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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.
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