Reliability of polyolefin fibre reinforced concrete beyond laboratory sizes and construction procedures

Research has shown that polyolefin fibres can meet the requirements of the standards that consider their post-cracking contribution in the structural design of fibre reinforced concrete (FRC). The final positioning of fibres plays a major role in FRC performance, especially in fracture results. In this study, laboratory specimens and structural sizes are tested and the results discussed. The main sources of fibre anisotropy are addressed: fresh-state properties of the concrete, pouring methods, compaction procedures, wall-effects and formwork geometries. The fracture behaviour shows a remarkably reliable performance of the polyolefin FRC. The differences in the final positioning of the polyolefin fibres are also analysed, with counting exercises being performed on the fracture surfaces. They reveal that when using elements longer than the standard specimens, there is no evidence of floating effects. In addition, they highlight the significant performance of self-compacting polyolefin fibre reinforced elements. Moreover, a numerical model, based on the fracture cohesive crack approach, is proposed for modelling the fracture of the tested specimens. A summary of the tests carried out by other researchers is presented, and the results compared with the presented in this work.