Uniaxial compressive strength and point load index of volcanic irregular lumps

The point load compression test for irregular lumps was actually proposed before the point load test for rock cores. The main advantage of this test is that no sample preparation (such as cutting and grinding) is needed. Results show that if the size of granite lumps is halved, the strength could be doubled. These studies laid the foundations for size effect correction that subsequently used in the International Society for Rock Mechanics. The Point Load Strength Test (PLST) was also proposed to estimate the point load strength by applying conical point contacts instead of flat platens. The diametral point load strength idex (PLSI) test was adopted by the US Bureau of Mines in 1965 as one of the ten index tests for rocks and the diametral PLSI test was found best correlated with uniaxial compressive strength (UCS). Here, Wong et al investigate the correlation between UCS and PLST on irregular lumps for volcanic rocks of different grain sizes and weathering grades found in Hong Kong.