Petrological control on engineering properties of carbonate rocks in arid regions

Petrological features of carbonate rocks that exert control on their mechanical and physical properties are examined in the study presented here. Ninety-four representative rock block samples were collected at outcrops and were tested for uniaxial compressive strength (UCS), point load index (PLI), indirect tensile strength (ITS), sonic velocity (SV; V_p and V_s), Schmidt hardness value (SHV), slake durability index (SDI), porosity (n), water absorption (WA), unit weight (UW), and specific gravity (SG), according to the standards. The carbonate rock samples were classified into four groups, according to their compositional and textural characteristics, using XRD, XRF, polarized-light microscope, and SEM. Different types of regression analyses were performed to find the most applicable relationship between measured mechanical/physical properties and mineralogical/textural features of these carbonate rocks. The results suggest that rocks with pure calcite (no dolomite component) and abundant iron oxide cement are more sensitive to mechanical failure than the other carbonate rocks tested here. High silica content appears to reduce the UCS and I_d2 values probably due to the presence of silica as separate chert nodules and detrital quartz grains. The results also suggest impact of the arid environmental conditions in the study area. The correlation data indicated wide range of variability and cover ranges reported in published literature on carbonate rocks from other regions. The derived correlation equations of the rock strength parameters may be specific within the arid environment of the investigated rocks, but the results may still provide comparative guidelines for rock testing in the region and regions of other carbonate rocks.