A full-solid-waste light-weight foam concrete thermal insulation material and a preparation method thereof

Abstract

The application discloses a kind of full solid waste light foam concrete thermal insulation materials, including following mass fraction component raw materials: magnesium slag 20~30 parts, mineral powder 30~40 parts, graphite tailings 10~20 parts, modified glass pumice 10~50 parts, ChNFs suspension 18~81 parts, high-efficiency polycarboxylic acid water reducing agent 0.025~0.03 parts, water 40~55 parts, animal protein foaming agent 0.2~0.36 parts, polyvinyl alcohol foam stabilizer 0.15~0.25 parts;Its preparation method is: one, mixed stirring dry powder material;Two, preparation slurry;Three, ChNFs suspension coating modified glass pumice;Four, preparation foam slurry;Five, into mould forming and maintenance.The application uses magnesium slag, mineral powder and graphite tailings to realize the resource utilization of solid waste, and uses ChNFs suspension to wrap modified glass pumice as functional coarse aggregate, and uses CO2 Physical foaming, and the strength, durability and functionality of thermal insulation material are improved.

Description

Technical Field

[0001] This invention belongs to the field of building material preparation technology, specifically relating to a lightweight foamed concrete insulation material made entirely of solid waste and its preparation method. Background Technology

[0002] The General Code for Energy Conservation and Renewable Energy Utilization in Buildings (GB 55015-2022) clearly requires that the limit for the heat transfer coefficient of external walls should be lower than 0.30 W / (m²). 2 Existing wall insulation materials generally suffer from the contradiction of simultaneously achieving the key performance characteristics of "high strength" and "low thermal conductivity". For example, pure organic insulation materials (such as EPS boards, XPS boards, etc.) have low thermal conductivity (0.028W / (m·K)~0.041W / (m·K)), but low strength (0.015MPa~0.7MPa) and poor fire resistance, making them unsuitable for direct use as infill wall materials. Pure inorganic insulation materials (such as foamed concrete, rock wool, expanded perlite products, etc.) have good thermal insulation, sound insulation, and seismic resistance, but generally suffer from good thermal insulation performance at low densities, but low strength and poor durability. Among them, foamed concrete is a lightweight concrete material with a porous structure, which has a relatively high thermal conductivity (0.21W / (m·K)) and excellent fire resistance at a density of 800kg / m³. 3 The compressive strength of cement concrete ranges from 1.8 MPa to 3.0 MPa, and it primarily uses cement as its main raw material. Cement production is not only energy-intensive but also pollutes the environment, leading to high material costs (300-500 RMB / cubic meter). Furthermore, it relies on non-renewable resources, resulting in high energy consumption and is not environmentally friendly. In addition, traditional lightweight aggregate concrete, such as expanded clay and pumice, can achieve strengths of 5 MPa to 30 MPa. However, to achieve these higher strengths, a higher cement content and aggregate density are often required, resulting in higher thermal conductivity (0.2 W / (m·K) to 1.0 W / (m·K)) and higher density (reaching 1600 kg / m³). 3 ~1900kg / m 3 While some composite insulation materials (such as sandwich panels and integrated insulation and decoration panels) can balance some performance aspects, they often have complex production processes, numerous construction procedures, high overall costs, or potential problems such as interface bonding issues and thermal bridging.

[0003] The invention patent with publication number CN114315248A uses 250-500 parts cement, 120-150 parts crushed stone, 300-750 parts fine sand, 100-120 parts silica fume, 50-100 parts glass pumice, 80-90 parts silica aerogel, 70-80 parts silica aerogel, and 1-3 parts water-reducing agent as raw materials to prepare concrete blocks. It utilizes glass pumice as a carrier to adsorb silica aerogel into its pore structure, improving the thermal insulation performance and strength of the resulting concrete blocks. Although some silica fume and glass pumice are used in the raw materials, the majority of the cementitious material is still cement. Cement production is not only energy-intensive and environmentally unfriendly, but also significantly increases costs. Meanwhile, this patent modifies the initially aged wet gel to improve the hydrophobicity of the silica aerogel, and adds the silica aerogel to a mixed solution of glass pumice and some water to promote the adsorption of silica aerogel by the glass pumice. However, in an aqueous solution environment, the surface-hydrophobic silica aerogel cannot be adsorbed in large quantities onto the pumice surface, resulting in low adsorption efficiency and weak bonding force, which affects the thermal insulation performance and strength of the concrete blocks. In addition, silica aerogel is expensive, which will lead to a significant increase in the price of raw materials.

