Correlation Between Cerchar Abrasivity Index with Rock Properties in Sandstone and Tuff Samples

The abrasivity of materials is of vital importance in selecting an affordable excavation method in the early stages of a tunneling project. The amount of specific energy and the Mode I and Mode II stress intensity factors in the eroded disc is more than the non-eroded disc. Vickers hardness number rock (VHNR), rock abrasivity index (RAI), Cerchar abrasivity index (CAI), LCPC abrasivity coefficient, and Norwegian University of Science and Technology (NTNU) abrasion test are among the methods for estimating rock abrasivity. Correlations were proposed in this study for estimating the CAI of sandstone and tuff. To achieve reliable comprehensive results, various kinds of sandstone and tuff with different geological properties were selected. Sandstone and tuff samples were collected from different regions. Various tests were then carried out on prepared rock specimens to determine the uniaxial compressive strength (UCS), tensile strength, longitudinal waves velocity, Schmidt hammer rebound hardness, and the equivalent quartz content (EQC). Two correlations were presented by analyzing the experimental results with the help of SPSS and Excel. The first correlation estimated the CAI of sandstone based on the UCS and EQC with a coefficient of determination (R2) of 0.81. Moreover, using data analysis in Excel, another correlation was proposed to estimate the CAI of tuff. The second correlation estimated the Schmidt hammer rebound hardness of tuff with an R2 of 0.88.