Concrete Mix Proportioning to Meet Durability Concerns For Confederation Bridge

Abstract

A 12.9 km bridge was recently constructed across the Northumberland Strait in Eastern Canada, connecting Prince Edward Island (Canada's smallest province and major tourist area) with the mainland. The bridge is a precast, post-tensioned segmental box girder structure. The bridge is believed to be the longest highway structure over seasonally frozen water. Durability concerns which had to be addressed in the design and construction of the bridge included abrasion of ice on the piers in late winter and early spring, corrosion of reinforcement in a marine environment, alkali-aggregate reactivity, sulphate attack, freezing and thawing resistance of concrete in a saturated condition, salt scaling and control of thermal cracking. The design life of the bridge was 100 years, a first of this magnitude in Canada. The paper discusses some of the unique features of the bridge and the selection of concrete mixture proportions to meet the durability requirements of bridge components.