INFLUENCE OF POLYPROPYLENE FIBER ON THE BOND STRENGTH BETWEEN STEEL BAR AND CONCRETE

Bonding between reinforcement and concrete play an important parameter in the behavior and strength of reinforced concrete. Many parameters influence the bond between reinforcement and concrete such as concrete cover depth, concrete conditions, overall thickness of the structural element and curing. In the present study, a total of sixty specimens as cube with four different percentages of polypropylene fiber (0, 0.5,1 and 1.5) % is used to evaluate the bond strength and stress-slip relationship. The compressive strength of concrete, rebar diameter, concrete cover, and embedded length of reinforcement are taken into account as variables. The test results show that the ultimate bond strength increases with increasing each of the compressive strength of concrete, concrete cover, polypropylene fiber content and decreasing the nominal diameter of the reinforcing bar. The best percentage that gave the maximum failure load, is 1.5% of polypropylene fiber.