Preparation method of concrete based on renewable lightweight aggregate and concrete

Abstract

The invention provides a preparation method of concrete based on renewable lightweight aggregate and the concrete, and belongs to the technical field of concrete preparation, the preparation method comprises the steps of preparation of tea residue derived porous carbon, preparation of a composite phase change material, modification treatment of the renewable lightweight aggregate and preparation of the concrete, the tea phase-change composite phase-change material and the modified recycled lightweight aggregate are added for preparing the concrete, so that the compressive strength, the breaking strength and the impact resistance of the concrete can be improved, the stability and the reliability of a concrete structure are enhanced, the service life of the concrete is prolonged, and the mechanical property of the concrete is improved. The concrete based on the renewable lightweight aggregate is prepared through the preparation method of the concrete based on the renewable lightweight aggregate, the strength of the concrete is obviously improved, the stability and reliability are improved, the service life is prolonged, and the mechanical property is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of concrete preparation, and more specifically, relates to a preparation method of concrete based on renewable lightweight aggregates and the concrete. Background Art

[0002] As one of the most widely used structural materials in modern construction projects, the performance and sustainability of concrete have a profound impact on the development of the construction industry. With the increasing global attention to environmental protection and sustainable resource utilization, the development of high-performance and green concrete materials has become a research hotspot and development trend in the field of building materials.

[0003] Traditional concrete mainly uses ordinary sand and gravel as aggregates. The over-exploitation of natural sand has led to a series of ecological and environmental problems, such as river ecological damage, coastline erosion, etc. At the same time, the exploitation of natural stone also consumes a large amount of non-renewable resources, and the exploitation process causes great damage to the environment, including land resource occupation, vegetation damage, and dust pollution, etc.

[0004] As a new type of building material, lightweight aggregate concrete effectively reduces the self-weight of concrete by using lightweight aggregates to replace part or all of the traditional sand and gravel aggregates, and at the same time improves the thermal insulation performance of concrete to a certain extent. Common lightweight aggregates include natural lightweight aggregates, artificial lightweight aggregates, and industrial waste lightweight aggregates. However, in the preparation process of these lightweight aggregates, some still have problems such as high energy consumption and certain environmental pollution, and the source stability of some industrial waste lightweight aggregates is limited.

[0005] With the in-depth implementation of the concept of sustainable development, the application of renewable materials in concrete has gradually attracted attention. The emergence of renewable lightweight aggregates provides a new way to solve the resource and environmental problems of traditional concrete. Renewable lightweight aggregates usually come from waste building materials, agricultural and forestry waste, etc. Through reasonable processing, these waste materials are transformed into lightweight aggregates with certain properties for the preparation of concrete. This method not only realizes the resource utilization of waste materials, reduces the dependence on natural resources, and reduces environmental pollution. However, there are still many deficiencies in the existing recycled aggregate concrete technology. For example, micro-cracks will be generated during the crushing process of recycled aggregates, and their surfaces are rough, porous, and have high water absorption, resulting in a decrease in the strength of concrete.

[0006] In summary, developing a high-strength concrete based on renewable lightweight aggregates and its preparation method has important practical significance and broad application prospects. Summary of the Invention

[0007] The purpose of the present invention is to provide a preparation method of concrete based on renewable lightweight aggregates and the concrete, aiming to solve the technical problem of low strength of the existing concrete prepared by recycled aggregates.

[0008] To achieve the above object, the technical solution adopted by the present invention is: to provide a preparation method of concrete based on renewable lightweight aggregate, including the following steps: S1: Preparation of tea residue-derived porous carbon; The tea residue soaked in anhydrous ethanol is subjected to hydrothermal carbonization and then carbonized in an argon environment to prepare tea residue-derived porous carbon; S2: Preparation of composite phase change material; The tea residue-derived porous carbon and carbon nanotubes are ultrasonically mixed, and then polyethylene glycol is added to the mixture for mixing and drying to obtain a composite phase change material; S3: Modification treatment of recycled lightweight aggregate; An inorganic modifier is prepared by mixing portland cement, silica fume and sodium silicate, and sodium methyl silicate solution is used as an organic modifier. First, the recycled coarse aggregate is sprayed with the inorganic modifier, and after curing and air drying, the cured recycled coarse aggregate is sprayed with the organic modifier to prepare the modified recycled lightweight aggregate; S4: Preparation of concrete; It is prepared according to the following mass fraction ratio: 240-392 parts of ordinary portland cement, 120-224 parts of fly ash, 24-56 parts of silica fume, 538-651 parts of modified recycled lightweight aggregate, 135-147 parts of composite phase change material, 6-35 parts of hollow glass microspheres, 5-13 parts of plastic steel fiber, 4-14 parts of high-range water reducer, and 98-139 parts of water. Using the above components as raw materials, concrete is prepared.

