City Streets

The first concrete street built in the United States was an 8 ft (2.4 m) wide strip of Main Street completed in 1891 in Bellefontaine, Ohio. Local residents were so pleased with the artificial stone road, scored to provide better footing for horses, that much of downtown Bellefontaine was paved with concrete several years later.

Many municipalities today choose concrete pavement because of its reputation for long-term serviceability and a sense that it provides better value for the investment. Although concrete's initial cost may be from 10% to 20% higher than the cost of asphalt, maintenance costs are generally lower. A 10-year survey concluded in the mid-1980s of 2,000 miles (3200 km) of municipal streets in Kansas revealed that asphalt pavement was nine times as expensive to maintain as concrete.

Aesthetic considerations, coupled with concrete's ability to reflect light and heat, have made it the paving material of choice for many cities. Because of its light color, concrete reflects from 33% to 50% more light than asphalt. As a result, cities can achieve the same street lighting standard, satisfying American National Standards Institute criteria, with a lower initial investment in lighting fixtures and equipment, and, as well, can sustain considerably lower long-term energy costs.

Fast- track paving techniques, in which the use of a high-early-strength concrete mix allows the road to reopen in as few as 12 hours, have increased the attractiveness of concrete for city street paving because of the inconvenience of closing busy urban routes.

New Technology
Ultra-thin whitetopping (UTW) is a concrete technology, first used in 1991, that many engineers believe holds promise for cost effective rehabilitation of aging urban asphalt paving. Like conventional whitetopping, used in the United States since 1918, the process involves overlaying a stratum of concrete on top of an asphalt road that needs rehabilitation because of rutting, shoving, or other types of deterioration. While conventional whitetopping requires a concrete thickness of 5 to 7 in. (12.7 to 18 cm) on secondary roads, and from 8 to 12 in. (20 to 30 cm) on primary roads, ultra-thin whitetopping requires a thickness of only 2 to 4 in. (5 to 10 cm)

Early test results indicate that the thinner layer of high-strength, fiber-reinforced concrete performs adequately because the concrete creates a structural bond with the prepared surface of the asphalt below. It becomes, in essence, a composite pavement. Joints are spaced closer together than with conventional concrete pavement, usually about 12 to 18 in. (30 to 40 cm) apart for each inch of concrete depth. This helps ensure the bond between the concrete and asphalt below, especially in freeze/thaw conditions where differential movement of the two materials would be anticipated. Although further long-term research needs to be done on the technology, ultra-thin whitetopping could be valuable for rehabilitating high-traffic city streets and intersections.