[0004] The invention patent with publication number CN120309300A utilizes multi-source solid waste (desulfurized gypsum, fly ash, and mineral powder) with additives and water to obtain a homogeneous slurry. This homogeneous slurry is then rapidly stirred while CO2 gas is introduced to prepare an aerated foamed slurry. After sealing and curing, it is dried to obtain a ternary solid waste foamed cement insulation material with low thermal conductivity. However, stirring at speeds up to 3000 rpm generates extremely strong shear forces and turbulence, causing violent motion that makes bubbles more prone to collision, merging, and enlarging. Simultaneously, the centrifugal force generated by high-speed rotation throws the slurry (especially near the surface) against the container wall, making it easier for bubbles to be carried to the surface and burst, resulting in low gas utilization, difficulty in achieving the expected foaming ratio, and unstable foam structure. Furthermore, high-speed stirring generates significant frictional heat, causing the slurry temperature to rise rapidly. The solubility of CO2 in water decreases significantly with increasing temperature; high temperatures greatly reduce the amount of CO2 that can dissolve and be retained in the slurry, which is detrimental to the formation of fine foam and thus reduces product performance.

[0005] The invention patent with publication number CN108585683A discloses a type of glass lightweight concrete, per 1m 3 The concrete contains 120-170 kg of expanded clay, 200-250 kg of glass stone, 400-450 kg of cement, 30-70 kg of fly ash, 680-720 kg of sand, 3-8 kg of water-reducing agent, and 130-180 kg of water; or per 1 m 3The concrete contains 190-230 kg of expanded clay, 120-160 kg of glass aggregate, 400-450 kg of cement, 30-70 kg of fly ash, 680-720 kg of sand, 3-8 kg of water-reducing agent, and 130-180 kg of water. From the examples, it can be seen that the density of the prepared glass lightweight stone concrete is 1680 kg / m³. 3 ~1820kg / m 3 The thermal conductivity is 0.234 W / (m·K)~0.241 W / (m·K), which shows that the thermal insulation performance is limited due to the high density of the material.

[0006] Therefore, the market urgently needs to develop new wall materials that combine high-efficiency thermal insulation, structural strength, and environmental friendliness. Summary of the Invention

[0007] The technical problem to be solved by this invention is to address the shortcomings of the prior art by providing a lightweight foamed concrete insulation material made entirely from solid waste and its preparation method. This lightweight foamed concrete insulation material uses industrial waste magnesium slag, mineral powder, and graphite tailings as cementing materials and fine aggregates, achieving resource utilization of solid waste and reducing raw material costs. Simultaneously, it introduces ChNFs suspension and modified glass pumice as functional coarse aggregates and performs physical foaming, forming a transition layer at the aggregate-slurry interface. This enhances the mechanical strength, long-term durability, and functionality of the lightweight foamed concrete insulation material, solving the problems of traditional lightweight foamed concrete's difficulty in simultaneously achieving high strength and low thermal conductivity, as well as poor durability and high cost.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a lightweight foamed concrete insulation material made entirely from solid waste, characterized in that it comprises the following raw materials in parts by weight: 20-30 parts magnesium slag, 30-40 parts mineral powder, 10-20 parts graphite tailings, 10-50 parts modified glass pumice, 18-81 parts ChNFs suspension, 0.025-0.03 parts high-efficiency polycarboxylate superplasticizer, 40-55 parts water, 0.2-0.36 parts animal protein foaming agent, and 0.15-0.25 parts polyvinyl alcohol foam stabilizer.

[0009] The above-mentioned lightweight foamed concrete insulation material made entirely from solid waste is characterized in that the magnesium slag is the undersize material after ball milling and passing through a 75µm sieve, the mineral powder is S95 grade mineral powder, and the particle size of the graphite tailings is less than 0.4mm, and the particle size less than 0.075mm does not exceed 15%.

[0010] The aforementioned lightweight foamed concrete insulation material made entirely from solid waste is characterized in that the modified glass aggregate has a particle size of 5mm~15mm and a density of 230kg / m³. 3 The glass pumice was obtained by modifying it with APTES ethanol solution.

[0011] The above-mentioned lightweight foamed concrete insulation material made entirely from solid waste is characterized in that the ChNFs suspension is prepared by TEMPO-mediated oxidation of chitin extracted from shrimp and crab shell waste.

[0012] Meanwhile, this invention also discloses a method for preparing the above-mentioned lightweight foamed concrete insulation material made entirely of solid waste, characterized in that the method includes the following steps: Step 1: Mixing and stirring dry powder materials: According to the component ratio of the target product, all-solid waste lightweight foamed concrete insulation material, weigh magnesium slag, mineral powder, high-efficiency polycarboxylate superplasticizer and polyvinyl alcohol foam stabilizer respectively, and put them into a mortar mixer for low-speed mixing to obtain a uniformly mixed dry powder material. Step 2: Prepare the slurry: Add the weighed water to the dry powder from Step 1, and add graphite tailings. Stir at low speed to form a slurry. Step 3: ChNFs suspension coating modified glass pumice: The modified glass pumice is immersed in ChNFs suspension and kept warm and shaken, and the excess suspension is drained. Then it is immersed in glutaraldehyde crosslinking solution and allowed to stand for reaction. After washing with deionized water, ChNFs suspension coating modified glass pumice is obtained. Step 4: Preparation of foam slurry: CO2 is introduced into the air compressor of the foaming machine, and the weighed animal protein foaming agent is diluted and then introduced into the foaming machine to foam and obtain CO2 foam group. Then, the CO2 foam group is quickly added to the slurry in step 2 and stirred at low speed to form foam slurry. Step 5, Molding and Curing: The ChNFs suspension obtained in Step 3 is used to coat the modified glass pumice, which is then added to the foam slurry in Step 4 and stirred at low speed. The mixture is then poured into a mold, covered with a film, and cured at room temperature for 12 hours. After that, it is placed in a curing chamber with a temperature of 40℃±2℃ and a humidity of over 90% for 24 hours. After that, it is demolded and cured in a standard curing chamber to obtain the all-solid-waste lightweight foamed concrete insulation material.

