JEFFERSON CITY -- The Missouri Department of Transportation is embracing a new roadway technology called warm-mix asphalt that increases pavement life, is easier on the environment and saves money.
When resurfacing highways, MoDOT has traditionally used a type of asphalt that requires extremely high temperatures - 300 degrees Fahrenheit - to produce. With the new warm-mix asphalt, the temperature needed for production is reduced by up to 100 degrees. With the decreased production temperature comes lower emissions from burning fuels, fumes, and odors generated at the plant and at the paving site. Below is a sample of common emission reductions:
Carbon Dioxide (CO2) - 20% - 40%
Sulfur Dioxide (SO2) - 20% - 35%
Carbon Monoxide (CO) - 10% - 30%
Volatile Organic Compounds (VOC) - 50%
Nitrous Oxides (NOx) - 70%
Warm-mix asphalt lengthens a road's life as well. Lower asphalt production temperatures improve pavement density, which strengthens the pavement and prevents water from seeping in - the main culprit for potholes. The stronger the road, the longer it lasts, resulting in less money spent for repair or replacement work.
Cost-savings also occur when preparing the warm-mix asphalt for use. Because less energy is used to get warm-mix asphalt ready for the road, the average savings for taxpayers is 10 to 30 cents per ton compared to traditional hot-mix asphalt.
Warm-mix asphalt extends the work year, too. Traditionally, a paving schedule starts in April and ends in October. Because warm-mix asphalt works well in colder temperatures, it allows paving work to stretch from March through December.
MoDOT leaves the warm-mix option open to all contractors, many of whom have embraced the process due to the economic benefit. Roughly 500,000 tons of warm-mix asphalt was used on Missouri roads in 2009. Roadways that have been improved with warm-mix include I-44, I-55, I-70, U.S. 54, U.S. 65, U.S. 50, U.S. 71 and Missouri 291.
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