Tensile behaviour of hybrid fibre-reinforced concrete

In this work, the tensile behaviour of hybrid fibre-reinforced concrete (FRC) was studied. Two different fibres, steel and polypropylene, were used to form single and hybrid FRC systems at five different volume fractions (1% to 5%). It was found that the tensile properties of FRC depended mostly on the type, content and selected FRC system. Single type steel fibre-reinforced concrete (SS-FRC) was found to behave in a typical manner, with peak load occurring at a very small deformation followed by a drop of the load to zero with no sign of load recovery. In the case of single type polypropylene fibre-reinforced concrete (SP-FRC) the behaviour was more ductile and presented mostly a double-peak response: a first peak at small deformation and a second peak large deformation. Steel fibres are believed to contribute more to strength whereas polypropylene fibres are believed to contribute to the ductility (i.e. toughness). For hybrid systems (Hy-FRC), it was found that the behaviour was in fact the combined behaviour of steel and polypropylene. The response of Hy-FRC was more balanced in terms of strength (first peak) and post-peak ductility.