This bridge rehabilitation, undertaken by University researchers from the Department of Civil Engineering in conjunction with the Center for Composite Materials, is one of the first of its kind in the United States. We had to find out why bridge damage was occurring and stop the cracks from spreading while reinforcing the existing structures. An examination of the structures, referred to as box beam bridges, led researchers to conclude that the problem centered in the original design of the beams, which made them susceptible to water damage. According to Chajes, water gets into hollow areas, or voids, which run the entire length of the beam. Once inside, the water is subject to periods of freezing and thawing, which can, over time, cause concrete to crack.
Water also can cause the steel reinforcing strands in the beams to corrode.
This corrosion causes the steel to expand, which also can cause the beams to crack. Because of the way these beams are reinforced, there is nothing to protect against the spreading of these cracks and the weakening of the structure. It's not just a matter of replacing a single beam. The researchers have identified about 30 bridges of this type in Delaware. A bridge on Foulk Road, just north of the Naamans Road intersection in northern New Castle County, provided Chajes and his team with the opportunity to conduct the first practical application of this reinforcing process.