A renovation waste regeneration fine powder thermal insulation mortar and a preparation method thereof

Abstract

The application relates to the field of building materials and thermal insulation mortar, in particular to a decoration waste regeneration fine powder thermal insulation mortar and a preparation method thereof. The mortar raw material is composed of cement, decoration waste regeneration powder, foam stabilizer and foaming agent, and the mass ratio of the cement, the decoration waste regeneration powder and the foaming agent is (45-76):(25-56):(5-9). The decoration waste regeneration powder comprises decoration waste regeneration fine powder containing aerated brick powder. The decoration waste regeneration powder comprises effective aluminum components and filler components, the effective aluminum components account for 1-3% of the total mass of the cement and the decoration waste regeneration powder, the maximum particle size of the decoration waste regeneration powder is not more than 0.075 mm, and the D50 of the decoration waste regeneration powder is 0.025-0.035 mm. The application meets the thermal insulation performance, improves the early strength and the frost resistance and impermeability, realizes the resource utilization of the decoration waste, reduces the cost input and realizes the sustainable development.

Description

Technical Field

[0001] This application relates to the fields of building materials and thermal insulation mortar, and more specifically, it relates to a recycled fine powder thermal insulation mortar made from construction waste and its preparation method. Background Technology With the accelerating pace of urbanization, urban construction activities in my country are becoming increasingly frequent, resulting in hundreds of millions of pieces of construction waste, a figure that continues to rise annually. Construction waste is not only enormous in quantity but also poses significant health risks. Landfilling occupies vast amounts of land and pollutes the soil, while leachate from rainwater contaminates water bodies, and dust and harmful gases severely pollute the air. During the generation and crushing stages of construction waste, a large amount of fine powder is formed, primarily composed of concrete powder and aerated brick powder. Recycled construction waste powder has high porosity, an uneven surface, and a large specific surface area, resulting in good adhesion to cement and improving the early strength, frost resistance, impermeability, and thermal insulation properties of mortar.

[0002] Thermal insulation mortar is a commonly used material for insulating building walls. It is mainly composed of cementitious materials, insulating aggregates, and various additives. However, existing thermal insulation mortars have several performance defects.

[0003] Inorganic thermal insulation mortar is highly absorbent and prone to moisture absorption, which significantly reduces its insulation performance and makes it difficult to achieve ideal energy-saving effects. Furthermore, the increased weight of the mortar after absorbing water can burden the building and easily lead to problems such as wall cracking and peeling. Traditional inorganic thermal insulation mortar faces bottlenecks such as high cost, low solid waste utilization rate, and an imbalance between insulation performance and strength. Applying recycled construction waste powder to mortar systems is a good way to solve the cost problem; however, directly using recycled construction waste powder also faces issues such as affecting the mortar's insulation performance and strength. Summary of the Invention

[0004] This application provides a thermal insulation mortar made from recycled fine powder of construction waste and its preparation method. The mortar uses recycled fine powder of construction waste to replace part of the cement and introduces a foaming agent. While meeting the thermal insulation performance requirements, it improves the early strength and freeze-thaw resistance and impermeability, realizes the resource utilization of construction waste, reduces cost input, and achieves sustainable development.

[0005] Firstly, this application provides a recycled fine powder thermal insulation mortar made from construction waste, employing the following technical solution: A type of thermal insulation mortar made from recycled construction waste, the raw materials of which include cement, recycled construction waste powder, foam stabilizer and foaming agent, wherein the mass ratio of cement, recycled construction waste powder and foaming agent is (45-76):(25-56):(5-9); The recycled construction waste powder includes fine recycled construction waste powder containing aerated brick powder, and the recycled construction waste powder includes effective aluminum components and filler components, wherein the effective aluminum components account for 1% to 3% of the total mass of cement and recycled construction waste powder; The maximum particle size of the recycled construction waste powder is no more than 0.075 mm, and the D50 of the recycled construction waste powder is 0.025~0.035 mm.

