Study On Thermal Insulation Properties Of Foamed Concrete And Its Composite Walls

As building energy efficiency standards continue to increase,walls should be continuously improved to meet energy efficiency standards.Foamed concrete is a green building material with light weight,thermal insulation,sound insulation,fire prevention,etc.It also has good seismic performance and durability.It has been widely used as a wall insulation material in buildings.In this paper,the thermal performance of composite wall with polystyrene pellet foam concrete is studied from three aspects:foam concrete material performance,on-site inspection of composite wall thermal performance and composite wall heat transfer simulation.The main research contents are as follows:(1)Performance test of foam concrete:The basic performance test was carried out on foam concrete materials with different density of polystyrene particles and prepared by chemical foaming method with dry density of 200-700 kg/m~3.The results show that:when dry density is 400 kg/m~3,the thermal conductivity,compressive strength and water absorption rate are balanced.Changing the particle size of polystyrene particles has little effect on the thermal conductivity of foam concrete,adding small particle size polystyrene particles can improve the compressive strength,reduce the water absorption rate;the thermal conductivity is greatly affected by the water content,and the greater the dry density,the more obvious the impact.According to the thermal conductivity of the foam concrete retaining moisture in the actual project and the drying condition,the thermal conductivity correction factor of dry density<413 kg/m~3was found to be 1.002.(2)On-site inspection of thermal performance of composite wall:foaming concrete with a dry density of 300kg/m~3prepared by using small-diameter polystyrene particles is poured into the composite wall,and the heat flow method is used in the coldest month of winter.The composite wall with different structures was used for on-site inspection of thermal performance.The results showed that during the detection period,from 6 o’clock in the evening of the previous day to 6 o’clock in the next day,the indoor temperature remained stable and the outdoor air temperature continued to decrease.The difference in surface temperature between indoor and outdoor walls is increasing,and the corresponding heat flux is increasing.The comparison of the heat transfer results of the two walls shows that the higher the light steel keel web has,the greater the influence on the thermal insulation performance of the composite wall.(3)Finite element simulation of thermal performance of composite wall:The thermal conductivity of the material used in foam concrete performance test is 0.065-0.12 W/m·K,and the composite wall with wall thickness of 220-320 mm is selected for finite element heat transfer simulation.The results show that:according to the comparison of finite element simulation and on-site detection of composite wall heat transfer coefficient,the finite element software can be used to simulate the heat transfer coefficient of composite wall;according to the heat transfer simulation results,the thermal conductivity of foam concrete and wall can be Corresponding selection of body thickness,and the empirical formula of heat transfer coefficient of composite wall with variable thermal conductivity of foam concrete,wall thickness and heat transfer of light steel keel is obtained.