Damage characteristics and thermo-physical properties changes of limestone and sandstone during thermal treatment from −30 °C to 1000 °C

A series of experiments were carried out to measure the damage characteristics of two common sedimentary rocks of limestone and sandstone at temperatures ranging from −30 °C to 1000 °C The apparent thermal conductivity, thermal diffusivity and specific heat capacity were investigated respectively. Then, several discrepancy reasons for the damage characteristics and thermo-physical properties of limestone and sandstone were probed. The results show that water migration and phase transition are two core factors for the frost damage and thermal behaviors improvement during the cooling process(20 °C → −30 °C).The heating process (20 °C → 1000 °C) was divided into three stages of 20 °C → 200 °C, 200 °C → 600 °Cand 600 °C → 1000 °C. The first stage was closely related to pore-water evaporation, and the next two stages were attributed to the thermal reactions of mineral partials. The mineral decomposition tended to be intensified and resulted in the interior damage or even the accelerated degradation of thermal properties until at a threshold temperature of 600 °C. In essential, the structural features and the sensitivity of mineral composition to temperature were two mainly influential factors on the damage effects and heat conduct of the sedimentary rocks during variations in environmental temperature.