[0006] By adopting the above technical solution, this application uses recycled fine powder from construction waste, rich in aerated brick powder, as the core raw material. Mechanical grinding breaks down the Al-O bond network in the aerated brick powder, transforming it into active [AlO4] monomers, significantly enhancing the reactivity of the micro-powder pozzolanic material. These active monomers react with cement through hydration, increasing mortar strength. Simultaneously, grinding the aerated brick powder reduces the particle size, releasing unreacted aluminum powder residues encapsulated in alumina. These residues react synergistically with the foaming agent, promoting foaming, accelerating foaming speed, generating uniform pores, and effectively blocking heat convection and conduction. Furthermore, the inert components in the construction waste fine powder act as fine aggregates, filling micropores, reducing the proportion of harmful pores, and densifying the cement stone structure, synergistically improving the early strength, impermeability, and frost resistance of the mortar. This application combines recycled fine powder from construction waste with a foaming agent, achieving efficient conversion and reuse of solid waste. It not only improves the workability of foamed mortar but also reduces costs, aligning with the concept of sustainable development and possessing both economic and environmental value. It should also be noted that the filler component in the recycled construction waste powder is an inert component that does not participate in the reaction. Cement and recycled construction waste powder are cementing materials.

[0007] Furthermore, the foaming agent is hydrogen peroxide.

[0008] Furthermore, the hydrogen peroxide has a mass concentration of 27.5%-35%.

[0009] By adopting the above technical solutions, hydrogen peroxide is preferred as the foaming agent. It can produce a better compounding effect with the fine powder of recycled construction waste, and the foaming rate is faster. This makes the pore structure of the mortar more uniform and stable, and reduces the impact on the subsequent setting of the mortar.

[0010] Furthermore, the foam stabilizer includes at least one of alkyl sulfonate, stearate, and protein-based foam stabilizer. The mass ratio of the cement, recycled construction waste powder, foaming agent, and foam stabilizer is (45-76):(25-56):(5-9):(0.5-2).

[0011] Furthermore, the foam stabilizer is calcium stearate powder with a mesh size greater than 200 mesh.

[0012] Furthermore, the cement is silicate cement with a mesh size greater than 200 mesh.

[0013] Secondly, this application provides a method for preparing recycled fine powder thermal insulation mortar from construction waste, employing the following technical solution: A method for preparing recycled fine powder thermal insulation mortar from construction waste includes the following steps: Grinding of construction waste recycled powder: The crushed construction waste recycled powder and grinding media are loaded into a ball mill jar for grinding, then dried and sieved to obtain construction waste recycled powder with a specified particle size; Mortar preparation: Grind the recycled construction waste powder and cement evenly to obtain a dry powder mixture; then add water and foam stabilizer to the dry powder mixture, mix evenly to obtain a slurry; add foaming agent to the slurry, stir, let stand, and mature to obtain thermal insulation mortar.

[0014] Furthermore, the crushed construction waste recycled powder and grinding media are loaded into a ball mill jar and run at 65%~75% of the critical speed. For the first 0.5~1 hours, a high-energy impact mode is used to achieve coarse crushing. For the next 1~3 hours, the grinding mode is switched to grind. The filling rate of the high-energy impact mode is 40%~45%, and the filling rate of the grinding mode is 60%~65%.

[0015] Furthermore, in the grinding step of the recycled construction waste powder, the moisture content of the wet powder during the grinding process is 5-30%.

[0016] Furthermore, the mass ratio of the cement to the water is (45-76):(50-70).

[0017] In summary, this application has the following beneficial effects: 1. Improved Thermal Insulation Performance: The grinding of aerated concrete brick powder breaks down the alumina film coating the unreacted aluminum powder, releasing a large amount of aluminum powder. This aluminum powder reacts synergistically with the foaming agent to release gas, improving the foaming effect and speed, and promoting the uniformity and stability of the pores. Within these pores, the movement of air molecules is restricted, making convective heat transfer difficult. The uniform distribution of numerous porous fine powders within the inorganic thermal insulation mortar prevents interconnection between pores, effectively blocking heat conduction. The foamed thermal insulation mortar prepared in this application effectively reduces heat transfer and convection within the mortar, exhibiting excellent thermal insulation performance, effectively meeting building insulation requirements, and reducing building energy consumption.

