Determination of rust formation to cracking at the steel–concrete interface by corrosion of steel in concrete

•FE model was used to quantify structural limit considering the rust formation.•No cracking was observed until the rust was formed within the interfacial gap.•Interfacial gap was the most dominant to the onset of cracking at the interface.•Cover depth was crucial to reach the failure arising from rust formation.•Increased steel diameter enhanced the structural buffering capacity against rust. In this study, a development of the rust formation was modelled to quantify the structural impact in steel reinforced concrete. The interfacial gap, cover depth and diameter of steel rebar were taken for variables in modelling. It was found that the interfacial gap was the most influencing on the structural limit at steel corrosion, followed by steel diameter and cover depth. At 75 mm of cover depth with 20 mm of the steel diameter, the rust amount to reach yielding accounted for 2.66–11.58 µm to 1–10 µm of the interfacial gap, while 16.95–27.69 µm to the equivalent rust formation.