Environment-friendly lightweight aggregate concrete and preparation method thereof

Abstract

The invention relates to the technical field of concrete, in particular to environment-friendly lightweight aggregate concrete and a preparation method thereof. The environment-friendly lightweight aggregate concrete provided by the invention comprises the following raw materials in parts by weight: 60-70 parts of cement; 15 to 25 parts of modified glass micro powder; 15 to 25 parts of fly ash; 80 to 120 parts of waste brick recycled aggregate; 20 to 40 parts of ceramsite; 0.18 to 0.54 part of waste polypropylene fiber; 25-35 parts of water and 0.9-2.1 parts of a water reducing agent. According to the environment-friendly lightweight aggregate concrete provided by the invention, the modified glass micropowder and the waste polypropylene fiber are added into an original concrete formula, so that the strength and durability of the concrete are improved, and efficient synergistic utilization of three types of construction wastes (waste bricks, glass and polypropylene) can be realized.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete, and particularly relates to an environment-friendly lightweight aggregate concrete and a preparation method thereof. Background Art

[0002] In the process of construction, the construction waste generated due to demolition is increasing day by day, and the contradiction of the ecological environment is also increasing day by day. In the new area, there are relatively more brick-concrete structure houses demolished, and fewer frame structure or shear wall structure houses. The proportion of waste bricks in the generated construction waste will be relatively high. A large amount of construction waste not only occupies a large amount of land, but also causes great harm to the environment. How to deal with a large amount of garbage is also an urgent problem to be solved. As the demand for concrete as an important building material is increasing, and the reserves of qualified aggregates are decreasing, it is becoming more and more difficult to prepare high-performance concrete. Under this background, using recycled aggregates to prepare concrete has become a trend in the industry's development. By efficiently using recycled aggregates, the resource utilization rate can be improved, and the pollution of construction waste to the environment can be reduced.

[0003] With the deepening of the concept of sustainable development, more and more scholars and research institutions have begun to pay attention to this field. Some research results show that recycled aggregates can be used to prepare concrete, and their performance can meet certain requirements. For example, institutions such as the China Academy of Building Research have studied the basic performance of recycled aggregates, and the results show that indicators such as the strength and abrasion resistance of recycled aggregates can meet the requirements. In addition, some places have also started to pilot and promote the application of recycled aggregates. For example, some construction projects in Beijing, Shanghai and other places have started to use recycled aggregates; in the construction of some indemnificatory housing projects in Nanjing, Jiangsu, concrete prepared with construction waste recycled aggregates has been adopted, realizing the resource utilization of construction waste and reducing the project cost; in the construction of a commercial complex in Wenzhou, Zhejiang, concrete prepared with construction waste has been adopted for the pouring of the walls and floors of some buildings.

[0004] However, at present, most of the recycled aggregates of construction waste studied in China are mixed aggregates produced from unclassified construction waste, and there are relatively few application studies on preparing lightweight aggregate concrete with recycled aggregates produced from construction waste mainly composed of waste bricks, which adds certain difficulties to the resource utilization of construction waste mainly composed of waste bricks. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides an environment-friendly lightweight aggregate concrete and a preparation method thereof. By adding modified glass micro-powder and waste polypropylene fibers to the original concrete formula, the strength and durability of the concrete are not only improved, but also the efficient collaborative utilization of three types of construction waste (waste bricks, glass, polypropylene) can be realized.

[0006] To this end, the present invention provides the following technical solutions:

[0007] In a first aspect, in an optional embodiment of the present invention, there is provided an environmentally friendly lightweight aggregate concrete, comprising the following raw materials in parts by weight: 60 - 70 parts of cement; 15 - 25 parts of modified glass powder; 15 - 25 parts of fly ash; 80 - 120 parts of waste brick recycled aggregate; 20 - 40 parts of ceramsite; 0.18 - 0.54 parts of waste polypropylene fiber; 25 - 35 parts of water; and 0.9 - 2.1 parts of water reducing agent.

[0008] In the present invention, SiO2 in the modified glass powder can undergo secondary hydration with the hydration product Ca(OH)2 of cement to generate C-S-H gel, filling the pores of the recycled aggregate and improving the density and compressive strength of the concrete. And the nano-CaCO3 coating layer in the modified glass powder forms a chemical bond with Ca in the cement paste. 2+ After modification, the waste polypropylene fiber is hydrogen-bonded to the C-S-H gel through -OH, and the two act together to improve the bonding strength of the aggregate-cementitious interface and reduce interface damage when stressed.

