Thermal Properties of Compost Biocover Subjected to Freeze-Thaw Cycles

Abstract

In this paper, the key heat-transfer parameters, thermal conductivity, and thermal diffusivity of biocover material made of compost subjected to freeze-thaw cycles (FTCs) for a wide range of water contents is investigated by means of the transient method. The samples were kept at −12°C to freeze and at room temperature (23°C) to thaw. The results obtained show that FTCs have an impact on the thermal properties of compost biocovers. However, more than approximately 7% of the total thermal conductivity changes occurred in the first two FTCs. Moreover, it was found that a linear relation between thermal conductivity and degree of saturation is valid even under FTCs. Furthermore, variations in the thermal properties are due to the combined effect of three factors: volume change, grain-size distribution, and crack formation. Finally, an empirical equation has been developed to predict thermal conductivity changes versus FTCs.