Low-thermal-conductivity foam light soil and preparation method thereof

Abstract

The invention belongs to the technical field of solid waste and waste gas recycling and road thaw collapse disease treatment in frozen soil areas, and mainly relates to low-heat-conductivity foam light soil and a preparation method thereof. The low-heat-conduction foam light soil is prepared from the following raw materials: foam glass particles, cement, waste gas and water. Compared with the prior art, the foam glass particles produced by using the waste glass as the raw material are used as the lightweight aggregate, and the waste gas of the coal-fired power plant is used for replacing air for foaming, so that the recycling of the waste gas is realized, and the heat insulation performance of the conventional foam lightweight soil is enhanced through the porous characteristic of the foam glass; the novel operation method of the low-heat-conductivity foam light soil is provided, resource reutilization of solid waste and waste gas can be achieved, carbon emission is reduced, carbon storage is promoted, the heat conductivity coefficient of the foam light soil can be further reduced, and when the foam light soil is used as a roadbed heat insulation plate in the frozen soil area, thaw collapse diseases of roads in the frozen soil area can be effectively relieved.

Description

Technical Field

[0001] The invention belongs to the technical field of solid waste, waste gas recycling and road thaw settlement disease treatment in frozen soil areas, and specifically relates to a green, environmentally friendly, emission-reducing, carbon-fixing, low-thermal-conductivity foamed lightweight soil and a preparation method thereof. Background Art

[0002] The Qinghai-Tibet Plateau is characterized by high altitude, strong ultraviolet radiation, low air pressure, large temperature difference between day and night, and high cold, with a large area of ​​permafrost. The existence of the highway changes the heat exchange conditions between the atmosphere and the surface, breaking the original water and heat balance under the roadbed. The high and wide roadbed and the exponential heat absorption of the black asphalt pavement of the highway expand the range of thermal disturbance of the frozen soil under the roadbed, the temperature of the frozen soil rises and continues to melt, and the road faces serious large deformation thaw settlement disease. At present, EPS foam boards are mostly placed in the roadbed in actual projects to delay the transfer of external heat to the lower frozen soil. However, EPS foam boards have poor durability, low strength and risk of spontaneous combustion under the complex hydrogeological environment and heavy traffic loads of the Qinghai-Tibet Plateau. At present, there is an urgent need for a thermal insulation material with good durability, high strength and controllable cost. Summary of the invention

[0003] The purpose of the present invention is to provide a foamed lightweight soil with low thermal conductivity, green circulation, emission reduction and carbon fixation, and a preparation method thereof, which is prepared using foamed glass particles, cement, waste gas from coal-fired power plants and water as raw materials. By using waste glass to make foamed glass particles with porous characteristics as lightweight aggregates and using waste gas from coal-fired power plants to replace air for foaming, while reducing the thermal conductivity, it has the advantages of high compressive strength, easy construction, low carbon and environmental protection, and the realization of solid waste and waste gas resource recycling, etc., providing a green, carbon-fixing, lightweight, porous cement-based composite thermal insulation material for the insulation board of the roadbed in frozen soil areas.

[0004] The present invention is considered in the process of conception:

[0005] Foamed lightweight soil is a lightweight civil engineering material containing a large number of closed pores formed by physical or chemical foaming, in which the prepared foam group is uniformly mixed with cementitious materials (cement, lime, gypsum, etc.), aggregates (such as slag, fly ash, etc.), admixtures (such as fiber, etc.), admixtures (such as early strength agent, water reducer, etc.) and water in a certain proportion, and finally hardened. It has the characteristics of water resistance and strong freeze-thaw durability. At the same time, foamed lightweight soil contains a large number of closed pores, has a small thermal conductivity, and is usually 500-1200kg / m 3The thermal conductivity of foamed lightweight soil in the range of 0.15-0.35W / m·K is between 0.15-0.35W / m·K, and the thermal resistance is about 10-20 times that of ordinary fill soil. If it is used in road projects in frozen areas, its material properties can be fully utilized to provide a new idea and method for building high-quality roads in frozen areas and improving their thermal stability, in order to alleviate the harm of frozen soil to road construction, extend the service life of frozen soil roads, and provide a certain guarantee for the safe and stable operation of roads.