[0013] Typically, the present invention determines the amount of CO2 foam group to be used based on the amount of animal protein foaming agent, so as to achieve the required thermal insulation performance of the target product, all-solid-waste lightweight foamed concrete insulation material.

[0014] This invention involves mixing magnesium slag, mineral powder, high-efficiency polycarboxylate superplasticizer, and polyvinyl alcohol foam stabilizer into a dry powder, then adding water and graphite tailings to form a slurry. Finally, CO2 foam groups and ChNFs suspension are added to coat and modify glass pumice before curing to obtain a lightweight foamed concrete insulation material made entirely from solid waste. In this preparation process, C2S in the magnesium slag hydrates to form CSH, and free CaO in the magnesium slag hydrates to form Ca(OH)2, providing a strongly alkaline environment (usually pH>12.5). This dissolves the Si-O and Al-O bonds in the mineral powder glass, releasing active SiO2 and Al2O3, generating cementitious materials such as CSH and CASH to produce the strength of the insulation material. At the same time, the continuous generation of Ca(OH)2 during magnesium slag hydration promotes the positive development of the mineral powder pozzolanic effect, generating cementitious materials such as CSH and CASH to continuously produce the strength of the insulation material. After adding CO2 foam, some of the Ca(OH)2 will directly carbonize into CaCO3, releasing heat to accelerate the mineral powder reaction. The large-scale formation of CaCO3 increases the strength of the lightweight foamed concrete and also achieves the purpose of sealing CO2, ensuring its lightweight properties.

[0015] Chitin is the second largest biomass resource on Earth, widely found in waste materials such as shrimp and crab shells. The lightweight foamed concrete insulation material of this invention uses a ChNFs suspension as a raw material. Specifically, chitin is first extracted from shrimp and crab shell waste, and then the C6 hydroxyl group of chitin is selectively oxidized to a carboxyl group (-COOH) using a TEMPO-mediated oxidation method to obtain a ChNFs suspension. Because the surface of ChNFs is rich in -COOH / -OH, it can combine with and anchor to the -NH2 on the surface of modified glass pumice, forming a coating structure. This forms a nanofiber network structure at the aggregate-solid waste-based cementitious material interface as a transition layer. This special structure affects the key performance of the lightweight foamed concrete insulation material. (1) Mechanical aspects: The aggregate-slurry interface of ordinary foamed concrete is often a weak link. The hydrophilic groups of the nanofiber network structure absorb water in the slurry, promote hydration reaction, generate CSH, enhance the interfacial bonding force between the modified glass pumice and the slurry, and improve the compressive strength of lightweight foamed concrete. At the same time, the nanofiber network structure has water retention properties, and the stored water is released in the later stage, thereby reducing shrinkage.

[0016] (2) Durability: The nanofiber network structure "bridges" between hydration products, fills the pores, forms a dense layer, and effectively blocks the intrusion of water, chloride ions and sulfates, thereby improving the durability of lightweight foamed concrete.

[0017] (3) Functionality: The nanofibers in the nanofiber network structure are interlaced, which prolongs the heat conduction path, effectively reduces the thermal conductivity of lightweight foamed concrete, and improves its thermal insulation performance. At the same time, the hydrophilic groups (-OH / -NH2) can adsorb environmental moisture and release moisture at high temperatures. That is, this structure is both water-retaining and vapor-permeable, which is suitable for building energy conservation requirements. In addition, the modified glass pumice in this invention does not float as easily as unmodified glass pumice during the mixing process, which improves the workability of lightweight foamed concrete.

[0018] Therefore, the ChNFs suspension coating modified glass pumice, as a coarse aggregate component, has carboxyl groups in its nanofiber network structure that react with the Ca dissolved from magnesium slag. 2+ and Ca in hydration products 2+ The formation of ionic bonds strengthens the aggregate-slurry interface, and the interlaced arrangement of the nanofiber network structure extends the heat conduction path, effectively reducing the thermal conductivity of lightweight foamed concrete and improving its insulation performance. In addition, the amino groups on the chitin molecular chains of this structure can chelate heavy metal ions (especially trace amounts of lead and chromium that may be dissolved from graphite tailings), preventing toxic heavy metal elements from leaching out of the insulation material and ensuring the safety of the insulation material.

[0019] Graphite tailings, as a component of fine aggregate, are in the form of flakes and are arranged randomly in the slurry, forming tortuous air channels, which prolongs the residence time of CO2 in the slurry and improves its carbonization efficiency. At the same time, graphite tailings fill the gaps between coarse aggregates, reducing the porosity and also prolonging the heat conduction path, further reducing the thermal conductivity of lightweight foamed concrete.