[0009] The modified glass powder can refine the pore structure of the recycled aggregate and narrow the path of water penetration. The waste polypropylene fiber can block the expansion of concrete cracks, forming a "dense matrix + flexible crack resistance" protection system, reducing the chloride ion penetration coefficient and increasing the number of freeze-thaw cycles. In addition, the nano-CaCO3 layer on the surface of the modified glass powder isolates the alkaline solution from SiO2 in the glass, preventing chemical reactions between the alkaline substances in the concrete and the active mineral components in the aggregate, and improving the long-term durability of the concrete.

[0010] Preferably, the particle size of the waste brick recycled aggregate is 5 - 20 mm; and / or, the length of the waste polypropylene fiber is 12 - 19 mm. The water reducing agent is a polycarboxylate water reducing agent.

[0011] Furthermore, the environmentally friendly lightweight aggregate concrete comprises the following raw materials in parts by weight: 65 parts of cement; 20 parts of modified glass powder; 20 parts of fly ash; 100 parts of waste brick recycled aggregate; 30 parts of ceramsite; 0.3 parts of waste polypropylene fiber; 30 parts of water; and 1.2 parts of water reducing agent.

[0012] In a second aspect, the present invention provides a preparation method of the above-mentioned environmentally friendly lightweight aggregate concrete, comprising the following steps:

[0013] S1: Weigh cement, modified glass powder, fly ash, waste brick recycled aggregate, ceramsite, waste polypropylene fiber, water, and water reducing agent respectively according to parts by weight;

[0014] S2: Then, after stirring cement, modified glass micro-powder, and fly ash, add recycled waste brick aggregates and ceramsite and stir. Then add waste polypropylene fibers and stir. Finally, add water and water reducer and stir to obtain the environmentally friendly lightweight aggregate concrete.

[0015] Preferably, the preparation method of the modified glass micro-powder includes the following steps: After crushing, grinding, and sieving waste glass, add an alkaline solution for activation. Then add a nano-calcium carbonate suspension for ultrasonic dispersion. Finally, perform drying to obtain the modified glass micro-powder.

[0016] In the present invention, the amorphous SiO2 on the surface of the glass micro-powder reacts with the alkaline solution to form soluble silicate, which can undergo a secondary hydration reaction with the cement hydration product Ca(OH)2 in the alkaline environment of the concrete. The hydroxyl groups (-OH) on the surface of nano-CaCO3 and the silanol groups (-SiOH) on the surface of the glass micro-powder form a "nano-bridging" structure through hydrogen bonds or chemical bonding, enhancing the bonding force at the aggregate-cementitious interface.

[0017] Preferably, the mass ratio of the waste glass to the alkaline solution is 1:4 - 6; and / or, the mass-to-volume ratio of the waste glass to the nano-calcium carbonate suspension is 1:8 - 12. The alkaline solution is selected from one or more of sodium hydroxide solution, potassium hydroxide solution, and sodium carbonate solution, and the concentration of the alkaline solution is 5 - 10%; and / or, the mass fraction of nano-calcium carbonate in the nano-calcium carbonate suspension is 5 - 8%. The ultrasonic power of the ultrasonic dispersion is 200 - 400 W, and the ultrasonic dispersion time is 30 - 50 min; and / or, the drying temperature is 80 - 100 °C, and the time is 4 - 6 h.

[0018] Preferably, before adding the waste polypropylene fibers, it further includes a step of modifying the waste polypropylene fibers; the modification method is: After washing the waste polypropylene fibers, add a sodium hydroxide solution for modification, and then wash with water until neutral.

[0019] Among them, the concentration of the sodium hydroxide solution is 5 - 10%, the modification temperature is 55 - 65 °C, and the time is 20 - 30 min.

[0020] Preferably, before adding the recycled waste brick aggregates and ceramsite, it further includes a step of pre-wetting the recycled waste brick aggregates and ceramsite; the pre-wetting method is: Immerse the recycled waste brick aggregates and ceramsite in water for 18 - 36 h to make the water content of the recycled waste brick aggregates and ceramsite between 8 - 12%, and then dry the surfaces of the recycled waste brick aggregates and ceramsite.

