Improved Compression Test Technique for Soft Rock

A long-standing and universal recognition exists about the influence exerted on the behavior of rock in laboratory compression tests by the nature of the specimen-platen contact. Further, the degree of end restraint has been shown to influence the strength, mode of failure, and shape of the stress-strain curve obtained in laboratory compression tests on rocks. A practicable method of overcoming the end effects problem is needed. Hilsdorf developed an ingenious approach to the end effects problem using brush platens. Details of a set of brush platens made for uniaxial compression tests and results of the testing are presented. This approach has considerable potential for use with other materials and other types of loading. The single disadvantage to brush platens is the amount of time needed for their construction.