A Laboratory Study on the Flexural and Shear Behavior of RC Beams Retrofitted with Steel Fiber-Reinforced Self-compacting Concrete Jacket

Abstract

In this research, the behavior of RC beams retrofitted with steel fiber-reinforced self-compacting concrete jacket (SFRSCC-J) is investigated. For this purpose, by constructing 25 different beams, flexural load-carrying capacity of beams retrofitted with different concrete jackets is examined. The variables studied are the type of concrete (conventional and self-compacting), the strength grade of concrete (C40, C50, and C60), and the presence or absence of reinforcement bar and steel fiber in the jacket. The beams were subjected to three-point flexural loading, and the response was evaluated in terms of load–displacement diagrams. The results show that by adding SFRSCC-J to the perimeter of the beams, their bearing capacity can be increased up to about 7.4 times to reach the yield load, and about 5.1 times to reach the ultimate load. Moreover, the combination of steel fibers (SFs) and steel rebar reduced the cracks more, and at the final moment, the cracks extended to the neutral axis of the cross-section. In the retrofitted beams with the combination of rebar and SFs, the bonding between the reinforcement and the concrete increased and the reinforcement bars slipped less into the specimen. Thus, with a better distribution of stress, besides the concentration of the cracks in the middle of the span, the diagonal cracks decreased, and as the load increased, crack lengths increased less.