[0006] Foam glass is made of waste broken glass, foaming agent and modified additives. Due to its porous structure, foam glass has good thermal insulation properties while having low density, which can effectively prevent the conduction of heat. In addition, it has the characteristics of low hygroscopicity, corrosion resistance and high compressive strength. After denitrification, dust removal and desulfurization treatment, the exhaust gas generated by coal-fired power plants is mainly composed of nitrogen and carbon dioxide. The thermal conductivity of nitrogen is close to that of air, while the thermal conductivity of carbon dioxide is half that of air. If the exhaust gas from coal-fired power plants replaces air in the foaming process, and foam glass made of waste glass is used, not only can foam lightweight soil with high compressive strength and low thermal conductivity be obtained, but also solid waste and waste gas can be recycled and reused, promoting carbon reduction and carbon fixation, complying with the carbon peak and carbon neutrality policies, and promoting green cycle sustainable low-carbon development.

[0007] The first aspect of the present invention provides a low thermal conductivity foam lightweight soil, wherein the raw material composition of the low thermal conductivity foam lightweight soil comprises, by weight: 20-300 parts of foam glass particles, 100-400 parts of cement, 20-40 parts of waste gas, and 100-500 parts of water.

[0008] Furthermore, the foam glass particles are obtained by recycling waste glass, foaming it at high temperature, and then crushing and grinding it to pass through a 2mm sieve.

[0009] Furthermore, the cement is 42.5 general purpose Portland cement that complies with the current GB 175 "General Purpose Portland Cement" standard.

[0010] Furthermore, the waste gas is the waste gas discharged from a coal-fired power plant after denitrification, dust removal and desulfurization treatment.

[0011] The second aspect of the present invention provides a method for preparing the low thermal conductivity foamed lightweight soil as described above, comprising the following steps:

[0012] S1. Prepare raw materials: 20-300 parts of foam glass particles, 100-400 parts of cement, and 100-500 parts of water;

[0013] S2, slurry preparation: placing foam glass particles and cement in a stirring device according to a proportion, stirring to make the foam glass particles and the cement uniformly mixed to obtain a mixed powder, adding 100-500 parts of water to the mixed powder, stirring, during the stirring process, the mixed powder must not clump, and no residue at the bottom or side wall of the stirring device, to ensure that the slurry is uniform and has no sediment, and the slurry is obtained after the stirring is completed;

[0014] S3. Preparation of waste gas bubble groups: The waste gas bubble groups are prepared by a pre-foaming method, and the waste gas used is the waste gas discharged from a coal-fired power plant after denitration, dust removal and desulfurization;

[0015] S4, stirring and mixing: adding 20-40 parts of the exhaust gas bubble group into the slurry and stirring, and obtaining a mixture after the stirring is completed;

[0016] S5. Casting and sampling: Cast the stirred mixture, and obtain the low thermal conductivity foam lightweight soil after curing.

[0017] Further, in S3, the method for preparing the exhaust gas bubble group includes:

[0018] A conventional foam concrete foaming machine is used as a preparation device for bubble groups. The conventional foam concrete foaming machine is composed of an air compressor and a water pump. The supply rate of the foaming liquid is controlled by adjusting the flow of the water pump. The air compressor is used to provide a stable high-pressure airflow and form bubble groups.

[0019] Dilute the foaming agent by 40-60 times, stir evenly to obtain the foaming liquid, and place the water pump suction pipe into the foaming liquid. Connect the air compressor air pipe to the gas cylinder filled with waste gas, turn on the switch of the gas cylinder, adjust the outlet pressure to 400kPa, turn on the water pump switch, wait until the air in the water pump suction pipe is exhausted and the foaming liquid completely enters the water pump, turn on the air compressor switch, adjust the water pump speed ratio button, and emit a delicate, dense and stable exhaust gas bubble group, so that the density of the exhaust gas bubble group is 48-52kg / m 3 , placed in a container waiting for use.

[0020] Furthermore, the steps from S3 to S5 are completed within the half-life of the blowing agent.

[0021] Further, in S2, the slurry preparation specifically includes the following steps:

[0022] The mixture is stirred at a speed of 180 r / min for 10 min to uniformly mix the foam glass particles and the cement to obtain a mixed powder, 100-500 parts of water are added to the mixed powder, and the mixture is stirred at a speed of 180 r / min for 10 min. During the stirring process, the mixed powder is prevented from agglomerating and remaining at the bottom or side wall of the stirring device to ensure that the slurry is uniform and free of sediment. The slurry is obtained after the stirring is completed.

