PERFORMANCE OF FRC AT DIFFERENT LEVELS OF CONCRETE STRENGTH

The high performance, arresting crack propagation, improvement ductility, toughness and residual strength after first crack formation and avoiding the growth of micro cracks has been gained fiber reinforced concrete (FRC) its popularity in the last decades. These improvement properties may be affected by concrete strength level. This paper investigated experimentally the effect of concrete strength and steel fiber volume fraction (Vf %) on the mechanical properties, strength relations and flexural energy of FRC. Three concrete strength levels representing normal strength concrete (NSC), moderate strength concrete (MSC) and high strength concrete (HSC) were designed. Hook-ends steel fibers (SFs) of length 35 mm and fiber aspect ratio of 43.75 were used by volume fractions of 0, 0.5%, 1.0% and 1.5%. The experimental results showed that the addition of SFs to the three types of concretes caused significant improvement on their mechanical properties involving compressive, indirect tensile and flexural strengths by different percentages. The maximum enhancement was recorded for NSC and the minimum was for HSC. The strengths relations were estimated and correlated. The addition of SFs to different types of concretes showed also a noticeable improvement in their flexural energy