Infrastructure repair efforts are far from limited to rebuilding a collapsed bridge like the Brisbane Riverwalk – in fact, these efforts are often needed to prevent bridges from collapsing. The American Society of Civil Engineers’ 2013 Report Card for America’s Infrastructure gave the United States an overall GPA of D+, with the bridges category earning a C+. While the U.S. has made strides to repair deficient bridges, with commuters making more than 200 million trips daily across crumbling bridges in the U.S.’s 102 largest metropolitan regions, there is still an urgent need to fix them.
The report rates one in nine of the nation’s bridges as structurally deficient, accounting for one-third of the total bridge decking area in the U.S. These aging bridges naturally pose a public safety risk, but also can cause congestion and require emergency vehicles and trucks to take detours. If the bridges cannot support the weight of a delivery truck, the truck must find a new route, making it more difficult and costly to bring goods to the market.
Corrosion is a major culprit for potential bridge failures, but wildlife can be a concern as well. Timber bridge piles in the Hudson River around Manhattan were unaffected by wildlife for years when the river was too polluted to support life. But a cleaner river, while great for the environment, unfortunately can lead to greater structural risks. “Thanks to the Environmental Protection Agency’s success in cleaning the waterways, marine life has come back [to the Hudson River], but they are eating these timber piles at alarming rates,” notes Mo Ehsani, president of QuakeWrap. The company offers a repair system using FRP jackets that strengthen bridge piles.
The need for infrastructure repair presents numerous opportunities for composites while still allowing for a robust ecosystem. Structural engineers from the U.S. Army Corps of Engineers (USACE) and professors and graduate students from West Virginia University’s Constructed Facilities Center (CFC) put composite repair methods to work recently in West Virginia. The CFC used two semi-circle shaped GFRP composite shells with a tongue-groove joint to encase corroded steel columns on the East Fork Bridge of East Lynn, W.Va. They sealed the bottom of the shells with special epoxy concrete to block water from coming up and pumped in self-consolidated concrete. The team finished the repairs within three weeks.
Composite repair methods can apply more than just quick fixes. Ehsani says composite shells can not only strengthen bridge piles, but can also prevent both future corrosion and wildlife damage by sealing out oxygen and moisture. This means less spent on infrastructure repairs in the future and less backlog of bridges needing repairs.