Behaviour of oil palm broom fibres (OPBF) reinforced concrete

Abstract

Recent concerns on global environmental sustainability and climate change have favoured the use of natural fibres as alternatives to traditional reinforcing steel in concrete due to their low carbon footprint. Oil palm broom fibres (OPBF) which are the ribs of oil palm leaflets have average length, cross-sectional area, density and tensile strength of 900 mm, 1.837 mm2, 0.84 g/cm3 and 389 MPa respectively, hence making the fibres superior to steel in terms of strength-to-weight ratio. A study on the effect of OPBF on some mechanical properties of concrete mix of 1:1.5:3 of cement, sand and gravel respectively, was carried out. Short discrete OPBF of 50 mm length were incorporated in the fresh concrete mix at 0.5%, 1%, 1.5%, 2%, 3% and 4% of total aggregate volume. A total of two hundred and seventy-six (276) samples of 150 cubic, 63 cylindrical and 63 prismatic specimens were cast to assess compressive strength of OPBF-concrete at 7, 14, 28, 56 and 112 days, and flexural and split-tensile strengths at 28, 56 and 112 days. Bond strength between OPBF and concrete matrix was also investigated through pull-out tests. Flexural strength and splitting tensile strength of concrete were slightly improved for 0.5–1% OPBF inclusion at 28 days but do not show marked improvements at 112 days. Failure of hardened OPBF-concrete was characterised by more fibre-pull-outs than fibre-fracture but with an enhanced ductility of the composite at failure. The post-yield behaviour of OPBF-concrete shows enhanced energy absorption capacity of between 70 and 320% at 112 days, thereby possessing potential application in low-cost earthquake resistant housing.