An environmentally friendly lightweight aggregate concrete and its preparation method

Abstract

This invention relates to the field of concrete technology, specifically to an environmentally friendly lightweight aggregate concrete and its preparation method. The environmentally friendly lightweight aggregate concrete provided by this invention comprises the following raw materials in parts by weight: 60-70 parts cement; 15-25 parts modified glass micropowder; 15-25 parts fly ash; 80-120 parts recycled waste brick aggregate; 20-40 parts ceramsite; 0.18-0.54 parts waste polypropylene fiber; 25-35 parts water; and 0.9-2.1 parts water-reducing agent. The environmentally friendly lightweight aggregate concrete provided by this invention, by adding modified glass micropowder and waste polypropylene fiber to the original concrete formula, not only improves the strength and durability of the concrete but also achieves the efficient synergistic utilization of three types of construction waste (waste brick, glass, and polypropylene).

Description

Technical Field

[0001] This invention relates to the field of concrete technology, specifically to an environmentally friendly lightweight aggregate concrete and its preparation method. Background Technology

[0002] As construction progresses, the amount of construction waste generated from demolition is increasing, and the conflict with the ecological environment is also growing. In new development areas, there are relatively more brick-concrete structures being demolished, and fewer frame or shear wall structures, resulting in a relatively high proportion of waste bricks in the construction waste. Large amounts of construction waste not only occupy significant amounts of land but also cause considerable environmental damage; how to dispose of this large amount of waste is a pressing issue. With the increasing demand for concrete as a crucial building material, and the dwindling reserves of qualified aggregates, the preparation of high-performance concrete is becoming increasingly difficult. Against this backdrop, utilizing recycled aggregates to prepare concrete has become a trend in the industry. The efficient use of recycled aggregates can improve resource utilization and reduce the environmental pollution caused by construction waste.

[0003] With the growing acceptance of the concept of sustainable development, more and more scholars and research institutions are paying attention to this field. Some research results indicate 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 properties of recycled aggregates, and the results show that the strength and wear resistance of recycled aggregates meet the requirements. Furthermore, some regions have begun to pilot and promote the application of recycled aggregates. For instance, some construction projects in Beijing and Shanghai have started using recycled aggregates; in Nanjing, Jiangsu Province, concrete made from recycled construction waste aggregates has been used in the construction of some affordable housing projects, realizing the resource utilization of construction waste and reducing project costs; and in Wenzhou, Zhejiang Province, concrete made from construction waste has been used in the construction of commercial complexes for the pouring of walls and floors in some buildings.

[0004] However, most of the research on recycled aggregates from construction waste in China is on mixed aggregates produced from unsorted construction waste. There is relatively little research on the application of recycled aggregates produced from construction waste, which is mainly composed of waste bricks, in preparing lightweight aggregate concrete. This adds some difficulty to the resource utilization of construction waste, which is mainly composed of waste bricks. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides an environmentally friendly lightweight aggregate concrete and its preparation method. This environmentally friendly lightweight aggregate concrete, by adding modified glass micropowder and waste polypropylene fiber to the original concrete formula, not only improves the strength and durability of the concrete, but also enables the efficient synergistic utilization of three types of construction waste (waste bricks, glass, and polypropylene).

[0006] Therefore, the present invention provides the following technical solution:

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

[0008] In this invention, the SiO2 in the modified glass micropowder can undergo secondary hydration with Ca(OH)2, a hydration product of cement, to generate CSH gel, which fills the pores of recycled aggregate, thereby improving the density and compressive strength of the concrete. Furthermore, the nano-CaCO3 coating layer in the modified glass micropowder interacts with the Ca in the cement paste... 2+ Chemical bonds are formed. After modification, waste polypropylene fibers are linked to CSH gel through hydrogen bonds with -OH groups. The combined effect of these two factors improves the bond strength of the aggregate-cement interface and reduces interfacial damage under stress.

