What are the three main technology categories used to produce WMA?

• A. Chemical, Foaming, and Wax
• B. Foaming, Wax, and Emulsions
• C. Chemical, Wax, and Emulsions
• D. Emulsions, Wax, and Foaming

Answer: (A)

Warm Mix Asphalt is produced by making the binder easier to handle at lower temperatures. The three main technology categories that achieve this are chemical additives, foaming, and wax.

Chemical additives are additives that modify the binder’s properties, lowering viscosity and improving coating and workability so the mix can be produced and placed at cooler temperatures.

Foaming works by injecting water into the hot asphalt binder to create a foam. This foam lowers the viscosity temporarily, allowing the mix to be produced and placed at reduced temperatures; the foam collapses as the water evaporates during mixing.

Wax additives introduce wax into the binder, which lowers viscosity during mixing and compaction. As the mixture cools, the wax crystals stiffen the binder, helping to resist deformation.

Emulsions are a different approach used in some asphalt applications, but they are not counted among the three main WMA technologies for reducing viscosity in the hot-m mix process.