Towards a rapid and practical determination of the pin-rock interaction parameters of the CERCHAR abrasivity test

The CERCHAR test is a widely used index test for evaluating rock abrasiveness and associated tool wear in rock excavation. However, routine testing only assesses the wear on the pin itself. To evaluate the advancement rates in rock cutting during excavation, it is also crucial to consider the material removal of the rock. Recent studies have begun to include this aspect by developing advanced methods, automated testing devices, or using customized equipment for test evaluation. Yet, these methods are too time-consuming and specialized to be used in routine laboratory testing. This study investigates the correlation between traditional CAI and associated material removal by complementary measurements of the scratch groove on the rock specimen using a stereomicroscope. The presented approach enables the straight forward determination of additional parameters, such as rock volume removal and pin tip loss, based on the inherent pin tip geometry and associated scratch groove geometry. These parameters are then used to calculate the CERCHAR Abrasion Ratio, which serves as a proxy for the excavability of different rock types. Despite some minor limitations, this approach can deliver values that are comparable to those obtained using specialized equipment. Therefore, it has the potential to be a practical method for assessing abrasion and excavation on job sites.