Some new aspects on the diametral point load testing

A new closed-form equation is presented to measure the tensile strength of rock based on point load strength index. The validity of the proposed equation is further examined experimentally through a set of diametral point load testing of monzonites and two different types of granite having various slenderness (length to diameter) ratio. Based on the results, it is concluded that the induced tensile stress at the centre of a diametral point load specimen as well as the point load strength index are a function of both Poisson's ratio and sample length. In general, when either Poisson's ratio or the length of the sample increases, the induced tensile stress decreases. However, results indicate that the gradient of the induced tensile stress is more sensitive to the sample length than the materials Poisson's ratio. The proposed formula successfully explains such behaviors and provides estimations that are in good agreement with the experimental data.