[0021] Compared with the prior art, the present invention has one of the following beneficial effects:

[0022] 1. The environmentally friendly lightweight aggregate concrete provided by the present invention not only improves the strength and durability of the concrete by adding modified glass micro-powder and waste polypropylene fibers to the original concrete formula, but also realizes the efficient collaborative utilization of three types of construction waste (waste bricks, glass, and polypropylene). Detailed implementation mode

[0023] In order to make the objectives, technical solutions and advantages of the present invention clearer, the following further details the present invention in combination with specific 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.

[0024] In the following examples and comparative examples, the water reducing agent is a polycarboxylate water reducing agent, purchased from Shandong Huangteng Building Materials Co., Ltd., with the model of HT polycarboxylate high-performance water reducing agent; the ceramsite is purchased from Kunming Xingsheng Ceramsite Factory, with the model of shale ceramsite; the average particle size of the waste brick recycled aggregate is 15 mm; the average length of the waste polypropylene fiber is 16 mm.

[0025] The following will illustrate the technical solutions of the present invention in combination with examples.

[0026] Example 1

[0027] This example provides an environmentally friendly lightweight aggregate concrete, including 65 kg of cement, 20 kg of modified glass micro-powder, 20 kg of fly ash, 100 kg of waste brick recycled aggregate, 30 kg of ceramsite, 0.3 kg of waste polypropylene fiber, 30 kg of water and 1.2 kg of water reducing agent.

[0028] The preparation method of the above-mentioned environmentally friendly lightweight aggregate concrete includes the following steps:

[0029] S1: Crush 100 kg of waste glass into particles ≤10 mm using a crusher, then put the particles into a ball mill and ball mill for 80 min at a rotation speed of 700 rpm to obtain glass micro-powder (D90≤10 μm). Then add the glass micro-powder to 500 kg of a 5% sodium hydroxide solution and react at 70°C for 3 h while stirring (stirring rate is 250 rpm). After the reaction, wash with deionized water 3 - 5 times until the pH value of the filtrate ≤8 to obtain activated glass micro-powder. Then add the activated glass micro-powder to 1000 kg of a nano-calcium carbonate suspension (mass fraction of nano-calcium carbonate is 5%) and stir evenly, then put it into an ultrasonic cleaner for ultrasonic dispersion (power is 300 W, time is 40 min). After ultrasonic dispersion, perform solid-liquid separation with a centrifuge, collect the precipitate, put the precipitate into a blast dryer and dry at 90°C for 5 h. After drying, pass through an 80-mesh sieve to obtain modified glass micro-powder;

[0030] S2: Add waste polypropylene fibers to a detergent with a concentration of 5%, soak at 60°C for 30 min, add the soaked waste polypropylene fibers to a sodium hydroxide solution with a concentration of 5%, modify at 60°C for 25 min, and finally rinse with clean water until neutral.

[0031] S3: Weigh cement, modified glass powder, fly ash, waste brick recycled aggregate, ceramsite, waste polypropylene fibers, water and water reducer according to the above weights. After soaking the waste brick recycled aggregate and ceramsite in water for 24 h to make the moisture content of the waste brick recycled aggregate and ceramsite between 8% - 12%, then dry the surfaces of the waste brick recycled aggregate and ceramsite.

[0032] S4: Add cement, modified glass powder and fly ash into a mixer and stir (rotation speed is 100 rpm) for 30 s, then add the pre - wetted waste brick recycled aggregate and ceramsite and stir (rotation speed is 100 rpm) for 60 s, then add the waste polypropylene fibers obtained in step S2 and stir (rotation speed is 120 rpm) for 90 s, and finally add water and water reducer into the mixer and stir (rotation speed is 80 rpm) for 3 min to obtain concrete.

[0033] Example 2

[0034] This example provides an environmentally friendly lightweight aggregate concrete, including 65 kg of cement, 15 kg of modified glass powder, 20 kg of fly ash, 100 kg of waste brick recycled aggregate, 30 kg of ceramsite, 0.53 kg of waste polypropylene fibers, 30 kg of water and 1.2 kg of water reducer.

