Chloride ion transport in bridge deck concrete under different curing durations

During freezing temperatures, ice accumulates on exposed concrete slabs such as bridge decks. Deicing salts such as calcium chloride are applied to control this ice formation. These salts migrate down to the reinforcing steel, and they can break down the passivation layer on steel, causing it to corrode. This paper is part of a broader research study to explore the possibility of opening the bridge decks earlier than the 10-12 days as practiced now, by decreasing the number of wet-mat curing days. Seven concrete mixtures typically used in Texas bridge decks were evaluated for chloride permeability using the ponding test (AASHTO T259). The primary experimental variables were the curing duration, type and percentage of supplemental cementitious materials, type of coarse aggregate, duration of ponding, and the surface preparation of ponded concrete specimens. Results of the investigation indicated that curing duration may be decreased for some concrete mixtures as no apparent improvement was shown after a specific curing duration, which ranged from 2 to 8 days depending on the mix.