Researcher using nanoclays to build better asphalt
Long before freeways and parking lots, a naturally occurring asphalt first appeared on roads in about 600 B.C. You can still see patches of it in the ancient city of Babylon.
Under the onslaught of 21st century traffic, modern asphalt isn鈥檛 likely to hold up for anywhere near 2,700 years. But at Michigan Technological University, Zhanping You is paving the way for brand-new asphalt blends to fight off cracks, rutting and potholes.
His work has drawn so much attention that one of his papers made SciVerse ScienceDirect鈥檚 Top 25 Hottest Articles of 2011 for the journal Construction and Building Materials.
鈥淣anoclay-Modified Asphalt Materials: Preparation and Characterization鈥� reviews recent literature on asphalt that has been doctored with nanomaterials. It also presents new discoveries from You鈥檚 team suggesting that adding nanoclays to asphalt materials could make for safer, longer-lasting roadways.
鈥淎sphalt is now made from petroleum, so it鈥檚 very expensive,鈥� said You, an associate professor of civil and environmental engineering. 鈥淎s a result, a lot of people are looking at ways to make it more durable.鈥�
Heat, cold and stress in the form of traffic take their toll on asphalt pavement, made from a mix of asphalt and aggregates like gravel. That leads to cracks, potholes and a process called rutting. Ruts are most likely to form on busy roads, sections with slow traffic, and areas with stop signs and stoplights, where the rubber hits the road hard thousands of times a day.
鈥淩utting can be very dangerous, especially in snow and ice,鈥� You said. 鈥淚f we could use advanced materials to reduce rutting, that would be very beneficial to the public.鈥�
You鈥檚 team tested two types of nanoclays, adding 2鈥�4 percent by weight to the asphalt. That鈥檚 a smidgeon--less than half of a percent of the total weight of the asphalt pavement itself. But it made a big difference.
鈥淚t improved the viscosity significantly,鈥� You said. 鈥淭hat means it will provide better stiffness, which means that it won鈥檛 deform as much in hot weather or under heavy traffic.鈥�
They don鈥檛 yet know if nanoclay can help asphalt resist cracking in cold weather or under heavy loads, since their testing isn鈥檛 completed. 鈥淏ut it is always our goal to develop new asphalt mixtures with those qualities,鈥� You said.
His lab is also testing how other nanomaterials, including nano-silica and nano-composites, will affect asphalt durability.
Provided by Michigan Technological University