[0035] The preparation method of the above - mentioned environmentally friendly lightweight aggregate concrete includes the following steps:

[0036] S1: Crush 100 kg of waste glass into particles with a size of ≤10 mm using a crusher, then put the particles into a ball mill and ball - mill at a rotation speed of 700 rpm for 80 min to obtain glass powder (D90 ≤ 10 μm). Then add the glass powder into 500 kg of a sodium hydroxide solution with a concentration of 5%, react at 70°C for 3 h, and stir during the reaction (stirring rate is 250 rpm). After the reaction, wash with deionized water 3 - 5 times until the pH value of the filtrate ≤ 8 to obtain the activated glass powder. Then add the activated glass powder into 1000 kg of a nano - calcium carbonate suspension (the mass fraction of nano - calcium carbonate is 5%) and stir evenly, then put it into an ultrasonic cleaner for ultrasonic dispersion (power is 300 W, time is 40 min). After ultrasonic dispersion, perform solid - liquid separation with a centrifuge, collect the precipitate, put the precipitate into a blast dryer, dry at 90°C for 5 h, and after drying, pass through an 80 - mesh sieve to obtain modified glass powder.

[0037] S2: Add the waste polypropylene fibers to a detergent solution with a concentration of 5%, soak them at 60°C for 30 min, then add the soaked waste polypropylene fibers to a sodium hydroxide solution with a concentration of 5%, modify them at 60°C for 25 min, and finally rinse with clean water until neutral.

[0038] S3: Weigh the cement, modified glass powder, fly ash, waste brick recycled aggregate, ceramsite, waste polypropylene fibers, water, and water reducer according to the above weights. After soaking the waste brick recycled aggregate and ceramsite in water for 24 h to make the moisture content of the waste brick recycled aggregate and ceramsite between 8% - 12%, then dry the surfaces of the waste brick recycled aggregate and ceramsite.

[0039] S4: Add the cement, modified glass powder, and fly ash into a mixer and stir (at a rotation speed of 100 rpm) for 30 s, then add the pre-wetted waste brick recycled aggregate and ceramsite and stir (at a rotation speed of 100 rpm) for 60 s. Then add the waste polypropylene fibers obtained in step S2 and stir (at a rotation speed of 120 rpm) for 90 s. Finally, add the water and water reducer into the mixer and stir (at a rotation speed of 80 rpm) for 3 min to obtain the concrete.

[0040] Example 3

[0041] This example provides an environmentally friendly lightweight aggregate concrete, which includes 65 kg of cement, 25 kg of modified glass powder, 20 kg of fly ash, 100 kg of waste brick recycled aggregate, 30 kg of ceramsite, 0.18 kg of waste polypropylene fibers, 30 kg of water, and 1.2 kg of water reducer.

[0042] The preparation method of the above environmentally friendly lightweight aggregate concrete includes the following steps:

[0043] S1: Crush 100 kg of waste glass into particles with a size of ≤10 mm using a crusher, then put the particles into a ball mill and ball mill them at a rotation speed of 700 rpm for 80 min to obtain glass powder (D90 ≤ 10 μm). Then add the glass powder into 500 kg of a sodium hydroxide solution with a concentration of 5%, react at 70°C for 3 h, and stir during the reaction (stirring rate is 250 rpm). After the reaction, wash with deionized water 3 - 5 times until the pH value of the filtrate ≤ 8 to obtain the activated glass powder. Then add the activated glass powder into 1000 kg of a nano-calcium carbonate suspension (the mass fraction of nano-calcium carbonate is 5%) and stir evenly, then put it into an ultrasonic cleaner for ultrasonic dispersion (power is 300 W, time is 40 min). After the ultrasonic dispersion, perform solid-liquid separation using a centrifuge, collect the precipitate, put the precipitate into a blast dryer, dry it at 90°C for 5 h, and after drying, pass it through an 80-mesh sieve to obtain the modified glass powder.

[0044] S2: Add waste polypropylene fibers to a detergent with a concentration of 5%, soak at 60°C for 30 min, add the soaked waste polypropylene fibers to a sodium hydroxide solution with a concentration of 5%, modify at 60°C for 25 min, and finally rinse with clean water until neutral.

