Field Performance of Warm-Mix Asphalt at National Center for Asphalt Technology Test Track

TLDR

The study evaluated the incorporation of Evotherm into warm‑mix asphalt (WMA) blends on the National Center for Asphalt Technology Test Track. WMA mixes produced by an emulsion process were applied as surface layers in two track sections and subjected to accelerated loading in three total sections. In‑place densities of the WMA layers matched or exceeded those of hot‑mix asphalt even with compaction temperatures lowered by 8 °C, laboratory rutting tests showed comparable performance, but moisture‑damage susceptibility was higher; field testing after 515,333 equivalent single‑axle loads demonstrated excellent rutting resistance and quick‑turnover sections performed well.

Abstract

Warm-mix asphalt (WMA) mixes produced by an emulsion process were evaluated under accelerated loading in three total sections of the National Center for Asphalt Technology Test Track and used as the surface mix for two of the sections. Evotherm was incorporated into the same mixes used previously on the track. In-place densities of the WMA surface layers were equal to or better than the hot-mix asphalt (HMA) surface layers, even when compaction temperatures were reduced by 8°C to 42°C (15°F to 75°F). Laboratory rutting-susceptibility tests conducted in the asphalt pavement analyzer indicated similar performance for the WMA and HMA surface mixes with the PG 67-22 base asphalt. However, laboratory tests indicated an increased potential for moisture damage with the WMA mixes. The two WMA sections and the HMA section showed excellent rutting performance in the field after the application of 515,333 equivalent single-axle loads in a 43-day period. One of the WMA sections was also evaluated for quick turnover to traffic and showed good performance.