MECHANISMS OF RUPTURE IN SPLITTING TESTS

The fracture mechanisms in the splitting tensile test (Brazilian test) are studied experimentally with special attention given to the influence of the width of the bearing strips. Tests of an extended size range (1:10) were conducted on mortar square prisms and granite discs. The tests were carried out on a closed-loop control system to obtain stable crack propagation. During the tests, crack initiation and propagation were recorded. The results confirm the existence of two fracture mechanisms in the splitting test: one associated with development of central cracks and the other with a secondary crack system on both sides of the bearing strips. These secondary cracks appear as a consequence of the stress redistribution induced by the central crack growth. The load-displacement curves recorded during the stable test show that two peak loads exist, one for each mechanism. The relative values of these peak loads depend on the specimen size and the width of the bearing strip: with a smaller size and a wider bearing strip, the relative value of the peak load associated with the secondary crack system increases.