Minimizing cracking on concrete bridge decks is key to a long service life. Cracks provide a direct path for water and other ions to the interior of the concrete and the reinforcing steel of the structure. Over time, this can jeopardize the structural integrity of the bridge and require unplanned maintenance to address the cracking. A bridge’s service life can be reduced by up to 50 percent depending on the depth and width of the cracking.
A primary cause of early age cracking is shrinkage, which occurs during the curing process as water in the pores of the concrete is lost. Notably, some shrinkage occurs independent of any exterior environmental conditions, so even rigorous application of external curing won’t fully prevent it. This can be amplified in concrete mixtures optimized for durability. One solution is to create an internal reservoir of water for curing that prevents shrinkage by using internally cured concrete (ICC).
Federal Lands Highway (FLH) has demonstrated this proven technology to be an effective tool to reduce shrinkage. Some of FLH’s successes with this technology are described in this tech brief, which evaluated ICC on three projects in Idaho and Georgia. After more than two- and a-half years in service, the featured bridge decks with ICC showed little, if any, cracking. In fact, during that survey, only 10 linear feet of shrinkage cracking was visible on approximately 43,000 square feet of bridge decking.
Implementing ICC also required only minimal modifications to standard contract language and the cost increase was only approximately $100 per cubic yard of concrete. On the two projects where this cost was calculated, this represented an average overall project cost increase of 0.7 percent.
This small investment in a material upgrade can result in major returns on investment through reduced maintenance over the bridge deck’s lifecycle.
To learn more about how your agency can benefit from or implement ICC, visit the enhancing performance with internally cured concrete (EPIC²) team’s webpage. Subscribe to EPIC² email updates to stay informed, or contact Tim Barrett, FHWA Turner-Fairbank Highway Research Center, or Mike Praul, FHWA Office of Infrastructure.