[0023] Furthermore, in S3, to ensure uniformity of the mixture, the stirring speed is 400-750 r / min and the stirring time is 5-10 min.

[0024] Furthermore, in S5, the curing time is 28 days.

[0025] Through the above technical solution, compared with the prior art, the present invention has the following beneficial effects:

[0026] 1) Compared with the EPS material commonly used in roadbed insulation boards in frozen soil areas, the present invention has the advantages of high compressive strength, strong durability, corrosion resistance and environmental friendliness.

[0027] 2) Compared with the cooling measures such as heat rods, ventilation pipe roadbeds, and block stone roadbeds commonly used in frozen soil area roadbeds, the present invention is used as a heat insulation board for frozen soil area roadbeds, and has the advantages of easy construction, strong feasibility, low energy consumption, and low cost.

[0028] 3) The present invention uses foam glass made of waste glass as lightweight aggregate, which not only further enhances the lightness and thermal insulation, but also promotes the resource recycling of solid waste and realizes green circulation. At the same time, the waste gas discharged from coal-fired power plants is used to replace air for foaming, which can not only further reduce the thermal conductivity, but also reuse the waste gas discharged from coal-fired power plants, promote the fixation and storage of CO2, alleviate the greenhouse effect, and provide a new way for energy conservation and emission reduction. Compared with traditional foam lightweight soil, the low thermal conductivity foam lightweight soil of the present invention can be prepared in a short time, has good thermal insulation performance, stronger durability and is easy to construct. It not only has the characteristics of energy saving, environmental protection, low carbon and high efficiency, but also makes up for some defects in the thermal insulation measures of roadbed in frozen soil areas, and meets the requirements of sustainable development for current engineering construction.

[0029] 4) The foam glass used in the low thermal conductivity foam lightweight soil of the present invention contains a certain amount of Na2O, K2O and SiO2, which can cause alkali-silicon reaction (ASR) in a high alkaline environment, and the generated alkali silica gel will cause volume expansion. However, the particle size of the foam glass particles used in the present invention is small, the porosity of the soil sample prepared is high, and the formed alkali silica gel has enough space to grow inside the foam glass aggregate, so there is no risk of cracking of the engineering structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the working principle of the low thermal conductivity foam lightweight soil of the present invention.

[0031] Figure 2 It is a graph showing the variation of the unconfined compressive strength of the samples of Examples 1, 2, 3, 4 and Comparative Examples 1, 2, 3.

[0032] Figure 3It is a graph showing the variation of thermal conductivity of samples of Examples 1, 2, 3, 4 and Comparative Examples 1, 2, 3. DETAILED DESCRIPTION

[0033] In general, by using foam glass particles produced from waste glass as raw materials as lightweight aggregate, and using waste gas from coal-fired power plants instead of air for foaming, Figure 1 This is a schematic diagram of the working principle of low thermal conductivity foam lightweight soil, which realizes the reuse of waste gas and enhances the thermal insulation performance of conventional foam lightweight soil through the porous characteristics of foam glass. The purpose is to propose a new operation method of low thermal conductivity foam lightweight soil, which can not only realize the resource reuse of solid waste and waste gas, reduce carbon emissions and promote carbon storage, but also further reduce the thermal conductivity of foam lightweight soil. When used as a roadbed insulation board in frozen soil areas, it can effectively alleviate the thaw settlement disease of roads in frozen soil areas.

[0034] In general, the low thermal conductivity foam lightweight soil in the present invention comprises, by weight, 20-300 parts of foam glass particles, 100-400 parts of cement, 20-40 parts of waste gas bubble groups, and 100-500 parts of water.

[0035] In the specific implementation, it is preferred that the foam glass is made by recycling waste glass and foaming it at high temperature, and its density should be 100-300kg / m 3 The thermal conductivity is between 0.01-0.06 W / m·K. More preferably, the foam glass is crushed and ground through a 2 mm sieve to obtain the foam glass particles.

[0036] In the specific implementation, it is preferred that the cement is 42.5 general Portland cement that complies with the current GB 175 "General Portland Cement" standard.

[0037] In the specific implementation, it is preferred that the foaming agent used in the waste gas bubble group is a synthetic surfactant (sodium dodecyl alcohol ether sulfate, sodium dobenzene sulfonate, etc.), and its density is 48-52kg / m 3 .

