STARTING TO WARM : CONTRACTORS IN THE U.S. ARE BEGINNING TO APPLY NEW ASPHALT MIX

This article addresses new asphalt technologies that are collectively grouped as warm-mix asphalt. This asphalt, as opposed to hot-mix asphalt (HMA), provides lower production temperature that should result in not only lower emissions but also in lower fuel costs. The article specifically examines processes that have been developed in Europe: Aspha-min zeolite, Sasobit, WAM foam, and Evotherm. The studies on these asphalts found that they appear to reduce optimum asphalt content with a gyroscopic compactor. Studies also compared warm-asphalt mixtures to HMAs and found that high-temperature grade warm-asphalt mix should be bumped by one grade as the binder's short-term aging is reduced during construction. Additional tests were conducted by field trials using the same types of mixtures over a year time span. The article describes warm-mix as a successful new technology that is being used more frequently in the industry. It closes with a number of case-specific scenarios of the deployment of this technology, and contends that the lower temperatures it promises will be attractive if it is economically viable and its performance is comparable to HMA.