MECHANICAL PROPERTIES OF HYBRID FIBER REINFORCED CONCRETE

Abstract

Fiber reinforcement is commonly used to provide toughness and ductility to brittle cementitious matrices. Reinforcement of concrete with a single type of fiber may improve the desired properties to a limited level. A composite can be termed as hybrid, if two or more types of fibers are rationally combined to produce a composite that derives benefits from each of the individual fibers and exhibits a synergetic response. This study aims to characterize and quantify the mechanical properties of hybrid fiber reinforced concrete. For this purpose nine mixes, one plain control mix and eight fiber reinforced mixes were prepared. Six of the mixes were reinforced in a hybrid form. Four different types of fibers were used in combination, two of which were macro steel fibers, and the other two were micro fibers. Volume percentage of fiber inclusion was kept constant at 1.5%. In hybrid reinforced mixes volume percentage of macro fibers was 1.0% whereas the remaining fiber inclusion was composed of micro fibers. 28-day compressive strength, flexural tensile strength,flexural toughness, and impact resistance tests were performed in the hardened state. Various numerical analyses were carried out to quantify the determined mechanical properties and to describe the effects of fiber inclusion on these mechanical properties. It was observed that micro steel fibers contributed to the strength and toughness whereas polypropylene fibers are effective in providing ductility.