A More Concrete Enterprise

It wasn't until his grandfather Michael Rhodes died in 2002, at age 82, that David Rosenberg gave up his career as a competitive fencer and put his M.B.A. to work turning the scientist's invention into a bona fide business. "I wanted to carry on his legacy," says Rosenberg, 35.

Rhodes, who was a chemist by training, had devised a water-based liquid in 1994 that makes concrete waterproof. Called Hycrete, short for hydrophobic concrete, the substance is added to concrete before it dries. Hycrete is a modified water molecule that, once it dries, takes on the properties of oil in order to repel water.

Conventional waterproofing involves wrapping dry concrete in a layer of plastic or tarlike material; mixing in Hycrete takes just a few minutes. Not only does this speed construction, but it's also more eco-friendly. "Twelve percent of landfill is concrete," says Rosenberg, because regular waterproofing makes it difficult to recycle.

Hycrete-infused concrete can be broken down and reused as raw material (along with cement, water and sand) to make more concrete. The product has been used in everything from a birdbath at the Bronx Zoo to a fountain in the Seattle Olympic Sculpture Park. Although Rosenberg's fencing career was foiled, he admits that Grandpa would have been "extremely excited" to see his work come to fruition.