The object of this paper is to share the experience gained from an investigation of prestressed concrete box beams of the elevated roadway of the F. G. Gardiner Expressway in Toronto, 16 years after construction. The 18–30 m long, simply supported beams, which are either pretensioned or posttensioned with prestressing strands, are covered by concrete topping and asphalt. Methods of investigation include coring, chloride-content tests, and power chipping of soffit areas. Rusted reinforcing steel, rusted prestressing strands, and delaminated or spalled concrete were found at transverse joints and at beam soffits. Concrete damage due to bird droppings, as well as a beam with nearly 60% strand loss, were discovered. Causes for deterioration are discussed and proposed repair methods are described.