[0009] In a possible implementation manner, in the preparation of the tea residue-derived porous carbon in step S1, the following steps are included: S1.1: After cleaning the tea residue with deionized water, soak it in anhydrous ethanol for 10-12 h. The soaked tea residue is subjected to hydrothermal carbonization at a temperature of 200-230 °C for 8-12 h, washed 2-3 times with anhydrous ethanol, and then dried at a temperature of 80-90 °C to obtain a dried product; S1.2: The dried product is carbonized in a tubular furnace in an argon environment and then cooled to room temperature to obtain tea residue-derived porous carbon.

[0010] In a possible implementation manner, in step S1.2, the carbonization parameters are to heat up to 350-400 °C at a rate of 5-8 °C / min, and then keep warm for 2-3 h; then heat up to 700-720 °C at a rate of 3-5 °C / min, and then keep warm for 2-3 h.

[0011] In a possible implementation manner, in the preparation of the composite phase change material in step S2, the following steps are included: S2.1: Add 0.5 - 0.8 parts by weight of tea residue-derived porous carbon to 500 - 520 parts by weight of absolute ethanol, then perform ultrasonic mixing treatment at a power of 300 - 320 W for 12 - 14 h. After that, add 0.5 - 0.8 parts by weight of carbon nanotubes and continue ultrasonic mixing treatment for 10 - 12 h. After drying, obtain a mixture of tea residue-derived porous carbon and carbon nanotubes; S2.2: Mix 10 - 12 parts by weight of the mixture of tea residue-derived porous carbon and carbon nanotubes with 5 - 8 parts by weight of polyethylene glycol, add 15 - 18 parts by weight of absolute ethanol, then stir and mix in a constant temperature water bath at 70 - 75 °C for 1 - 2 h. After that, place the mixed solution in an oven at 80 - 85 °C for drying for 10 - 12 h to obtain a composite phase change material.

[0012] In a possible implementation, the modification treatment of the recycled lightweight aggregate in step S3 includes the following steps: S3.1: Stir and mix 100 - 120 parts by weight of water with 100 - 120 parts by weight of portland cement, then add 8 - 10 wt% of silica fume and 20 - 30 wt% of water glass to the system, and stir and mix for 1 - 2 h to obtain an inorganic modifier. Add sodium methyl silicate to deionized water and stir and mix for 30 - 40 min to obtain a sodium methyl silicate solution with a concentration of 8 - 10%, which is the organic modifier; S3.2: Spray the recycled coarse aggregate with the inorganic modifier at a spraying flow rate of 4 - 5 mL / s for 10 - 20 s, and perform the spraying cycle 2 - 3 times. After being treated with the inorganic modifier, cure for 7 - 8 d, and after curing, air dry. Then spray the cured recycled coarse aggregate with the organic modifier at a spraying flow rate of 4 - 5 mL / s for 10 - 20 s, and perform the spraying cycle 2 - 3 times. Finally, air dry at room temperature for 7 - 9 d to obtain the modified recycled coarse aggregate.

[0013] In a possible implementation, the preparation of the concrete in step S4 includes the following steps: S4.1: Mix 538 - 651 parts by weight of pretreated recycled lightweight aggregate, 240 - 392 parts by weight of portland cement, 120 - 224 parts by weight of fly ash, and 6 - 35 parts by weight of hollow glass microspheres evenly to obtain a mixture; S4.2: Then add 98 - 139 parts by weight of water and 4 - 14 parts by weight of high-range water reducer to the mixture, stir evenly, then add 5 - 13 parts by weight of plastic-steel fiber and 135 - 147 parts by weight of composite phase change material, and continue to stir for 2 - 3 h to obtain a concrete slurry; S4.3: Pour the concrete slurry into a mold for static treatment to obtain a concrete embryo, and place the concrete embryo in a curing room for curing to obtain the concrete.

