It’s been cold lately.
But the cold doesn’t bother road engineers — in fact, they welcome it and wouldn’t mind the temperature staying below freezing through the spring thaw.
Yankton Public Works Director Adam Haberman told the Press & Dakotan that it’s preferable to have long stretches of cold to preserve roads during the winter.
“The cold weather is better if it remains constant because you don’t have all of the expansion and contraction in the pavement,” he said. “With the expansion and contraction, you can get pavement cracking. If moisture gets into those cracks, it expands when it gets colder and can cause potholes and damage to the pavement.”
He added that movement is the enemy of roads.
“Less freeze-thaw cycles means you’d have less pavement contraction and expansion and movement,” he said. “The movement is what damages the pavement.”
Rod Gall, Yankton area engineer with the South Dakota Department of Transportation (SDDOT), said this moisture problem exists along the state’s highway system as well, due to the jointed nature of the roadways.
“Once it gets cold, the pavement contracts, and they all have joints in them — or cracks,” he said. “These cracks get wider and the joints get wider. It lets moisture in. If it stays cold and doesn’t melt, that’s OK, but when you get up-and-down temperatures and you get a thaw cycle, the moisture that thaws from the snow gets into these cracks if they’re not sealed properly. When it freezes again, it puts a lot of pressure on the pavement, something has to give and usually it’s the pavement that gives.”
If the road is constantly freezing and thawing, it can lead to spalling — a breakup of the pavement.
He added that in extreme cases, this can mimic the buckling witnessed on roadways during bouts of extreme heat.
“Once these cracks don’t have joint sealant in them, what gets in there is gravel,” he said. “When they start expanding, something has to give, and it’s usually right at the joint and it goes upward.”
Gall said road crews are able to help stave off some spalling with preemptive measures.
“In the winter time, there’s not a lot you can do about it,” he said. “The thing you can do is in the summer time or in the fall, put crack sealant in these cracks or the joints,” he said. “If it’s working properly, the material in the crack will expand enough so that it won’t let the moisture get into it. If we can keep the moisture out of it, we won’t have a problem with spalling.
He added the department has a few remedies come springtime for roads that have been damaged by freeze-thaw cycles.
“In the spring, you’ve got to wait until all of the frost goes out,” he said. “If you do have spall areas, you can get some asphalt and throw it in the hole. If you have a lot of it, you might have to put a patch over the top of it.”
Perhaps to the chagrin of road crews hoping for constant cold, another period of warmer temperatures is expected later next week.
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