[0009] Modified glass micropowder can refine the pore structure of recycled aggregates and reduce the path of water penetration. Waste polypropylene fibers can block the propagation of concrete cracks, forming a "dense matrix + flexible crack-resistant" protective system, which reduces the chloride ion penetration coefficient and increases the number of freeze-thaw cycles. In addition, the nano-CaCO3 layer on the surface of the modified glass micropowder isolates alkaline solutions from the SiO2 in the glass, preventing alkaline substances in the concrete from reacting chemically with the active mineral components in the aggregate, thus improving the long-term durability of the concrete.

[0010] Preferably, the particle size of the recycled aggregate from waste bricks is 5-20 mm; and / or, the length of the waste polypropylene fibers 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 cement; 20 parts modified glass micro powder; 20 parts fly ash; 100 parts recycled waste brick aggregate; 30 parts ceramsite; 0.3 parts waste polypropylene fiber; 30 parts water; and 1.2 parts water-reducing agent.

[0012] Secondly, the present invention provides a method for preparing the above-mentioned environmentally friendly lightweight aggregate concrete, comprising the following steps:

[0013] S1: Weigh out cement, modified glass powder, fly ash, recycled aggregate from waste bricks, ceramsite, waste polypropylene fiber, water, and water-reducing agent according to the weight parts.

[0014] S2: Then, after mixing cement, modified glass powder and fly ash, add recycled aggregate from waste bricks and ceramsite and mix. Then add waste polypropylene fiber and mix. Finally, add water and water-reducing agent and mix to obtain environmentally friendly lightweight aggregate concrete.

[0015] Preferably, the preparation method of the modified glass micro powder includes the following steps: crushing, grinding and sieving waste glass, activating it with an alkaline solution, then adding a nano calcium carbonate suspension for ultrasonic dispersion, and finally drying it to obtain the modified glass micro powder.

[0016] In this invention, the amorphous SiO2 on the surface of glass micropowder reacts with an alkaline solution to generate soluble silicates, which can undergo a secondary hydration reaction with the cement hydration product Ca(OH)2 in the alkaline environment of concrete. The hydroxyl groups (-OH) on the surface of nano-CaCO3 and the silanol groups (-SiOH) on the surface of glass micropowder form a "nano-bridging" structure through hydrogen bonds or chemical bonds, which enhances the adhesion of the aggregate-cement 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 dispersion uses an ultrasonic power of 200-400W and a dispersion time of 30-50 min; and / or, the drying temperature is 80-100℃ and the drying time is 4-6 h.

[0018] Preferably, before adding the waste polypropylene fiber, the method further includes a step of modifying the waste polypropylene fiber; the modification method is as follows: after cleaning the waste polypropylene fiber, add sodium hydroxide solution for modification, and then wash with water until neutral.

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

[0020] Preferably, before adding the recycled waste brick aggregate and ceramsite, a pre-wetting step is included; the pre-wetting method is as follows: soaking the recycled waste brick aggregate and ceramsite in water for 18-36 hours to make the moisture content of the recycled waste brick aggregate and ceramsite between 8-12%, and then drying the surface of the recycled waste brick aggregate 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 this invention not only improves the strength and durability of concrete by adding modified glass micro powder and waste polypropylene fiber to the original concrete formula, but also enables the efficient synergistic utilization of three types of construction waste (waste bricks, glass, and polypropylene). Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

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

[0025] The technical solution of the present invention will be described below with reference to embodiments.

[0026] Example 1

[0027] This embodiment provides an environmentally friendly lightweight aggregate concrete, comprising 65kg cement, 20kg modified glass micropowder, 20kg fly ash, 100kg recycled aggregate from waste bricks, 30kg expanded clay, 0.3kg waste polypropylene fiber, 30kg water, and 1.2kg water-reducing agent.

