Evaluation of Historic Reinforced Concrete Bridges

The procedures used to evaluate seven historic reinforced concrete bridges in different regions of the United States are discussed. Constructed between 1907 and 1938, three of the bridges have soil infill above arched vaults, three are open spandrel arch structures, and the seventh is a continuous span structure in the states of Nevada, Indiana, Rhode Island, Washington and Pennsylvania. A combination of visual inspection, nondestructive methods and coring followed by laboratory testing was used in all cases. Advanced NDT methods were used to maximize information obtained, while minimizing invasive investigation and disruption to bridge operations. Laboratory testing addressed such topics as the extent of deterioration and chloride concentration in the concrete, as well as identification of aggregates and cement constituents, so repair concrete could be developed to match existing. These cost-effective programs provided vital structural and material information necessary for successful rehabilitation.