[0020] The above-described preparation method is characterized in that the modified glass pumice in step three is prepared as follows: glass pumice is weighed and dried at 105°C for 2 hours, then immersed in a 2% (w / w) APTES ethanol solution and heated to 60°C with shaking reaction for 4 hours. After drying, it is ready for use. Based on conventional modification methods, this invention limits the concentration of APTES and uses ethanol as the reaction medium, and through a 4-hour shaking reaction at 60°C, improves the modification reaction rate and reduces energy consumption and time costs. The above preparation method is characterized in that the preparation process of the ChNFs suspension in step three is as follows: (1) Extraction of chitin: Shrimp and crab shell waste was soaked in 4% HCl solution for 24 hours and then washed with deionized water until neutral. Then it was boiled in 10% NaOH solution for 6 hours and dried at 80℃~100℃ to obtain white chitin tablets. The chitin tablets were ball-milled and passed through a 75μm sieve. The material passing through the sieve was chitin. (2) Oxidation nano-sizing: Take the chitin in (1) and deionized water, TEMPO and NaBr in a mass ratio of 53:4000:0.85:5.3 and stir to dissolve. Then add NaClO with 10% active chlorine content, and add NaOH to adjust the pH to 10. After reacting for 4 hours, add ethanol to terminate the reaction. Wash with distilled water until neutral to obtain the oxidized gel. (3) High-pressure homogenization dispersion: The oxidized gel in (2) was homogenized and dispersed under high pressure using a high-pressure homogenizer at a pressure of 150 MPa for 8 cycles to obtain a semi-transparent gel suspension with a mass fraction of 0.5%.

[0021] By controlling the pressure and number of cycles of high-pressure homogenization dispersion, the problems of conventional ultrasonic and high-speed stirring methods, such as insufficient pressure to completely dissociate oxidized fibers and excessive pressure leading to excessive mechanical degradation, damage to fiber length, and a surge in energy consumption, are avoided. At the same time, the problems of incomplete dispersion due to too few cycles and low efficiency and unnecessary fiber damage due to too many cycles are also avoided.

[0022] The above preparation method is characterized in that, in step three, the mass fraction of the ChNFs suspension is 0.5%, the temperature for heat preservation and shaking is 40°C, and the time is 4 hours; the mass fraction of the glutaraldehyde crosslinking solution is 0.5% and the pH is adjusted to 4-5 with acetic acid; the temperature for the static reaction is 25°C, and the time is 12 hours. This invention uses a relatively low concentration of glutaraldehyde crosslinking solution to achieve gentle crosslinking while ensuring crosslinking efficiency, avoiding excessive crosslinking that leads to fiber brittleness.

[0023] The above preparation method is characterized in that, in step four, the animal protein foaming agent is diluted at a ratio of 1:30, and the CO2 volume concentration is 99.9%.

[0024] The preparation method described above is characterized in that, in step one, the low-speed stirring speed is 60 r / min and the time is 1 min; in step two, the low-speed stirring speed is 60 r / min and the time is 2 min; in step four, the low-speed stirring speed is 60 r / min and the time is 3 min; and in step five, the low-speed stirring speed is 60 r / min and the time is 1 min.

[0025] In this invention, TEMPO is an abbreviation for 2,2,6,6-tetramethylpiperidine oxide, and APTES is an abbreviation for 3-aminopropyltriethoxysilane.

[0026] Compared with the prior art, the present invention has the following advantages: 1. The lightweight foamed concrete insulation material of the present invention uses industrial waste magnesium slag, mineral powder and graphite tailings as core components—cementing materials and fine aggregate materials, respectively, to construct an efficient substitution system for cement and natural sand, realize the resource utilization of solid waste, reduce raw material costs, and introduce ChNFs suspension and modified glass pumice as functional coarse aggregates and perform physical foaming to form a transition layer at the interface of aggregate-solid waste-based cementitious material slurry, giving the material fireproof and heat insulation properties, reducing the material density, and enhancing the mechanical strength, long-term durability and functionality of the lightweight foamed concrete insulation material, achieving an optimized balance of heat insulation, mechanical properties, durability and economic benefits.

[0027] 2. The lightweight foamed concrete insulation material of the present invention uses industrial waste magnesium slag, mineral powder and graphite tailings as the main raw materials. It not only solves the problem of industrial waste slag occupying land and polluting the environment, but also realizes the recycling of resources and solves the problems of high energy consumption, high pollution and high cost of existing foamed concrete using cement as raw material.

[0028] 3. This invention uses chitin extracted from shrimp and crab shell waste to prepare ChNFs (chitin nanofibers) suspension, and utilizes it to coat modified glass pumice to construct a unique organic-inorganic composite transition layer at the aggregate-cement matrix interface, which greatly improves the thermal insulation performance and strength of lightweight foamed concrete insulation material; at the same time, it fills the pores to form a dense layer, effectively blocking the intrusion of moisture, chloride ions and sulfates, thereby improving the durability of lightweight foamed concrete insulation material.