[0038] In a specific implementation, it is preferred that the water is tap water or distilled water, including the water used for the exhaust gas bubble group.

[0039] The preparation method of low thermal conductivity foamed lightweight soil based on waste glass and waste gas from coal-fired power plants specifically comprises the following steps:

[0040] S1. Prepare raw materials: including weighing 50-300 parts of foam glass particles, 100-400 parts of cement, and 100-500 parts of water.

[0041] S2. Preparation of slurry: Place foam glass particles and cement in a stirring device according to a proportion, stir at a speed of 180 r / min for 10 minutes, and mix the foam glass particles and cement evenly to obtain a mixed powder. Add 100-500 parts of water to the mixed powder, and stir at a speed of 180 r / min for 10 minutes. During the stirring process, the mixed powder should not clump or remain at the bottom or side wall of the stirring device, and ensure that the slurry is uniform and has no sediment. The slurry is obtained after the stirring is completed.

[0042] S3. Preparation of CO2 bubble group: dilute the foaming agent with the water at a dilution ratio of 40-60 times, stir evenly to obtain the foaming liquid, and place the water pump suction pipe into the foaming liquid. Connect the air compressor air pipe to the gas cylinder filled with waste gas, turn on the switch of the gas cylinder, adjust the outlet pressure to 400kPa, turn on the water pump switch, wait until the air in the water pump suction pipe is exhausted and the foaming liquid completely enters the water pump, turn on the air compressor switch, and adjust the water pump speed ratio button on the water pump according to the instructions of the foaming machine or adjust it by yourself to emit a delicate, dense and stable waste gas bubble group, so that the density of the waste gas bubble group is 48-52kg / m 3 , placed in a container and waiting for use. Different foaming agents and different foaming agent dilution ratios will result in different water pump speed ratios. The water pump speed ratio is 70-90, and the corresponding water pump flow rate is 3L / min-4L / min.

[0043] S4, stirring and mixing: add 20-40 parts of waste gas bubble groups into the slurry for stirring. To ensure uniformity of the mixture, the stirring speed is 400-750r / min, the stirring time is 5-10min, and the mixture is obtained after the stirring is completed. The stirring time should not be too long, and the stirring speed should not be too fast, otherwise it will cause the foam to burst and increase the wet density of the finished soil sample.

[0044] S5. Casting and sampling: Cast the stirred mixture, and obtain the low thermal conductivity foamed lightweight soil after curing for 28 days.

[0045] As a further preference during specific implementation, the preparation of the waste gas bubble group in step S3 and the sample preparation in step S5 must be completed within the half-life of the foaming agent to avoid defoaming of the waste gas bubble group leading to an increase in the wet density of the finished soil sample.

[0046] As a further preferred embodiment, the raw material composition includes, by weight: 140-235 parts of foam glass particles, 140-235 parts of cement, 26-36 parts of waste gas bubble groups, and 183-305 parts of water.

[0047] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. Any features such as preparation means, materials, structures or composition ratios not clearly described in this technical solution are regarded as common technical features disclosed in the prior art.

[0048] In the following examples, the foam glass used was purchased from a foam glass manufacturer in Jiaxing, Zhejiang, with its chemical composition shown in Table 1 and its basic properties shown in Table 2; the cement used was Conch brand 42.5 general-purpose Portland cement, with its chemical composition shown in Table 1; the foaming waste gas used was taken from a coal-fired power plant in Dongying, Shandong, and its composition is shown in Table 3.

[0049] Table 1 Chemical composition of foam glass and cement

[0050]

[0051] Table 2 Basic properties of foam glass

[0052]

[0053] Table 3 Composition of exhaust gas from coal-fired power plants

[0054]

[0055] Example 1

[0056] A low thermal conductivity foam lightweight soil, wherein each cubic meter of the low thermal conductivity foam lightweight soil contains: 140 parts of foam glass particles, 140 parts of cement, 36 parts of waste gas bubble groups and 183 parts of water.

[0057] The purchased foam glass plate is crushed and ground to pass through a 2mm sieve to obtain foam glass particles. The water used is tap water or distilled water, including the water used by the exhaust gas bubble group.

[0058] The foaming agent is an existing synthetic surfactant foaming agent purchased from the market. 0.250 parts of foaming liquid is taken and diluted by 40 times to obtain 10 parts of foaming liquid. The foaming rate is 1200 times and the half-life is 30-40 minutes.

