STRENGTH AND FRACTURE PROPERTIES OF HYBRID FIBRE REINFORCED CONCRETE

This paper investigated the shear, impact and fracture strengths of high-strength
concrete reinforced with two different industrial waste fibres. Locally available steel lathe waste
and nylon waste were used at different volume fractions as fibre cocktails in concrete. Steel lathe
wastes were used as-received lengths and nylon fibres were chopped into 40 mm lengths in this
investigation. In total, 12 hybrid mixes were casted and tested at four different volume fractions
(0.5%, 1.0%, 1.5% and 2.0%). The experimental programme was used the slump test and the air
content test on the fresh concrete. The hardened concrete was tested for its shear and impact
strength. A flexural test on notched beams under three-point bending was also carried out
according to the RILEM 50-FMC committee recommendations. Load vs. mid-span deflection and
load vs. crack mouth opening displacement were obtained and the fracture energy was evaluated.
The best performance was obtained in hybrid which was enhanced due to the hybrid nature of the
fibre cocktails of all the mixes, 2% volume fraction with a combination of steel ½ + nylon ½ fibres
gives the best performance. The steel lathe waste fibres mainly contributed to limiting the crack
initiation and lightweight non-metallic nylon fibres restricted the crack propagation. The combined
advantages of these fibres provide high mechanical and fracture strength. Hence this hybrid fibre
reinforced concrete with industrial waste fibres is doubly advantageous as it provides a superior
performance without increasing the cost of the concrete.