Messenger - Vol. 2, No. 3, Page 12 Summer 1993 On Research Civil engineers can shore up crumbling infrastructure with composites Pick up any newspaper in the mid-1990s and you can read about the crumbling infrastructure in America on one page and about our increasingly threatened environment on another. Although these issues may seem unrelated, composite materials research at the University is addressing both concerns. Composites are materials that combine two or more components to yield characteristics superior to any one of the individual constituents. Strong and lightweight, composites offer resistance to corrosion and chemical attack. They can be tailored to control heat expansion and vibration, and they can also be designed to be non-magnetic and non-conductive. All of these characteristics make composites useful to civil engineers for construction and infrastructure rehabilitation. Led by Associate Scientist Vistasp M. Karbhari, researchers at the University's Center for Composite Materials (CCM) are investigating ways to use composites to shore up cracking bridge columns or create a lighter concrete. Using concrete and steel to repair a degraded structure like a bridge deck can actually cause its collapse, and traditional repair methods usually require closing the structure to traffic. Rehabilitation using composites is potentially quick and can be done with the structures kept open. Karbhari's team is adopting several approaches. Crumbling concrete columns and piers can be wrapped with fiber-reinforced composites, a technique advanced by the Japanese. In this area, Karbhari's team has obtained good results with the use of a unique, resin-infusion process that results in performance improvements of as high as 100 percent. They have already shown that the use of combinations of two or more fiber types can offer capabilities beyond those of reinforced concrete and steel. In a project supported by the Delaware Department of Transportation, Karbhari and civil engineering colleagues are studying the use of composite plates to rehabilitate cracked bridge girders. And, in another project, members of the team are exploring the reuse of scrap composites in construction applications. "We may be able to solve two problems simultaneously-the waste disposal of composites as well as concrete deterioration and low performance," says Karbhari. Karbhari also is involved in plans to build a revolutionary bridge largely out of composites. "Although the initial costs may be higher, the overall costs can be reduced if we can lower maintenance needs through the use of composites. The light weight of the overall structure also decreases the need for expensive, specialized equipment." -Diane S. Kukich