[0045] S3: Weigh cement, modified glass powder, fly ash, waste brick recycled aggregate, ceramsite, waste polypropylene fibers, water and water reducer according to the above weights. After soaking the waste brick recycled aggregate and ceramsite in water for 24 h, make the water content of the waste brick recycled aggregate and ceramsite between 8 - 12%, and then dry the surfaces of the waste brick recycled aggregate and ceramsite.

[0046] S4: Add cement, modified glass powder and fly ash to a mixer and stir (at a speed of 100 rpm) for 30 s, then add the pre-wetted waste brick recycled aggregate and ceramsite and stir (at a speed of 100 rpm) for 60 s, then add the waste polypropylene fibers obtained in step S2 and stir (at a speed of 120 prm) for 90 s, and finally add water and water reducer to the mixer and stir (at a speed of 80 rpm) for 3 min to obtain concrete.

[0047] Comparative Example 1

[0048] This comparative example provides an environmentally friendly lightweight aggregate concrete, including 65 kg of cement, 20 kg of fly ash, 100 kg of waste brick recycled aggregate, 30 kg of ceramsite, 0.53 kg of waste polypropylene fibers, 30 kg of water and 1.2 kg of water reducer.

[0049] The preparation method of the above environmentally friendly lightweight aggregate concrete includes the following steps:

[0050] S1: Add waste polypropylene fibers to a detergent with a concentration of 5%, soak at 60°C for 30 min, add the soaked waste polypropylene fibers to a sodium hydroxide solution with a concentration of 5%, modify at 60°C for 25 min, and finally rinse with clean water until neutral.

[0051] S2: Weigh cement, fly ash, waste brick recycled aggregate, ceramsite, waste polypropylene fibers, water and water reducer according to the above weights. After soaking the waste brick recycled aggregate and ceramsite in water for 24 h, make the water content of the waste brick recycled aggregate and ceramsite between 8 - 12%, and then dry the surfaces of the waste brick recycled aggregate and ceramsite.

[0052] S3: After adding cement and fly ash into a mixer and stirring (at a rotation speed of 100 rpm) for 30 s, add the pre-wetted waste brick recycled aggregate and ceramsite and stir (at a rotation speed of 100 rpm) for 60 s. Then add the waste polypropylene fiber obtained in step S2 and stir (at a rotation speed of 120 prm) for 90 s. Finally, add water and water reducer into the mixer and stir (at a rotation speed of 80 rpm) for 3 min to obtain concrete.

[0053] Comparative Example 2

[0054] This comparative example provides an environmentally friendly lightweight aggregate concrete, including 65 kg of cement, 15 kg of modified glass micro-powder, 20 kg of fly ash, 100 kg of waste brick recycled aggregate, 30 kg of ceramsite, 30 kg of water and 1.2 kg of water reducer.

[0055] The preparation method of the above-mentioned environmentally friendly lightweight aggregate concrete includes the following steps:

[0056] S1: Crush 100 kg of waste glass into particles ≤10 mm using a crusher. Then put the particles into a ball mill and ball mill at a rotation speed of 700 rpm for 80 min to obtain glass micro-powder (D90≤10 μm). Then add the glass micro-powder into 500 kg of sodium hydroxide solution with a concentration of 5% and react at 70 °C for 3 h while stirring (stirring rate is 250 rpm). After the reaction, wash with deionized water 3 - 5 times until the pH value of the filtrate ≤8 to obtain the activated glass micro-powder. Then add the activated glass micro-powder into 1000 kg of nano-calcium carbonate suspension (mass fraction of nano-calcium carbonate is 5%) and stir evenly. Then put it into an ultrasonic cleaner for ultrasonic dispersion (power is 300 W, time is 40 min). After the ultrasonic dispersion, perform solid-liquid separation using a centrifuge, collect the precipitate, put the precipitate into a blast dryer and dry at 90 °C for 5 h. After drying, pass through an 80-mesh sieve to obtain modified glass micro-powder;

[0057] S2: Weigh cement, modified glass micro-powder, fly ash, waste brick recycled aggregate, ceramsite, water and water reducer according to the above weights. Immerse the waste brick recycled aggregate and ceramsite in water for 24 h to make the moisture content of the waste brick recycled aggregate and ceramsite between 8 - 12%. Then dry the surfaces of the waste brick recycled aggregate and ceramsite;

[0058] S3: After adding cement, modified glass micro-powder and fly ash into a mixer and stirring (at a rotation speed of 100 rpm) for 30 s, add the pre-wetted waste brick recycled aggregate and ceramsite and stir (at a rotation speed of 100 rpm) for 60 s. Finally, add water and water reducer into the mixer and stir (at a rotation speed of 80 rpm) for 3 min to obtain concrete.

