Abstract
This paper describes an examination of concrete cores drilled from an old motorway bridge that had manifested deterioration and was in need of repair. Site observations and the nature of cracking indicated that alkali-silica reaction was suspect. Cores taken from the damaged structure were analyzed by using optical petrography for potential presence of reactive phases in aggregates, and chemical analyses to estimate the residual alkali content in the concrete. Results from the test methods were consistent with existence of alkali-silica reaction damage mechanism in the concrete. The level of severity of alkali-silica reactivity appeared to be moderate. The diagnostic features determined from tests indicate with some certainty, that alkali-silica reaction might have partly or solely contributed to distress in the bridge structure.