NAtioNAl CooperAtive HigHwAy reseArCH progrAm

TLDR

Warm mix asphalt (WMA) has gained acceptance in the U.S. and Canada, with state DOTs conducting demonstrations to evaluate its constructibility and environmental benefits, and now over 25 commercial technologies exist, though most states require well‑documented demo projects for approval.

Abstract

INTROdu CTION Warm mix asphalt (WMA) has been gaining acceptance across the United States and Canada in recent years. A large number of state departments of transportation (DOTs) have hosted WMA demonstrations to determine if WMA should be allowed for state-funded paving projects. These demonstrations have shown that WMA is constructible and can reduce fuel usage and emissions associated with hot mix asphalt (HMA) production. However, many of these demonstrations were conducted with only one or two WMA technologies. Now there are over 25 commercially available WMA technologies in the United States. Most states do not approve a WMA technology for use on state-maintained roads without a welldocumented demonstration project. The WMA technology suppliers that were not part of these early demonstration projects often are required to organize a demonstration on their own to gain approval for state paving projects. A standard evaluation program for con