Recently completing a term as president of the ACI, Darwin has a doctorate in structural engineering. He is a professor at the University of Kansas in Lawrence, where he teaches courses in structural engineering materials, reinforced concrete, and prestressed concrete. But he is recognized by CC for his research in three areas: evaluating corrosion protection systems for steel reinforcing, bond strength between steel and concrete, and the reduction of cracking in concrete.
Given the state of the infrastructure, building more durable bridges is in the national interest. Nineteen state DOTs currently are involved with Darwin in a long-term study to find methods and materials to reduce cracking in bridge decks—the first defense against the corrosion of steel reinforcement. Currently more than 100 bridges owned by the Kansas DOT are being monitored, including 14 with new low-cracking, high-performance concrete decks.
Darwin helped design durable mixes and determine placing techniques for these projects. His team will continue to revisit the bridges to check deck cracking for several years after construction. He says one of the interesting things learned so far is that higher slump concretes, with or without admixtures, lead to increased cracking. Concretes with slumps of 2 to 3 inches resist cracking best, and also involve different placing and consolidation technology.
In addition, Darwin has been active in steel to concrete bond studies since the early 1980s and corrosion studies with the FHWA and other organizations since the late 1980s.
View other 2009 Most Influential honorees.