[0059] Comparative Example 3

[0060] This comparative example provides an environmentally friendly lightweight aggregate concrete, including 65 kg of cement, 15 kg of glass micro powder, 20 kg of fly ash, 100 kg of waste brick recycled aggregate, 30 kg of ceramsite, 0.53 kg of waste polypropylene fiber, 30 kg of water and 1.2 kg of water reducer.

[0061] The preparation method of the above-mentioned environmentally friendly lightweight aggregate concrete includes the following steps:

[0062] S1: Crush 100 kg of waste glass into particles ≤10 mm using a crusher, then put the particles into a ball mill and mill for 80 min at a rotation speed of 700 rpm to obtain glass micro powder (D90 ≤10 μm);

[0063] S2: Add waste polypropylene fiber to a detergent with a concentration of 5%, soak at 60 °C for 30 min, add the soaked waste polypropylene fiber to a sodium hydroxide solution with a concentration of 5%, modify at 60 °C for 25 min, and finally rinse with clean water until neutral;

[0064] S3: Weigh cement, glass micro powder, fly ash, waste brick recycled aggregate, ceramsite, waste polypropylene fiber, water and water reducer respectively according to the above weights. After soaking the waste brick recycled aggregate and ceramsite in water for 24 h, make the moisture content of the waste brick recycled aggregate and ceramsite between 8-12%, and then dry the surfaces of the waste brick recycled aggregate and ceramsite;

[0065] S4: Put cement, glass micro powder and fly ash into a mixer and stir (rotation speed is 100 rpm) for 30 s, then add the pre-wetted waste brick recycled aggregate and ceramsite and stir (rotation speed is 100 rpm) for 60 s, then add the waste polypropylene fiber obtained in step S2 and stir (rotation speed is 120 prm) for 90 s, and finally add water and water reducer to the mixer and stir (rotation speed is 80 rpm) for 3 min to obtain concrete.

[0066] Comparative Example 4

[0067] This comparative example provides an environmentally friendly lightweight aggregate concrete, including 65 kg of cement, 15 kg of modified glass micro powder, 20 kg of fly ash, 100 kg of waste brick recycled aggregate, 30 kg of ceramsite, 0.53 kg of waste polypropylene fiber, 30 kg of water and 1.2 kg of water reducer.

[0068] The preparation method of the above-mentioned environmentally friendly lightweight aggregate concrete includes the following steps:

[0069] S1: Crush 100 kg of waste glass into particles ≤10 mm in size using a crusher, then put the particles into a ball mill and ball mill for 80 min at a rotational speed of 700 rpm to obtain glass micro-powder (D90 ≤10 μm). Then add the glass micro-powder to 500 kg of a 5% sodium hydroxide solution and react at 70 °C for 3 h while stirring (stirring rate is 250 rpm). After the reaction, wash with deionized water 3 - 5 times until the pH value of the filtrate ≤8 to obtain activated glass micro-powder. Then add the activated glass micro-powder to 1000 kg of a nano-calcium carbonate suspension (mass fraction of nano-calcium carbonate is 5%) and stir evenly, then put it into an ultrasonic cleaner for ultrasonic dispersion (power is 300 W, time is 40 min). After ultrasonic dispersion, perform solid-liquid separation using a centrifuge, collect the precipitate, put the precipitate into a blast dryer and dry at 90 °C for 5 h. After drying, pass through an 80-mesh sieve to obtain modified glass micro-powder;

[0070] S2: Add waste polypropylene fibers to a 5% detergent and soak at 60 °C for 30 min, and finally rinse with clean water;

[0071] S3: Weigh cement, modified glass micro-powder, fly ash, waste brick recycled aggregate, ceramsite, waste polypropylene fibers, water and water reducer according to the above weights respectively. After soaking the waste brick recycled aggregate and ceramsite in water for 24 h, make the moisture content of the waste brick recycled aggregate and ceramsite between 8 - 12%, and then dry the surfaces of the waste brick recycled aggregate and ceramsite;