[0014] In a possible implementation, in step S4.2, the high-range water reducer is a polycarboxylate-based water reducer.

[0015] In a possible implementation, in step S4.3, the temperature for static curing is 25 - 27 °C, the humidity is 42 - 43%, and the time is 30 - 40 h.

[0016] In a possible implementation, in step S4.3, the concrete is cured for 28 - 30 d in an environment where the curing parameter temperature is 20 - 23 °C and the humidity is 93 - 95%.

[0017] The present invention also provides a concrete based on renewable lightweight aggregate, which is prepared by the preparation method of a concrete based on renewable lightweight aggregate described in any one of the above.

[0018] The preparation method of a concrete based on renewable lightweight aggregate provided by the present invention and the beneficial effects of the concrete are as follows: Compared with the prior art, 1) A composite phase change material is added to the concrete. The tea residue-derived porous carbon in the composite phase change material has a porous structure, a large specific surface area and adsorption capacity, and can adsorb the excess water generated during the cement hydration process in the concrete, regulate the humidity environment inside the concrete, contribute to the full hydration of cement, and improve the strength and durability of the concrete; Carbon nanotubes have extremely high strength and modulus, and when added to the concrete, they can play a role in enhancing toughness, effectively improving the compressive strength, flexural strength and impact resistance of the concrete, enhancing the stability and reliability of the concrete structure, and extending the service life of the concrete; Adding polyethylene glycol to the concrete can endow the concrete with phase change energy storage function, which can absorb or release heat when the temperature changes, play a role in regulating the internal temperature of the concrete, reduce temperature stress, and improve the crack resistance of the concrete; The composite material formed by tea residue-derived porous carbon, carbon nanotubes and polyethylene glycol has a synergistic effect among its components, exerting more excellent performance than single materials, and improving the mechanical properties of the concrete. 2) The gel substances generated by cement hydration in the modified recycled lightweight aggregate can fill the pores and microcracks on the surface and inside of the recycled lightweight aggregate; Silica fume has high activity and can undergo a secondary hydration reaction with the calcium hydroxide in the cement hydration products to generate more gel substances, refine the pores and enhance the interfacial bond; Sodium silicate can improve the bonding performance of the paste, make the interfacial transition zone between the recycled lightweight aggregate and the fresh concrete denser, thereby improving the overall strength of the concrete. After the inorganic modifier is sprayed and cured, it can penetrate into the interior of the recycled lightweight aggregate and react with the active components therein to generate new hydration products. These products fill the defects inside the aggregate, enhance the compactness of the aggregate itself, enable the aggregate to better transmit stress when bearing loads, and improve the strength of the concrete. After spraying the organic modifier sodium methyl silicate solution, a hydrophobic protective film can be formed on the surface of the recycled lightweight aggregate. On the one hand, this protective film can prevent water from entering the interior of the aggregate and reduce the internal structure damage caused by water migration; On the other hand, it can improve the bonding force between the aggregate and the cement stone. When the concrete is loaded, the cooperative working ability between the aggregate and the cement stone is enhanced, further improving the strength of the concrete. The hydrophobic film formed by the organic modifier can also prevent the intrusion of water and harmful ions, significantly improving the impermeability of the concrete, thereby enhancing the durability of the concrete. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0020] Figure 1 This is a flowchart of a preparation method of concrete based on renewable lightweight aggregate provided by an embodiment of the present invention. Detailed implementation manners

