally friendly permeable concrete is laid and cured to form environmentally friendly permeable concrete.

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