[0029] 4. This invention modifies glass pumice by grafting -NH2 onto its surface, which combines with the -COOH / -OH abundant on the surface of ChNFs to achieve the coating of modified glass pumice by ChNFs suspension. It also utilizes the lightweight, highly closed-cell structure of glass pumice and its intrinsic fireproof and heat-insulating properties, combined with particle size distribution design, to synergistically reduce the density of lightweight foamed concrete insulation material, improve its heat insulation performance, and realize the large-scale recycling of waste glass (the raw material for glass pumice preparation).

[0030] 5. This invention uses animal protein foaming agent and introduces it into a foaming machine with CO2 to prepare CO2 foam clusters. Not only does it utilize CO2 as a foaming gas, but it can also seal CO2 in the structure of lightweight foamed concrete insulation material, realizing the fixation and utilization of carbon resources. In addition, the CO2 in the foam cluster reacts with Ca(OH)2 to generate CaCO3, which greatly improves the strength of lightweight foamed concrete insulation material.

[0031] 6. The preparation method of the present invention uses chitin nanofiber suspension to coat modified glass pumice and combines it with solid waste-based cementitious materials, so that the material has high strength, light weight and excellent heat insulation properties, and consumes waste shrimp and crab shells, industrial solid waste materials and CO2 waste gas.

[0032] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0033] Figure 1 This is a flowchart illustrating the preparation process of the all-solid-waste lightweight foamed concrete insulation material of the present invention.

[0034] Figure 2 This is a schematic diagram of the interface bonding between ChNFs and modified glass pumice in the all-solid-waste lightweight foamed concrete insulation material of the present invention.

[0035] Figure 3 This is a microstructure diagram of the solid waste lightweight foamed concrete insulation material prepared in Example 3 of the present invention.

[0036] Figure 4 The images show the SEM (Scanning Electron Microscopy) image and EDS (Energy Dispersive Spectroscopy) analysis diagram of the solid waste lightweight foamed concrete insulation material prepared in Example 3 of this invention. Detailed Implementation

[0037] Example 1 The all-solid-waste lightweight foamed concrete insulation material of this embodiment includes the following raw materials in parts by weight: 20 parts magnesium slag, 40 parts mineral powder, 10 parts graphite tailings, 16 parts modified glass pumice, 29 parts ChNFs suspension, 0.030 parts high-efficiency polycarboxylate superplasticizer, 43 parts water, 0.25 parts animal protein foaming agent, and 0.2 parts polyvinyl alcohol foam stabilizer. The magnesium slag is the undersize material after ball milling and passing through a 75µm sieve; the mineral powder is S95 grade mineral powder; the graphite tailings have a particle size of less than 0.4mm, and the particle size less than 0.075mm does not exceed 15%; the modified glass pumice has a particle size of 5mm~15mm and a density of 230kg / m³. 3 The glass pumice was modified with APTES ethanol solution; the ChNFs suspension was prepared by TEMPO-mediated oxidation of chitin extracted from shrimp and crab shell waste.

[0038] like Figure 1 As shown, the preparation method of the all-solid-waste lightweight foamed concrete insulation material in this embodiment includes the following steps: Step 1: Mixing and stirring dry powder materials: According to the composition ratio of the target product, all-solid waste lightweight foamed concrete insulation material, weigh magnesium slag, mineral powder, high-efficiency polycarboxylate superplasticizer and polyvinyl alcohol foam stabilizer respectively, and put them into a mortar mixer and stir at a low speed of 60r / min for 1min to obtain a uniformly mixed dry powder material. Step 2: Prepare the slurry: Add the weighed water to the dry powder in Step 1, and add the graphite tailings. Stir at a low speed of 60 r / min for 2 minutes to form a slurry. Step 3: ChNFs suspension coating of modified glass pumice: Weigh glass pumice and dry it at 105℃ for 2 hours. Then, immerse it in a 2% (w / w) APTES (i.e. KH-550) ethanol solution and heat it to 60℃ with shaking for 4 hours. After drying, it is ready for use to obtain modified glass pumice. Simultaneously, a ChNFs suspension was prepared: (1) Extraction of chitin: Shrimp and crab shell waste was soaked in 4% HCl solution for 24 hours and then washed with deionized water until neutral. Then it was boiled in 10% NaOH solution for 6 hours and dried at 80℃~100℃ to obtain white chitin tablets. The chitin tablets were ball-milled and passed through a 75μm sieve. The material passing through the sieve was chitin. (2) Oxidation nano-sizing: Take 53g of chitin from (1) and 4000g of deionized water, 0.85g of TEMPO and 5.3g of NaBr and stir to dissolve. Then add 265mL of NaClO with 10% active chlorine content and add NaOH to adjust the pH to 10. After reacting for 4h, add ethanol to terminate the reaction. Wash with distilled water until neutral to obtain the oxidized gel. (3) High-pressure homogenization dispersion: The oxidized gel in (2) was homogenized and dispersed under high pressure using a high-pressure homogenizer at a pressure of 150 MPa for 8 cycles to obtain a semi-transparent gel suspension with a mass fraction of 0.5%. Modified glass pumice was immersed in a 0.5% (w / w) ChNFs suspension and kept at 40℃ with shaking for 4 hours. Excess suspension was drained, and then the pumice was immersed in a 0.5% (w / w) glutaraldehyde crosslinking solution with pH adjusted to 4-5 by acetic acid. The mixture was allowed to react at 25℃ for 12 hours. Unreacted glutaraldehyde was removed by washing with deionized water, resulting in ChNFs-coated modified glass pumice. The interface between the two materials showed good bonding. Figure 2 As shown; Step 4: Preparation of foam slurry: 99.9% CO2 is introduced into the air compressor of the foaming machine, and the weighed animal protein foaming agent is diluted at a ratio of 1:30 and then introduced into the foaming machine to obtain CO2 foam group. Then the CO2 foam group is quickly added to the slurry in step 2 and stirred at a low speed of 60r / min for 3min to form foam slurry. Step 5, Molding and Curing: The ChNFs suspension obtained in Step 3, coated with modified glass pumice, is added to the foam slurry in Step 4 and stirred at a low speed of 60 r / min for 1 min. Then, it is poured into a 100mm×100mm×100mm triple mold, gently vibrated to ensure the mold is filled tightly, and the surface is smoothed with a scraper. After covering with plastic film, it is cured at room temperature for 12 hours. Then, it is placed in a curing chamber with a temperature of 40℃±2℃ and a humidity of over 90% for 24 hours. After that, it is demolded and cured in a standard curing chamber for 28 days at a temperature of 20℃±1℃ and a humidity of over 90% to obtain all-solid waste lightweight foamed concrete insulation material.