[0059] The low thermal conductivity foamed lightweight soil is prepared by the following steps:

[0060] S1. Raw material preparation: prepare 140 parts of foam glass particles, 140 parts of cement, 36 parts of waste gas bubble groups and 183 parts of water.

[0061] S2. Slurry preparation: Place foam glass particles and cement into a stirring device, stir at a speed of 180 r / min for 10 minutes, and mix the foam glass particles and cement evenly to obtain a mixed powder. Add 183 parts of water to the mixed powder, and stir at a speed of 180 r / min for 10 minutes. During the stirring process, the mixed powder should not clump or remain at the bottom or side wall of the stirring device, and ensure that the slurry is uniform and has no sediment. The slurry is obtained after the stirring is completed.

[0062] S3. Preparation of waste gas bubble group: dilute the foaming agent with the water at a dilution factor of 40 times, stir evenly to obtain the foaming liquid, and place the water pump suction pipe into the foaming liquid. Connect the air compressor air pipe to the gas cylinder filled with waste gas, turn on the switch of the gas cylinder, adjust the outlet pressure to 400kPa, turn on the water pump switch, wait until the air in the water pump suction pipe is exhausted and the foaming liquid completely enters the water pump, turn on the air compressor switch, adjust the water pump speed ratio to 70-90, and the foam group density to 48-52kg / m 3 Take it out and place it in a container for later use.

[0063] S4, stirring and mixing: adding 36 parts of exhaust gas bubble groups into the slurry and stirring them, the stirring speed is 600r / min, the stirring time is 10min, and the mixture is obtained after the stirring is completed.

[0064] S5. Casting and sampling: Cast the stirred mixture, and obtain the low thermal conductivity foamed lightweight soil after curing for 28 days.

[0065] Example 2

[0066] A low thermal conductivity foamed lightweight soil, wherein each cubic meter of the low thermal conductivity foamed lightweight soil contains: 172 parts of foamed glass particles, 172 parts of cement, 32 parts of waste gas bubble groups, and 224 parts of water. The foamed glass particles, cement, waste gas bubble groups, water, and foaming agent are the same as those in Example 1, and the treatment methods for various materials are also consistent.

[0067] The preparation method of the low thermal conductivity foamed lightweight soil in Example 2 is the same as that in Example 1, the curing time is 28 days, and the wet density is 600 kg / m 3 .

[0068] Example 3

[0069] A low thermal conductivity foamed lightweight soil, wherein each cubic meter of the low thermal conductivity foamed lightweight soil contains: 203 parts of foamed glass particles, 203 parts of cement, 29 parts of waste gas bubble groups, and 264 parts of water. The foamed glass particles, cement, waste gas bubble groups, water, and foaming agent are the same as those in Example 1, and the treatment methods for various materials are also consistent.

[0070] The preparation method of the low thermal conductivity foamed lightweight soil in Example 3 is the same as that in Example 1, the curing time is 28 days, and the wet density is 700 kg / m 3 .

[0071] Example 4

[0072] A low thermal conductivity foamed lightweight soil, wherein each cubic meter of the low thermal conductivity foamed lightweight soil contains: 235 parts of foamed glass particles, 235 parts of cement, 26 parts of waste gas bubble groups, and 305 parts of water. The foamed glass particles, cement, waste gas bubble groups, water, and foaming agent are the same as those in Example 1, and the treatment methods for various materials are also consistent.

[0073] The preparation method of the low thermal conductivity foamed lightweight soil in Example 4 is the same as that in Example 1, the curing time is 28 days, and the wet density is 800 kg / m 3 .

[0074] Comparative Example 1

[0075] A low thermal conductivity foamed lightweight soil, wherein each cubic meter of the low thermal conductivity foamed lightweight soil contains: 281 parts of cement, 36 parts of waste gas bubble groups, and 183 parts of water. The cement, waste gas bubble groups, water, and foaming agent are the same as those in Example 1, and the treatment methods for various materials are also consistent.

[0076] The preparation method of low thermal conductivity foamed lightweight soil in Comparative Example 1 is the same as that in Example 1, the curing time is 28 days, and the wet density is 500 kg / m 3 .

[0077] Comparative Example 2

[0078] A low thermal conductivity foamed lightweight soil, wherein each cubic meter of the low thermal conductivity foamed lightweight soil contains: 70 parts of foamed glass particles, 211 parts of cement, 36 parts of waste gas bubble groups, and 183 parts of water. The foamed glass particles, cement, waste gas bubble groups, water, and foaming agent are the same as those in Example 1, and the treatment methods for various materials are also consistent.

