Method for preparing building self-insulation wall concrete from waste concrete and waste brick powder

Abstract

The invention provides a method for preparing building self-heat-preservation wall concrete from waste concrete and waste brick powder, and relates to the technical field of building facilities, the method comprises the following steps: raw material pretreatment, ingredient preparation, segmented stirring and molding maintenance; the raw material pretreatment comprises the steps of carrying out crushing, spray grinding and steam pre-wetting treatment on waste concrete to obtain modified recycled aggregate, and carrying out grinding, calcination activation and surface modification treatment on waste brick powder to obtain activated waste brick powder; according to the step of segmented stirring, aggregate dry stirring, cementing material dry stirring and wet stirring are sequentially carried out in a forced stirring machine, waste brick powder is subjected to a dual process of calcination activation and silane coupling agent modification, the volcanic ash activity of the waste brick powder is improved by 30% or above through calcination, chemical bridging is formed between the powder and a cement matrix through a silane coupling agent, and then the waste brick powder is subjected to wet stirring. The conversion of the waste brick powder from an inert filler to an active gelling component is realized, so that the strength and durability are synchronously improved when the waste concrete and the waste brick are compositely utilized.

Description

Technical Field

[0001] This invention relates to the field of building facilities technology, and in particular to a method for preparing self-insulating concrete for building walls from waste concrete and waste brick powder. Background Technology

[0002] With the acceleration of urbanization and the increasing demand for the replacement of existing buildings in my country, a large amount of construction waste is generated every year, of which waste concrete and waste bricks account for more than 60%. At present, this type of construction waste is mainly disposed of through landfill or simple crushing and recycling, which not only occupies land resources but also causes environmental pollution and resource waste. At the same time, the increasing requirements for building energy conservation have led to a surge in demand for self-insulating wall materials. Traditional self-insulating concrete often uses natural lightweight aggregates or special insulation components, which have the problems of high raw material costs and high resource consumption.

[0003] Existing recycled concrete technologies, such as the recycled micro powder preparation method disclosed in CN202210080534.4, only focus on the refinement of single waste materials and do not achieve the synergistic utilization of waste concrete and waste brick powder. Although the carbon-fixed concrete technology of China Construction Western Construction has achieved the recycling of construction waste, it has not optimized the self-insulating performance, and the thermal conductivity is difficult to meet the requirements of wall insulation.

[0004] Existing technologies generally suffer from the following defects: 1. Poor compatibility when waste concrete and waste brick powder are combined, which easily leads to an imbalance between strength and thermal insulation performance; 2. High water absorption rate of recycled aggregates, resulting in poor workability of concrete and a high risk of shrinkage cracking; 3. The thermal insulation components are not tightly bonded to the cementitious system, which easily leads to performance degradation after long-term use. Summary of the Invention

[0005] This invention provides a method for preparing self-insulating wall concrete for buildings from waste concrete and waste brick powder, in order to solve the problems of poor compatibility of waste concrete and waste brick powder, which easily leads to an imbalance between strength and thermal insulation performance; high water absorption of recycled aggregates, which leads to poor workability of concrete and a high risk of shrinkage cracking; and poor bonding between thermal insulation components and cementitious system, which easily leads to performance degradation after long-term use.

[0006] This invention provides a method for preparing self-insulating wall concrete for buildings using waste concrete and waste brick powder, specifically including the following steps: Raw material pretreatment, ingredient preparation, segmented mixing, and molding and curing; The raw material pretreatment includes crushing, spraying, grinding and steam pre-wetting of waste concrete to obtain modified recycled aggregate, and grinding, calcining and surface modification of waste brick powder to obtain activated waste brick powder. In the preparation of the ingredients, the raw materials, by weight, include: 350-450 parts of the modified recycled aggregate, 80-120 parts of the activated waste brick powder, 180-220 parts of cement, 100-150 parts of lightweight aggregate, 50-80 parts of mineral admixture, 3-5 parts of water-reducing agent, 0.5-1 part of air-entraining agent, and 120-150 parts of water. The segmented mixing is carried out in a forced mixer in the order of dry mixing of aggregates, dry mixing of cementitious materials, and wet mixing. The molding and curing process adopts a composite curing system of "low temperature moisturizing and high temperature steam pressing"; The prepared concrete has a 28-day compressive strength ≥30MPa, a thermal conductivity ≤0.45W / (m·K), and a dry apparent density ≤1800kg / m³.

