Mixing carbon fibers into concrete to make a beefier material isn't new. But research at the State University of New York at Buffalo has turned up a fresh reason for putting space-age fibers in concrete: They also add a dose of smarts, enabling buildings and bridges to warn of needed repairs.
In essence, the so-called smart concrete electrically groans when tiny cracks begin to develop. That's because the carbon fibers make the concrete 10 times as conductive as normal. Since even tiny cracks will affect this conductivity, and the change can be easily detected with standard electrical probes, repairs can be made on the cheap--before the cracks widen into visible fractures. Deborah D.L. Chung, head of materials research, estimates that a concrete mix with 0.2% fibers will boost costs by 20%. But this will be offset by lower maintenance costs, plus the need to use less material, since the fiber-reinforced concrete is stronger.