Relationship between Point Load Strength Index and Slake Durability Index of sandstones from the Amile Formation, Tansen Group, West-Central Nepal

Point load strength index (PLSI) and slake durability index (SDI) are two important indices of rocks used to evaluate strength and durability for various engineering applications. This research investigates these two indices in sandstones from the Amile formation coupled with petrography, aiming to determine the strength and durability of rock, and test for correlations among mineral constituents, texture, PLSI, and SDI to develop empirical relationships among them. The study provides insights into the geotechnical properties of an important geological formation in the Lesser Himalayan Zone, contributing valuable data for infrastructure development. The methodology involved field sampling, petrographic analysis of thin sections, SDI testing over two cycles, and PLSI testing on irregular lump samples. Correlations between SDI, PLSI, water absorption, packing density, and packing proximity were statistically analyzed. Quarztose sandstones have extremely high durability (SDI: 99.17–99.78%), very strong to extremely strong compressive strength (PLSI: 5.94–14.81 MPa), and low water absorption values (WAV: 0–2.17%). Very high positive correlations were found between SDI and PLSI with R2 =0.804. Based on this correlation, future research can use the equation SDI = 0.0712PLSI + 98.727 to estimate durability from strength for similar sandstones, saving time and resources.