Preparation,Modeling And Optimization Of A New Type Of Ultralight Thermal Insulative Aerogel Foam Concrete

Due to the large scale and high energy consumption of buildings in China,thermal insulation is particularly important for energy-saving buildings.In the development of building insulation materials,the lightweight insulation foam concrete has attracted more and more attention due to its excellent performance in building energy conservation.However,currently lightweight foam concretes still exhibit high values both in density(~400kg/m~3)and in thermal conductivity(~0.08 W/(m·K)),which is beyond the application field of green and near-zero energy buildings.It is difficult to realize low density and low thermal conductivity without a problem of easy collapse.Aerogels,known as solid air,have extremely low density,very low thermal conductivity,high hydrophobic properties and high fire rating.They are considered as the first choice for thermal insulation materials.It can greatly improve the thermal insulation performance of buildings in the field of building thermal insulation,but the low mechanical strength and fragility impedes its application.In this paper,a super-adiabatic nano-porous silica aerogel was prepared by sol-gel drying method.A super-adiabatic nano-porous aerogel was added to the microcellular foam concrete to successfully prepare a novel aerogel foam concrete with multi-stage pore structure.The density of aerogel foam concrete is as low as 198 kg/m~3,and thermal conductivity is as low as0.049 W/(m·K),and it has an excellent mechanical strength.The microstructure of aerogel foam concrete and aerogel particles was characterized.The density and compressive strength of aerogel foam concrete and aerogel were tested.The thermal conductivity,density and compressive strength of aerogel foam concrete were tested.Compared with existing reported foamed concrete,the thermal conductivity and density of aerogel foam concrete under the same porosity are much smaller than those of ordinary foam concrete,and the compressive strength of aerogel foam concrete at the same density level is slightly higher than that of the other two types of foam concrete and still higher than the standard.Based on the hypothetical physical model and several commonly used thermal conductivity calculation models,the calculation model of the effective thermal conductivity of aerogel foam concrete is established.The model prediction values of effective thermal conductivity are in good agreement with the measured ones,with the deviations within 4%.By using the model,the effects of the ternary ratios on the thermal conductivity were investigated.The optimization aiming at the minimum thermal conductivity was then carried out.Accordingly,a ternary aerogel foam concrete sample with the optimal ratio was experimentally prepared,whose thermal conductivity and density were approximately 50%lower than those of existing foam concrete.The new aerogel foam concrete solves the problems that the lightweight foamed concrete still has excessive density and thermal conductivity,and the difficulty in forming without collapse at a low density and a low thermal conductivity.The fragile aerogel powder can be well applied to the field of building thermal insulation.Therefore,the novel type aerogel foam concrete,yielding high performance,could be extensively used for potential applications in green and nearly zero-energy consumption buildings.