[0039] Example 2 The difference between this embodiment and Embodiment 1 is that the all-solid-waste lightweight foamed concrete insulation material includes the following raw materials in parts by weight: 25 parts magnesium slag, 40 parts mineral powder, 10 parts graphite tailings, 45 parts modified glass pumice, 81 parts ChNFs suspension, 0.032 parts high-efficiency polycarboxylate superplasticizer, 48 parts water, 0.36 parts animal protein foaming agent, and 0.2 parts polyvinyl alcohol foam stabilizer.

[0040] Example 3 The difference between this embodiment and Embodiment 1 is that the all-solid-waste lightweight foamed concrete insulation material includes the following raw materials in parts by weight: 30 parts magnesium slag, 40 parts mineral powder, 10 parts graphite tailings, 16 parts modified glass pumice, 29 parts ChNFs suspension, 0.030 parts high-efficiency polycarboxylate superplasticizer, 43 parts water, 0.26 parts animal protein foaming agent, and 0.2 parts polyvinyl alcohol foam stabilizer.

[0041] Figure 3 This is a microstructure image of the solid waste lightweight foamed concrete insulation material prepared in this embodiment. Figure 3 It can be seen that the solid waste lightweight foamed concrete insulation material has a dense porous structure with clear and non-connected pore edges, which lays the foundation for the good insulation performance of the insulation material.

[0042] Figure 4 The images shown are SEM (Scanning Electron Microscopy) and EDS (Energy Dispersive Spectroscopy) analysis diagrams of the solid waste lightweight foamed concrete insulation material prepared in this embodiment. The porous structure can be clearly observed in the SEM image on the left, indicating that the hydration product calcium hydroxide reacts with the introduced waste gas carbon dioxide to form calcium carbonate. The large amount of carbon elements in the EDS analysis diagram on the right confirms the presence of calcium carbonate.

[0043] Example 4 The difference between this embodiment and Embodiment 1 is that the all-solid-waste lightweight foamed concrete insulation material includes the following raw materials in parts by weight: 30 parts magnesium slag, 35 parts mineral powder, 20 parts graphite tailings, 16 parts modified glass pumice, 29 parts ChNFs suspension, 0.032 parts high-efficiency polycarboxylate superplasticizer, 43 parts water, 0.27 parts animal protein foaming agent, and 0.2 parts polyvinyl alcohol foam stabilizer.

[0044] Example 5 The difference between this embodiment and Embodiment 1 is that the all-solid-waste lightweight foamed concrete insulation material includes the following raw materials in parts by weight: 30 parts magnesium slag, 30 parts mineral powder, 10 parts graphite tailings, 45 parts modified glass pumice, 81 parts ChNFs suspension, 0.032 parts high-efficiency polycarboxylate superplasticizer, 48 parts water, 0.35 parts animal protein foaming agent, and 0.2 parts polyvinyl alcohol foam stabilizer.

[0045] Example 6 The difference between this embodiment and Embodiment 1 is that the all-solid-waste lightweight foamed concrete insulation material includes the following raw materials in parts by weight: 20 parts magnesium slag, 40 parts mineral powder, 15 parts graphite tailings, 16 parts modified glass pumice, 29 parts ChNFs suspension, 0.030 parts high-efficiency polycarboxylate superplasticizer, 43 parts water, 0.27 parts animal protein foaming agent, and 0.2 parts polyvinyl alcohol foam stabilizer.