[0021] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0022] Please refer to Figure 1 simultaneously, and a preparation method of concrete based on renewable lightweight aggregate provided by the present invention will be described. The preparation method of the concrete based on renewable lightweight aggregate includes the following steps: S1: Preparation of tea residue-derived porous carbon; The tea residue soaked with absolute ethanol is subjected to hydrothermal carbonization, and then carbonized in an argon atmosphere to prepare tea residue-derived porous carbon; S2: Preparation of composite phase change material; The tea residue-derived porous carbon and carbon nanotubes are ultrasonically mixed, and then polyethylene glycol is added to the mixture for mixing and drying to obtain a composite phase change material; S3: Modification treatment of recycled lightweight aggregate; An inorganic modifier is prepared by mixing portland cement, silica fume and water glass, and sodium methyl silicate solution is used as an organic modifier. The recycled coarse aggregate is first sprayed with the inorganic modifier, and after curing and air drying, the cured recycled coarse aggregate is sprayed with the organic modifier to prepare the modified recycled lightweight aggregate; S4: Preparation of concrete; It is prepared according to the following component ratios by mass: 240 - 392 parts of ordinary portland cement, 120 - 224 parts of fly ash, 24 - 56 parts of silica fume, 538 - 651 parts of modified recycled lightweight aggregate, 135 - 147 parts of composite phase change material, 6 - 35 parts of hollow glass microspheres, 5 - 13 parts of plastic steel fibers, 4 - 14 parts of high-range water reducer, and 98 - 139 parts of water. The above components are used as raw materials to prepare concrete.

[0023] Example 1 A preparation method of concrete based on renewable lightweight aggregate, please refer to Figure 1 simultaneously, and includes the following steps: S1: Preparation of tea residue-derived porous carbon S1.1: After cleaning the tea dregs with deionized water, soak them in absolute ethanol for 10 h. Hydrothermally carbonize the soaked tea dregs at 200 °C for 8 h, wash them twice with absolute ethanol, and then dry them at 80 °C to obtain a dried product. S1.2: Carbonize the dried product in an argon atmosphere in a tube furnace. The parameters are as follows: heat up to 350 °C at a rate of 5 °C / min and hold for 2 h; then heat up to 700 °C at a rate of 3 °C / min and hold for 2 h, and then cool to room temperature to obtain tea dregs-derived porous carbon. S2: Preparation of composite phase change material S2.1: Add 0.5 parts by weight of tea dregs-derived porous carbon to 500 parts by weight of absolute ethanol, then ultrasonically treat it at 300 W for 12 h, then add 0.5 parts by weight of carbon nanotubes, and continue ultrasonic treatment for 10 h. After drying, obtain a mixture of tea dregs-derived porous carbon and carbon nanotubes. S2.2: Mix 10 parts by weight of the mixture of tea dregs-derived porous carbon and carbon nanotubes and 5 parts by weight of polyethylene glycol, then add 15 parts by weight of absolute ethanol, and then stir and mix in a constant temperature water bath at 70 °C for 1 h. Then place the mixed solution in a drying oven at 80 °C and dry for 10 h to obtain the composite phase change material. S3: Modification treatment of recycled lightweight aggregate S3.1: Stir and mix 100 parts by weight of water and 100 parts by weight of P.O42.5 portland cement, then add 8 wt% silica fume and 20 wt% water glass to the system, and stir and mix for 1 h to obtain an inorganic modifier. Add sodium methyl silicate to deionized water and stir and mix for 30 min to obtain an 8% sodium methyl silicate solution, which is the organic modifier. S3.2: Spray the recycled coarse aggregate with the inorganic modifier at a spraying flow rate of 4 mL / s for 10 s, and spray 2 cycles. After being treated with the inorganic modifier, cure for 7 d, and after curing, air-dry. Then spray the cured recycled coarse aggregate with the organic modifier at a spraying flow rate of 4 mL / s for 10 s, and spray 2 cycles. Finally, air-dry at room temperature for 7 d to obtain the modified recycled lightweight aggregate. S4: Preparation of concrete S4.1: Mix 538 parts by weight of pretreated recycled lightweight aggregate, 240 parts by weight of P.O52.5 grade ordinary portland cement, 120 parts by weight of fly ash, and 6 parts by weight of hollow glass microspheres evenly to obtain a mixture. S4.2: Then add 98 parts by weight of water and 4 parts by weight of water reducer to the mixture, stir evenly, then add 5 parts by weight of plastic-steel fiber and 135 parts by weight of composite phase change material and continue to stir for 2 h to obtain a concrete slurry. S4.3: Pour the concrete slurry into a mold for static treatment. The static temperature is 25 °C, the humidity is 42%, and the time is 30 h to obtain a concrete embryo. Place the concrete embryo in a curing room and cure it for 28 d in an environment of 20 °C and 93% humidity to obtain concrete.

