Mixed mode fracture of polyolefin fibre reinforced concrete

Throughout the last 60 years, the use of fibre reinforced concrete (FRC) has evolved favourably. By this technique, it is possible to reduce or substitute the traditional steel-bar reinforcement in the structural design of concrete elements for both civil and building construction. The most used fibres for this purpose are made of steel, though there have been remarkable advances in the plastic fibres that have made them an attractive alternative. Thus, macro polyolefin fibres have shown to meet the requirements set in the standards in order to consider their contribution in the structural design. To do so, fracture behaviour under Mode I has been the main topic of research in the last years. Nevertheless, there is still a lack of knowledge about the behaviour of polyolefin fibre reinforced concrete (PFRC) under other modes of fracture or the combination of them. This study assesses the behaviour of PFRC with several fibre dosages when subjected to Mixed mode fracture with several fibre dosages as well as the influence of the size effect with various sizes. Moreover, this paper supplies relevant information about the cracking processes and the variation in the orientation factor and residual strengths that take place when Mode I and Mode II of fracture occur simultaneously.