Paving

County engineers visit one of the test strips at the National Center for Asphalt Technology in Lee County.

Millions of miles of testing in nearby Lee County will lead to Elmore County making millions of dollars of paving material last longer on its streets, roads and highways.

Elmore County, which is responsible for 1,000 miles of roads, according to the Association of County Commissions of Alabama, is expected to receive $1.22 million each year in Rebuild Alabama funds from the gas tax increase passed earlier this year, county engineer Richie Beyer said.

To make the most of those taxpayer dollars, Beyer said Elmore County hopes to follow a roadmap drawn by the National Center for Asphalt Technology in Auburn, which researches wear and tear on paving materials.

The NCAT conducts continual tests of experimental asphalt pavements on its 1.7-mile oval. Highway agencies and industry sponsors fund the research in 200-foot test sections. It started testing in 2000 with what is called a research cycle and 1.4 million miles were driven over its surfaces in the previous cycle from 2015-18. Five trucks weighing an average of 156,995 pounds apiece were simultaneously driven.

“They have a two-lane test track with truck traffic going 24/7,” Beyer said. “They hire truck drivers to do nothing but run it. It is segmented and several states pay for research to be done. They use sensors in the ground to show the stresses.”

Counties benefit by seeing the results of testing on the oval instead of failure on actual roads.

“A lot of good research is being done over there,” Beyer said. “Instead of waiting 15 years to see what will happen, we can see it a lot quicker. They’ve got test strips down for six or seven years that mimic 20 years of wear. We want to get the most out of the revenue we’re fortunate to be getting. We listen to their research, what’s working well, and we can integrate that into the mixes we’re using.”

Beyer said NCAT has innovated ways to reuse asphalt and find ways to utilize materials native and readily available to an area.

“They come up with their own design and use local materials to keep the cost down,” he said. “They find a way to use recycled asphalt milled off a road. The key for them is they can mimic that traffic load and what would take years for us to see is done much quicker and the feedback goes to county engineers and elected officials.”

Beyer said he hopes what has been learned at NCAT can be integrated into Elmore County’s roads, streets highways in the next year to 18 months.

“We have some five- and six-year-old roads that look like they’re 20 years old,” he said. “Most counties don’t have the heavy, repetitive loads you see on an interstate. Those use drier, stiffer mixes. They have less liquid asphalt in them and they become more brittle quicker. Using that on a county road, they don’t hold up as well. Our bases are a little more flexible. We’ve talked to them about our base mixes with more of the liquid asphalt in it. We need it to be more forgiving.”

Elmore County has largely practiced preventive maintenance in the last decade.

“We do a lot of microsurfacing,” Beyer said. “It’s a way to seal off the older layers and retain the life of them. When drier mixes get older, this is a way to extend their life. It costs a third to a quarter of traditional asphalt overlay and you get another seven to 10 years out of it, depending on traffic. Traditional asphalt overlay lasts 10 to 15 years. If you can catch (a road) while it’s good, you can maximize the use of resources.”

Beyer said earlier this year 164 miles of roads and streets in Elmore County grade below a 79.

“That means you’re getting more into the rehabilitation of the roadway, which is more expensive,” he said. “People start having an uncomfortable ride on that kind of road. Their front ends get knocked out due to potholes.”