With the mechanical testing system (MTS) hydrostatic pressures up to 140 MPa and temperatures up to 200 °C can be simulated. The pressure and temperature within the chamber are continuously monitored by an external pressure sensor and two internal thermocouples (Type K). Within the pressure chamber, the thermocouples are located at top and bottom of the test specimen. To measure the axial and lateral strains of the sandstone samples, two axial extensometers and one circumferential chain …