[0018] 2. Enhanced Mechanical and Durability Properties: The grinding process of recycled construction waste powder disrupts the Al-O bond network in aerated brick powder, transforming it into active [AlO4] monomers. This significantly enhances the reactivity of pozzolanic materials. These active monomers react with cement through hydration, increasing mortar strength. After grinding, the particle size of other components in the recycled construction waste powder decreases, thus blocking the interconnected pores in the mortar and acting as micro-aggregate fillers. This optimizes the pore structure, significantly improving the early strength of the mortar. Simultaneously, the mortar's frost resistance and impermeability are also noticeably improved, greatly enhancing its durability.

[0019] 3. Cost and resource savings and promotion of sustainable development: This application replaces part of the cement with recycled fine powder from construction waste, which reduces cement usage, production costs, and dependence on natural resources, thus realizing the resource utilization of construction waste. Simultaneously, it provides an effective solution for construction waste treatment, transforming it into building materials, reducing land occupation and pollution, promoting the sustainable development of the construction industry, and reaping economic and environmental benefits, in line with environmental protection and resource recycling requirements. Detailed Implementation

[0020] The present application will be further described in detail below with reference to the embodiments.

[0021] Example This application provides a fine powder thermal insulation mortar made from recycled construction waste. The raw materials include cement, water, recycled construction waste powder, foaming agent, and foam stabilizer in a mass ratio of (45-76):(50-70):(25-56):(5-9):(0.5-2).

[0022] The foaming agent is hydrogen peroxide; the foam stabilizer includes at least one of alkyl sulfonate, stearate, and protein-based foam stabilizer; the cement is silicate cement with a mesh size greater than 200 mesh, conforming to the silicate cement specified in the "General Silicate Cement" (GB175-2023) standard.

[0023] In this embodiment, the recycled decoration waste powder is obtained by grinding decoration waste containing aerated brick powder. The recycled decoration waste powder includes effective aluminum components and filler components. According to the hydrochloric acid method, the effective aluminum components account for 1% to 3% of the total mass of cement and recycled decoration waste powder. The maximum particle size of the recycled decoration waste powder does not exceed 0.075 mm, and the D50 of the recycled decoration waste powder is 0.025 to 0.035 mm.

[0024] The grinding process for recycled construction waste powder is as follows: Grinding of Recycled Construction Waste Powder: The crushed recycled construction waste powder and grinding media are loaded into a ball mill jar and run at 65%~75% of the critical speed, usually 25~35 r / min; for the first 0.5~1 h, a high-energy impact mode is used for coarse crushing, with a filling rate of 40%~45%; for the next 1~3 h, the grinding mode is switched to grinding, with a filling rate of 60%~65%; during the grinding process, the moisture content of the wet powder is 5~30%; after grinding, the wet powder is spread evenly on a stainless steel tray (thickness ≤30 mm), placed in a forced-air drying oven to dry, and then put into an ultrasonic vibrating screen for sieving to obtain recycled construction waste powder of the specified particle size.

[0025] In this embodiment of the application, the method for preparing thermal insulation mortar includes the following steps: Accurately weigh the cement and recycled construction waste powder using a balance, and pour them into a high-speed mixer according to the specific ratio. Start the mixer and stir at 100~150 r / min for 3-5 minutes until the mixture is visually homogeneous and forms a uniform dry powder mixture.

[0026] Transfer the prepared dry powder to a horizontal shaft mixer, and add water and foam stabilizer precisely according to the predetermined water-cement ratio. Turn on the mixer and stir continuously at a low speed (about 100~240 r / min) for 1.5 minutes to ensure that the dry powder and water are fully in contact and mixed to form a uniform slurry without lumps.

