Building better bridges

Civil engineers at Purdue University are developing a new generation of bridges that will contain corrosion-resistant plastic bars reinforced with glass or carbon fibres, promising to double the number of years between expensive repairs.

Concrete-strengthening steel bars called “rebar,” currently used in bridges, are susceptible to corrosion, especially in the “deck,” which is the uppermost portion of the bridge that serves as the riding surface. The rebar embedded in bridge-deck concrete is exposed to de-icing road salt that seeps through cracks in the pavement, said Robert Frosch, an associate professor of civil engineering.

“Bridge decks generally have to be replaced every 20 or 30 years, which is very expensive, but replacing the rebar with bars made out of fibre-reinforced polymers could extend the lifetime of a deck to perhaps 50 to 100 years,” Frosch said.

Purdue civil engineers have installed a bridge deck containing the fibre-reinforced polymer bars in a span over Interstate 65 at Thayer Road near Demotte, Ind. It is the first fibre-reinforced polymer-bar bridge deck ever installed in an Indiana bridge.