Elastic modulus of thermally treated fine grained sandstone using non-contact laser extensometer

Processes such as Underground Coal Gasification (UCG), Enhanced Oil Recovery (EOR) and underground disposal of nuclear waste involve the exposure of the surrounding rocks to extreme temperatures. At such high temperatures, the rock suffers substantial structural damage due to the anisotropy in the geotechnical properties of its constituent minerals. Due to variable thermal expansion within minerals, thermal stresses are generated in the rock microstructure which cause change in the fracture pattern. New cracks may develop and pre-existing one may migrate and widen further; thereby reducing the mechanical strength of the rock. In this study, an attempt has been made to study the elastic modulus of thermally treated fine grained sandstone from the Dholpur district of Rajasthan. The elastic modulus was measured by using a MTS LX-Laser Extensometer. The rock specimens were thermally treated at various temperatures for a fixed duration. The change in the rock microstructure was studied viewing the rock specimen under a scanning electron microscope.