Whitetopping, placing a concrete overlay on deteriorated asphalt pavements, is Iowa's solution to higher maintenance costs. Since 1960, Iowa counties have whitetopped more than 300 miles of asphalt pavement, eliminating potholes, cracks, raveling and rutting surfaces, and loose gravel.
Iowa is a national leader in the use of portland cement concrete for paving, dating back as far as 1918. The Iowa Concrete Paving Association has detailed records documenting outstanding performance of 6- and 7-inch-thick plain, concrete pavements. Many Iowa pavements 30 years or older have required only minimal maintenance.
Acknowledging the historical performance of Iowa's concrete pavements, engineers began to examine the recurring costs of maintaining and resurfacing Iowa's existing asphalt roadways at typical 12- to 15-year intervals. Cost comparisons of concrete and asphalt overlays showed that a 5- or 6-inch-thick concrete overlay might cost up to 50% more initially than a 2- or 3- inch asphalt overlay, but the concrete would last at least twice as long as asphalt with little difference in maintenance costs. Life-cycle analysis, supported by actual concrete pavement performance records, proved that concrete was the "best buy."