Mitigation of Alkali-Silica Reaction in the Bibb Graves Bridge

Abstract

The Bibb Graves Bridge in Wetumpka, AL has severe damage due to alkali-silica reaction (ASR) in two of its reinforced concrete arches. A mitigation procedure developed in the summer of 2010 by the FHWA, ALDOT, and Auburn University was implemented during the fall of 2010. The mitigation procedure included the application of a silane sealant, flexible sealant in the large cracks, and an epoxy flood coat to fill the small cracks on the tops of the arches. For this research, the internal relative humidity and external concrete strains in the aches of span 4 and 5 were monitored and analyzed to determine the effectiveness of the ASR mitigation procedure. Additionally, time frames in which results from the ASR mitigation procedure may be seen were determined through analytical methods. It was found that over the 18-month data collection period, the ASR mitigation procedure was not effective at lowering the relative humidity to a level such that ASR expansion slowed.