[0024] Example 2 A preparation method of concrete based on renewable lightweight aggregates is as Figure 1 shown, and includes the following steps: S1: Preparation of tea residue-derived porous carbon S1.1: Clean the tea residue with deionized water, soak it in absolute ethanol for 10 h, hydrothermally carbonize the soaked tea residue at 200 °C for 8 h, wash it with absolute ethanol twice, and dry it at 80 °C to obtain a dried product; S1.2: Carbonize the dried product in an argon atmosphere in a tube furnace. The parameters are to heat it up to 400 °C at a rate of 5 °C / min and hold for 2 h; then heat it up to 700 °C at a rate of 3 °C / min and hold for 2 h, and then cool it to room temperature to obtain tea residue-derived porous carbon; S2: Preparation of composite phase change material S2.1: Add 0.8 parts by weight of tea residue-derived porous carbon to 520 parts by weight of absolute ethanol, then ultrasonically treat it at 300 W for 12 h, then add 0.8 parts by weight of carbon nanotubes, continue to ultrasonically treat for 10 h, and after drying, obtain a mixture of tea residue-derived porous carbon and carbon nanotubes; S2.2: Mix 20 parts by weight of the mixture of tea residue-derived porous carbon and carbon nanotubes and 5 - 8 parts by weight of polyethylene glycol, add 18 parts by weight of absolute ethanol, then stir and mix in a constant temperature water bath at 70 °C for 1 h, and then place the mixed solution in an 80 °C drying oven and dry it for 10 h to obtain a composite phase change material; S3: Modification treatment of recycled lightweight aggregates S3.1: Stir and mix 120 parts by weight of water and 120 parts by weight of P.O42.5 portland cement, add 10 wt% of silica fume and 30 wt% of water glass to the system, and stir and mix for 1 h to obtain an inorganic modifier. Add sodium methyl silicate to deionized water and stir and mix for 30 min to obtain a 10% sodium methyl silicate solution, which is an organic modifier; S3.2: Spray the recycled coarse aggregates with the inorganic modifier at a spraying flow rate of 4 mL / s for 10 s, and spray 2 cycles. After treatment with the inorganic modifier, cure for 7 d, air dry after curing, then spray the cured recycled coarse aggregates with the organic modifier at a spraying flow rate of 4 mL / s for 10 s, and spray 2 cycles. Finally, air dry at room temperature for 7 d to obtain modified recycled lightweight aggregates; S4: Preparation of concrete S4.1: Mix 651 parts by weight of pretreated recycled lightweight aggregate, 392 parts by weight of P.O 52.5 ordinary portland cement, 224 parts by weight of fly ash and 35 parts by weight of hollow glass microspheres evenly to obtain a mixture. S4.2: Then add 139 parts by weight of water and 14 parts by weight of water reducer to the mixture. After stirring evenly, add 13 parts by weight of plastic-steel fiber and 147 parts by weight of composite phase change material and continue to stir for 2 h to obtain a concrete slurry. S4.3: Pour the concrete slurry into a mold for static treatment. The static temperature is 25 °C, the humidity is 42%, and the time is 30 h to obtain a concrete embryo. Place the concrete embryo in a curing room and cure it for 28 d in an environment of 20 °C and 93% humidity to obtain concrete.

