Abstract
Reinforced beams with deteriorated concrete can be repaired by replacing the deteriorated part or the entire beam using new concrete. Either of the two scenarios is decided to be used based on the degree and distribution of deterioration along the beam. This paper compares the structural performance of composite and monolithic reinforced concrete beams which represents the two cases of partial and entire replacement of concrete, respectively. In total, 10 beams with dimensions of 3200x250x400 mm (LxWxD) were constructed. The reference monolithic beams were cast with either self-consolidating concrete (SCC) or fiber-reinforced self-consolidating concrete (FR-SCC). Composite beams were cast with conventional vibrated concrete (CVC) to a depth of 275 mm from the top then with either SCC or FR-SCC for the remaining third of the beam's depth (125 mm) at the bottom. The composite beams were prepared to simulate beams repaired in the tension zone after the removal of the deteriorated concrete. The test variables were fiber inclusion, fiber type, and beam type. One hybrid, one steel, and two polypropylene fiber types were employed in the FR-SCC. All fiber types were added at 0.5% by volume. The beams were simply supported and were loaded in four-point bending. Test findings indicate that both composite and monolithic beams exhibited similar cracking patterns at failure. However, the crack width of composite beams was lower due to enhanced fiber orientation along the tension zone and concrete confinement during the casting process. The structural performance of the beams was found to be mainly governed by mechanical characteristics of the fibers in the case of monolithic beams and mainly by the fiber length in the case of composite beams where fibers take preferential orientation during casting in the repair zone.