[0079] The preparation method of low thermal conductivity foamed lightweight soil in Comparative Example 2 is the same as that in Example 1, the curing time is 28 days, and the wet density is 500 kg / m 3 .

[0080] Comparative Example 3

[0081] A low thermal conductivity foamed lightweight soil, wherein each cubic meter of the low thermal conductivity foamed lightweight soil contains: 211 parts of foamed glass particles, 70 parts of cement, 36 parts of waste gas bubble groups, and 183 parts of water. The foamed glass particles, cement, waste gas bubble groups, water, and foaming agent are the same as those in Example 1, and the treatment methods for various materials are also consistent.

[0082] The preparation method of low thermal conductivity foamed lightweight soil in Comparative Example 3 is the same as that in Example 1, the curing time is 28 days, and the wet density is 500 kg / m 3 .

[0083] Comparative Example 4

[0084] A foam glass foam lightweight soil, wherein each cubic meter of the foam glass foam lightweight soil contains: 140 parts of foam glass particles, 140 parts of cement, 36 parts of air bubble groups and 183 parts of water. The foam glass particles, cement, water and foaming agent are the same as those in Example 1, the bubble groups are directly foamed by air, and the treatment methods for the other types of materials are also consistent.

[0085] The preparation method of the foam glass foam lightweight soil in Comparative Example 4 is the same as that in Example 1, the curing time is 28 days, and the wet density is 500 kg / m 3 .

[0086] Verification Example 1

[0087] 1. Unconfined compressive strength test

[0088] The unconfined compressive strength test was performed on the samples prepared in Examples 1, 2, 3, 4 and Comparative Examples 1, 2, 3, 4 after 28 days of curing. The test process was carried out in accordance with "CJJT 177-2012 Technical Specification for Bubble Mixed Lightweight Soil Filling Engineering".

[0089] Unconfined compressive strength test results

[0090] Table 4 Compressive strength of low thermal conductivity foam lightweight soil

[0091]

[0092] It can be seen from Table 4 that: Through Examples 1, 2, 3, and 4, it is found that when the foam glass ratio remains unchanged, the greater the wet density, the greater the unconfined compressive strength of the sample. This is because the foam group content in the sample gradually decreases, and the connection between the foam glass and the cement hydration product becomes denser, resulting in the external load borne by the soil skeleton formed by the hydration product and the lightweight aggregate gradually increasing. Through Comparative Examples 1, 2, 3, and 4, it is found that when the wet density remains unchanged, the unconfined compressive strength decreases as the foam glass ratio increases. Although foam glass has good unconfined compressive strength, the core of the strength growth still comes from cement, a cementitious material. Too little cement is not conducive to the growth of sample strength. Compared with Comparative Example 4, in Example 1, the foaming gas is changed from exhaust gas to air, and the unconfined compressive strength is slightly reduced, but it can be ignored. Figure 2 It is a graph showing the variation of the unconfined compressive strength of the samples of Examples 1, 2, 3, 4 and Comparative Examples 1, 2, 3.

[0093] 2. Thermal conductivity test

[0094] The thermal conductivity test was performed on the samples prepared in Examples 1, 2, 3, 4 and Comparative Examples 1, 2, 3, 4 after 28 days of curing. The test process was carried out in accordance with the "SL / T352-2020 Hydraulic Concrete Test Procedure".

[0095] Table 5 Thermal conductivity of low thermal conductivity foam lightweight soil

[0096]

[0097] It can be seen from Table 5 that: through Examples 1, 2, 3, and 4, it is found that the amount of foam glass added remains unchanged, the greater the wet density, the higher the thermal conductivity. This is because the transfer of heat in foam lightweight soil only relies on cement and its hydration products, and the efficiency of transfer through the gas phase is low. The lower the wet density, the more bubble groups there are, and the better the solid insulation effect. And through Comparative Examples 1, 2, 3, and 4, it is found that foam glass can significantly reduce the thermal conductivity due to its porous characteristics, from 0.1287W / m·K when no foam glass is added to 0.0454W / m·K when 75% foam glass is added, a decrease of 68.07%. Compared with Comparative Example 4, in Example 1, the foaming gas is changed from exhaust gas to air, and the thermal conductivity of the sample increases by 18.58%. Figure 3 It is a graph showing the variation of thermal conductivity of samples of Examples 1, 2, 3, 4 and Comparative Examples 1, 2, 3.

