Effect of Crumb Rubber on Pull Out Response of FRP Rebar in Fiber-reinforced Lightweight Concrete

Use of crumb rubber from scrap tire in the reinforced concrete along with Fibre Reinforced Polymer (FRP) bar is a novel way of recycling tire and providing durable and sustainable concrete structure. The performance of reinforced concrete structures depends on the proper transfer of forces between concrete and reinforcement. And this proper transfer of forces depends of the quality of bond between concrete and reinforcement bar. In this study, the bond characteristics of sand coated Glass Fibre Reinforced Polymer (GFRP) bar embedded in lightweight concrete with crumb rubber as partial or full replacement of sand has been evaluated. Quasi static bond pullout tests were performed on 60 cylindrical test specimens to determine the effects of crumb rubber percentage, FRP bar diameter and short steel fibre presence on bond performance. Two different bar sizes (10mm and 16 mm diameters) were used while keeping the constant embedment length of five times the bar diameter. The study showed that increase in crumb rubber content reduces the bond strength. Presence of short steel fibre disrupts the bond with FRP bar. The research also showed that bond strength is higher with 16 mm bar compare to 10mm bar due to prominent surface roughness.