[0007] Furthermore, the raw material pretreatment step specifically includes: the waste concrete is crushed in three stages by a jaw crusher, an impact crusher, and a sand making machine, respectively, to coarse crushing, medium crushing, and fine crushing; the waste concrete is sprayed and ground with cement slurry with a water-cement ratio of 0.3-0.4 by a wheel bucket sand washing machine; and then steam pre-humidification is performed using a steam pre-humidifier at a steam temperature of 80-100℃ for a processing time of 30-45 minutes, so that the moisture content of the obtained modified recycled aggregate is controlled at 5-7%.

[0008] Furthermore, the raw material pretreatment step specifically includes: grinding the waste brick powder into a particle size of no more than 100 μm using a jaw crusher and a ball mill, then calcining and activating it in a rotary kiln at 600-700℃ and holding it at that temperature for 20-30 minutes, and finally adding 1-2% of a silane coupling agent by mass of the waste brick powder for surface modification to obtain the activated waste brick powder.

[0009] Furthermore, in the preparation of the ingredients, the specific composition of each raw material is as follows: 350-450 parts of the modified recycled aggregate, 80-120 parts of the activated waste brick powder, 180-220 parts of 42.5 grade ordinary Portland cement, 100-150 parts of fly ash ceramsite, 50-80 parts of phosphorus slag powder, 3-5 parts of polycarboxylate superplasticizer, 0.5-1 part of rosin thermal polymer air-entraining agent, and 120-150 parts of water.

[0010] Furthermore, the total time for segmented mixing is not less than 250 seconds; in the molding and curing process, the conditions for high-temperature autoclaving are: temperature 80-90℃, pressure 0.1-0.15MPa, and autoclaving curing time 24 hours.

[0011] Furthermore, the forced mixer has a through-hole oscillation groove in its side wall, a compensation groove at the end of the oscillation groove, and an oscillation guide hole in its bottom.

[0012] Furthermore, the top of the forced mixer is connected to a semi-open cover with a fan-shaped opening, the semi-open cover is connected to an injection pipe, a drive motor is installed at the center above the semi-open cover, the shaft of the drive motor is connected to a concrete mixing shaft, a mixing blade is connected to the outside of the concrete mixing shaft, a square slot with a square cross-section is opened at the bottom of the concrete mixing shaft, and the lower end of the concrete mixing shaft is rotatably connected to the bottom of the forced mixer through a bearing and a sealing ring.

[0013] Furthermore, the bottom of the forced mixer is provided with a vibration tray, and four reset tension springs are connected between the vibration tray and the lower surface of the forced mixer. An eccentric wheel is rotatably connected to the inner wall of the vibration tray, and a driven gear is fixedly connected to the support shaft end of the eccentric wheel.

[0014] Furthermore, a linkage rotary disk is rotatably connected inside the excitation tray. A linkage square column is vertically welded to the top of the linkage rotary disk. The linkage square column is slidably inserted into the square slot. A rotary disk gear ring is fixedly connected to the lower surface edge of the linkage rotary disk. The rotary disk gear ring meshes with the driven gear.

[0015] Furthermore, the excitation tray is externally connected to an excitation guide rod, which is slidably connected to an oscillation groove. The upper end of the excitation guide rod is provided with a guide rod blocking plate, which is slidably connected to a compensation groove. The inner surface of the guide rod blocking plate is provided with excitation ridges, and the excitation guide rod is provided with an excitation insert that is slidably connected to the oscillation guide hole.

