Shear Strength of Hybrid Fibre-Reinforced Ternary Blend Geopolymer Concrete Beams under Flexure

The need to promote sustainable civil infrastructure is one of the most important concerns in the construction industry. Geopolymer composites are one of the promising eco-friendly materials for the development of low carbon concrete. The main objective of this experimental investigation is to study the effect of hybrid fibres on the shear strength of flexural members made with ternary blend geopolymer concrete (TGPC). A total number of 27 reinforced concrete beams of size 100 mm × 150 mm × 1200 mm were cast and tested for shear. M55 grade of concrete was considered in this study. Crimped steel fibres and polypropylene fibres with an aspect ratio of 66 and 300, respectively, were used in this work. The main variables considered in this investigation involve two volume proportions of steel fibres, viz., 0.5% and 1% as well as four volume proportions of polypropylene fibres viz., 0.1%, 0.15%, 0.2% and 0.25%. The hybrid fibre-reinforced ternary blend geopolymer concrete (HTGPC) beams were compared with TGPC beams without fibres. From the test results, it was clear that incorporating hybrid fibres improved the shear strength and changed the type of failure of the beam from shear to flexure. Moreover, a method to predict the ultimate shear strength of HTGPC was proposed, and the estimated values were found to be the same as the test results.