Lightweight low-carbon thermal insulation mortar and preparation method thereof

Abstract

The invention discloses lightweight low-carbon thermal insulation mortar, which is characterized by being prepared from the following ingredients in parts by weight: 100 to 160 parts of quick lime, 250 to 350 parts of phosphogypsum, 300 to 450 parts of mineral powder, 350 to 550 parts of coal gangue pottery sand, 60 to 100 parts of polystyrene foam particles, 70 to 110 parts of rice hulls, 180 to 260 parts of coffee grounds, 10 to 20 parts of polypropylene fibers, 2 to 4 parts of dispersing agents, 1 to 2 parts of air entraining agents and 600 to 700 parts of water. An alkali-activated cementing material composed of quicklime, ardealite and slag powder is adopted to replace a traditional cement-based cementing material, coal gangue pottery sand is adopted to replace common sand, and rice husks and coffee grounds are introduced as light filling materials, so that the light low-carbon thermal insulation mortar is successfully prepared and has good thermal insulation performance and mechanical performance, and the thermal insulation performance of the light low-carbon thermal insulation mortar is greatly improved. The carbon emission of buildings can be effectively reduced, and the strategic requirements of green buildings and sustainable development are met.

Description

Technical Field

[0001] The present invention belongs to the technical field of building materials, and particularly relates to a lightweight low-carbon thermal insulation mortar and a preparation method thereof. Background Art

[0002] As an important building material, thermal insulation mortar is widely used in building exterior wall insulation systems, which can effectively improve the insulation performance of buildings, reduce energy consumption, and is of great significance for realizing building energy conservation and sustainable development. However, traditional thermal insulation mortar has significant deficiencies in terms of strength and environmental protection. Traditional thermal insulation mortar usually uses cement as the main binder. The production process of cement requires high-temperature calcination, consuming a large amount of energy and emitting a large amount of carbon dioxide, which does not meet the requirements of low-carbon environmental protection. Secondly, the ordinary sand used in traditional thermal insulation mortar has a relatively large density, increasing the self-weight of the wall, bringing an additional burden to the building structure, and the wall is prone to cracks and peeling over time, affecting the safety, durability and insulation performance of the building. In addition, as an important field of carbon emissions, the construction industry urgently needs to develop a lightweight low-carbon thermal insulation mortar to meet the needs of green buildings and sustainable development. Summary of the Invention

[0003] In view of the above problems, the present invention uses an alkali-activated binder composed of quicklime, phosphogypsum and slag powder to replace the traditional cement-based binder, uses coal gangue ceramsite sand to replace ordinary sand, and also introduces rice husk and coffee grounds as lightweight filling materials, and successfully prepares a lightweight low-carbon thermal insulation mortar, which not only has good insulation performance and mechanical properties, but also can effectively reduce the carbon emissions of buildings, meeting the strategic requirements of green buildings and sustainable development.

[0004] To achieve the above object, the following technical solutions are adopted:

[0005] A lightweight low-carbon thermal insulation mortar, the composition of which is as follows by weight parts:

[0006] 100 - 160 parts of quicklime, 250 - 350 parts of phosphogypsum, 300 - 450 parts of slag powder, 350 - 550 parts of coal gangue ceramsite sand, 60 - 100 parts of polystyrene foam particles, 70 - 110 parts of rice husk, 180 - 260 parts of coffee grounds, 10 - 20 parts of polypropylene fiber, 2 - 4 parts of dispersant, 1 - 2 parts of air-entraining agent, 600 - 700 parts of water.

[0007] Preferably, the CaO content of the quicklime is above 75wt%.

[0008] Preferably, the phosphogypsum is raw phosphogypsum with a moisture content of 8 - 15wt%.

[0009] Preferably, the slag powder is S95 grade blast furnace slag powder.

[0010] Preferably, the particle size of the coal gangue ceramsite sand is 0.16 - 3 mm, and the cylinder compressive strength is above 12 MPa.

[0011] Preferably, the particle size of the polystyrene foam particles is 1 - 2 mm.