[0016] This invention provides a method for preparing self-insulating wall concrete for buildings using waste concrete and waste brick powder, which has the following beneficial effects: This invention employs a composite treatment of waste concrete aggregates using "cement slurry grinding modification plus steam pre-wetting," significantly reducing the aggregate water absorption rate from over 12% to 5-7%. This effectively seals internal pores, fundamentally solving the key problems of poor workability and construction difficulties caused by the high water absorption of recycled aggregates. For waste brick powder, a dual process of "calcination activation plus silane coupling agent modification" is used. Calcination increases its pozzolanic activity by over 30%, while the silane coupling agent forms a chemical "bridge" between the powder and the cement matrix, transforming the waste brick powder from an inert filler to an active cementitious component. This allows for a simultaneous improvement in strength and durability when waste concrete and waste bricks are combined and utilized.

[0017] The concrete prepared by this invention has a stable compressive strength of ≥30MPa after 28 days, a thermal conductivity of ≤0.45W / (m·K), and a dry apparent density of ≤1800kg / m³. It perfectly meets the core requirements of GB / T 23450-2009 "Technical Specification for External Wall Insulation Engineering" for self-insulating wall materials, realizing the integrated function of load-bearing and thermal insulation. The product also has excellent durability, with a frost resistance of up to F200 grade and a permeability grade of P6 grade. It can resist the erosion of harsh climatic environments for a long time, ensuring the long service life and safety of building exterior walls.

[0018] This invention achieves high-value utilization of construction waste, with a solid waste comprehensive utilization rate exceeding 60%. Each cubic meter of product can absorb 350-450 kg of waste concrete and 80-120 kg of waste brick powder, significantly reducing the environmental pressure on landfill disposal. Compared to traditional self-insulating concrete that relies on natural raw materials or chemical insulation materials, its raw material costs can be reduced by 20-30%, demonstrating outstanding economic efficiency. Furthermore, the addition of phosphorus slag powder to the formula brings significant carbon sequestration environmental benefits. Calculations show that each cubic meter of concrete can help reduce CO2 emissions by approximately 40 kg, making it a green building material technology path that combines resource recycling, cost advantages, and low-carbon attributes. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments will be briefly described below.

[0020] The accompanying drawings described below are only related to some embodiments of the invention and are not intended to limit the invention.

[0021] In the attached diagram: Figure 1 A schematic diagram of the method steps of this application is shown; Figure 2 A schematic diagram of the raw material processing procedure of this application is shown; Figure 3 A schematic diagram of the forced mixer structure of this application is shown; Figure 4 A schematic diagram of the internal structure of the forced mixer of this application is shown; Figure 5 A schematic diagram of the square slot structure of this application is shown; Figure 6 A schematic diagram of the structure of the excitation guide rod of this application is shown; Figure 7 A schematic diagram of the linkage rotary disk of this application is shown; Figure 8 A schematic diagram of the structure of the rotary toothed ring of this application is shown; Figure 9 A schematic diagram of the oscillation groove of this application is shown; Figure 10 A schematic diagram of the jaw crusher of this application is shown; Figure 11 This application shows Figure 4 A magnified structural diagram of point A in the middle; Figure 12 This application shows Figure 5 A magnified structural diagram of point B in the middle.

