On the Reliability of the Uniaxial Compressive Strength Obtained from the Point Load Index

In literature one can find plenty of formulas that relate the point load index with the uniaxial compressive strength of rock material. In this article it is shown that the uniaxial compressive strength of rock material obtained with these kinds of empirical formulas may be in most of the cases unreliable. It is finally recommended here avoid the use of the point load index as a unique tool to assess the uniaxial compressive strength, even though the equipment and the method to obtain it give to the engineer an economic and in-hand information of one of the most used rock material mechanical value.