[0012] Preferably, the rice husk is the shell separated from paddy, with a length of 5 - 8 mm and a width of 2.5 - 5.0 mm.

[0013] Preferably, the coffee grounds are the residues collected after making coffee, and the moisture is removed by drying at 100 °C.

[0014] Preferably, the polypropylene fiber is a bundle of monofilament fibers with a length - to - diameter ratio of 340 - 360 and a tensile strength of 350 - 400 MPa.

[0015] Preferably, the dispersant is carboxymethyl cellulose.

[0016] Preferably, the air - entraining agent is one of sodium dodecyl benzene sulfonate and sodium dodecyl sulfate.

[0017] The preparation method of the above - mentioned lightweight low - carbon thermal insulation mortar comprises the following steps:

[0018] Mix quicklime, phosphogypsum, mineral powder with 1 / 4 of water and wet - grind to > 250 meshes to obtain mixture A; mix polypropylene fiber, dispersant, air - entraining agent, coal gangue ceramsite sand with 1 / 4 of water and stir evenly to obtain mixture B;

[0019] Put mixture A and polystyrene foam particles into a disk granulator so that the surface of the polystyrene foam particles is coated with the mixture A slurry;

[0020] Mix the polystyrene foam particles coated with mixture A, the remaining mixture A, mixture B, rice husk, coffee grounds, and 1 / 2 of water and stir evenly to obtain the lightweight low - carbon thermal insulation mortar.

[0021] The present invention uses an alkali-activated cementitious material composed of quicklime, phosphogypsum, and slag powder to replace the traditional cement-based cementitious material. Without high-temperature calcination, it has low energy consumption and low carbon emissions during the production process, and has significant low-carbon environmental protection advantages. At the same time, the alkali-activated cementitious material has good mechanical properties and durability, and high early strength, which can meet the usage requirements of building thermal insulation mortar. In addition, the present invention uses coal gangue ceramsite to replace ordinary sand, which can not only significantly reduce the weight of the thermal insulation mortar, reduce the wall load, increase the mechanical properties and thermal insulation performance, but also effectively utilize the industrial solid waste of coal gangue, realizing the recycling of resources. To further improve the thermal insulation performance of the thermal insulation mortar, the present invention also introduces rice husk and coffee grounds as lightweight filling materials. Rice husk and coffee grounds are common agricultural and food processing waste, with a porous structure and low thermal conductivity, which can significantly improve the thermal insulation performance of the thermal insulation mortar. At the same time, the utilization of rice husk and coffee grounds not only reduces the density of the thermal insulation mortar, but also realizes the resource utilization of waste, further reflecting the concept of low-carbon environmental protection.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] 1. Using the alkali-activated cementitious material to replace the traditional cement-based cementitious material significantly reduces the carbon emissions during the production process. The alkali-activated cementitious material is composed of quicklime, phosphogypsum, and slag powder, without high-temperature calcination, with low production energy consumption, meeting the requirements of low-carbon environmental protection. In addition, this thermal insulation mortar also utilizes various industrial and agricultural solid wastes such as coal gangue, rice husk, and coffee grounds, which not only realizes the recycling of resources, alleviates the pressure of solid waste disposal, but also further reduces the production cost of the thermal insulation mortar, with significant environmental and economic benefits.

[0024] 2. Using coal gangue ceramsite to replace ordinary sand, coal gangue ceramsite has a porous structure, which can effectively reduce the density of the thermal insulation mortar, reduce the self-weight of the wall. At the same time, its porous structure also provides good thermal insulation and heat insulation performance. The round structure of coal gangue ceramsite can play a ball-rolling effect and an arch-shell effect, improving the workability and mechanical properties of the thermal insulation mortar. In addition, the incorporation of polypropylene fibers further improves the crack resistance of the thermal insulation mortar, effectively preventing the generation of wall cracks and improving the safety and durability of buildings.

