Quantifying the relationship between uniaxial compressive strength and slake durability index in gneiss rocks: an experimental approach

This study investigated the relationship between Uniaxial Compressive Strength (UCS) and slake durability index (SDI) in gneiss rocks collected from two aggregate quarry sites. The analysis revealed varying correlations between these two parameters depending on the grouping and categorisation of the data. Initially, a moderate correlation was observed between experimental and estimated UCS values when considering all the data together. However, further examination of the data by dividing it into two categories based on UCS values greater than or equal to 40 MPa and less than 40 MPa yielded insightful results. Within these divided categories, a robust correlation was found between experimental and estimated UCS values for cycles two and four of SDI. Moreover, this study reveals that fresh rock samples from the quarry locations maintained a durability of over 98% through four cycles of the slake durability test. Nonetheless, these same samples exhibited decreased strength, which can be attributed to their mineral composition and internal structural arrangements of the rock samples tested. Therefore, this study incorporated complementary testing methods such as Ultrasonic Pulse Wave Velocity (UPV) and Scanning Electron Microscope/Energy Dispersive X-ray Spectroscopy (SEM/EDX). These tests served as valuable tools for validating the results and enhancing the understanding of micro-scale changes within the gneiss rock samples. The comparison of test values and the exploration of underlying factors confirmed the reliability and usefulness of UPV and SEM/EDX as supporting tools for this study. The study also recommended that the developed equations can be useful for engineers and researchers in estimating rock strength quickly and inexpensively by replacing the laborious tasks involved in traditional laboratory testing.