[0072] S4: Add cement, modified glass micro-powder and fly ash to a mixer and stir (rotational speed is 100 rpm) for 30 s, then add the pre-wetted waste brick recycled aggregate and ceramsite and stir (rotational speed is 100 rpm) for 60 s, then add the waste polypropylene fibers obtained in step S2 and stir (rotational speed is 120 prm) for 90 s, and finally add water and water reducer to the mixer and stir (rotational speed is 80 rpm) for 3 min to obtain concrete.

[0073] Comparative Example 5

[0074] This comparative example provides an environmentally friendly lightweight aggregate concrete, including 65 kg of cement, 20 kg of fly ash, 100 kg of waste brick recycled aggregate, 30 kg of ceramsite, 30 kg of water and 1.2 kg of water reducer.

[0075] The preparation method of the above environmentally friendly lightweight aggregate concrete includes the following steps:

[0076] S1: Weigh cement, fly ash, waste brick recycled aggregate, ceramsite, water and water reducer according to the above weights respectively. After soaking the waste brick recycled aggregate and ceramsite in water for 24 hours, make the moisture content of the waste brick recycled aggregate and ceramsite between 8-12%, and then dry the surfaces of the waste brick recycled aggregate and ceramsite.

[0077] S4: Put cement and fly ash into a mixer and stir (at a speed of 100 rpm) for 30 s, then add the pre-wetted waste brick recycled aggregate and ceramsite and stir (at a speed of 100 rpm) for 60 s. Finally, add water and water reducer into the mixer and stir (at a speed of 80 rpm) for 3 min to obtain concrete.

[0078] Experimental example

[0079] According to the method in GB / T 50080-2016, the apparent density of the concrete prepared in Examples 1-3 (accurate to 10 kg / m 3 ) was detected, and the apparent densities of the concrete prepared in Examples 1-3 were detected to be 1900 kg / m 3 , 1880 kg / m 3 and 1920 kg / m 3 , all ≤ 1950 kg / m 3 , belonging to lightweight aggregate concrete.

[0080] The concrete prepared in Examples 1-3 and Comparative Examples 1-5 was tested for strength (compressive strength, splitting tensile strength and flexural strength) and durability (freeze-thaw cycle resistance and chloride ion penetration coefficient). The specific method is as follows:

[0081] The compressive strength, splitting tensile strength and flexural strength were all tested according to the method in GB / T 50081-2019.

[0082] The freeze-thaw cycle resistance and chloride ion penetration coefficient were both tested according to the rapid freezing method and the rapid chloride migration coefficient method in GB / T 50082-2024.

[0083] See Table 1 for the test results

[0084] Table 1 Strength and durability tests of concrete prepared in examples and comparative examples

[0085]

[0086]

[0087] Conclusion: The compressive strengths of Examples 1-3 are all ≥ 36 MPa, significantly higher than those of Comparative Example 1 and Comparative Example 5, with an increase range of 28%-54%. After freeze-thaw cycles (300 times), the mass loss of Examples 1-3 is ≤ 2.8%, the dynamic elastic modulus retention is ≥ 82%, and the chloride ion penetration coefficient is ≤ 0.92×10 -12 m 2 / s, all of which are superior to the comparative examples. It can be seen that adding modified glass micro powder and waste polypropylene fiber to the concrete in the examples can improve the strength and durability of the concrete. When any one of the components is missing or unmodified in the comparative examples alone, the performance decreases to varying degrees. Therefore, by adding modified glass micro powder and waste polypropylene fiber, the present invention realizes high strength (compressive strength ≥ 36 MPa) and high durability (freeze-thaw resistance ≥ 300 times, chloride ion penetration coefficient ≤ 0.92×10 -12 m 2 / s) of the environmentally friendly lightweight aggregate concrete, and three types of construction waste (waste bricks, glass, polypropylene) are efficiently utilized.