[0025] 3. The present invention introduces rice husk and coffee grounds as lightweight filling materials. The two can optimize the voids and filling effect of the mortar, improve the interfacial transition zone of the mortar, enhance the adhesion with coal gangue ceramsite sand and polystyrene foam particles. At the same time, by adsorbing moisture and regulating the hydration process, the risk of drying shrinkage and cracking is reduced. The fibrous structure of rice husk and the porous surface of coffee grounds form a microscopic network, further enhancing the crack resistance and toughness of the thermal insulation mortar. The lightweight porosity and large specific surface area of rice husk and coffee grounds can not only synergistically reduce the density of the mortar, improve the thermal insulation performance, have good sound insulation effect to enhance the living comfort of buildings, but also play an internal curing effect to inhibit shrinkage. The porous structure can serve as a nucleation site to promote the growth of hydration products and thus improve the strength.

[0026] 4. By the method of granulating and spheronizing polystyrene particles with alkali-activated cementitious material slurry, the disadvantage that polystyrene particles cannot be evenly distributed in traditional thermal insulation mortar is solved. It forms a network structure with polypropylene fibers and rice husk in the mortar, effectively blocking the dissipation of temperature and enhancing the integrity and stability of the material. Specific embodiments

[0027] The following examples further illustrate the technical solutions of the present invention, but do not limit the protection scope of the present invention.

[0028] The raw materials used in the specific embodiments are as follows:

[0029] Quicklime with a CaO content of more than 75% is used. Phosphogypsum in its original state with a moisture content of 8 - 15% is used. S95 grade blast furnace slag powder is used as the mineral powder. Coal gangue ceramsite sand with a particle size of 0.16 - 3 mm and a cylinder compressive strength of more than 12 MPa is used. Polystyrene foam particles with a particle size of 1 - 2 mm are used. Rice husk separated from rice with a length of 5 - 8 mm and a width of 2.5 - 5.0 mm is used. Coffee grounds collected after making coffee and dried at 100°C to remove moisture are used. Polypropylene fibers with a length-to-diameter ratio of 340 - 360 and a tensile strength of 350 - 400 MPa in the form of bundled monofilament fibers are used. Carboxymethyl cellulose with a substitution degree > 1.0 is used as the dispersant. One of sodium dodecylbenzene sulfonate and sodium dodecyl sulfate with an active ingredient of more than 99% is used as the air-entraining agent.

[0030] Example 1

[0031] 120 parts of quicklime, 300 parts of phosphogypsum, 400 parts of mineral powder, 350 parts of coal gangue ceramsite sand, 60 parts of polystyrene foam particles, 70 parts of rice husk, 180 parts of coffee grounds, 15 parts of polypropylene fibers, 2 parts of dispersant, 1 part of air-entraining agent, 600 parts of water.

[0032] S1. Mix 120 parts of quicklime, 300 parts of phosphogypsum, 400 parts of ore powder with 150 parts of water, and wet grind them to a particle size greater than 250 mesh to form mixture A;

[0033] S2. Put 60 parts of polystyrene foam particles and mixture A into a disk granulator so that the surface of the polystyrene foam particles is coated with a slurry of mixture A;

[0034] S3. Mix 15 parts of polypropylene fiber, 2 parts of dispersant, 1 part of air-entraining agent, 350 parts of coal gangue ceramsite with 150 parts of water and stir evenly to obtain mixture B;

[0035] S4. Mix the polystyrene foam particles coated with mixture A, the remaining mixture A, mixture B, 70 parts of rice husk, 180 parts of coffee grounds, and 300 parts of water, stir for 2 minutes, and form them to prepare a lightweight low-carbon thermal insulation mortar.

[0036] Example 2

[0037] 120 parts of quicklime, 300 parts of phosphogypsum, 400 parts of ore powder, 450 parts of coal gangue ceramsite, 60 parts of polystyrene foam particles, 70 parts of rice husk, 180 parts of coffee grounds, 15 parts of polypropylene fiber, 2 parts of dispersant, 1 part of air-entraining agent, 600 parts of water.

