The point load tester is used to determine the Point Load Strength Index (Is(50)). This index provides a method for establishing rock strength classification. The point load test apparatus and procedure enables economical testing of core or lump rock samples. In order to estimate uniaxial compressive strength, index-to-strength conversion factors are used.
The testing equipment consists of a loading frame, which measures the force required to break the sample, and a system for measuring the distance between the two platen contact points. Rock specimens in the form of either core, cut blocks, or irregular lumps are broken by application of concentrated load through a pair of spherically truncated, conical platens.