OPTIMIZING MIX COMPOSITION FOR STEEL FIBRE REINFORCED CONCRETE WITH ULTRA HIGH FLEXURAL STRENGTH

摘要

Manufacturers of pre-cast elements are constantly increasing the compressive strength of the concrete they use without necessarily taking into account that the failure of high strength concrete is more brittle than that of concrete with a lower strength. The flexural strength of concrete is normally approximately 10% of the compressive strength but the ratio between tensile and compressive strength decreases with increased strength. At high strengths the flexural strength and ductility of concrete can be significantly affected by the mix composition and the fibre content. Experiments have been conducted to establish the effect of low carbon slit sheet crimped profile fibres and hard-drawn hooked end steel wire fibres on the properties of high strength concrete. The aim of this investigation was to establish the effect of increasing concrete strength (by reducing water/cement ratios) on the compressive and flexural failure of fibre reinforced concrete. The experimental results for various mix compositions are discussed and recommendations are made regarding the optimisation of mix compositions and fibre contents.