Major airports usually pave runways, taxiways, and other important areas with concrete, but general aviation airports generally use asphalt. This makes them excellent candidates for whitetopping. Most runway surfaces need 5 or 6 inches of concrete. Marketing concrete to airports is essential since many airport boards do not know the benefits of concrete. In order to take advantage of this market, make contact with local aviation officials and consulting engineers, and educate them about the benefits of concrete.