[0022] Figure label: 1. Forced mixer; 101. Vibration tank; 102. Compensation tank; 103. Vibration guide hole; 2. Semi-open cover; 201. Injection pipe; 3. Drive motor; 4. Concrete mixing shaft; 401. Mixing blades; 402. Square slot; 5. Vibration tray; 501. Return spring; 502. Eccentric wheel; 503. Driven gear; 6. Vibration guide rod; 601. Guide rod blocking plate; 602. Vibration convex pattern; 603. Vibration insert; 7. Linkage gyroscope; 701. Gyroscope toothed ring; 702. Linkage square column; 8. Discharge port; 9. Jaw crusher; 10. Impact crusher; 1001. Sand making machine; 11. Wheel bucket sand washer; 12. Steam prehumidifier; 13. Ball mill; 14. Rotary kiln. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the described embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Example 1: Please refer to Figures 1 to 12 : This invention proposes a method for preparing self-insulating wall concrete for buildings using waste concrete and waste brick powder, comprising the following steps: Raw material pretreatment, batching preparation, segmented mixing, and molding curing; raw material pretreatment includes crushing, spray grinding, and steam pre-wetting of waste concrete to obtain modified recycled aggregate, and grinding, calcining activation, and surface modification of waste brick powder to obtain activated waste brick powder; in batching preparation, the raw materials, by weight, include: 350-450 parts modified recycled aggregate, 80-120 parts activated waste brick powder, 180-220 parts cement, 100-150 parts lightweight aggregate, 50-80 parts mineral admixture, 3-5 parts water-reducing agent, 0.5-1 part air-entraining agent, and 120-1... 50 portions; the staged mixing adopts the order of dry mixing of aggregates, dry mixing of cementitious materials, and wet mixing in forced mixer 1; the molding and curing adopts the composite curing system of "low temperature moisturizing and high temperature autoclaving"; the concrete obtained has a 28-day compressive strength ≥30MPa, thermal conductivity ≤0.45W / (m·K), and dry apparent density ≤1800kg / m³. This special mixing sequence can ensure that the coarse and fine aggregates and powders are premixed evenly, avoid agglomeration during subsequent wet mixing, thereby improving the overall homogeneity. This system can effectively promote the hydration and pozzolanic reaction of cementitious materials, accelerate strength development, and optimize the final pore structure.

[0025] In this embodiment, the raw material pretreatment step specifically includes: the waste concrete is subjected to three-stage crushing (coarse crushing, medium crushing, and fine crushing) by a jaw crusher 9, an impact crusher 10, and a sand making machine 1001; the concrete is then sprayed and ground using a cement slurry with a water-cement ratio of 0.3-0.4 by a wheel sand washing machine 11; and then pre-wetting is performed using a steam pre-wetting machine 12 at a steam temperature of 80-100℃ for 30-45 minutes, so that the moisture content of the resulting modified recycled aggregate is controlled at 5-7%. This process utilizes cement particles to fill and strengthen the old mortar and micro-cracks attached to the surface of the aggregate, significantly reducing its water absorption rate. This pre-wetting treatment can stabilize the internal moisture of the aggregate and prevent it from absorbing water too quickly during the mixing process, thus affecting its workability.

[0026] In this embodiment of the disclosure, the raw material pretreatment step further includes: grinding the waste brick powder into a particle size of no more than 100 μm using a jaw crusher 9 and a ball mill 13 to significantly increase its specific surface area; then calcining and activating it in a rotary kiln 14 at 600-700℃ and holding it at that temperature for 20-30 minutes. This thermal activation process can effectively stimulate the potential pozzolanic activity of the waste brick powder; finally, adding 1-2% of a silane coupling agent by mass of the waste brick powder for surface modification to obtain activated waste brick powder. This coupling agent can form a chemical bridge between the powder surface and the cement hydration products, significantly enhancing the interfacial bonding force.

[0027] In this embodiment of the disclosure, the specific composition of each raw material in the batching preparation is as follows: 350-450 parts of modified recycled aggregate, 80-120 parts of activated waste brick powder, 180-220 parts of 42.5 grade ordinary Portland cement, 100-150 parts of fly ash ceramsite, 50-80 parts of phosphorus slag powder, 3-5 parts of polycarboxylate superplasticizer, 0.5-1 part of rosin thermal polymer air-entraining agent, and 120-150 parts of water. Among them, fly ash ceramsite, as a lightweight aggregate, is the key to achieving a low thermal conductivity. Phosphorus slag powder, as a mineral admixture, not only has an active effect but also contributes a certain carbon fixation effect. The combined use of polycarboxylate superplasticizer and air-entraining agent optimizes the workability and internal pore structure of the mixture while ensuring strength.

