STUDY OF THE EFFECT OF FIBRE ADDITION ON MODE II FRACTURE OF QUASI-BRITTLE MATERIALS

Abstract

Fracture of quasi-brittle materials, such as concrete or gypsum, has been studied for decades. These studies have given light on the fracture mechanisms as well as on the parameters that drive these processes, allowing producing numerical models that reproduce fracture using tools such as the Finite Element Analysis. On another note, the three possible Modes of fracture that can be identified in the field of Fracture Mechanics, Mode I is very well known, experimentally reproduced and used as the base for most numerical models. Nevertheless, in some cases fracture takes place as a combination of a stress state that induces a fracture mechanism where Modes I and II are involved. In this sense, Mode II fracture has been studied less often, partly because Mode I fracture is more usual, but also because reproducing Mode II experimentally is quite more complex. This study is focused on inducing Mode II fracture on fibre-reinforced gypsum specimens by using two different experimental tests. More specifically, the experimental test proposed by the Japanese standards JSCE and the push-off test are employed. The displacement field is obtained by means of the digital image correlation technique (DIC), which helps to understand how fibres modify the fracture mechanisms of the gypsum matrix when this takes place under Mode II conditions.