Lehman-Roberts Co. test drives warm mix asphalt

After completing the project, Lehman-Roberts took a core sample of the warm mix asphalt and ran tests to compare those results against the hot mix control sample’s tests results taken from the airport application.

The warm mix design posted nearly identical results for AC content, gradation, theoretical gravity, bulk-specific gravity and air voids. Nuclear densities ranged from 91 to 94 percent for the warm mix, slightly less than the densities achieved at the airport, but Nelson expected this due to poor subbase conditions.

The warm mix design actually outperformed the control hot mix sample in the rut tests.

Overall, Lehman-Roberts was very pleased with these initial results.

“Aesthetically, there was no noticeable difference, and the mix remained very workable for a long period of time despite the cold ambient temperatures,” Nelson says. “The results from this one test showed the warm mix asphalt is at least as good as, if not better than the ‘normal’ mix.”