Montana DOT choses asphalt modifier for reduced road maintenance costs
In Montana, where winter temperatures may drop to minus 40 degrees F, while summer highs top 105 degrees F, maintaining the state's highway system is a challenge.
"With this kind of extreme temperature cycling, we have an ongoing battle trying to keep our highways driveable," says George Friez, an estimating engineer with Gilman Construction, Butte, Mont., a paving contractor for the State of Montana.
"Although asphalt can be made softer and more flexible to accommodate a road's expansion and contraction during freeze-thaw cycles," says Friez, "the softer oil makes it prone to rutting in hot weather. And if the asphalt is formulated harder to resist rutting, it's prone to cracking in cold weather. Either way, you're looking at a substantial amount of ongoing road maintenance."
In the mid-1990s, Montana first used Elvaloy® RET asphalt modifier to help handle the temperature extremes. A project at Deer Lodge showed reduced temperature cracking, and led to further specification for Highway 83 north and south of Condon, Montana.
According to Gilman's Friez, improved binder is especially useful in Montana: "If the long-term economics prove as convincing as the visual evidence we're seeing today, I think PMAs will become the standard material, particularly for heavy traffic areas, and for states like Montana with broad temperature swings. From what we're seeing, PMAs give the public a lot better roadway for the money."