Flexural Behaviour of Hybrid Fibre-Reinforced Ternary Blend Geopolymer Concrete Beams

Abstract

Geopolymer concrete is one of the innovative eco-friendly materials that has gained the attention of many researchers in the sustainable development of the construction industry. The primary objective of this experimental investigation is to study the flexural behaviour of the ternary blend geopolymer concrete (TGPC) with various proportions of hybrid fibres. In this study, 27 reinforced concrete beams were cast with a TGPC grade of M55 and tested under monotonic loading conditions. The specimens were beams of length 1200 mm, depth of 150 mm, and width of 100 mm. Crimped steel (metallic) fibres and polypropylene (non-metallic) fibres were used in hybrid form to study the effect on the TGPC beams under flexure. The volume fractions of steel fibres were varied up to 1% with an increment of 0.5%, and polypropylene fibres varied from 0.1% to 0.25% with an increment of 0.05%. The test results were analysed based on the first crack load, ultimate load, load-deflection behaviour, energy absorption capacity, moment-curvature relationship, and ductility behaviour and compared with TGPC specimens without fibres. The experimental study reveals that the TGPC is one of the best alternatives for conventional cement concrete. The addition of hybrid fibres potentially improves the flexural properties of TGPC to a great extent. The test results showcased that the HTGPC with 1% steel and 0.1% polypropylene fibres exhibited better flexural properties than the other combinations of hybrid fibres considered in this study. Additionally, an effort was made to develop a model to estimate the flexural strength of TGPC with hybrid fibres, and the predicted values were found satisfactorily with the test results.