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

[0029] S1: 100 kg of waste glass is crushed into particles ≤10 mm using a crusher. The particles are then placed in a ball mill and milled at 700 rpm for 80 min to obtain glass micro powder (D90≤10 μm). The glass micro powder is then added to 500 kg of 5% sodium hydroxide solution and reacted at 70℃ for 3 h while stirring (stirring rate 250 rpm). After the reaction, the glass micro powder is washed 3-5 times with deionized water until the pH of the filtrate is ≤8 to obtain activated glass micro powder. The activated glass micro powder is then added to 1000 kg of nano-calcium carbonate suspension (nano-calcium carbonate mass fraction is 5%) and stirred evenly. The mixture is then placed in an ultrasonic cleaner for ultrasonic dispersion (power 300W, time 40 min). After ultrasonic dispersion, solid-liquid separation is performed using a centrifuge, and the precipitate is collected. The precipitate is placed in a blower dryer and dried at 90℃ for 5 h. After drying, the precipitate is passed through an 80-mesh sieve to obtain modified glass micro powder.

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

[0031] S3: Weigh out cement, modified glass powder, fly ash, recycled waste brick aggregate, ceramsite, waste polypropylene fiber, water and water-reducing agent according to the above weights. Soak the recycled waste brick aggregate and ceramsite in water for 24 hours to make the moisture content of the recycled waste brick aggregate and ceramsite between 8-12%. Then dry the surface of the recycled waste brick aggregate and ceramsite.

[0032] S4: Add cement, modified glass powder and fly ash to the mixer and mix (100 rpm) for 30 seconds. Then add pre-wetted recycled waste brick aggregate and ceramsite and mix (100 rpm) for 60 seconds. Next, add the waste polypropylene fiber obtained in step S2 and mix (120 rpm) for 90 seconds. Finally, add water and water-reducing agent to the mixer and mix (80 rpm) for 3 minutes to obtain concrete.

[0033] Example 2

[0034] This embodiment provides an environmentally friendly lightweight aggregate concrete, comprising 65kg cement, 15kg modified glass micro powder, 20kg fly ash, 100kg recycled aggregate from waste bricks, 30kg expanded clay, 0.53kg waste polypropylene fiber, 30kg water, and 1.2kg water-reducing agent.

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

[0036] S1: 100 kg of waste glass is crushed into particles ≤10 mm using a crusher. The particles are then placed in a ball mill and milled at 700 rpm for 80 min to obtain glass micro powder (D90≤10 μm). The glass micro powder is then added to 500 kg of 5% sodium hydroxide solution and reacted at 70℃ for 3 h while stirring (stirring rate 250 rpm). After the reaction, the glass micro powder is washed 3-5 times with deionized water until the pH of the filtrate is ≤8 to obtain activated glass micro powder. The activated glass micro powder is then added to 1000 kg of nano-calcium carbonate suspension (nano-calcium carbonate mass fraction is 5%) and stirred evenly. The mixture is then placed in an ultrasonic cleaner for ultrasonic dispersion (power 300W, time 40 min). After ultrasonic dispersion, solid-liquid separation is performed using a centrifuge, and the precipitate is collected. The precipitate is placed in a blower dryer and dried at 90℃ for 5 h. After drying, the precipitate is passed through an 80-mesh sieve to obtain modified glass micro powder.

[0037] S2: Add waste polypropylene fibers to a 5% detergent solution and soak at 60°C for 30 minutes. Add the soaked waste polypropylene fibers to a 5% sodium hydroxide solution and modify at 60°C for 25 minutes. Finally, rinse with water until neutral.

[0038] S3: Weigh out cement, modified glass powder, fly ash, recycled waste brick aggregate, ceramsite, waste polypropylene fiber, water and water-reducing agent according to the above weights. Soak the recycled waste brick aggregate and ceramsite in water for 24 hours to make the moisture content of the recycled waste brick aggregate and ceramsite between 8-12%. Then dry the surface of the recycled waste brick aggregate and ceramsite.

[0039] S4: Add cement, modified glass powder and fly ash to the mixer and mix (100 rpm) for 30 seconds. Then add pre-wetted recycled waste brick aggregate and ceramsite and mix (100 rpm) for 60 seconds. Next, add the waste polypropylene fiber obtained in step S2 and mix (120 rpm) for 90 seconds. Finally, add water and water-reducing agent to the mixer and mix (80 rpm) for 3 minutes to obtain concrete.