[0088] Although the principle of the present invention has been described in detail above in conjunction with the preferred embodiments of the present invention, those skilled in the art should understand that the above embodiments are only explanations of the illustrative implementation modes of the present invention and do not limit the scope of the present invention. The details in the embodiments do not constitute a limitation on the scope of the present invention. Without departing from the spirit and scope of the present invention, any obvious changes such as equivalent transformations and simple replacements based on the technical solutions of the present invention all fall within the protection scope of the present invention.

Claims

1. An environmentally friendly lightweight aggregate concrete, characterized in that, It comprises the following raw materials in parts by weight: 60 - 70 parts of cement; 15 - 25 parts of modified glass micro-powder; 15 - 25 parts of fly ash; 80 - 120 parts of waste brick recycled aggregate; 20 - 40 parts of ceramsite; 0.18 - 0.54 parts of waste polypropylene fiber; 25 - 35 parts of water and 0.9 - 2.1 parts of water reducer.

2. The environmentally friendly lightweight aggregate concrete according to claim 1, characterized in that, The particle size of the waste brick recycled aggregate is 5 - 20 mm; and / or, The length of the waste polypropylene fiber is 12 - 19 mm.

3. The environmentally friendly lightweight aggregate concrete according to claim 1, wherein The water reducer is a polycarboxylate water reducer.

4. The environmentally friendly lightweight aggregate concrete according to claim 1, wherein, The environmentally friendly lightweight aggregate concrete comprises the following raw materials in parts by weight: 65 parts of cement; 20 parts of modified glass micro-powder; 20 parts of fly ash; 100 parts of waste brick recycled aggregate; 30 parts of ceramsite; 0.3 parts of waste polypropylene fiber; 30 parts of water and 1.2 parts of water reducer.

5. A preparation method of the environment-friendly lightweight aggregate concrete according to any one of claims 1-4, characterized in that, It comprises the following steps: S1: Weigh cement, modified glass micro-powder, fly ash, waste brick recycled aggregate, ceramsite, waste polypropylene fiber, water and water reducer respectively according to the parts by weight; S2: Then stir cement, modified glass micro-powder and fly ash, add waste brick recycled aggregate and ceramsite and stir, then add waste polypropylene fiber and stir, and finally add water and water reducer and stir to obtain the environmentally friendly lightweight aggregate concrete.

6. The preparation method of the environment-friendly lightweight aggregate concrete according to claim 5, characterized in that, The preparation method of the modified glass micro-powder comprises the following steps: Crush, grind and sieve waste glass, add an alkaline solution for activation, then add a nano-calcium carbonate suspension for ultrasonic dispersion, and finally dry to obtain the modified glass micro-powder.

7. The preparation method of the environment-friendly concrete according to claim 6, characterized in that, The mass ratio of the waste glass to the alkaline solution is 1:4 - 6; and / or, The mass-volume ratio of the waste glass to the nano-calcium carbonate suspension is 1:8 - 12; and / or, The alkaline solution is selected from one or more of sodium hydroxide solution, potassium hydroxide solution and sodium carbonate solution, and the concentration of the alkaline solution is 5 - 10%; and / or, The mass fraction of nano-calcium carbonate in the nano-calcium carbonate suspension is 5 - 8%.

8. The preparation method of the environment-friendly concrete according to claim 6, characterized in that, The ultrasonic power of the ultrasonic dispersion is 200 - 400 W, and the ultrasonic dispersion time is 30 - 50 min; and / or, The drying temperature is 80 - 100 °C, and the time is 4 - 6 h.

9. The preparation method of the environment-friendly concrete according to claim 5, wherein, Before adding the waste polypropylene fiber, it also includes the step of modifying the waste polypropylene fiber; The modification method is: wash the waste polypropylene fiber, add sodium hydroxide solution for modification, and then wash with water until neutral; Wherein, the concentration of the sodium hydroxide solution is 5 - 10%, the modification temperature is 55 - 65 °C, and the time is 20 - 30 min.

10. The preparation method of the environment-friendly concrete according to claim 5, characterized in that, Before adding the waste brick recycled aggregate and ceramsite, it also includes the step of pre-wetting the waste brick recycled aggregate and ceramsite; The pre-wetting method is: soak the waste brick recycled aggregate and ceramsite in water for 18 - 36 h, make the water content of the waste brick recycled aggregate and ceramsite between 8 - 12%, and then dry the surfaces of the waste brick recycled aggregate and ceramsite.

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