FLEXURAL BEHAVIOUR OF TERNARY BLENDED STEEL FIBRE REINFORCED CONCRETE BEAMS USING CRIMPED FIBRES

In the present investigation an attempt has been made to study the Moment of resistance of ternary blended steel fiber reinforced concrete beams. The mineral admixtures used in the study are fly ash and metakaolin. Fly ash is the waste product from the therma l power plants and its production in large amount poses severe environmental problem. So its use in concrete contributes to the environmental pollution control. The binary blend of concrete using fly ash has the advantage of producing better workability bu t there is a late development of strength. When metakaolin is used in the concrete, there is an early gain of strength but the concrete produced is lesser workable. So, when the fly ash and metakaolin are used, the ternary blend of concrete gives better wo rkability as well as there is an early gain in strength. The steel fibres used in the experiments are of crimped shape with an aspect ratio of 80. Varying percentages of metakaolin and fly ash by weight of cement as partial replacement of cement were take n for the tests. The percentage of mix proportions of ternary blend yielding optimum results for M30 grade concrete were obtained. Tests were conducted on ternary blended concrete beams with varying percentages of crimped steel fibres (0%, 0.5%, 0.75%, 1%, and 1.25%). Compressive strength of concrete has been determined by testing standard cubes (150mmx150mmx150mm) at 7 days and 28 days of curing. Flexure strength of ternary blended fibre reinforced concrete beams is determined by testing beams of size 1400 mmx100mmx150mm under two point loads in the universal testing machine at the age of 7 days and 28 days. The beams have been provided with longitudinal reinforcement. 6mm bars dia at tension member and 12mm bars dia at compression member.