[0046] Example 7 The difference between this embodiment and Embodiment 1 is that the all-solid-waste lightweight foamed concrete insulation material includes the following raw materials in parts by weight: 30 parts magnesium slag, 30 parts mineral powder, 10 parts graphite tailings, 50 parts modified glass pumice, 81 parts ChNFs suspension, 0.030 parts high-efficiency polycarboxylate superplasticizer, 48 parts water, 0.36 parts animal protein foaming agent, and 0.25 parts polyvinyl alcohol foam stabilizer.

[0047] Example 8 The difference between this embodiment and Embodiment 1 is that the all-solid-waste lightweight foamed concrete insulation material includes the following raw materials in parts by weight: 30 parts magnesium slag, 30 parts mineral powder, 10 parts graphite tailings, 10 parts modified glass pumice, 18 parts ChNFs suspension, 0.025 parts high-efficiency polycarboxylate superplasticizer, 40 parts water, 0.20 parts animal protein foaming agent, and 0.15 parts polyvinyl alcohol foam stabilizer.

[0048] Example 9 The difference between this embodiment and Embodiment 1 is that the all-solid-waste lightweight foamed concrete insulation material includes the following raw materials in parts by weight: 20 parts magnesium slag, 40 parts mineral powder, 15 parts graphite tailings, 16 parts modified glass pumice, 29 parts ChNFs suspension, 0.032 parts high-efficiency polycarboxylate superplasticizer, 55 parts water, 0.27 parts animal protein foaming agent, and 0.2 parts polyvinyl alcohol foam stabilizer.

[0049] Comparative Example 1 The difference between this comparative example and Example 1 is that the all-solid-waste lightweight foamed concrete insulation material includes the following raw materials in parts by weight: 20 parts magnesium slag, 40 parts mineral powder, 10 parts graphite tailings, 16 parts modified glass pumice, 0.030 parts high-efficiency polycarboxylate superplasticizer, 43 parts water, 0.25 parts animal protein foaming agent, and 0.2 parts polyvinyl alcohol foam stabilizer.

[0050] Comparative Example 2 The difference between this comparative example and Example 1 is that the all-solid-waste lightweight foamed concrete insulation material includes the following raw materials in parts by weight: 20 parts magnesium slag, 40 parts mineral powder, 16 parts modified glass pumice, 29 parts ChNFs suspension, 0.026 parts high-efficiency polycarboxylate superplasticizer, 43 parts water, 0.25 parts animal protein foaming agent, and 0.2 parts polyvinyl alcohol foam stabilizer.

[0051] Comparative Example 3 The difference between this comparative example and Example 1 is that the all-solid-waste lightweight foamed concrete insulation material includes the following raw materials in parts by weight: 20 parts magnesium slag, 40 parts mineral powder, 10 parts natural sand, 0.032 parts high-efficiency polycarboxylate superplasticizer, 43 parts water, 0.25 parts animal protein foaming agent, and 0.2 parts polyvinyl alcohol foam stabilizer.

[0052] The performance test results of the all-solid-waste lightweight foamed concrete insulation materials prepared in Examples 1-6 and Comparative Examples 1-3 of this invention are shown in Table 1.

[0053] Table 1

[0054] Table 1 shows that the examples mainly compared the effects of different cementitious material combinations, graphite tailings content, glass pumice content, whether or not ChNFs suspension was used to coat the pumice, and the amount of CO2 foam clusters added on the 7-day compressive strength, 28-day compressive strength, dry density, and thermal conductivity of lightweight foamed concrete. Comparing Example 1 and Comparative Example 1, it can be seen that ChNFs suspension coating of pumice increases the bonding between the slurry and the pumice surface, leading to an increase in the compressive strength of the foamed concrete insulation material; the interlaced arrangement of nanofibers extends the heat conduction path, thus reducing the thermal conductivity of the foamed concrete insulation material. Comparing Example 1 and Example 2, it can be seen that increasing the amount of pumice added can reduce the dry density and thermal conductivity, but it also results in a loss of some compressive strength. Comparing Example 6 and Comparative Example 2, it can be seen that the addition of graphite tailings, due to the graphite tailings in… The disordered arrangement of CO2 in the slurry forms a tortuous air path, prolonging the residence time of CO2 in the slurry and improving carbonation efficiency, which increases the compressive strength of the foamed concrete insulation material. In addition, the graphite tailings fill the gaps between the coarse aggregates, reducing the open porosity and also prolonging the heat conduction path, thus reducing the thermal conductivity of the foamed concrete insulation material. Comparing Example 1 and Comparative Example 3, it can be seen that adding pumice, ChNFs suspension, and graphite tailings to replace natural sand will increase the compressive strength of the foamed concrete insulation material, significantly reduce its density, and reduce its thermal conductivity.

