What is Warm Mix Asphalt?

Warm mix asphalt (abbreviated as WMA) refers to a range of technologies designed to reduce the asphalt binder’s viscosity (Abbas and Ali, 2011). The decrease in viscosity allows asphalt–aggregate mixes to be produced at lower mixing and workable temperatures as low as 90°C, hence lowering energy consumption and pollutants emitted throughout asphalt mix manufacturing and placement. WMA methods reduce the viscosity of asphalt binders by adding organic or chemical additives or by inserting cold water into hot molten asphalt under regulated temperature and pressure settings, resulting in a substance known as a foamed asphalt binder. In many states and countries, construction jobs are becoming more interested in the second method because it doesn’t require expensive chemicals.

Warm mix asphalt production is straightforward and requires no substantial changes to the hot-mix plant system. WMA contains patented chemicals with diverse production processes. The processes include:

  • A fine powder is added in one production technique, releasing its hydration-bound water and foams the asphalt binder when heated. The lubricant keeps the mix workable at 130–140°C.
  • Warm mix asphalt manufacturing is done in two stages. In the first stage, a mild asphalt binder is applied to 100-120°C aggregate. A more rigid asphalt binder is applied to the pre-coated aggregates as powder, foam, or emulsion in the second stage. At 80-90°C, the finished mixture may be compressed.
  • In another approach, organic compounds that melt at 100°C are combined with the asphalt binder to modify its viscosity-temperature behavior. For any given construction jobs, the combination is workable at 90°C.

Warm mix asphalt has additional advantages, such as:

  • VOC (volatile organic compound) emissions at mix facilities are lower when warm mix asphalt is made at low temperatures.
  • When used in construction jobs, workers’ exposure to fumes is reduced by using warm mix asphalt.
  • Burn risks are reduced because of the lower construction temperatures.
  • Because it compresses more easily, WMA is better for stiff mixes and blends with RAP and reduces the number of roller passes needed in construction jobs.
  • Less fuel is used when warm mix asphalt is produced and placed.
  • It is possible to build in remote places with lower temperatures, more extended workability, and more flexible transit schedules.

Warm mix asphalt is a unique and valuable solution to explore for your next construction jobs, from healthier working conditions to absolute performance. Our professional consultants are here to answer any questions you might have. To get in touch with a Kilgore representative, click here for a free online quotation.