[0038] S1. Mix 120 parts of quicklime, 300 parts of phosphogypsum, 400 parts of ore powder with 150 parts of water, and wet grind them to a particle size greater than 250 mesh to form mixture A;

[0039] S2. Put 60 parts of polystyrene foam particles and mixture A into a disk granulator so that the surface of the polystyrene foam particles is coated with a slurry of mixture A;

[0040] S3. Mix 15 parts of polypropylene fiber, 2 parts of dispersant, 1 part of air-entraining agent, 450 parts of coal gangue ceramsite with 150 parts of water and stir evenly to obtain mixture B;

[0041] S4. Mix the polystyrene foam particles coated with mixture A, the remaining mixture A, mixture B, 70 parts of rice husk, 180 parts of coffee grounds, and 300 parts of water, stir for 2 minutes, and form them to prepare a lightweight low-carbon thermal insulation mortar.

[0042] Example 3

[0043] 120 parts of quicklime, 300 parts of phosphogypsum, 400 parts of ore powder, 350 parts of coal gangue ceramsite, 60 parts of polystyrene foam particles, 100 parts of rice husk, 180 parts of coffee grounds, 15 parts of polypropylene fiber, 2 parts of dispersant, 1 part of air-entraining agent, 600 parts of water.

[0044] S1. Mix 120 parts of quicklime, 300 parts of phosphogypsum, 400 parts of ore powder with 150 parts of water and wet grind them to >250 mesh to form mixture A;

[0045] S2. Put 60 parts of polystyrene foam particles and mixture A into a disk granulator so that the surface of the polystyrene foam particles is coated with a slurry of mixture A;

[0046] S3. Mix 15 parts of polypropylene fiber, 2 parts of dispersant, 1 part of air-entraining agent, 350 parts of coal gangue ceramsite with 150 parts of water and stir evenly to obtain mixture B;

[0047] S4. Mix the polystyrene foam particles coated with mixture A, the remaining mixture A, mixture B, 100 parts of rice husk, 180 parts of coffee grounds, 300 parts of water and stir for 2 min, then form them to prepare lightweight low-carbon thermal insulation mortar.

[0048] Example 4

[0049] 120 parts of quicklime, 300 parts of phosphogypsum, 400 parts of ore powder, 350 parts of coal gangue ceramsite, 60 parts of polystyrene foam particles, 70 parts of rice husk, 240 parts of coffee grounds, 15 parts of polypropylene fiber, 2 parts of dispersant, 1 part of air-entraining agent, 600 parts of water.

[0050] S1. Mix 120 parts of quicklime, 300 parts of phosphogypsum, 400 parts of ore powder with 150 parts of water and wet grind them to >250 mesh to form mixture A;

[0051] S2. Put 60 parts of polystyrene foam particles and mixture A into a disk granulator so that the surface of the polystyrene foam particles is coated with a slurry of mixture A;

[0052] S3. Mix 15 parts of polypropylene fiber, 2 parts of dispersant, 1 part of air-entraining agent, 350 parts of coal gangue ceramsite with 150 parts of water and stir evenly to obtain mixture B;

[0053] S4. Mix the polystyrene foam particles coated with mixture A, the remaining mixture A, mixture B, 70 parts of rice husk, 240 parts of coffee grounds, 300 parts of water and stir for 2 min, then form them to prepare lightweight low-carbon thermal insulation mortar.

[0054] Comparative Example 1

[0055] 840 parts of cement, 350 parts of coal gangue ceramsite, 60 parts of polystyrene foam particles, 70 parts of rice husk, 180 parts of coffee grounds, 15 parts of polypropylene fiber, 2 parts of dispersant, 1 part of air-entraining agent, 600 parts of water.

[0056] S1. Mix 840 parts of cement with 150 parts of water and wet grind them to >250 mesh to form mixture A;

[0057] S2. Put 60 parts of polystyrene foam particles and mixture A into a disk granulator so that the surface of the polystyrene foam particles is coated with a layer of mixture A slurry.

[0058] S3. Mix 15 parts of polypropylene fiber, 2 parts of dispersant, 1 part of air-entraining agent, 350 parts of coal gangue ceramsite and 150 parts of water evenly to obtain mixture B.

