“…The dissolved chlorides from the external environment could permeate through sound concrete or cracks to the steel surface thus inducing corrosion of the steel bar (Grengg et al, 2018). In sewers, however, gaseous H 2 S and the biogenic sulfuric acid, produced in corrosion biofilms (Parker, 1945a, b), are commonly accepted to be the corrosive substances rather than chlorides (Fernandes et al, 2012). In the active corrosion regions of sewers, such as the pipe crown area (Jiang et al, 2014a, Jiang et al, 2015b, the roles and interactions of chloride, H 2 S and sulfuric acid in the rebar corrosion process are unknown.…”