Elevated-temperature thermal properties of lightweight foamed concrete

This paper reports the results of an experimental and analytical study to quantify the thermal properties of lightweight foamed concrete (LFC) at high temperatures. The density of LFC ranges from 600 to 1800 kg/m3. The primary objective of this study is to obtain the thermal conductivity of LFC at high temperatures so as to obtain material property data for prediction of fire resistance of LFC based systems. In the analytical approach, LFC is considered to be a two phase material with solid cement and air pores. Therefore, it is assumed that the thermal conductivity of LFC is a function of its porosity and pore size. The porosity of LFC can be easily obtained from the volume of foam inside the material. The effective pore size is based on the dominant internal pore size of the foamed concrete. The Hot Guarded Plate (HGP) test was carried out at different elevated temperatures for foamed concrete of different densities. The HGP test and analytical prediction results are in close agreement. To validate the thermal property results, transient heating tests were conducted in an electric kiln on LFC slabs and the recorded temperatures were compared with a validated one-dimensional heat transfer program in which the aforementioned thermal properties were treated as input data. Close agreement between the measured and predicted temperature results confirms the thermal property results.