[0025] Example 3 A preparation method of concrete based on renewable lightweight aggregate, as Figure 1 shown, includes the following steps: S1: Preparation of tea residue-derived porous carbon S1.1: Clean the tea residue with deionized water, soak it in absolute ethanol for 12 h, hydrothermally carbonize the soaked tea residue at 230 °C for 10 h, wash it with absolute ethanol three times and then dry it at 90 °C to obtain a dried product. S1.2: Carbonize the dried product in an argon atmosphere in a tube furnace. The parameters are heating up to 400 °C at a rate of 8 °C / min and holding for 3 h; then heating up to 720 °C at a rate of 5 °C / min and holding for 3 h, and then cooling to room temperature to obtain tea residue-derived porous carbon. S2: Preparation of composite phase change material S2.1: Add 0.5 part by weight of tea residue-derived porous carbon to 500 parts by weight of absolute ethanol, then ultrasonically treat it at 320 W for 14 h, then add 0.5 part by weight of carbon nanotubes and continue to ultrasonically treat for 12 h. After drying, obtain a mixture of tea residue-derived porous carbon and carbon nanotubes. S2.2: Mix 10 parts by weight of the mixture of tea residue-derived porous carbon and carbon nanotubes and 5 parts by weight of polyethylene glycol, add 15 parts by weight of absolute ethanol, then stir and mix in a constant temperature water bath at 75 °C for 2 h, and then place the mixed solution in a drying oven at 85 °C and dry for 12 h to obtain a composite phase change material. S3: Modification treatment of recycled lightweight aggregate S3.1: After mixing 100 parts by weight of water with 100 parts by weight of Portland cement P.O42.5, 8 wt% of silica fume and 20 wt% of water glass are added to the system and stirred for 2 h to obtain an inorganic modifier. Sodium methyl silicate is added to deionized water and stirred for 40 min to obtain a sodium methyl silicate solution with a concentration of 8%, which is the organic modifier. S3.2: Spraying the recycled coarse aggregate with the inorganic modifier at a spraying flow rate of 5 mL / s for 20 s, and repeating the spraying 3 times. After treatment with the inorganic modifier, it is cured for 8 d, air-dried after curing, and then the cured recycled coarse aggregate is sprayed with the organic modifier at a spraying flow rate of 5 mL / s for 20 s, and the spraying is repeated 3 times. Finally, it is air-dried at room temperature for 9 d to obtain the modified recycled lightweight aggregate. S4: Preparation of concrete S4.1: Mix 538 parts by weight of the pretreated recycled lightweight aggregate, 240 parts by weight of Portland cement P.O52.5, 120 parts by weight of fly ash, and 6 parts by weight of hollow glass microspheres evenly to obtain a mixture. S4.2: Then, 98 parts by weight of water and 4 parts by weight of water reducer are added to the mixture, and after stirring evenly, 5 parts by weight of plastic-steel fiber and 135 parts by weight of composite phase change material are added and stirred for another 3 h to obtain a concrete slurry. S4.3: Pour the concrete slurry into a mold for static treatment. The static temperature is 27 °C, the humidity is 43%, and the time is 40 h to obtain a concrete embryo. The concrete embryo is placed in a curing room and cured for 30 d at 23 °C and a humidity of 95% to obtain the concrete.

[0026] Comparative Example 1 Compared with Example 1, the difference in Comparative Example 1 is that Comparative Example 1 removes steps S1 - S2 and the composite phase change material in step S4.2, and the concrete is prepared with the remaining steps unchanged, denoted as Comparative Example 1.

[0027] Comparative Example 2 Compared with Example 1, the difference in Comparative Example 2 is that Comparative Example 2 removes step S3, replaces the pretreated recycled lightweight aggregate in step S4.1 with recycled lightweight aggregate, and the concrete is prepared with the remaining steps unchanged, denoted as Comparative Example 2.

[0028] The compressive strength and flexural strength of the concrete prepared in Examples 1 - 3 and Comparative Examples 1 - 2 are measured with reference to relevant national standards, and the measurement results are shown in Table 1.

[0029] Table 1. Strength measurement results of Examples 1 - 3 and Comparative Examples 1 - 2 As can be seen from the data in Table 1, the concrete prepared by the present invention has good strength. From the data of Comparative Example 1 and Comparative Example 2, it can be seen that both the composite phase change material and the modified recycled lightweight aggregate added in the present invention can effectively improve the strength of the concrete.

