Condition assessment of a decommissioned pier cap affected by alkali–silica reaction after 57 years of service

Champlain Bridge, which stood from 1962 to 2019, was a significant highway structure spanning the St. Lawrence River and St. Lawrence Seaway. It was constructed using concrete incorporating an alkali–silica reactive aggregate. Decommissioning of the structure presented a unique research opportunity to investigate how damage owing to alkali–silica reaction (ASR) developed in a concrete member with various levels of restraint. Following decommissioning of the pier cap, cores were extracted longitudinally from a number of restraint locations within the member (i.e. top, middle and bottom regions) and investigated using a multi-level assessment protocol through microscopic (i.e. damage rating index) and mechanical (i.e. stiffness damage test) test procedures. Cracking travelling parallel to the coring direction in the extracted cores (i.e. parallel to main reinforcement) was observed in all regions, indicating an influence of restraint conditions on ASR-induced development. Moreover, increased expansion due to ASR, similar to reference cores extracted transversally, was identified in cores extracted from the highest reinforcement region, while cores from the middle and bottom regions displayed a reduced deterioration.