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...