Impact of corrosion on bond in uncracked concrete with confined and unconfined rebar

•For confined specimens bond strength initially increases as corrosion proceeds.•Unconfined specimens display no clear relationship.•The variation between top and bottom cast bars reduced as cover increased.•The effect of confinement reduced as cover increased.•There was little scaling effect between the 12 and 16mm bars. This paper examines the variation in bond strength in corroding specimens, before surface cracks are visible. Reinforced concrete specimens containing 16mm and 12mm diameter bars at covers of 1, 2 and 3 times bar diameter, with and without confinement, were subjected to accelerated corrosion. Bond strength is seen to increase during the early stages of corrosion (pre external cracking) for confined bars at all covers and unconfined bars at 3 times cover. However, while 16mmbars, 1 and 2 times cover showed similar behaviour the 12mm bars displayed a decrease in bond once corrosion was initiated.