[0030] In some embodiments, in step S1.2, the carbonization parameters are heating to 350 - 400 °C at a rate of 5 - 8 °C / min, and then holding for 2 - 3 h; subsequently heating to 700 - 720 °C at a rate of 3 - 5 °C / min, and then holding for 2 - 3 h. In step S4.2, the high - efficiency water - reducing agent is a polycarboxylate - based water - reducing agent. In step S4.3, the static temperature is 25 - 27 °C, the humidity is 42 - 43%, and the time is 30 - 40 h. In step S4.3, the curing parameters are curing for 28 - 30 d in an environment with a temperature of 20 - 23 °C and a humidity of 93 - 95%.

[0031] The present invention also provides a concrete based on recycled lightweight aggregate, and the concrete is prepared by the preparation method of a concrete based on recycled lightweight aggregate described in any one of the above.

[0032] The beneficial effects of the concrete based on recycled lightweight aggregate of the present invention refer to the beneficial effects of the preparation method of the concrete based on recycled lightweight aggregate as above, and will not be elaborated here.

[0033] Ultrasonic mixing is a technology that uses ultrasonic energy for material mixing. The high - frequency sound waves generated by the ultrasonic generator propagate through the medium, generating vibration energy, forming a cavitation effect in the liquid, and enabling the materials to be quickly and evenly mixed, dispersed, or emulsified in the liquid.

[0034] Silica fume is an ultra - fine silica powder material produced in a high - temperature environment, mainly derived from the ultra - fine dust generated during the smelting of silicon metal or ferrosilicon alloy. Its particle size is extremely fine, usually less than 1 micron, and it appears as a gray or off - white powder in appearance, with a refractoriness of over 1600 °C. It has unique physical and chemical properties and plays an irreplaceable role especially in ultra - high - performance concrete (UHPC) and refractory materials.

[0035] Sodium silicate, also known as water glass, is a water - soluble alkaline silicate material, usually existing in the form of a colorless or slightly yellowish transparent liquid or solid.

[0036] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A preparation method of concrete based on renewable lightweight aggregate, characterized in that, It includes the following steps: S1: Preparation of tea residue-derived porous carbon; The tea residue soaked in absolute ethanol is hydrothermally carbonized and then carbonized in an argon environment to prepare tea residue-derived porous carbon; S2: Preparation of composite phase change material; The tea residue-derived porous carbon and carbon nanotubes are ultrasonically mixed, and then polyethylene glycol is added to the mixture for mixing and drying to obtain a composite phase change material; S3: Modification treatment of recycled lightweight aggregate; An inorganic modifier is prepared by mixing portland cement, silica fume and water glass, and sodium methyl silicate solution is used as an organic modifier. First, the recycled coarse aggregate is sprayed with the inorganic modifier, and after curing and air drying, the cured recycled coarse aggregate is sprayed with the organic modifier to prepare the modified recycled lightweight aggregate; S4: Preparation of concrete; It is prepared according to the following mass parts ratio: 240-392 parts of ordinary portland cement, 120-224 parts of fly ash, 24-56 parts of silica fume, 538-651 parts of modified recycled lightweight aggregate, 135-147 parts of composite phase change material, 6-35 parts of hollow glass microspheres, 5-13 parts of plastic steel fiber, 4-14 parts of high-range water reducer, 98-139 parts of water. Using the above components as raw materials, concrete is prepared.

2. The preparation method of a kind of concrete based on renewable lightweight aggregate according to claim 1, characterized in that, In the preparation of the tea residue-derived porous carbon in step S1, it includes the following steps: S1.1: After cleaning the tea residue with deionized water, soak it in absolute ethanol for 10-12 h. The soaked tea residue is hydrothermally carbonized at a temperature of 200-230 °C for 8-12 h, washed 2-3 times with absolute ethanol, and then dried at a temperature of 80-90 °C to obtain a dried product; S1.2: The dried product is carbonized in a tubular furnace in an argon environment and then cooled to room temperature to obtain tea residue-derived porous carbon.

3. The preparation method of a kind of concrete based on renewable lightweight aggregate according to claim 2, characterized in that, In step S1.2, the carbonization parameters are to heat up to 350-400 °C at a rate of 5-8 °C / min, and then keep the temperature for 2-3 h; then heat up to 700-720 °C at a rate of 3-5 °C / min, and then keep the temperature for 2-3 h.

