Investigating the effects of micro-texture and geo-mechanical properties on the abrasiveness of volcanic rocks

The abrasiveness of rocks is a fundamental rock property that affects sawing and cutting performance, wear of Tunnel Boring Machine (TBM) heads. The CERCHAR Abrasiveness Index (CAI) test is a commonly used procedure to define rock abrasivity. This paper investigates the relationship between quantitative mineralogical and petrographic data and CAI values for some selected volcanic rocks. In addition, the research examines the relationship between physical (e.g., effective porosity and P-wave velocities) and mechanical (e.g., uniaxial compressive strength (UCS), Brazilian Tensile Strength (BTS), Young's Modulus (E)) properties including brittleness values and CAI values. Quantitative mineralogical and petrographic analyses reveal the variations in micro-textural properties as defined by different groundmass-phenocryst ratios. Analyses also suggest that the dimensions of opaque minerals and plagioclase feldspar apparently have individual effects on CAI values. Additionally, the combined effects of grain size and primary types of constituent minerals have a significant on CAI values. Additionally, results of physical and mechanical tests indicate that as P-wave velocities increase, CAI values increase. The increasing values of UCS, BTS and E cause CAI values to increase significantly. However, only one of three brittleness values was found to have a considerable relationship with CAI values. This research demonstrates the importance of evaluating the micro-textural variations and the combined effects of micro-texture, physical properties and mechanical properties on the CAI values of volcanic rocks.