[0059] S4. Mix the polystyrene foam particles coated with mixture A, the remaining mixture A, mixture B, 70 parts of rice husk, 180 parts of coffee grounds and 300 parts of water and stir for 2 minutes, then form them to prepare a lightweight thermal insulation mortar.

[0060] Comparative Example 2

[0061] 120 parts of quicklime, 300 parts of phosphogypsum, 400 parts of mineral powder, 350 parts of manufactured sand, 60 parts of polystyrene foam particles, 70 parts of rice husk, 180 parts of coffee grounds, 15 parts of polypropylene fiber, 2 parts of dispersant, 1 part of air-entraining agent, 600 parts of water.

[0062] S1. Mix 120 parts of quicklime, 300 parts of phosphogypsum, 400 parts of mineral powder and 150 parts of water and wet grind them to >250 mesh to form mixture A.

[0063] S2. Put 60 parts of polystyrene foam particles and mixture A into a disk granulator so that the surface of the polystyrene foam particles is coated with a layer of mixture A slurry.

[0064] S3. Mix 15 parts of polypropylene fiber, 2 parts of dispersant, 1 part of air-entraining agent, 350 parts of manufactured sand and 150 parts of water evenly to obtain mixture B.

[0065] S4. Mix the polystyrene foam particles coated with mixture A, the remaining mixture A, mixture B, 70 parts of rice husk, 180 parts of coffee grounds and 300 parts of water and stir for 2 minutes, then form them to prepare a low-carbon thermal insulation mortar.

[0066] Comparative Example 3

[0067] Repeat Example 1, cancel the addition of rice husk and coffee grounds components, and keep the rest unchanged.

[0068] 120 parts of quicklime, 300 parts of phosphogypsum, 400 parts of mineral powder, 350 parts of coal gangue ceramsite, 60 parts of polystyrene foam particles, 70 parts of rice husk, 180 parts of coffee grounds, 15 parts of polypropylene fiber, 2 parts of dispersant, 1 part of air-entraining agent, 600 parts of water.

[0069] S1. Mix 120 parts of quicklime, 300 parts of phosphogypsum, 400 parts of mineral powder and 150 parts of water and wet grind them to >250 mesh to form mixture A.

[0070] S2. Put 60 parts of polystyrene foam particles and mixture A into a disk granulator so that the surface of the polystyrene foam particles is coated with a slurry of mixture A.

[0071] S3. Mix 15 parts of polypropylene fiber, 2 parts of dispersant, 1 part of air-entraining agent, 350 parts of coal gangue ceramsite sand and 150 parts of water and stir evenly to obtain mixture B.

[0072] S4. Mix the polystyrene foam particles coated with mixture A, the remaining mixture A, mixture B and 300 parts of water and stir for 2 min to form and prepare a lightweight low-carbon thermal insulation mortar.

[0073] Performance test

[0074] According to the standard of GB / T 20473-2021, the performance tests of the thermal insulation mortars prepared in Examples 1-4 and Comparative Examples 1 and 2 were carried out, including dry apparent density, thermal conductivity, 28-day compressive strength and 28-day linear shrinkage rate. The test results are shown in Table 1.

[0075] Table 1

[0076]