[0028] In this embodiment, the total mixing time in stages is not less than 250 seconds to ensure that each component, especially the modified recycled aggregate and activated brick powder, can be fully mixed and coated with the new cementitious system. During molding and curing, the conditions for high-temperature autoclaving are: temperature 80-90℃, pressure 0.1-0.15MPa, and autoclaving curing time of 24 hours. These mild autoclaving conditions can significantly accelerate the cementitious reaction without damaging the structure of lightweight ceramsite, enabling the concrete to obtain high early strength and stable volume stability in a short period of time.

[0029] In this embodiment, the forced mixer 1 has a through-hole oscillation groove 101 on its side wall, a compensation groove 102 at the end of the oscillation groove 101, and an oscillation guide hole 103 at the bottom of the forced mixer 1. The forced mixer 1 has a discharge port 8 at its bottom side. A semi-open cover 2 with a fan-shaped opening is connected to the top of the forced mixer 1. An injection pipe 201 is connected to the semi-open cover 2. A drive motor 3 is installed at the center of the top of the semi-open cover 2. The shaft of the drive motor 3 is connected to a concrete mixing shaft 4. Mixing blades 401 are connected to the outside of the concrete mixing shaft 4. A square slot 402 with a square cross-section is opened at the bottom of the concrete mixing shaft 4. The lower end of the concrete mixing shaft 4 is rotatably connected to the bottom of the forced mixer 1 via a bearing and a sealing ring. Liquid raw materials and additives are added into the forced mixer 1 through the injection pipe 201. The drive motor 3 drives the concrete mixing shaft 4 and the mixing blades 401 to rotate, thus mixing the raw materials inside the forced mixer 1 and ensuring thorough mixing of different raw materials.

[0030] In this embodiment, a linkage disc 7 is rotatably connected inside the vibrating tray 5. A linkage square column 702 is vertically welded to the top of the linkage disc 7. The linkage square column 702 is slidably inserted into the square slot 402. A disc gear ring 701 is fixedly connected to the lower surface edge of the linkage disc 7. The disc gear ring 701 meshes with the driven gear 503. The bottom of the forced mixer 1 is provided with a vibrating tray 5. Four reset tension springs 501 are connected between the vibrating tray 5 and the lower surface of the forced mixer 1. An eccentric wheel 502 is rotatably connected to the inner wall of the vibrating tray 5. A driven gear 503 is fixedly connected to the end of the support shaft of the eccentric wheel 502. A vibrating guide rod 6 is connected to the outside of the vibrating tray 5. The vibrating guide rod 6 is slidably connected to the oscillation groove 101. A guide rod blocking plate 601 is provided at the upper end of the vibrating guide rod 6. The guide rod block plate 601 is slidably connected to the compensation groove 102. The inner surface of the guide rod block plate 601 is provided with vibration ridges 602. The vibration guide rod 6 is provided with a vibration insertion post 603 slidably connected to the oscillation guide hole 103. The torque is transmitted to the linkage rotary disc 7 through the linkage square column 702 by the rotation of the concrete mixing shaft 4. The rotation disc gear ring 701 and the driven gear 503 drive the eccentric wheel 502 to rotate at high speed. Due to the eccentric effect, the vibration force is generated, which drives the vibration tray 5 and the vibration guide rod 6 to vibrate up and down at high frequency. The vibration ridges 602 and the vibration insertion post 603 contact the raw materials inside the forced mixer 1, which can transmit the vibration, expel the air bubbles in the raw materials inside the forced mixer 1 more quickly, improve the density of concrete, and reduce the generation of air bubbles.

