Effect of Mixing Fiber Cocktail on Flexural Strength of Concrete

Abstract

Abstract The objective of this study was to examine the effect of mixing fiber cocktail on cracking strength of concrete. The research work has been carried out to evaluate the effect of “cocktail fibers” on reinforced concrete. Cocktail fiber is a mixture of steel fibers (SF) and polypropylene fibers (PPF). Comparison was carried out by preparing and testing 30 specimens of plain & reinforced concrete incorporating different ratios of fibers. Monofilament polypropylene fibers and undulated steel fibers were used in various dosages and their effect on the cracking strength in terms of compressive strength as well as ultimate load capacity was observed. For this purpose cubes (150 x 150 x 150 mm) and beams (150 x 225 x 1975 mm) were cast for compressive strength test on cubes and two point loading test on beams. The cubes and beams were cast in groups, such as, group A (concrete without any fiber), group B (steel fibers @ 60 kg/m3), group C (PP fibers @ 0.7 kg/m3), group D (PP fibers @ 1.5 kg/m3), group E (cocktail fibers @ 60 kg/m3 of steel fibers + 0.7 kg/m3 of PP fibers) and group F (cocktail fibers @ 60 kg/m3 of steel fibers + 1.5 kg/m3 of PP fibers). From test results, it was concluded that the addition of polypropylene, steel and cocktail fibers enhanced the initial cracking and post cracking behaviour of reinforced concrete. However, with the addition of steel fibers the compressive strength of concrete reduced which is a trade-off between the initial cracking strength and compressive strength.