Effect of Cracking on Chloride Content in Concrete Bridge Decks

Field survey studies measuring bridge deck cracking and chloride contents of both cracked and uncracked concrete are presented in this paper, as part of a larger overall evaluation of bridge deck performance. The authors study three deck types, including monolithic decks, decks that have a conventional high density concrete overlay, and decks with high density concrete overlay that also contain either a 5% or 7% cement replacement by silica fume. Field survey results show that chloride content is not significantly affected by bridge deck type. Regarding chloride concentrations, samples taken away from cracks show the average concentration at the top of transverse reinforcement rarely exceeds even the most conservative estimates of the corrosion threshold for conventional reinforcements. However, at crack locations, chloride concentrations often are shown to exceed the corrosion threshold of conventional reinforcement in less than one year.