Field Performance of Modified Asphalt Binders Evaluated with Superpave Test Methods: I-80 Test Project

In the early 1980s heavy-duty pavements in Pennsylvania showed evidence of excessive rutting. As a consequence, the Pennsylvania Department of Transportation adopted several changes in its materials specifications and mixture design procedures. In addition, a number of modified binders were evaluated in an experimental test road that was constructed in 1989 in Clearfield County on Interstate 80. The construction was a 175-mm thick asphalt concrete overlay over an existing portland cement concrete pavement. Although the construction predated Superpave, original samples of the asphalt binder and loose asphalt mix were retained and were characterized using Superpave test methods. Field performance evaluations were performed immediately after construction and in subsequent years, giving a record of rutting, cracking, raveling, and overall visual performance. Overall, the mixtures have performed well during their 9 years of service. However, differences in the performance of the mixtures with the different binders are evident. These differences are related to the properties of the binder and the properties of the mixture as measured with the Superpave mixture and binder tests.