DEFLECTION AND STRAINS PERFORMANCE OF KENAF FIBRE-REINFORCED CONCRETE BEAMS

Abstract

There has been a need to find a lasting means to improve beams' deflection and strain performance without necessarily increasing the beam stirrups. The limitations of steel and other synthetic fibres have reduced their application. Given its tensile strength, renewability, sustainability, and affordability compared to steel and synthetic fibres, kenaf fibre development is of great interest in Malaysia. Therefore, this research work experimentally investigated the deflection and strain performance of Kenaf Fibre Reinforced concrete beams. The volume and length of kenaf fibre used were 0.75% and 25mm, respectively. Kenaf fibre was treated with 5% NaOH to improve its performance. The alkaline-treated and untreated kenaf fibres morphology was observed under a variable-pressure scanning electron microscope. It was discovered inclusion of kenaf fibre reduced the workability of concrete. Also, plain and KFR concrete morphology was observed under a variable-pressure scanning electron microscope. Four beams were designed to study the deflection and strain performance of the KFR concrete beam; one was well reinforced but without kenaf fibre. The stirrups spacings were increased by 25%, 50%, and 75% for the other three beams. The beams were tested under centre loading. Deflection and concrete strain at the centre and along the beam span were measured using LVDTs and concrete strain gauges for the four beams. Furthermore, the strains on the shear and bottom flexural reinforcements at the centre of the beam were measured using steel strain gauges. It was discovered that kenaf fibre enhanced the deflection and strain performance of beams between 25% and 50% stirrups deficiency.