Warm-mix asphalt hailed as industry trend

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Print this page by Heather B. Hayes

The difference between hot-mix and warm-mix asphalt is only 50 to 75 degrees. Nonetheless, that temperature gap results in a more environmentally friendly process, say officials from Williamsburg-based Branscome Inc. The highway and general contracting company recently completed its first major project in Hampton Roads using warm-mix asphalt. City officials from Portsmouth, Norfolk and Virginia Beach stopped by to observe as the company paved a secondary Portsmouth street.

“In five years, this is probably going to be the standard,” says Rob Sinclair, Branscome’s marketing manager, noting that the company has already made a switch to 100 percent warm-mix asphalt at its Hampton plant. “We decided to go ahead and make the investment necessary to get out in front of this trend.”

The key benefit of warm-mix asphalt is environmental, he explains.  Hot-mix asphalt must be heated to more than 300 degrees to keep it flexible enough for paving. The warm-mix process, by contrast, relies on lower temperatures and a water-based foaming system to expand volume and keep the asphalt soft and pliable for a longer period of time. The lower temperature results in less fuel used in the heating process and a major reduction in other harmful emissions.

“Normally, when you make asphalt, there’s this blue smoke that comes off of it when it’s coming out of the trucks and going into the paver,” Sinclair notes. “Warm-mix asphalt completely eliminates that.  You don’t see any smoke at all.”

Warm-mix asphalt offers other benefits as well, he says. Because it stays flexible longer, the asphalt can be transported farther to job sites without danger of it hardening on the way. Warm-mix asphalt also holds up better in the cold. That means construction crews can work more days during the winter.

There is no difference in the end product, however, Sinclair says. Warm-mix asphalt has the same compaction rate and density as the hot-mix kind, and construction crews can use the same road-building equipment.

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