FRACTURE TOUGHNESS OF POLYPROPYLENE FIBRE CONCRETE

Abstract The paper describes two simple tests which have been developed to determine the fracture toughness of concrete materials. In the first case, the test is carried out using ordinary concrete cubes, modified by the introduction of two slits, and then subjected to an eccentric load. In the second case, CTS specimens are used to evaluate fracture toughness. Tests have been carried out using a ‘stiff’ Instron testing machine and a ‘soft’ hydraulic bench-mounted test rig. The fracture toughness is determined from the load at crack initiation. The effect on fracture toughness of introducing various amounts of polypropylene fibre into a concrete mix is discussed. The results show that there is very little variation in fracture toughness values, as determined by this test, for the range of fibres added. However, the complete load-displacement curve during the fracture process shows considerable variation.