[0031] Example 2, based on Example 1, involves the following raw material pretreatment: After removing impurities from waste concrete blocks, recycled aggregate is obtained through coarse, medium, and fine crushing. It is then sprayed and ground with cement slurry (water-cement ratio 0.3) until the mud content is 1.8%, pre-wetted with steam at 80℃ for 45 minutes, and the moisture content is controlled at 5%. Waste bricks are crushed and ball-milled for 50 minutes to obtain brick powder with a particle size ≤100μm. The powder is then calcined at 650℃ for 25 minutes, and 1.5% silane coupling agent KH-550 is added and stirred for 18 minutes.

[0032] Ingredient preparation: Take 400 parts by weight of modified recycled aggregate, 100 parts of activated waste brick powder, 200 parts of 42.5 grade ordinary Portland cement, 120 parts of fly ash ceramsite, 60 parts of phosphorus slag powder, 4 parts of polycarboxylate superplasticizer, 0.8 parts of rosin air-entraining agent, and 135 parts of water, and dissolve the admixtures in water.

[0033] Segmented mixing: First, dry mix the aggregate for 30 seconds, then add the cementitious material and dry mix for 20 seconds, and finally add the admixture solution and wet mix for 2.5 minutes, with the slump controlled at 135 mm.

[0034] Molding and curing: Vibrate for 18 seconds to form, and after demolding, first keep moist at 45℃ for 12 hours, then steam press at 85℃ and 0.12MPa for 24 hours, and then cool naturally.

[0035] Finished product performance: 28-day compressive strength 32.5MPa, thermal conductivity 0.42W / (m·K), dry apparent density 1750kg / m³, frost resistance F200, impermeability grade P6.

[0036] Example 3: Based on Example 2, the raw material pretreatment is as follows: waste concrete aggregate is treated with cement slurry (water-cement ratio 0.4) to a mud content of 2%, pre-wetted with steam at 100℃ for 30 minutes, and the moisture content is 7%; waste brick powder is ball-milled for 60 minutes, calcined at 700℃ for 20 minutes, and 2% silane coupling agent is added and stirred for 15 minutes.

[0037] Ingredients preparation: 450 parts modified recycled aggregate, 120 parts activated waste brick powder, 220 parts cement, 150 parts fly ash ceramsite, 80 parts phosphorus slag powder, 5 parts water-reducing agent, 1 part air-entraining agent, and 150 parts water.

[0038] Mixing and curing: Mix according to the same process, with a slump of 150mm; cure by keeping moist at 50℃ for 12 hours, and then steam pressurize at 90℃ and 0.15MPa for 24 hours.

[0039] Finished product performance: 28-day compressive strength 35MPa, thermal conductivity 0.40W / (m·K), dry apparent density 1780kg / m³.

