Edge load strength test for indirect estimation of unconfined compressive strength

In this paper a new test called “Edge Load Strength” (ELS) for indirect estimation of unconfined compressive strength (UCS) of rock samples is introduced. The test apparatus is almost the same as point load test apparatus except that a flat seating replaces the lower conical platen of the point load apparatus. A cubic rock sample is placed on this seating and the point load is applied by the upper conical platen at a certain point close to the edge of the sample. The applied loads and the vertical displacements are continuously recorded during loading. The failure surface passes through the point of application of the point load by the upper conical platen and the front face of the specimen. ELS is carried out on 10 rock types and the results are correlated with the results obtained from UCS tests. It is shown that rather good correlations exist between ELS and UCS tests for the estimation of rock strength and elastic modulus.