[0040] Example 3

[0041] This embodiment provides an environmentally friendly lightweight aggregate concrete, comprising 65kg cement, 25kg modified glass micropowder, 20kg fly ash, 100kg recycled aggregate from waste bricks, 30kg expanded clay, 0.18kg waste polypropylene fiber, 30kg water, and 1.2kg water-reducing agent.

[0042] The above-mentioned method for preparing environmentally friendly lightweight aggregate concrete includes the following steps:

[0043] S1: 100 kg of waste glass is crushed into particles ≤10 mm using a crusher. The particles are then placed in a ball mill and milled at 700 rpm for 80 min to obtain glass micro powder (D90≤10 μm). The glass micro powder is then added to 500 kg of 5% sodium hydroxide solution and reacted at 70℃ for 3 h while stirring (stirring rate 250 rpm). After the reaction, the glass micro powder is washed 3-5 times with deionized water until the pH of the filtrate is ≤8 to obtain activated glass micro powder. The activated glass micro powder is then added to 1000 kg of nano-calcium carbonate suspension (nano-calcium carbonate mass fraction is 5%) and stirred evenly. The mixture is then placed in an ultrasonic cleaner for ultrasonic dispersion (power 300W, time 40 min). After ultrasonic dispersion, solid-liquid separation is performed using a centrifuge, and the precipitate is collected. The precipitate is placed in a blower dryer and dried at 90℃ for 5 h. After drying, the precipitate is passed through an 80-mesh sieve to obtain modified glass micro powder.

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

[0045] S3: Weigh out cement, modified glass powder, fly ash, recycled waste brick aggregate, ceramsite, waste polypropylene fiber, water and water-reducing agent according to the above weights. Soak the recycled waste brick aggregate and ceramsite in water for 24 hours to make the moisture content of the recycled waste brick aggregate and ceramsite between 8-12%. Then dry the surface of the recycled waste brick aggregate and ceramsite.

[0046] S4: Add cement, modified glass powder and fly ash to the mixer and mix (100 rpm) for 30 seconds. Then add pre-wetted recycled waste brick aggregate and ceramsite and mix (100 rpm) for 60 seconds. Next, add the waste polypropylene fiber obtained in step S2 and mix (120 rpm) for 90 seconds. Finally, add water and water-reducing agent to the mixer and mix (80 rpm) for 3 minutes to obtain concrete.

[0047] Comparative Example 1

[0048] This comparative example provides an environmentally friendly lightweight aggregate concrete, comprising 65 kg of cement, 20 kg of fly ash, 100 kg of recycled waste brick aggregate, 30 kg of expanded clay, 0.53 kg of waste polypropylene fiber, 30 kg of water, and 1.2 kg of water-reducing agent.

[0049] The above-mentioned method for preparing environmentally friendly lightweight aggregate concrete includes the following steps:

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

[0051] S2: Weigh out cement, fly ash, recycled waste brick aggregate, ceramsite, waste polypropylene fiber, water and water-reducing agent according to the above weights. Soak the recycled waste brick aggregate and ceramsite in water for 24 hours to make the moisture content of the recycled waste brick aggregate and ceramsite between 8-12%. Then dry the surface of the recycled waste brick aggregate and ceramsite.

[0052] S3: Add cement and fly ash to the mixer and mix (100 rpm) for 30 seconds. Then add pre-wetted recycled waste brick aggregate and ceramsite and mix (100 rpm) for 60 seconds. Next, add the waste polypropylene fiber obtained in step S2 and mix (120 rpm) for 90 seconds. Finally, add water and water-reducing agent to the mixer and mix (80 rpm) for 3 minutes to obtain concrete.

