As our nation’s highways age, the quest is on to find a magic pavement solution which lasts longer than 20 years.

Ohio’s Dept. of Transportation has embarked on an experiment. An 8-mile four-lane highway segment scheduled to open in 2005 is being paved with two different mediums - one direction gets concrete (4" crushed aggregate, then 3" hot-mix asphalt, and topped with 10" of unreinforced cement concrete) and the other gets 16" of asphalt over a 6 inch aggregate base. Monitoring instruments buried inside will show interior changes.

Meanwhile Arizona’s DOT is spending $34 million to overlay 115 mi. of roads with rubberized asphalt. The original intent was to reduce cracking and extend useful life (it’s estimated to extend it 30 – 50%), but they have discovered that the rubberized asphalt also cuts road noise levels from 50 to 90 percent, which makes it very popular with drivers as well.

More than 4.2 million tons of rubberized asphalt have been used on Arizona highways. Those projects have resulted in the recycling of about 15 million old tires. Typical mixes generally contain 20 percent rubber with approximately 1,500 tires used for every lane-mile of paving. Studies are being initiated to see if it also has a positive effect on gas mileage.

 

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