Thermal degradation of diverse rock suites: Insights from fractures and physical and mechanical analysis

Abstract

        Understanding the effects of thermal treatment on the physical and mechanical properties of rocks is essential for evaluating their behaviour under extreme conditions and optimizing engineering designs. Thermal treatment significantly influences these properties, either enhancing or degrading them, depending on the mineralogical composition of the rocks. This study provides a detailed investigation into the thermal impact on the physical and mechanical properties of various rock types, including limestone, sandstone, granitic gneiss, rhyolite, quartzite, dolerite, gabbronorite, amphibolite, and granulite. The rock samples were exposed to heat treatment at temperatures ranging from 150°C to 1000°C. Subsequently, destructive (uniaxial compressive strength, point load index) and non-destructive tests (specific gravity, ultrasonic pulse wave velocity, porosity, and water absorption) were conducted to assess the rocks' responses to varying temperatures. The density of thermally induced fractures is calculated for each rock type at the investigated temperatures. The results indicate a reduction in uniaxial compressive strength, specific gravity, ultrasonic pulse velocity, and point load strength as the temperature increases. Conversely, elevated temperatures increased fracture density, porosity, and water absorption levels. A noticeable and abrupt change in all properties is observed when the temperature exceeds 300°C. These results highlight the deterioration of rocks and the alterations in their physical and mechanical properties caused by heat exposure, which hold critical importance for industries like mining and construction. Combining the physical and mechanical test results at different temperature levels, equations were derived for each rock type that can be used to estimate the respective properties at the desired temperatures. This study is significant for understanding how thermal exposure affects the integrity of rocks, providing crucial understanding for industries such as mining, construction, and geothermal energy. It enables better prediction and management of rock behaviour under high-temperature conditions, enhancing safety and performance in engineering applications.