[0077] As can be seen from the above table, the thermal insulation mortar prepared in Examples 1-4 of the present invention meets the requirements of the standard GB / T 20473-2021. By comparing Example 1 with Comparative Example 1, it can be seen that the alkali-activated system cementitious material using solid waste-based materials has higher strength, better thermal insulation performance, and smaller shrinkage than the pure cement system. The strength of the cementitious materials such as solid waste-based materials increases significantly in the later stage, generating more C-S-H gels, filling pores, and improving compactness. Moreover, the pure cement has a large shrinkage and is prone to cracking. By comparing Example 1 with Comparative Example 2, it can be seen that the porous circular structure of coal gangue ceramsite can effectively reduce the density, improve the thermal insulation performance, and ensure the strength. By comparing Example 1 with Comparative Example 3, it can be seen that the fibrous structure of rice husk can form a microscopic network with the porous surface of coffee grounds, further improving the thermal insulation performance, enhancing the crack resistance and toughness of the mortar. The high water absorption and water retention of both can further regulate the moisture distribution in the mortar, reducing the risk of drying shrinkage and cracking. By comparing the data of Examples 1 and 2, it can be seen that the increase in coal gangue ceramsite can improve the thermal insulation performance, compressive strength, and linear shrinkage rate, but the dry apparent density will increase. The pores of coal gangue ceramsite are more, and the circular structure provides an arch shell effect to effectively improve various properties. By comparing the data of Examples 1 and 3, it can be seen that the increase in the content of rice husk can reduce the dry apparent density and thermal conductivity, but the 28-day compressive strength decreases and the 28-day linear shrinkage rate increases. Since there are a large number of pores inside the rice husk, a stable gas layer can be formed to effectively isolate the internal and external temperature differences, thus enhancing the thermal insulation effect. By comparing the data of Examples 1 and 4, it can be seen that the increase in the content of coffee grounds reduces the dry apparent density and thermal conductivity, increases the 28-day compressive strength, and reduces the 28-day linear shrinkage rate. This benefits from the porous structure of coffee grounds, which can effectively play the internal curing effect to inhibit shrinkage and can also serve as a nucleation site to promote the growth of hydration products and increase the strength.

Claims

1. A lightweight low-carbon thermal insulation mortar, characterized in that The composition is calculated by weight as follows: 100-160 parts of quicklime, 250-350 parts of phosphogypsum, 300-450 parts of mineral powder, 350-550 parts of coal gangue sand, 60-100 parts of polystyrene foam particles, 70-110 parts of rice husks, 180-260 parts of coffee grounds, 10-20 parts of polypropylene fiber, 2-4 parts of dispersant, 1-2 parts of air entraining agent, and 600-700 parts of water.

2. The lightweight low-carbon thermal insulation mortar according to claim 1, characterized in that The CaO content of the quicklime is above 75wt%; the phosphogypsum is original phosphogypsum with a moisture content of 8-15wt%; and the mineral powder is S95 grade blast furnace slag powder.

3. The lightweight low-carbon thermal insulation mortar according to claim 1, characterized in that The coal gangue ceramic sand has a particle size of 0.16-3 mm and a cylinder pressure strength of more than 12 MPa.

4. The lightweight low-carbon thermal insulation mortar according to claim 1, characterized in that The particle size of the polystyrene foam particles is 1-2 mm.

5. The lightweight low-carbon thermal insulation mortar according to claim 1, characterized in that The rice husk is the husk separated from rice grains, with a length of 5-8 mm and a width of 2.5-5.0 mm.

6. The lightweight low-carbon thermal insulation mortar according to claim 1, characterized in that The coffee grounds are the residues collected after making coffee and are dried at 100° C. to remove moisture.

7. The lightweight low-carbon thermal insulation mortar according to claim 1, characterized in that The polypropylene fiber is a bundled monofilament fiber with an aspect ratio of 340-360 and a tensile strength of 350-400 MPa.

8. The lightweight low-carbon thermal insulation mortar according to claim 1, characterized in that The dispersant is carboxymethyl cellulose.

9. The lightweight low-carbon thermal insulation mortar according to claim 1, characterized in that The air entraining agent is one of sodium dodecylbenzene sulfonate and sodium dodecyl sulfate.

10. The method for preparing the lightweight low-carbon thermal insulation mortar according to any one of claims 1 to 9, characterized in that The following steps are involved: Mix quicklime, phosphogypsum, mineral powder and 1 / 4 water and grind them to >250 mesh to obtain mixture A; mix polypropylene fiber, dispersant, air entraining agent, coal gangue ceramic sand and 1 / 4 water and stir them evenly to obtain mixture B; Putting mixture A and polystyrene foam particles into a disc granulator so that the surface of the polystyrene foam particles is covered with the mixture A slurry; The polystyrene foam particles wrapped with the mixture A, the remaining mixture A, the mixture B, rice husks, coffee grounds and 1 / 2 water were mixed and stirred to obtain a lightweight and low-carbon thermal insulation mortar.

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