[0053] Comparative Example 2

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

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

[0056] S1: 100 kg of waste glass is crushed into particles ≤10 mm using a crusher. The particles are then placed in a ball mill and milled at 700 rpm for 80 min to obtain glass micro powder (D90≤10 μm). The glass micro powder is then added to 500 kg of 5% sodium hydroxide solution and reacted at 70℃ for 3 h while stirring (stirring rate 250 rpm). After the reaction, the glass micro powder is washed 3-5 times with deionized water until the pH of the filtrate is ≤8 to obtain activated glass micro powder. The activated glass micro powder is then added to 1000 kg of nano-calcium carbonate suspension (nano-calcium carbonate mass fraction is 5%) and stirred evenly. The mixture is then placed in an ultrasonic cleaner for ultrasonic dispersion (power 300W, time 40 min). After ultrasonic dispersion, solid-liquid separation is performed using a centrifuge, and the precipitate is collected. The precipitate is placed in a blower dryer and dried at 90℃ for 5 h. After drying, the precipitate is passed through an 80-mesh sieve to obtain modified glass micro powder.

[0057] S2: Weigh out cement, modified glass powder, fly ash, recycled waste brick aggregate, ceramsite, water and water-reducing agent according to the above weights. Soak the recycled waste brick aggregate and ceramsite in water for 24 hours to make the moisture content of the recycled waste brick aggregate and ceramsite between 8-12%. Then dry the surface of the recycled waste brick aggregate and ceramsite.

[0058] S3: Add cement, modified glass powder and fly ash to the mixer and mix (100 rpm) for 30 seconds. Then add pre-wetted recycled waste brick aggregate and ceramsite and mix (100 rpm) for 60 seconds. Finally, add water and water-reducing agent to the mixer and mix (80 rpm) for 3 minutes to obtain concrete.

[0059] Comparative Example 3

[0060] This comparative example provides an environmentally friendly lightweight aggregate concrete, comprising 65 kg of cement, 15 kg of glass micron powder, 20 kg of fly ash, 100 kg of recycled waste brick aggregate, 30 kg of expanded clay, 0.53 kg of waste polypropylene fiber, 30 kg of water and 1.2 kg of water-reducing agent.

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

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

[0063] S2: Add waste polypropylene fibers to a 5% detergent solution and soak at 60°C for 30 minutes. Add the soaked waste polypropylene fibers to a 5% sodium hydroxide solution and modify at 60°C for 25 minutes. Finally, rinse with water until neutral.

[0064] S3: Weigh out cement, glass powder, fly ash, recycled waste brick aggregate, ceramsite, waste polypropylene fiber, water and water-reducing agent according to the above weights. Soak the recycled waste brick aggregate and ceramsite in water for 24 hours to make the moisture content of the recycled waste brick aggregate and ceramsite between 8-12%. Then dry the surface of the recycled waste brick aggregate and ceramsite.

[0065] S4: Add cement, glass powder and fly ash to the mixer and mix (100 rpm) for 30 seconds. Then add pre-wetted recycled waste brick aggregate and ceramsite and mix (100 rpm) for 60 seconds. Next, add the waste polypropylene fiber obtained in step S2 and mix (120 rpm) for 90 seconds. Finally, add water and water-reducing agent to the mixer and mix (80 rpm) for 3 minutes to obtain concrete.

[0066] Comparative Example 4

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

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

[0069] S1: 100 kg of waste glass is crushed into particles ≤10 mm using a crusher. The particles are then placed in a ball mill and milled at 700 rpm for 80 min to obtain glass micro powder (D90≤10 μm). The glass micro powder is then added to 500 kg of 5% sodium hydroxide solution and reacted at 70℃ for 3 h while stirring (stirring rate 250 rpm). After the reaction, the glass micro powder is washed 3-5 times with deionized water until the pH of the filtrate is ≤8 to obtain activated glass micro powder. The activated glass micro powder is then added to 1000 kg of nano-calcium carbonate suspension (nano-calcium carbonate mass fraction is 5%) and stirred evenly. The mixture is then placed in an ultrasonic cleaner for ultrasonic dispersion (power 300W, time 40 min). After ultrasonic dispersion, solid-liquid separation is performed using a centrifuge, and the precipitate is collected. The precipitate is placed in a blower dryer and dried at 90℃ for 5 h. After drying, the precipitate is passed through an 80-mesh sieve to obtain modified glass micro powder.