[0040] The working principle of this embodiment is as follows: First, the waste concrete is pre-treated: after removing impurities such as steel bars and plastics from the waste concrete blocks, it is sequentially crushed by a jaw crusher 9 (particle size ≤ 50mm), an impact crusher 10 (particle size ≤ 20mm), and a sand making machine 1001 to obtain recycled aggregate; the recycled aggregate is placed in a wheel sand washing machine 11 and sprayed and ground with cement slurry with a water-cement ratio of 0.3-0.4 to remove the surface mortar and control the mud content to ≤ 2%; then it is pre-humidified by a steam pre-humidifier 12 at a temperature of 80-100℃ for 30-45 minutes to stabilize the moisture content of the aggregate. At 5-7%, modified recycled aggregate is obtained. Waste bricks are crushed by jaw crusher 9 and then fed into ball mill 13 for ultrafine grinding. The grinding time is controlled at 40-60 minutes to obtain waste brick powder with a particle size ≤100μm. The waste brick powder is then placed in rotary kiln 14 for calcination and activation at a temperature of 600-700℃ for 20-30 minutes. After cooling, 1-2% of silane coupling agent KH-550 is added, and the mixture is stirred at high speed for 15-20 minutes to obtain activated waste brick powder. The following raw materials are prepared by weight: 350-450 parts modified recycled aggregate, activated waste brick powder... 80-120 parts of modified recycled aggregate, 180-220 parts of ordinary Portland cement (grade 42.5), 100-150 parts of fly ash ceramsite (particle size 5-10mm), 50-80 parts of phosphorus slag powder, 3-5 parts of water-reducing agent (polycarboxylate), 0.5-1 part of air-entraining agent (rosin resin), and 120-150 parts of water; wherein the water-reducing agent and air-entraining agent are pre-dissolved in water to prepare a composite admixture solution. The mixture is stirred in stages using a forced mixer 1. First, add the modified recycled aggregate and fly ash ceramsite, and dry mix for 30 seconds; then add the activated waste brick powder, ordinary Portland cement, and phosphorus slag powder, and continue dry mixing for 20 seconds; finally, add the remaining ingredients at a uniform speed. The composite admixture solution is wet-mixed for 2-3 minutes until the concrete mixture is uniformly workable and the slump is controlled at 120-150mm. For molding and curing, the concrete mixture is poured into the wall mold and compacted using high-frequency vibration (frequency 50-60Hz) for 15-20 seconds. Demolding is carried out within 24 hours after molding, and then the mixture is transferred to an autoclave for curing. It is first cured at a temperature of 40-50℃ and humidity ≥90% for 12 hours, then the temperature is increased to 80-90℃ and the pressure is 0.1-0.15MPa for 24 hours, and finally the mixture is allowed to cool naturally to room temperature to obtain the self-insulating wall concrete for the building.

[0041] The following points should be noted in this article: 1. The accompanying drawings of the embodiments disclosed herein only relate to the structures involved in the embodiments disclosed herein; other structures can be referred to in general design.

[0042] 2. Where there is no conflict, the embodiments of this disclosure and the features in the embodiments can be combined with each other to obtain new embodiments.

[0043] The above are merely specific embodiments of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A method for preparing self-insulating wall concrete for buildings from waste concrete and waste brick powder, characterized in that, Includes the following steps: Raw material pretreatment, ingredient preparation, segmented mixing, and molding and curing; The raw material pretreatment includes crushing, spraying, grinding and steam pre-wetting of waste concrete to obtain modified recycled aggregate, and grinding, calcining and surface modification of waste brick powder to obtain activated waste brick powder. In the preparation of the ingredients, the raw materials, by weight, include: 350-450 parts of the modified recycled aggregate, 80-120 parts of the activated waste brick powder, 180-220 parts of cement, 100-150 parts of lightweight aggregate, 50-80 parts of mineral admixture, 3-5 parts of water-reducing agent, 0.5-1 part of air-entraining agent, and 120-150 parts of water. The segmented mixing is carried out in a forced mixer (1) in the order of dry mixing of aggregates, dry mixing of cementitious materials, and wet mixing. The molding and curing process adopts a composite curing system of "low temperature moisturizing and high temperature steam pressing"; The prepared concrete has a 28-day compressive strength ≥30MPa, a thermal conductivity ≤0.45W / (m·K), and a dry apparent density ≤1800kg / m³.

2. The method for preparing self-insulating wall concrete from waste concrete and waste brick powder according to claim 1, characterized in that, The raw material pretreatment steps specifically include: Waste concrete is crushed in three stages: coarse crushing, medium crushing, and fine crushing by a jaw crusher (9), an impact crusher (10), and a sand making machine (1001). It is then sprayed and ground with cement slurry with a water-cement ratio of 0.3-0.4 by a wheel bucket sand washing machine (11). Subsequently, it is pre-humidified with steam by a steam pre-humidifier (12) at a steam temperature of 80-100℃ for 30-45 minutes, so that the moisture content of the resulting modified recycled aggregate is controlled at 5-7%.

