STRUCTURAL PERFORMANCE OF FIBER BASED CONCRETE

Abstract

Fibre based concrete may be defined as a composite material made from concrete ingredient incorporating discrete, randomly fibres. In ancient time, many natural fibres have been used in concrete to improve its tensile strength. The steel and glass fibres, used in early work of fibre based concrete, were straight and smooth. Since then, moreover complicated geometries have been developed, mainly to modify their mechanical bonding with concrete ingredients. Thus, modern fibres may have deformed shape and configuration, fibrillated or bundled filaments. The fibres has been mainly used in concrete not for to increase its strength, rather than to control its cracking behaviour as well as to improve its ductility. The aim of present study is to investigate the effect of steel and Polypropylene fibres on various properties of concrete for different fibre volume fraction. The mechanical properties of concrete such as compressive and tensile strength have been studied. The experimental investigation consists of casting hundreds of cube, cylinder and prismatic specimen with plain and fibre reinforced concrete. The fibres have been added to the concrete with various volume fractions. Ranging from 0.5% to1.5% for steel & 0.05% to 0.25% for polypropylene fiber having different aspect ratio. The results showed that, steel fibres are more effective as compare to polypropylene fibres as regard to mechanical properties. However, handling of steel fiber based concrete was more difficult in fresh state at higher fibre volume fractions whereas it was not so in case of polypropylene fibre. The steel fibres were found to have more impact on the tensile strength of concrete as compare to Polypropylene fibres. The improvement was very significant as the aspect ratio of fibres increases. The analytical study of experimental data has been done and the relation between tensile strength and compressive strength was proposed. Based on the regression analysis, relation between cube and cylinder strength was also proposed for fibre based concrete (FBC).