Effects of carnallite content on mechanical properties of Maha Sarakham rock salt

Mechanical characterization tests are performed to determine the effects of carnallite contents on the strength, elasticity, and time-dependent parameters of rock salt specimens obtained from the Lower Member of the Maha Sarakham formation. The specimens are prepared with carnallite content (C-%) varying from 0% (pure halite) to 100% (pure carnallite). The compressive and tensile strengths and elastic moduli of the specimens exponentially decrease with increasing C-%. Specimens with higher C-% tend to dilate more than those with lower C-%, as evidenced by the increasing of the Poisson's ratio. The strength reduction due to the carnallite content decreases as the confining pressures increase. The elastic, visco-elastic, and visco-plastic parameters of the creep test specimens are defined as a function of C-%. They rapidly decrease with increasing C-%. Pure halite tends to behave as the Burgers material while pure carnallite behaves as the Max well material. The different creep rates and deformation mechanisms between halite and carnallite explain the occurrences and structures of potash ore deposit at the shelves and flanks of the salt domes and anticlines in the salt basin.