3. The method for preparing self-insulating wall concrete from waste concrete and waste brick powder according to claim 2, characterized in that, The raw material pretreatment step specifically includes: Waste brick powder is ball-milled to a particle size of no more than 100 μm using a jaw crusher (9) and a ball mill (13). Then, it is calcined and activated in a rotary kiln (14) at 600-700℃ and kept at that temperature for 20-30 min. Finally, 1-2% of the mass of the waste brick powder is added to modify the surface, thus obtaining the activated waste brick powder.

4. The method for preparing self-insulating wall concrete from waste concrete and waste brick powder according to claim 1, characterized in that, In the preparation of the ingredients, the specific composition of each raw material is as follows: The modified recycled aggregate is 350-450 parts. The activated waste brick powder consists of 80-120 parts. 180-220 parts of 42.5 grade ordinary Portland cement 100-150 parts fly ash ceramsite 50-80 parts of phosphorus slag powder 3-5 parts of polycarboxylate superplasticizer Rosin thermal polymer air-entraining agent 0.5-1 part, 120-150 parts water.

5. The method for preparing self-insulating wall concrete from waste concrete and waste brick powder according to claim 1, characterized in that, The total time for the segmented mixing is not less than 250 seconds; in the molding and curing process, the conditions for the high-temperature autoclaving are: temperature 80-90℃, pressure 0.1-0.15MPa, and autoclaving curing time of 24 hours.

6. The method for preparing self-insulating wall concrete for buildings from waste concrete and waste brick powder according to claim 1, characterized in that, The forced mixer (1) has a oscillation groove (101) through the side wall, a compensation groove (102) at the end of the oscillation groove (101), and an oscillation guide hole (103) through the bottom of the forced mixer (1).

7. The method for preparing self-insulating wall concrete from waste concrete and waste brick powder according to claim 6, characterized in that, The forced mixer (1) is connected to a semi-open cover (2) with a fan-shaped opening at the top. The semi-open cover (2) is connected to an injection pipe (201). A drive motor (3) is installed at the center above the semi-open cover (2). The shaft of the drive motor (3) is connected to a concrete mixing shaft (4). A mixing blade (401) is connected to the outside of the concrete mixing shaft (4). A square slot (402) with a square cross section is opened at the bottom of the concrete mixing shaft (4). The lower end of the concrete mixing shaft (4) is rotatably connected to the bottom of the forced mixer (1) through a bearing and a sealing ring.

8. The method for preparing self-insulating wall concrete for buildings from waste concrete and waste brick powder according to claim 7, characterized in that, The forced mixer (1) is provided with a vibration tray (5) at the bottom. Four reset tension springs (501) are connected between the vibration tray (5) and the lower surface of the forced mixer (1). An eccentric wheel (502) is rotatably connected to the inner wall of the vibration tray (5). A driven gear (503) is fixedly connected to the end of the support shaft of the eccentric wheel (502).

9. The method for preparing self-insulating wall concrete for buildings from waste concrete and waste brick powder according to claim 8, characterized in that, The vibration tray (5) is rotatably connected to a linkage rotary disk (7). A linkage square column (702) is vertically welded to the top of the linkage rotary disk (7). The linkage square column (702) is slidably inserted into the square slot (402). A rotary disk gear ring (701) is fixedly connected to the lower surface edge of the linkage rotary disk (7). The rotary disk gear ring (701) meshes with the driven gear (503).

10. The method for preparing self-insulating wall concrete for buildings from waste concrete and waste brick powder according to claim 9, characterized in that, The excitation tray (5) is externally connected to an excitation guide rod (6), which is slidably connected to an oscillation groove (101). The upper end of the excitation guide rod (6) is provided with a guide rod blocking plate (601), which is slidably connected to a compensation groove (102). The inner surface of the guide rod blocking plate (601) is provided with excitation ridges (602), and the excitation guide rod (6) is provided with an excitation insert (603) slidably connected to an oscillation guide hole (103).

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