4. The preparation method of a kind of concrete based on renewable lightweight aggregate according to claim 1, characterized in that, In the preparation of the composite phase change material in step S2, it includes the following steps: S2.1: Add 0.5-0.8 parts by weight of tea residue-derived porous carbon to 500-520 parts by weight of absolute ethanol, and then carry out ultrasonic mixing treatment at a power of 300-320 W for 12-14 h. Then add 0.5-0.8 parts by weight of carbon nanotubes and continue ultrasonic mixing treatment for 10-12 h. After drying, a mixture of tea residue-derived porous carbon and carbon nanotubes is obtained; S2.2: Mix 10-12 parts by weight of the mixture of tea residue-derived porous carbon and carbon nanotubes and 5-8 parts by weight of polyethylene glycol, add 15-18 parts by weight of absolute ethanol, and then stir and mix in a constant temperature water bath at a temperature of 70-75 °C for 1-2 h. Then place the mixed solution in a drying oven at a temperature of 80-85 °C for drying for 10-12 h to obtain a composite phase change material.

5. The preparation method of a concrete based on renewable lightweight aggregate according to claim 1, characterized in that, In the modification treatment of the recycled lightweight aggregate in step S3, it includes the following steps: S3.1: After stirring and mixing 100 - 120 parts by weight of water and 100 - 120 parts by weight of Portland cement, 8 - 10 wt% of silica fume and 20 - 30 wt% of water glass are added to the system, and stirred and mixed for 1 - 2 h to obtain an inorganic modifier. Sodium methyl silicate is added to deionized water and stirred and mixed for 30 - 40 min to obtain a sodium methyl silicate solution with a concentration of 8 - 10%, which is the organic modifier. S3.2: The recycled coarse aggregate is sprayed with the inorganic modifier at a spraying flow rate of 4 - 5 mL / s for 10 - 20 s, and the spraying cycle is 2 - 3 times. After being treated with the inorganic modifier, it is cured for 7 - 8 d, and then air-dried. Then, the recycled coarse aggregate after curing is sprayed with the organic modifier at a spraying flow rate of 4 - 5 mL / s for 10 - 20 s, and the spraying cycle is 2 - 3 times. Finally, it is air-dried at room temperature for 7 - 9 d to obtain the modified recycled coarse aggregate.

6. The preparation method of a kind of concrete based on renewable lightweight aggregate according to claim 1, characterized in that, In the preparation of the concrete in step S4, the following steps are included: S4.1: 538 - 651 parts by weight of pretreated recycled lightweight aggregate, 240 - 392 parts by weight of Portland cement, 120 - 224 parts by weight of fly ash, and 6 - 35 parts by weight of hollow glass microspheres are mixed and stirred evenly to obtain a mixture. S4.2: Then, 98 - 139 parts by weight of water and 4 - 14 parts by weight of high-range water reducer are added to the mixture. After stirring evenly, 5 - 13 parts by weight of plastic-steel fiber and 135 - 147 parts by weight of composite phase change material are added, and stirring continues for 2 - 3 h to obtain a concrete slurry. S4.3: The concrete slurry is poured into a mold for static treatment to obtain a concrete embryo, and the concrete embryo is placed in a curing room for curing to obtain the concrete.

7. The preparation method of a concrete based on renewable lightweight aggregate according to claim 6, characterized in that In step S4.2, the high-range water reducer is a polycarboxylate-based water reducer.

8. The preparation method of a kind of concrete based on renewable lightweight aggregate according to claim 6, characterized in that, In step S4.3, the temperature for static treatment is 25 - 27 °C, the humidity is 42 - 43%, and the time is 30 - 40 h.

9. The preparation method of a concrete based on renewable lightweight aggregate according to claim 6, characterized in that, In step S4.3, the curing parameters are curing for 28 - 30 d in an environment with a temperature of 20 - 23 °C and a humidity of 93 - 95%.

10. A concrete based on renewable lightweight aggregate, characterized in that, It is prepared by the preparation method of a kind of concrete based on recycled lightweight aggregate described in any one of claims 1 - 9.

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