Effect of Reinforcement Corrosion on Bond Behaviour in Reinforced Concrete with Recycled Fine Aggregates

This study investigates the bond behaviour of reinforced concrete incorporating fine recycled aggregate (RFA) under reinforcement corrosion, focusing on the effects of RFA replacement and radial confinement. Four concrete mixtures were produced with 0%, 20%, 50% and 100% replacement of natural fine aggregate by RFA obtained from a demolished concrete bridge. Pull-out specimens incorporating 16 mm reinforcing bars were manufactured with specimen diameters of 100 and 150 mm to provide different levels of radial confinement. Reinforcement corrosion was accelerated by impressed current at a nominal current density of 150 μA/cm², considering non-corroded, low-corrosion and high-corrosion conditions. Corrosion-induced steel mass loss and peak bond stress were determined from the experimental tests. The imposed corrosion exposure did not result in the same actual corrosion level for all mixtures. Steel mass loss generally decreased with increasing RFA content despite the controlled galvanostatic exposure. Bond strength was generally lower at higher RFA replacement ratios, although the effect was not monotonic across all corrosion and confinement conditions. Comparisons at similar corrosion mass losses showed a more consistent influence of specimen diameter, with the larger diameter generally providing higher bond strength. Radial confinement had a more pronounced influence on bond behaviour than RFA content, although the percentage of RFA also affected bond strength and should be considered. The actual corrosion mass loss should also be accounted for when assessing bond degradation.