Effect of fiber hybridization on mechanical properties of concrete

Ten concrete mixtures, using long and medium length hooked-end and short wave-shaped steel fibers, were designed to experimentally investigate the effect of hybrid reinforcement on workability, drying shrinkage, and mechanical properties of hybrid steel fiber reinforced concrete. The steel fibers reduced the workability and drying shrinkage. Hybrid fibers, including long hooked-end steel fiber, can produce a synergistic effect on compressive strength. For the adopted materials, a linear relationship was observed between shrinkage strain and compressive strength. The tensile splitting strength increased with the volume fraction of the hybrid fibers. The hybrid steel fibers generated a synergistic effect on the tensile splitting strength, with an almost constant ratio of tension splitting strength to compressive strength of hooked-end steel fiber reinforced concrete. The use of long hooked-end steel fiber reinforcement led to a higher modulus of rupture, residual strength, and toughness than other mono fibers. Flexural strength increased with the increasing volume fraction of hybrid fibers. Residual strength of hybrid steel fiber reinforced concrete varied with fiber hybridization. Overall, a concrete reinforced with a hybrid mix of all the considered steel fibers had the best performance among the considered ones.