Stop Rutting in Its Tracks

High-performance-grade asphalt coud change the future of busy intersections

By Nick Fortuna

For many years, the main claim to fame for the West Texas city of Pecos was that it hosted the world’s first public rodeo on July 4, 1883.

But now, the city of 13,000 residents in the Permian Basin is making headlines for a different reason—an innovative project showcasing how high-performance-grade (HPG) asphalt binders can solve the problem of rutting at busy intersections.

This successful project figures to garner plenty of attention during a presentation at TXAPA’s 51st Annual Meeting in San Antonio from September 14–17. Clifton Kay, president of the TXAPA Board of Directors, whose company placed the HPG asphalt at that intersection, said he expects a full house for the event, with industry stakeholders eager to learn more.

“This project has been a home run and has really gotten people’s attention,” said Kay, division manager for Buffalo, Tex. based A.L. Helmcamp, Inc. “Attendees won’t be sneaking off to play golf during this presentation; that’s for sure.”

Kay will be speaking alongside Dr. Fujie Zhou, a senior research engineer at the Texas A&M Transportation Institute. With funding from the Texas Department of Transportation, Zhou’s research team designed and evaluated the asphalt mixes and HPG binders used at the Pecos intersection, which sees heavy traffic from trucks serving oilfield operations.

Zhou said traditional asphalt mixes typically perform well under free-flowing traffic traveling at regular speeds. However, at intersections with slowmoving or standing traffic, the same pavement structure with the same materials routinely buckles under the weight of heavy trucks.

Ruts deeper than two inches have been observed at multiple highway intersections, including those designed with premium mixes such as stone-matrix asphalt, a gap-graded asphalt mix known for its durability, Zhou said. Extensive rutting is a major safety concern for motorists and pedestrians because the depressions can collect rainwater, leading to hydroplaning when tires lose contact with the pavement.

At Texas intersections with standing truck traffic, deep rutting has occurred within one or two years of construction, an issue that’s exacerbated by long, hot summers, extreme weather conditions, and an increase in truck traffic.

Asphalt softens in extreme heat, and during the sultry Texas summer, pavement temperatures can exceed 140 degrees Fahrenheit, even when ambient temperatures are significantly lower. Under those conditions, asphalt binders lose stiffness, becoming more like a viscous material that can slowly displace under heavy loads.

Repairing rutting and shoving—another type of pavement distortion where traffic pushes the hot-mix asphalt layer toward the sides of the roadway—can cost millions of dollars and cause significant disruptions to motorists and local businesses. HPG asphalt offers an attractive solution, speeding up construction and making maintenance less frequent, Zhou said.

Zhou’s research team developed the HPG asphalt mix design for the Pecos project by subjecting samples to a tougher version of the Hamburg Wheel Tracking Test. That test evaluates the rutting resistance and moisture susceptibility of asphalt mixes by submerging compacted specimens in a 50-degree Celsius water bath and subjecting them to 20,000 passes of a 158-pound loaded steel wheel.

To ensure that the HPG asphalt mix would be even more durable, Zhou’s team increased the temperature of the water bath to 70 degrees Celsius, and the mixture aced the test, signaling that it was time for real-world asphalt placement.

A Streamlined Construction Process

The Pecos project involved placing HPG asphalt along a 0.21-mile stretch of U.S. 285 and a 0.25-mile section of Business Interstate 20-B in September 2025. The contractor divided the intersection into eight sections and completed the work in just nine days, with HPG asphalt allowing for full-depth placement of the hot-mix asphalt in one pass.

Kay said there were some raised eyebrows among A.L. Helmcamp’s experienced equipment operators when told that they’d be placing hot-mix asphalt at a depth of six inches on U.S. 285 and seven inches on BI 20-B in a single pass. Hot-mix asphalt typically is placed in lifts of two to three inches to optimize compaction.

If lifts are significantly thicker, the bottom layer may not compact suffi ciently before the top layer cools. Th ick lifts also are more likely to contain air voids that can allow for water infiltration and shorten pavement life.

Through polymer modification, the research team was able to create a mix design with HPG binders that are stiff enough to hold up to stationary truck traffic but still soft enough to avoid cracking at cooler temperatures, Zhou said. Thicklift paving—placing asphalt in a single layer that’s signifi cantly thicker than standard lifts enabled the crew to complete the work faster, minimizing disruptions for the traveling public and businesses situated along the thoroughfare.

“If you did this with conventional liquid asphalt, it probably would take twice as long, and it still wouldn’t stand up to truck traffic,” Kay said. “You really need highperformance-graded binders at these intersections. We fnally developed asphalt that will compete with concrete as far as rutting.

For construction crews, working with HPG asphalt requires only minor adjustments, Kay said. Since the product has a short shelf life, crews need to coordinate closely with the hot-mix asphalt plant to ensure that they order precisely the right amount for each shift, he said. Since the HPG binders can quickly degrade if stored at high temperatures, crews might end up discarding leftover HPG asphalt at the end of the shift.

Secondly, crews need to begin compaction immediately after placement because the material will cool off faster than conventional liquid asphalt, Kay said. Those minor process adjustments are among the pointers offered to contractors in a tip-sheet produced by the Asphalt Pavement EXchange (APEX), a collaboration of TxDOT and TXAPA, Kay added.

“You have to schedule your liquid deliveries precisely, and your paving crew needs to get on it quickly,” Kay said. “Those are really the only changes. For some of our operators, the process blew their minds because they had never laid that thick a lift of asphalt in their entire careers. It was really great to get in there and get out in such a short amount of time—just unreal.

A Quick Turnaround Time

One major benefit of using HPG asphalt is that roadways can be reopened to traffic as soon as the material has cooled, typically in just a few hours. Crews that perform work overnight or during off -peak hours can upgrade a busy roadway with minimal inconvenience to the traveling public, Kay said.

Had the construction crew used conventional concrete, which is common at high-traffic intersections, the project could have taken as long as 96 days, since each of the eight sections would have required about a week to cure, Kay said. Using fast-curing concrete could have reduced the timeline to about 72 days but would have added significantly to the project’s total cost, he said.

Kay performed a detailed analysis of the intersection project and found that using HPG asphalt cost only about 58 percent as much as using rigid pavement. “That doesn’t include the additional costs of project overhead due to additional time required to place concrete in lieu of asphalt,” he said.

One year after construction, the Pecos intersection shows no signs of rutting, illustrating the potential of HPG asphalt to become the preferred pavement solution for high-traffic intersections across Texas and the United States.

“We’ll have an employee go there every few months and lay down a straight edge, and he reports back that nothing has changed, and it looks great,” Kay said. “We’ve had zero rutting so far.”

Zhou said using highly modified binders like those in HPG asphalt costs more than conventional liquid asphalt, but if the surface holds up for 10 years, then maintenance costs will be greatly reduced. In addition, having to mill and repave major intersections every few years due to rutting significantly inconveniences local communities, so the increased durability of HPG asphalt is a major benefit.

Intersections that don’t experience rutting are safer for the traveling public, especially in wet weather conditions, Zhou said. Likewise, motorists may notice a smoother, quieter ride on HPG asphalt since they’re no longer traveling over concrete joints, which are responsible for the “ba-bump” sound commonly heard on concrete roadways.

“We needed a quick way to fix the problem of rutting at intersections, and using a durable, stiffer asphalt is a great solution,” Zhou said. “Surely, the experience and knowledge gained from the HPG asphalt intersection at Pecos will benefit other parts of Texas and beyond.