Impact resistance of concrete using dovetailed fibres and type 2 synthetic fibres

This paper investigates the relative performance of new dovetailed (DT) cross section fibres with regard to impact resistance and energy absorption of concrete. The DT fibres are compared to concrete made with other commercially available Type 2 (T2) fibre types and plain concrete. The two diameters of the prototype DT fibre as tested; are currently in their development stage and not commercially available at present. The test examines two diameters of polypropylene DT fibres and a single size Type 2 structural synthetic fibre, to evaluate the relative mix performance. The parameters of the test are: compressive strength, flexural strength, energy absorption (toughness) measured with load and deflection and time dependant absorbed energy using a drop hammer impact test. Dosage rates for all samples were 6kg/m³ and 30kg/m³. The compressive strength test was carried out using plain concrete. Impact tests showed that the peak force required to induce a crack in the beams, was generally increased with the addition of fibres to the concrete mix. Total energy absorption was also increased utilising a higher fibre dosage; with a 30 kg/m³ dosage displaying the greatest increase. The post crack toughness indices of the concrete utilising DT fibres at a 30 kg/m³ fibre dosage produced superior values to the other concrete types tested. These findings suggest that the addition of DT fibres at the correct dosage will increase the impact resistance and energy absorption of concrete.