NAtioNAl CooperAtive HigHwAy reseArCH progrAm

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…