Effect of Short Steel Fibre Reinforcement on Laterized Concrete Columns

This paper reports on experimental investigation conducted to determine the effect of short randomly oriented and discontinuous steel fibres on the structural behaviour of laterized concrete columns. Thirty fibre reinforced concrete columns of 150 x 150mm cross-sectional area and 1200mm in height and sixty number 150 x 150 x 150mm cubes were cast and tested. Fifteen fibre reinforced concrete columns were provided with 8mm mild steel links at 300mm spacing while the remaining fifteen (15) specimens of the fibre reinforced concrete columns were not provided with links except at the top and bottom of the bars to hold the longitudinal reinforcements in position. The mix proportion for this investigation is 2:3:6 (cement: Laterite/sand: Granite) with 0.65 water/cement ratio. The specimens were cured in water at different ages up to 28 days at temperature of 21 degree +/- 1 degree C. The steel fibre was varied from 0% to 2% at 0.5% interval. The first crack load and ultimate column strength increases with increasing fibre proportion up to an optimum fibre content of 1.5% of the volume of laterized concrete. There is approximately linear relationship between the ultimate strength and the percentage of fibres in the laterized concrete up to this optimum level. Results also indicate that an addition of 1% fibre by volume of concrete can be an effective replacement for 8mm non-shear links in laterized concrete columns. It was observed that there was no appreciable effect of additional steel links on loading when fibres are present in the mix, showing that fibre reinforced laterized concrete short columns may be used without additional steel links in provision of minor structures, as well as low rise buildings, where nominal shear reinforcement is needed.