Behaviour of Oil Palm Broom Fibres (OPBF) Reinforced Concrete

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 900mm, 1.837mm2, 0.84g/cm3 and 389MPa 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 50mm 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-
320% at 112 days, thereby possessing potential application in low-cost
earthquake resistant housing.