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

[0071] S3: Weigh out cement, modified glass powder, fly ash, recycled waste brick aggregate, ceramsite, waste polypropylene fiber, water and water-reducing agent according to the above weights. Soak the recycled waste brick aggregate and ceramsite in water for 24 hours to make the moisture content of the recycled waste brick aggregate and ceramsite between 8-12%. Then dry the surface of the recycled waste brick aggregate and ceramsite.

[0072] S4: Add cement, modified glass powder and fly ash to the mixer and mix (100 rpm) for 30 seconds. Then add pre-wetted recycled waste brick aggregate and ceramsite and mix (100 rpm) for 60 seconds. Next, add the waste polypropylene fiber obtained in step S2 and mix (120 rpm) for 90 seconds. Finally, add water and water-reducing agent to the mixer and mix (80 rpm) for 3 minutes to obtain concrete.

[0073] Comparative Example 5

[0074] This comparative example provides an environmentally friendly lightweight aggregate concrete, comprising 65 kg of cement, 20 kg of fly ash, 100 kg of recycled waste brick aggregate, 30 kg of expanded clay, 30 kg of water, and 1.2 kg of water-reducing agent.

[0075] The above-mentioned method for preparing environmentally friendly lightweight aggregate concrete includes the following steps:

[0076] S1: Weigh out cement, fly ash, recycled waste brick aggregate, ceramsite, water and water-reducing agent according to the above weights. Soak the recycled waste brick aggregate and ceramsite in water for 24 hours to make the moisture content of the recycled waste brick aggregate and ceramsite between 8-12%. Then dry the surface of the recycled waste brick aggregate and ceramsite.

[0077] S4: Add cement and fly ash to the mixer and mix (100 rpm) for 30 seconds. Then add pre-wetted recycled waste brick aggregate and ceramsite and mix (100 rpm) for 60 seconds. Finally, add water and water-reducing agent to the mixer and mix (80 rpm) for 3 minutes to obtain concrete.

[0078] Experimental Example

[0079] The apparent density of the concrete prepared in Examples 1-3 was determined according to the method in GB / T 50080-2016 (all accurate to 10 kg / m³). 3 The tests revealed that the apparent densities of the concrete prepared in Examples 1-3 were 1900 kg / m³, respectively. 3 1880kg / m 3 and 1920kg / m 3 All are ≤1950kg / m 3 It belongs to lightweight aggregate concrete.

[0080] The concrete prepared in Examples 1-3 and Comparative Examples 1-5 were subjected to strength (compressive strength, splitting tensile strength, and flexural strength) and durability (resistance to freeze-thaw cycles and chloride ion permeability) tests, specifically as follows:

[0081] Compressive strength, splitting tensile strength and flexural strength were tested according to the methods in GB / T 50081-2019.

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

[0083] The test results are shown in Table 1.

[0084] Table 1. Coagulation strength and durability tests of the concrete prepared in the examples and comparative examples.

[0085]

[0086]

[0087] Conclusion: The compressive strength of Examples 1-3 is ≥36MPa, significantly higher than that of Comparative Example 1 and Comparative Example 5, with an improvement of 28%-54%. After 300 freeze-thaw cycles, the mass loss of Examples 1-3 is ≤2.8%, the dynamic elastic modulus is retained ≥82%, and the chloride ion permeability coefficient is ≤0.92×10⁻⁶. -12 m 2 The strength and durability of the concrete in the examples are superior to those in the comparative example. It is evident that the simultaneous addition of modified glass micropowder and waste polypropylene fiber to the concrete in these examples improves its strength and durability. In contrast, the performance of the comparative example, lacking either component or remaining unmodified, exhibits varying degrees of performance degradation. Therefore, this invention, by adding modified glass micropowder and waste polypropylene fiber, achieves high strength (compressive strength ≥36MPa) and high durability (freeze-thaw resistance ≥300 cycles, chloride ion permeability coefficient ≤0.92×10⁻⁶) in environmentally friendly lightweight aggregate concrete. -12 m 2 / s), and three types of construction waste (waste bricks, glass, and polypropylene) are utilized efficiently.

