Heat Transfer Analysis And Numerical Simulation Of Shale Ceramsite Concrete Shear Wall Thermal Bridge

With the development of modern buildings to high-rise,long-span and low energy consumption,higher requirements are put forward for the lightweight,high strength,thermal insulation and other properties of concrete.Lightweight aggregate concrete has become one of the development direction of modern concrete materials because of its advantages such as light weight,high strength,excellent thermal insulation and good fire resistance.This paper taked shale ceramsite concrete as the research object,and relied on the national"13th Five-Year"science and technology support project"Design and Preparation Technology and Application of High Performance Concrete for Products(2017YFB0310003)".The performance of shale ceramsite concrete was tested,and on this basis,the heat transfer analysis and numerical simulation of the shale ceramsite concrete shear wall thermal bridge were carried out.The main research contents and conclusions are as follows:(1)The effects of water-binder ratio,ceramsite density grade,and moisture content of concrete on bulk density,compressive strength,and thermal conductivity of ceramsite concrete are studied.The results show that the bulk density,compressive strength and thermal conductivity of ceramsite concrete decrease with the increase of water binder ratio.With the increase of ceramsite density grade,the bulk density,compressive strength and thermal conductivity of ceramsite concrete increase.With the increase of moisture content,the compressive strength and thermal conductivity of ceramsite concrete decrease and increase,respectively.The shale ceramsite concrete with bulk density of 1514.74-1907.43 kg/m3,7d compressive strength of 20.12-35.61MPa,28d compressive strength of 24.36-49.67 MPa,and thermal conductivity of0.6261-1.0827 W/(m·K)can be prepared.When the water binder ratio is 0.4 and the density grade of ceramsite is 800,the shale ceramsite concrete with the bulk density of1800 kg/m~3,thermal conductivity of 0.87 w/(m·K)and compressive strength of 38.92MPa can be prepared.(2)The previously optimized shale ceramsite concrete shear wall material is applied to the load-bearing structure of L-shaped filling wall-shear wall and floor-shear wall,and the thermal insulation structure and thermal bridge blocking design of the wall are carried out.The analysis of two-dimensional steady state thermal bridge shows that the average heat transfer coefficient of the improved L-shaped infill wall-shear wall and shear wall-floor model is 19.08%and 28.36%lower than that of the conventional structure,respectively,and that of the optimized structure is 23.17%and 31.41%lower than that of the conventional structure,respectively.The equivalent heat transfer coefficient of L-shaped filled wall-shear wall and shear wall-floor model is 26.75%and51.77%lower than that of conventional structure,and that of optimized structure is37.10%and 67.52%lower than that of conventional structure,respectively.After the improvement and optimization of the conventional structure,the thermal insulation performance of the wall has been greatly improved.(3)Through the analysis of two-dimensional unsteady state thermal bridge,it is shown that under the conventional structure,improved structure and optimized structure of L-type infilled wall-shear wall and shear wall-floor,the lowest indoor temperature occurs at the corner of the wall and is higher than 10.1℃,and no condensation occurs.The change rules of temperature under the different structural forms is similar,showing that the outdoor wall temperature changes greatly and shows a sinusoidal curve,while the indoor wall temperature changes slightly.Under the improved and optimized structure,24h indoor wall temperature is higher than that of the conventional structure.The temperature difference between the optimized and improved indoor wall mainly lies in the thermal bridge and the area affected by the thermal bridge,and the indoor wall temperature of the optimized structure is higher.In summary,the application of Shale ceramsite concrete products in building structures can not only reduce self-weight,but also effectively improve its thermal insulation performance.