Abrasiveness evaluation of selected river gravels of Pakistan using LCPC rock abrasivity test

Abstract

Abrasivity of rock and soil causes tool wear in excavation or drilling operations, and the presence of sandy gravels stratum also plays a significant role in causing serious damage to the cutting tools. Understanding the wear mechanism is important for the cost estimation and planning of projects. Abrasivity of cobbles and boulders present within soil matrix may vary from negligible in some cases to severe under certain conditions depending upon the volume and characteristics of those cobbles and boulders being encountered. Several methods have been proposed to assess the abrasivity of rock. In the present research, LCPC rock abrasivity tests were performed on 14 gravel samples collected from different river deposits of Pakistan. Practical extensions to the standard LCPC abrasivity test were used and fraction larger than 6.3 mm was incorporated in accordance with the method proposed by Thuro et al. (2007). Moreover, in order to observe the effect of increasing grain size on LCPC abrasivity coefficient (LAC g/t), 3 river gravel samples (out of initially selected 14 samples) were chosen and evaluated along with the computation of brittleness coefficient (LBC, %). Correlations were developed with LAC values of originally rounded grains against crushed/angular grains. XRD analysis was incorporated in order to determine the mineralogical composition of each sample and the possible correlation of LAC (g/t) with abrasive mineral content (AMC, %) for both modes of testing (rounded and crushed samples) were developed. Moreover, the correlations of LAC (g/t) with quartz content, equivalent quartz content, and mass-weighted average Moh’s hardness were also discussed.