[0088] Although the principles of the present invention have been described in detail above with reference to preferred embodiments, those skilled in the art should understand that the above embodiments are merely illustrative explanations of the implementation of the present invention and are not intended to limit the scope of the present invention. The details in the embodiments do not constitute a limitation on the scope of the present invention. Any obvious changes, such as equivalent transformations or simple substitutions, based on the technical solutions of the present invention without departing from the spirit and scope of the present invention fall within the protection scope of the present invention.

Claims

1. A method for preparing environmentally friendly lightweight aggregate concrete, characterized in that, Includes the following steps: S1: Weigh out cement, modified glass powder, fly ash, recycled aggregate from waste bricks, ceramsite, waste polypropylene fiber, water, and water-reducing agent according to the weight parts. S2: Then, cement, modified glass powder and fly ash are mixed, waste brick recycled aggregate and ceramsite are added and mixed, waste polypropylene fiber is added and mixed, and finally water and water-reducing agent are added and mixed to obtain environmentally friendly lightweight aggregate concrete. The environmentally friendly lightweight aggregate concrete comprises the following raw materials by weight: 60-70 parts cement; 15-25 parts of modified glass micro powder; 15-25 parts fly ash; 80-120 parts recycled aggregate from waste bricks; 20-40 parts expanded clay; 0.18-0.54 parts waste polypropylene fiber; 25-35 parts water; and 0.9-2.1 parts water-reducing agent; The method for preparing the modified glass micropowder includes the following steps: After crushing, grinding and sieving waste glass, it is activated by adding an alkaline solution, then ultrasonically dispersed by adding a nano calcium carbonate suspension, and finally dried to obtain modified glass micro powder. The mass ratio of the waste glass to the alkaline solution is 1:4-6; The mass-to-volume ratio of the waste glass and 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%. The mass fraction of nano-calcium carbonate in the nano-calcium carbonate suspension is 5-8%; Before adding waste polypropylene fibers, the process also includes a step of modifying the waste polypropylene fibers; The modification method is as follows: after cleaning the waste polypropylene fiber, add sodium hydroxide solution for modification, and then wash with water until neutral. The concentration of the sodium hydroxide solution is 5-10%, the modification temperature is 55-65℃, and the modification time is 20-30 min.

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

3. The method for preparing environmentally friendly lightweight aggregate concrete according to claim 1, characterized in that, The water-reducing agent is a polycarboxylate water-reducing agent.

4. The method for preparing environmentally friendly lightweight aggregate concrete according to claim 1, characterized in that, The environmentally friendly lightweight aggregate concrete comprises the following raw materials by weight: 65 parts cement; 20 parts of modified glass micro powder; 20 parts fly ash; 100 parts recycled aggregate from waste bricks; 30 parts ceramsite; 0.3 parts waste polypropylene fiber; 30 parts water; and 1.2 parts water-reducing agent.

5. The method for preparing environmentally friendly lightweight aggregate concrete according to claim 1, characterized in that, The ultrasonic dispersion power is 200-400W, and the ultrasonic dispersion time is 30-50 minutes; and / or, The drying temperature is 80-100℃, and the time is 4-6 hours.

6. The method for preparing environmentally friendly lightweight aggregate concrete according to claim 1, characterized in that, Before adding the recycled waste brick aggregate and ceramsite, the process also includes a pre-wetting step for the recycled waste brick aggregate and ceramsite. The pre-wetting method is as follows: the recycled aggregate and ceramsite from waste bricks are soaked in water for 18-36 hours to make the moisture content of the recycled aggregate and ceramsite between 8-12%, and then the surface of the recycled aggregate and ceramsite is dried.

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