Assessment of physical and mechanical properties of a number of sandstone formations in the Central Alborz sedimentary-structural zone

The central Alborz structural-sedimentary area in the middle part of the Alborz Mountain Range has endured geological events from the Precambrian to the present era, and contains numerous geological structures and formations. Among these, sandstone formations also have a significant expansion. In this research, 6 different sandstone formations were sampled in 2 locations and tested to determine their physical and mechanical characteristics. In general, in the sandstone formations of central Alborz, top quartzite has stronger mechanical parameters than other formations. Shemshak Formation has the lowest mechanical parameters among the selected formations. Based on regression analysis, the conversion factor of PLT, BST and CPI parameters to unconfined resistance or UCS showed 20.6, 6 and 20.40 respectively with R2s of 0.75, 0.90 and 0.78. In terms of the Cerchar Abrasivity Index (CAI) as an index that can show the amount of abrasion, top quartzite has the most abrasiveness, which is due to its lithological composition. This sandstone formation is placed in the category of stones with high abrasive ability, and Shemshak Formation has the lowest Cerchar index among the formations and is placed in the group of stones with extremely low abrasiveness.