[0098] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A low thermal conductivity foamed lightweight soil, characterized in that: The raw material composition of the low thermal conductivity foam lightweight soil includes, by weight: 20-300 parts of foam glass particles, 100-400 parts of cement, 20-40 parts of waste gas, and 100-500 parts of water.

2. The low thermal conductivity foamed lightweight soil according to claim 1, characterized in that: The foam glass particles are obtained by recycling waste glass, foaming it at high temperature, and then crushing and grinding it to pass through a 2mm sieve.

3. The low thermal conductivity foamed lightweight soil according to claim 1, characterized in that: The cement is 42.5 general purpose Portland cement that complies with the current GB 175 "General Purpose Portland Cement" standard.

4. The low thermal conductivity foamed lightweight soil according to claim 1, characterized in that: The waste gas is the waste gas discharged from a coal-fired power plant after being treated with denitrification, dust removal and desulfurization.

5. A method for preparing low thermal conductivity foamed lightweight soil according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1. Prepare raw materials: 20-300 parts of foam glass particles, 100-400 parts of cement, and 100-500 parts of water; S2, slurry preparation: placing foam glass particles and cement in a stirring device according to a proportion, stirring to make the foam glass particles and the cement uniformly mixed to obtain a mixed powder, adding 100-500 parts of water to the mixed powder, stirring, during the stirring process, the mixed powder must not clump, and no residue at the bottom or side wall of the stirring device, to ensure that the slurry is uniform and has no sediment, and the slurry is obtained after the stirring is completed; S3. Preparation of waste gas bubble groups: The waste gas bubble groups are prepared by a pre-foaming method, and the waste gas used is the waste gas discharged from a coal-fired power plant after denitration, dust removal and desulfurization; S4, stirring and mixing: adding 20-40 parts of the exhaust gas bubble group into the slurry and stirring, and obtaining a mixture after the stirring is completed; S5. Casting and sampling: Cast the stirred mixture, and obtain the low thermal conductivity foam lightweight soil after curing.

6. The method for preparing low thermal conductivity foamed lightweight soil according to claim 4, characterized in that: In S3, the method for preparing the exhaust gas bubble group includes: A conventional foam concrete foaming machine is used as a preparation device for bubble groups. The conventional foam concrete foaming machine is composed of an air compressor and a water pump. The supply rate of the foaming liquid is controlled by adjusting the flow of the water pump. The air compressor is used to provide a stable high-pressure airflow and form bubble groups. Dilute the foaming agent by 40-60 times, stir evenly to obtain the foaming liquid, and place the water pump suction pipe into the foaming liquid. Connect the air compressor air pipe to the gas cylinder filled with waste gas, turn on the switch of the gas cylinder, adjust the outlet pressure to 400kPa, turn on the water pump switch, wait until the air in the water pump suction pipe is exhausted and the foaming liquid completely enters the water pump, turn on the air compressor switch, adjust the water pump speed ratio button, and emit a delicate, dense and stable exhaust gas bubble group, so that the density of the exhaust gas bubble group is 48-52kg / m 3 , placed in a container waiting for use.

7. The method for preparing low thermal conductivity foamed lightweight soil according to claim 4, characterized in that: The process from S3 to S5 is completed within the half-life of the blowing agent.

8. The method for preparing low thermal conductivity foamed lightweight soil according to claim 4, characterized in that: In S2, the slurry preparation specifically includes the following steps: The mixture is stirred at a speed of 180 r / min for 10 min to uniformly mix the foam glass particles and the cement to obtain a mixed powder, 100-500 parts of water are added to the mixed powder, and the mixture is stirred at a speed of 180 r / min for 10 min. During the stirring process, the mixed powder is prevented from agglomerating and remaining at the bottom or side wall of the stirring device to ensure that the slurry is uniform and free of sediment. The slurry is obtained after the stirring is completed.

9. The method for preparing low thermal conductivity foamed lightweight soil according to claim 4, characterized in that: In S3, to ensure uniform mixing, the stirring speed is 400-750 r / min and the stirring time is 5-10 min.

10. The method for preparing low thermal conductivity foamed lightweight soil according to claim 4, characterized in that: In S5, the curing time is 28 days.

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