Determination of direct tensile strength of rocks using a load converter

Abstract The tensile strength of rocks is of great importance in many engineering and geophysical applications. Considered a key parameter in rock mechanics projects, its determination in the laboratory has been discussed for years by many researchers with two approaches: the direct tensile test, considered the ideal and most realistic, has its credibility compromised due to eventual poor execution issues; and, on the other hand, indirect tests, due to its practicality and dissemination around the world. In this context, the present work presents the results obtained with an equipment named compression to tension load converter (CTC), which allows the determination of the tensile strength of rocks in a direct and reliable way. A numerical analysis was carried out to study the stress distribution in the specimen during testing with the apparatus. Uniaxial compression tests, Brazilian and CTC tests were performed in a granitic rock from Southeastern Brazil, in order to compare the results obtained with results available in the literature. This work presents and discusses the results obtained with the CTC apparatus and compared them with results obtained with conventional indirect tensile strength tests.