3. Results and discussion As a thermal insulating material, the thermal conductivity is one of the most important properties that should be investigated.The thermal conductivity of fibrous insulation materials is affected by a number of basic factors: density, moisture content, temperature, and particle size [35]. In general, thermal conductivity increases with rising temperature, moisture content and density.Fundamentally, this variation originates from the porous structure of fibrous insulation materials and the difference in thermal conductivity of a solid, liquid and gas, which is believed to be caused by the different inter molecular distance of the matter at different states. To optimize the performance of RSTIB, the effect of high frequency heating, board density, particle size and ambient temperature on the thermal conductivity of RSTIB was investigated as following. Meanwhile their mechanical and physical properties were also discussed due to its application for building materials