Asphalt Could Go Green
It turns out that the pavement is greener on the other side of the world. Here's an article about cold-mix asphalt - something that has been used extensively for some time in South Africa and may some day be used in North America:
"At U.S. refineries today, there are very mature, establishedspecifications for hot binders - our paving grade asphalts," he said ina statement this week. "But for emulsions, there is no clear agreementon how to define the quality. So, we have emulsions already, but wedon't produce them as much because the specifications aren't as clear."
Bahia plans to experiment with adding polymers or plastics to thecold-mix process to make pavement more durable, safer and even quieter.
The big question: Why didn't the United States switch to cold mixeslong ago? We haven't had to, Bahia said, because we've long had awealth of resources that supported the less efficient hot-mix approach.
"In South Africa, they initially decided to go with the low-energyapproach because it can save a lot of money," says Bahia. "Then astheir economy grew, they had to build high-performance roads. Butinstead of switching to hot mixes, they improved their knowledge tobuild better cold mixes."