Rock abrasion plays a significant role in geotechnical design, tunneling operations and the safety of foundations from scour. It is imperative Rock Abrasion to determine such properties of uniaxial compression strength (UCS), rock quality designation (RQD) and hardness for rock engineering to help determine the amount of scour at foundation locations in order to prevent structural collapse, wear on drilling tools and help predict unstable rock conditions. Current practice for estimating maximum rock abrasion is based on the Los Angeles abrasion test; however, more research is needed to provide a more accurate and compatible method for all subsurface materials used in mining and civil engineering projects. This report will provide simple correlations relating abrasion resistance to RQD, UCS, Geological Strength Index (GSI) and Rock Mass Rating (RMR) and shear strength of metamorphic rock (Quartzite). Methods, results, recommendations and conclusions are presented. The paper also introduces recommendations for future rock abrasion techniques and discusses the use of these correlations exhibiting strong relationships between the mentioned rock properties.

Rock quality designation (RQD), Uniaxial Compression Strength (UCS), hardness and rock abrasion all place a significant role in rock mechanics. Like RQD, hardness exhibits the quality of the rock where the UCS provides strength of the rock. Abrasion resistance of rock combines both the strength (binding material) and quality of the rock (how broken the material can become). Rock abrasion can be defined as the process of wearing away a surface by friction when particles of sand or small pieces of rock are carried across its surface by a glacier, stream, other materials or the wind. Noted and tested by [1] Okubo et al. (2011), rock abrasion resistance has a direct relationship with the wear occurring in the bits of rock drills, road headers, tunnel boring machines and other equipment, and has long been researched; however, further rock properties may be correlated to help predict wear of mining equipment, slope stability and underground rock conditions. Other notable past research indicating the need for further rock abrasion testing and showing distinct correlations between rock abrasion and other rock properties include [2] Yavuz et al. (2008), [3] Cargill and Shakoor (1990), [4] Kılıç and Teymen (2008), and [5] Petrica et al. (2013). As mentioned by [6] Kahraman & Gunaydin (2007), the boundaries and pores between grains represent weaknesses in the rock structure and failure of rocks generally takes place at the grain boundaries. Therefore, rock abrasion and RQD can be correlated according to the strength of the rock.

RQD is a field measurement to estimate the degree of fracturing in a rock mass in situ. RQD value depends on a number of parameters such as the state of in-situ stress, direction of drilling, degree of weathering, amount of jointing and is used as one parameter to determine rock mass rating (RMR). As the RQD percentage value increases, the less amount of fracturing should be observed and the quality of rock should improve. Like RQD, LA abrasion resistance is measured on a 0 to 100 percentage scale to determine the amount of material loss due to erodibility factors (i.e. wind, grinding, impact). LA Abrasion test results will indicate if a material (rock) is susceptible to wear indirectly by crushability; hence, will show how “intact” a rock mass is. Intact rock can be defined as the rock sections between fractures of the rock mass and do not contain major fractures within. A low RQD value will indicate higher weathering and contain less abrasion resistance due to lower hardness and intact strength properties. LA Abrasion like RQD can show an indirect relationship indicating the quality (rock mass) and strength (intact rock) as well as showing how cohesive rock specimens are. The higher the weathering and less cohesive the rock (regardless if intact or rock mass), the less the abrasion resistance and RQD will be. RQD and LA Abrasion property also have been used in comparison to determine scourability of bedrock of bridge foundations. Higher RQD and rock abrasion resistance will produce less scour potential. This paper investigated and compared LA Abrasion and RQD based on both rock mass and intact rock properties. The paper also proposes results using LA Abrasion testing to correlate RQD, shear strength, Geological Strength Index (GSI) and Rock Mass Rating (RMR) and UCS. Results, recommendations and conclusions are presented in the paper.