[0027] Slowly and evenly add the foaming agent to the prepared slurry, while simultaneously adjusting the mixer speed to 300 rpm and stirring continuously for 10 seconds to fully disperse the foaming agent and initiate foaming, forming a stable foam structure. Then, pour the slurry into a constant-temperature sealed container and let it stand for 5-10 minutes in an environment of 20-30℃ to allow it to fully mature. The finished product is the foamed thermal insulation mortar.

[0028] The following explanation is provided through specific examples.

[0029] Examples 1-9 The difference between Examples 1-9 is that the content of each raw material is different, as shown in Table 1.

[0030] Table 1. Raw material usage for Examples 1-9 The difference between Example 10 and Example 1 is that the foaming agent is 35% hydrogen peroxide, and the amount used is 650g.

[0031] Comparative Example The difference between Comparative Example 1 and Example 1 is that the effective aluminum content accounts for 4.8% of the mass of the cementitious material.

[0032] The difference between Comparative Example 2 and Example 1 is that the effective aluminum content accounts for 0.7% of the mass of the cementitious material.

[0033] The difference between Comparative Example 3 and Example 1 is that the particle size of the recycled construction waste powder is 0.095 mm at the maximum and D50 is 0.055 mm.

[0034] The difference between Comparative Example 4 and Example 1 is that the particle size of the recycled construction waste powder is 0.055 mm at the maximum and D50 is 0.025 mm.

[0035] The difference between Comparative Example 5 and Example 1 is that the amount of foaming agent used is 1100g.

[0036] The difference between Comparative Example 6 and Example 1 is that the amount of foaming agent used is 380g.

[0037] The difference between Comparative Example 7 and Example 1 is that the foaming agent is animal protein.

[0038] Performance testing The performance of the thermal insulation mortars obtained in the examples and comparative examples was tested, specifically as follows: The thermal conductivity was determined using the protective hot plate method according to GB / T10294-2008, with specimen dimensions of 300mm×300mm×25mm. The dry bulk density was determined using the constant mass method according to GB / T5486-2008, with a specimen size of 100mm×100mm×100mm; the wet bulk density was determined using the immersion weighing method according to GB / T5486-2008, with a specimen size of 100mm×100mm×100mm. The compressive strength was tested using the cubic compression test according to GB / T23451-2009, with specimen dimensions of 70.7mm × 70.7mm × 70.7mm. The softening coefficient was determined using the compressive strength ratio method after immersion in water, as specified in GB / T23451-2009. The specimen size was 70.7mm × 70.7mm × 70.7mm. The impermeability grade adopts the step-by-step pressure method of the GB / T23440-2009 standard, and the specimen size is a 175mm (top) / 185mm (bottom) × 150mm frustum. The frost resistance was tested using the rapid freezing method specified in GB / T50082-2009, with specimens measuring 100mm×100mm×400mm prisms.

[0039] The test results are shown in Tables 2 and 3.

[0040] Table 2 Performance test results of the embodiments Table 3 Performance test results of the comparative examples As can be seen from the performance of the embodiments, the thermal insulation mortar of this application, in summary, not only meets the thermal insulation performance, but also improves early strength and frost and water resistance, and realizes the resource utilization of decoration waste.

[0041] Analysis of the performance of Comparative Examples 1 and 5 shows that excessive use of effective aluminum and foaming agent will significantly reduce dry bulk density and 3d compressive strength, and the irreversible collapse of the bubble structure will lead to an abnormal increase in 28d water-soaked bulk density; the surge in porosity will cause a surge in water absorption, which will accelerate the loss of compressive strength after softening, and the softening coefficient will show a short-term artificial high. At the same time, due to the thermal convection effect of the porosity and the intrusion of liquid water, the thermal conductivity will rise abnormally.

[0042] Analysis of the performance of Comparative Examples 2 and 6 shows that insufficient effective aluminum content and foaming agent (or the use of animal protein foaming agent) will systematically increase the dry density, 3-day and 28-day compressive strength. However, due to insufficient bubble formation, the porosity is too low, which significantly weakens the thermal insulation function (increases the thermal conductivity) and violates the core performance requirements of thermal insulation materials. Although the compressive strength is relatively stable after softening due to the decrease in water absorption, the loss of thermal insulation performance constitutes a fundamental defect.

