Mechanical strength and water penetration depth of palmyra fibre reinforced concrete

Abstract

Natural fibre reinforced composites are replacing the conventional fibre reinforced composites for several applications due to natural fibre availability, variety and lesser raw material cost. Using natural fibres in composites also reduces the issue of agricultural residue disposals, which are in abundance. Different natural fibres exhibit unique properties when it is used in composites and hence there is a need to study the behaviour of scarcely used natural fibres. Indian palmyra trees (Borassus flabellifer) are fast growing commonly found trees in Southern India. From the base of these palm tree leaves, palmyra fibres are taken out. Though these fibres are locally available in huge quantities, these are very rarely used as reinforcing material in concrete compared to other natural fibres like coir, sisal, jute etc. Palmyra fibre reinforced cement composite specimens were prepared by varying the fibre content (0.5%, 1% and 2% by weight of cement) and length of fibre (25 mm and 50 mm). Plain concrete and palmyra fibre reinforced concrete specimens of identical size were tested for mechanical strength and also for its depth of water penetration. The work carried out revealed that the water penetration of palmyra fibre reinforced concrete increased with fibre content increase. The compressive strength of palmyra fibre reinforced concrete improved up to 1% of fibre content and further increase in fibre content upto 2% resulted in compressive strength reduction for both the fibre lengths. However, split tensile strength, flexure strength and shear strength increased with fibre content increase in the mix. Based on the mechanical strength properties investigated, increase in shear strength was found to be more significant with the inclusion of palmyra fibres in concrete.