Toward A Greener Blacktop
When it comes to greening America's transportation system, most people focus on cars - producing their fuel differently, using different forms of energy, or shifting commutes away from them entirely. But what of the roads we drive on?
Asphalt, which is used to pave over 90 percent of American roads, is processed in Western countries through a process requiring the tar-like substance to be heated to 300 degrees Fahrenheit, an energy-intensive procedure that also produces carbon emissions. In less wealthy parts of the world, though, a "cold mix" approach has long been used; the asphalt isn't heated, but is sheared into fine particles and mixed with water and surfactants so it can be spread across a road's surface until it hardens.
Now a researcher at the University of Wisconsin-Madison, Dr. Hussain Bahia, intends to adapt these African and Indian techniques - developed by road-builders who couldn't afford to heat asphalt to make it pliable - for use here. Under the auspices of the Asphalt Research Consortium (a group working with the Federal Highway Administration to improve road-surface performance), he has established a Modified Asphalt Research Center with the goal of improving asphalt in various ways by developing cold mixtures that blend polymers or plastics with crude oil-derived asphalt.
A prerequisite to such innovation, though - and to the acceptance of cold-mix asphalt here - is the development of solid laboratory tests to evaluate each new mixture's safety and durability. Bahia's team is at work now developing the tests and standards that will allow American engineers and chemists to weigh greener asphalt against conventional mixes.
He sums up his mission, which recently received $5 million in funding, this way: "Why are we spending so much money on something [other than cold-mix]? I think there's a very good reason: lack of sufficient knowledge. And our job as a university is to provide the knowledge that will hopefully one day get us there."