Tribological study of sand-grain contacts

In the study, micromechanical experiments are conducted on a variety of geological and manufactured sand-sized grains to obtain insights into the important factors that influence the inter-particle coefficient of friction (μ). Chrome steel balls (CSB), glass beads (GB), Leighton Buzzard quartz sand (LBS), limestone grains (LS) and completely decomposed granite (CDG) of size between 1.18 and 3.00 mm are studied. The experiments are conducted using a custom-built micromechanical loading apparatus at the City University of Hong Kong (Senetakis and Coop, 2014). The normal load contact tests are performed to obtain the apparent Young’s modulus based on Hertzian fitting. The tangential load contact tests are conducted to measure the inter-particle coefficient of friction. The results show that the coupled increase of roughness and decrease in Young’s modulus increase μ (Sandeep and Senetakis, 2018). Greater scatter of the data is acknowledged for rougher grains or grains subjected to weathering in comparison to un-weathered and smoother geological materials as well as manufactured grains.