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
     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
     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