Monday, April 12, 2010
Not too hot, not too cold... but just right. That's what many road paving crews and transportation officials think about a fairly-new road technology called warm-mix asphalt. I hadn't heard of the stuff until recently, and to be honest, I never aggressively investigated warm-mix asphalt either. What could have possibly changed in the asphalt world that would transform the way we think about paving roads?
I was quite impressed with what I found when I visited the latest warm-mix paving job in St. Louis. Turns out the asphalt world is spinning in a wonderful direction that lengthens a road’s life, helps the environment and saves money too.
When I arrived at the work site I immediately noticed the absence of pungent smells and odors created when paving work is traditionally done. Work zones involving asphalt are typically hot with thick emission-filled air ... this one wasn't. With 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.
I found out that using warm-mix asphalt helps extend the life of roads too. Lower temperatures during asphalt production allows for better pavement density, which determines the durability and strength of the road. Because warm-mix asphalt strengthens the pavement, it prevents water from seeping in – the main culprit for potholes!
MoDOT used about 500,000 tons of warm-mix asphalt on Missouri highways in 2009, which is about 13 percent of the total amount of asphalt used. I'm told these numbers will increase dramatically in the next five years. I hope so. Saving money and our environment, while keeping roads stronger for longer, just makes sense.