Hybrid fiber reinforced self-compacting concrete under static and dynamic loadings

The influence of the combination of the recycled fibres with the polypropylene and glass fibres on the mechanical parameters of the self-compacting concrete under quasi-static and dynamic conditions was analysed. The volume ratio was equal to 1.5% in the case of steel fibres coming from end-of-life tires and 0.5% and 0.25% for glass and polypropylene fibres, respectively. The mixes of fibres improved the toughness of the SCC under quasi-static condition. The effect of polypropylene fibres on the quasi-static compressive strength fc of SCC reinforced with recycled fibres was insignificant. Meanwhile, the addition of glass fibres pronouncedly enhanced the fc but decreased the toughness. The response of HFR-SCC to the high compressive strain rates was investigated with use of the Hopkinson Pressure Bar arrangement with a diameter equal to 40 mm. The results indicate that the HFR-SCC is highly strain rate sensitive material. The dynamic compressive strength was the two times higher than the quasi-static fc. The increase of fc under dynamic conditions was mainly caused by the addition of other fibres not depending on their type.