[0043] Analysis of the performance of Comparative Example 3 shows that the increased particle size of the recycled powder leads to insufficient filling of the channels between the pores, weakening the support structure of the bubble walls, resulting in a slight decrease in the 28-day compressive strength and the compressive strength after softening. At the same time, due to the improved pore connectivity, the 28-day water-soaked bulk density increases slightly, but the optimization of the microporous structure can slightly reduce the thermal conductivity.

[0044] Analysis of the performance of Comparative Example 4 shows that the small particle size of the regenerated powder causes particle agglomeration, reduces the hydration reaction activity, and leads to a slight decrease in 3-day and 28-day compressive strength. The agglomerates form local dense areas, which slightly reduce the thermal conductivity, but significantly increase the energy consumption of fine powder grinding and deteriorate the cost-effectiveness.

[0045] Analysis of the performance of Comparative Example 7 shows that the use of other types of foaming agents, such as animal protein, results in poor compounding of the foaming agent and recycled powder, affecting bubble generation and significantly weakening the thermal insulation function (increasing the thermal conductivity).

[0046] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A type of thermal insulation mortar made from recycled construction waste fine powder, characterized in that, The raw materials consist of cement, recycled construction waste powder, foam stabilizer, and foaming agent, wherein the mass ratio of cement, recycled construction waste powder, and foaming agent is (45-76):(25-56):(5-9). The recycled construction waste powder includes fine recycled construction waste powder containing aerated brick powder, and the recycled construction waste powder includes effective aluminum components and filler components, wherein the effective aluminum components account for 1% to 3% of the total mass of cement and recycled construction waste powder; The maximum particle size of the recycled construction waste powder is no more than 0.075 mm, and the D50 of the recycled construction waste powder is 0.025~0.035 mm.

2. The thermal insulation mortar made from recycled construction waste according to claim 1, characterized in that, The foaming agent is hydrogen peroxide.

3. The thermal insulation mortar made from recycled construction waste according to claim 1, characterized in that, The hydrogen peroxide concentration is 27.5%-35%.

4. The thermal insulation mortar made from recycled construction waste according to claim 1, characterized in that, The foam stabilizer includes at least one of alkyl sulfonates, stearates, and protein-based foam stabilizers.

5. The thermal insulation mortar made from recycled construction waste according to claim 1, characterized in that, The mass ratio of the cement, recycled construction waste powder, foaming agent, and foam stabilizer is (45-76):(25-56):(5-9):(0.5-2).

6. The thermal insulation mortar made from recycled construction waste according to claim 1, characterized in that, The foam stabilizer is calcium stearate powder with a mesh size greater than 200 mesh.

7. The thermal insulation mortar made from recycled construction waste according to claim 1, characterized in that, The cement is silicate cement with a mesh size greater than 200 mesh.

8. A method for preparing recycled fine powder thermal insulation mortar from construction waste as described in any one of claims 1-7, characterized in that, Includes the following steps: Grinding of construction waste recycled powder: The crushed construction waste recycled powder and grinding media are loaded into a ball mill jar for grinding, then dried and sieved to obtain construction waste recycled powder with a specified particle size; Mortar preparation: Grind the recycled construction waste powder and cement evenly to obtain a dry powder mixture; then add water and foam stabilizer to the dry powder mixture, mix evenly to obtain a slurry; add foaming agent to the slurry, stir, let stand, and mature to obtain thermal insulation mortar.

9. The method for preparing a fine powder thermal insulation mortar made from recycled construction waste according to claim 7, characterized in that, In the grinding step of the reclaimed construction waste powder, the moisture content of the wet powder is 5-30% during the grinding process.

10. The method for preparing a fine powder thermal insulation mortar made from recycled construction waste according to claim 7, characterized in that, The mass ratio of cement to water is (45-76):(50-70).

Images