[0055] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A lightweight foamed concrete insulation material made entirely of solid waste, characterized in that, The raw materials include the following components by weight: 20-30 parts magnesium slag, 30-40 parts mineral powder, 10-20 parts graphite tailings, 10-50 parts modified glass pumice, 18-81 parts ChNFs suspension, 0.025-0.03 parts high-efficiency polycarboxylate superplasticizer, 40-55 parts water, 0.2-0.36 parts animal protein foaming agent, and 0.15-0.25 parts polyvinyl alcohol foam stabilizer; the modified glass pumice has a particle size of 5mm-15mm and a density of 230kg / m³. 3 The glass pumice was modified with APTES ethanol solution; the ChNFs suspension was prepared by TEMPO-mediated oxidation of chitin extracted from shrimp and crab shell waste. The preparation method of this all-solid-waste lightweight foamed concrete insulation material includes the following steps: Step 1: Mixing and stirring dry powder materials: According to the component ratio of the target product, all-solid waste lightweight foamed concrete insulation material, weigh magnesium slag, mineral powder, high-efficiency polycarboxylate superplasticizer and polyvinyl alcohol foam stabilizer respectively, and put them into a mortar mixer for low-speed mixing to obtain a uniformly mixed dry powder material. Step 2: Prepare the slurry: Add the weighed water to the dry powder from Step 1, and add graphite tailings. Stir at low speed to form a slurry. Step 3: ChNFs suspension coating modified glass pumice: The modified glass pumice is immersed in ChNFs suspension and kept warm and shaken, and the excess suspension is drained. Then it is immersed in glutaraldehyde crosslinking solution and allowed to stand for reaction. After washing with deionized water, ChNFs suspension coating modified glass pumice is obtained. Step 4: Preparation of foam slurry: CO2 is introduced into the air compressor of the foaming machine, and the weighed animal protein foaming agent is diluted and then introduced into the foaming machine to foam and obtain CO2 foam group. Then, the CO2 foam group is quickly added to the slurry in step 2 and stirred at low speed to form foam slurry. Step 5, Molding and Curing: The ChNFs suspension obtained in Step 3 is used to coat the modified glass pumice, which is then added to the foam slurry in Step 4 and stirred at low speed. The mixture is then poured into a mold, covered with a film, and cured at room temperature for 12 hours. After that, it is placed in a curing chamber with a temperature of 40℃±2℃ and a humidity of over 90% for 24 hours. After that, it is demolded and cured in a standard curing chamber to obtain the all-solid-waste lightweight foamed concrete insulation material.

2. The lightweight foamed concrete insulation material made entirely from solid waste according to claim 1, characterized in that, The magnesium slag is the undersize material after ball milling and passing through a 75µm sieve. The mineral powder is S95 grade mineral powder. The particle size of the graphite tailings is less than 0.4mm, and the particle size less than 0.075mm does not exceed 15%.

3. The all-solid-waste lightweight foamed concrete insulation material according to claim 1, characterized in that, The preparation process of the modified glass pumice in step three is as follows: weigh the glass pumice, dry it at 105℃ for 2 hours, then immerse it in a 2% (w / w) APTES ethanol solution and heat it to 60℃ with shaking reaction for 4 hours, and then dry it for later use.

4. The all-solid-waste lightweight foamed concrete insulation material according to claim 1, characterized in that, The preparation process of the ChNFs suspension in step three is as follows: (1) Extraction of chitin: Shrimp and crab shell waste was soaked in 4% HCl solution for 24 hours and then washed with deionized water until neutral. Then it was boiled in 10% NaOH solution for 6 hours and dried at 80℃~100℃ to obtain white chitin tablets. The chitin tablets were ball-milled and passed through a 75μm sieve. The material passing through the sieve was chitin. (2) Oxidation nano-sizing: Take the chitin in (1) and deionized water, TEMPO and NaBr in a mass ratio of 53:4000:0.85:5.3 and stir to dissolve. Then add NaClO with 10% active chlorine content, and add NaOH to adjust the pH to 10. After reacting for 4 hours, add ethanol to terminate the reaction. Wash with distilled water until neutral to obtain the oxidized gel. (3) High-pressure homogenization dispersion: The oxidized gel in (2) was homogenized and dispersed under high pressure using a high-pressure homogenizer at a pressure of 150 MPa for 8 cycles to obtain a semi-transparent gel suspension with a mass fraction of 0.5%.

5. The all-solid-waste lightweight foamed concrete insulation material according to claim 1, characterized in that, In step three, the ChNFs suspension has a mass fraction of 0.5%, the temperature for heat preservation and shaking is 40°C, and the time is 4 hours; the mass fraction of the glutaraldehyde crosslinking solution is 0.5%, and the pH is adjusted to 4-5 with acetic acid; the temperature for the static reaction is 25°C, and the time is 12 hours.

6. The all-solid-waste lightweight foamed concrete insulation material according to claim 1, characterized in that, In step four, the animal protein foaming agent is diluted at a ratio of 1:30, and the CO2 volume concentration is 99.9%.

7. The all-solid-waste lightweight foamed concrete insulation material according to claim 1, characterized in that, The low-speed stirring speed in step one is 60 r / min for 1 min; the low-speed stirring speed in step two is 60 r / min for 2 min; the low-speed stirring speed in step four is 60 r / min for 3 min; and the low-speed stirring speed in step five is 60 r / min for 1 min.

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