CN-121248244-B - Low-heat-conductivity concrete and preparation method thereof

Abstract

The invention belongs to the technical field of building materials, and relates to low-heat-conductivity concrete and a preparation method thereof. The invention provides a preparation method of low-heat-conductivity concrete, which comprises the steps of modifying polypropylene fibers by tannic acid solution and then modifying by polydimethylsiloxane solution to obtain modified polypropylene fibers, mixing a foaming agent and water to obtain foaming liquid, uniformly mixing cement, fly ash, the modified polypropylene fibers, an additive and water to obtain a mixture, foaming the foaming liquid to generate foam, adding the foam into the mixture, and uniformly mixing the foam with the mixture to obtain the low-heat-conductivity concrete. The invention aims to solve the technical problems that the heat conductivity coefficient of foam concrete can be effectively reduced (low heat conductivity requirement is met) by doping polypropylene fibers in the preparation process of the foam concrete, but the strength of the foam concrete is obviously reduced, and finally the low heat conductivity and the high strength of the concrete are difficult to be simultaneously considered.

Inventors

• NING YU
• ZHANG JUN
• ZHAO PENGBO
• LI SHANGZHE
• YIN YUJIE
• WANG YI
• Fu Duoduo

Assignees

• 陕西建工集团股份有限公司

Dates

Publication Date

20260508

Application Date

20251205

Claims (6)

1. 1. A preparation method of low-heat-conductivity concrete comprises the steps of immersing polypropylene fibers in tannic acid solution, carrying out oscillation reaction for 12-24 hours at 25-35 ℃, taking out the fibers after the reaction is finished, washing away unadsorbed tannic acid molecules with deionized water, finishing tannic acid modification, immersing the polypropylene fibers in polydimethylsiloxane solution after tannic acid modification, carrying out reaction for 6-12 hours at 60-80 ℃, taking out the polypropylene fibers after the reaction is finished, sequentially carrying out alternating cleaning with ethanol and deionized water, carrying out vacuum drying after the polydimethylsiloxane modification, carrying out drying for at least 6 hours at 50-60 ℃ to obtain modified polypropylene fibers, mixing foaming agent and water to obtain a mixture, foaming cement, fly ash, the modified polypropylene fibers, an additive and water uniformly, and then adding the foaming liquid into the mixture to obtain foam, wherein the concentration of the polydimethylsiloxane solution is 2-5 mg/mL, and the concentration of the polydimethylsiloxane solution is 5- 2 mg/mL.
2. 2. A low heat-conducting concrete, characterized in that it is prepared by the method for preparing a low heat-conducting concrete according to claim 1.
3. 3. The low heat conductive concrete according to claim 2, wherein the admixture is an early strength agent, a water reducing agent and an accelerator.
4. 4. The low heat-conducting concrete according to claim 3, wherein the mixing amount of the early strength agent is 0.1-0.3%, the mixing amount of the water reducer is 0.1-0.3% and the mixing amount of the accelerator is 1-3% by mass.
5. 5. The low heat conductive concrete according to claim 2, wherein the water cement ratio of the low heat conductive concrete is 0.45 to 0.50.
6. 6. The low heat-conducting concrete according to claim 2, wherein the replacement amount of fly ash relative to cement is 4-6% by mass, the mixing amount of the modified polypropylene fiber is 0.3-0.5% by mass, and the foaming agent is 0.5-1% by mass.

Description

Low-heat-conductivity concrete and preparation method thereof Technical Field The invention belongs to the technical field of building materials, and relates to low-heat-conductivity concrete and a preparation method thereof. Background Green construction has become the core direction of the transformation and upgrading of the construction industry, and the green construction has put stringent demands on energy conservation, environmental protection and structural performance of construction materials. The foam concrete is used as a light heat-insulating building material, and is widely applied to the parts of a wall body, a roof heat-insulating layer and the like of a green building due to good heat-insulating performance, light high-strength characteristics and green environmental protection advantages. The heat conductivity coefficient of the foam concrete is used as a key index for evaluating heat insulation performance, and the energy consumption level of the building is directly influenced. In order to reduce the heat conductivity coefficient of foam concrete, the prior art adopts the modes of doping lightweight aggregate, optimizing the pore size distribution of foam or introducing fiber materials. The polypropylene fiber has the characteristics of low density, strong chemical corrosion resistance, moderate cost, low heat conductivity coefficient and the like, and is widely used for modifying and researching foam concrete. The research shows that the polypropylene fiber can form three-dimensional disordered support system in the concrete matrix, has certain blocking effect on heat transfer and can reduce heat conductivity coefficient to a certain extent, and meanwhile, the fiber can inhibit the generation and expansion of cracks in the concrete and improve the toughness and crack resistance of the concrete. However, in practical application, the interface bonding performance between the polypropylene fiber and the foam concrete matrix is poor, when the fiber mixing amount exceeds a certain proportion, the internal porosity of the concrete is increased, the defects of the interface transition area are increased, and the mechanical properties such as the compressive strength and the like of the foam concrete are obviously reduced. In order to balance the heat conducting property and the mechanical property of the polypropylene fiber modified foam concrete, researchers try to improve the heat conducting property and the mechanical property by adjusting the mixing amount of fibers, optimizing the length of the fibers or improving the stirring process and the like. For example, the method can limit the reduction range of the heat conductivity coefficient, and hardly meet the requirement of a high-star green building on the ultra-low heat conductivity coefficient, and for example, the interface combination of the fiber and a matrix is improved by adopting a mode of coating a silane coupling agent on the surface, but the hydrolytic stability of the silane coupling agent is poor, and the silane coupling agent is easy to fail in an alkaline cement matrix, so that the modification effect is unstable. In addition, some researches adopt steel fibers, glass fibers and the like to replace polypropylene fibers, and although the mechanical properties can be improved to a certain extent, the fibers have higher self heat conductivity coefficient, so that the heat preservation advantage of the foam concrete can be offset, the cost is obviously increased, and the large-scale popularization and application are not facilitated. Disclosure of Invention The invention aims to solve the technical problems that the compressive strength of the foam concrete is obviously reduced due to the fact that polypropylene fibers are doped in the foam concrete, so that low heat conduction and high strength are difficult to achieve. In this regard, the present invention provides a low heat conductive concrete and a method of preparing the same to meet such a need in the art. In the technical scheme provided by the invention, the total weight of the cementing material is the sum of the weights of concrete and concrete substitutes (fly ash), the calculation formula of the concrete substitutes is calculated by taking the total weight of the cementing material as a reference, the calculation formula of the concrete additives is calculated by taking ‌ the total weight of the cementing material as a reference, the calculation formula of the concrete cement ratio is calculated by taking the total weight of the cementing material as a reference, and the calculation formula is calculated by taking the cement ratio as the weight of water/the total weight of the cementing material. On one hand, the invention relates to a preparation method of low heat conduction concrete, which comprises the steps of modifying polypropylene fibers by tannic acid solution and then modifying the polypropylene fibers by polydimethylsiloxane solution to obtain modified p