Optimizing Asphalt Mixture Designs for Low-Volume Roads of Minnesota

Project summary:

Minnesota has a large number of low-volume asphalt roads. These roads typically fail because of environmental factors, such as frigid temperatures, freeze-thaw cycles, and seasonal and daily temperature variations. The goal of this project was to suggest modifications to asphalt mixture designs currently used for low-volume roads in Minnesota to improve the resistance of the mixes against the environmentally driven distresses. The project was conducted by accomplishing multiple tasks, such as a literature review; online survey; fieldwork studying the cause of the asphalt pavement distresses; laboratory work comparing asphalt mixtures designed with Superpave-4, Superpave-5, and regressed air voids methods; and studying the field compaction of Superpave-5 mixes. The mechanical performance of the asphalt mixes was studied by conducting disc-shaped compact tension (DCT), indirect tensile strength (ITS), and dynamic modulus (DM) tests. The project included both laboratory- and plant-produced mixes. The project found that asphalt layers for the low-volume roads did not get enough densification, which augments environmentally driven distresses, such as thermal cracks, and longitudinal joint cracks. The Superpave-5 method holds considerable promise for the design of asphalt mixtures for low-volume roads in Minnesota, which may likely increase the asphalt layer densification and mitigate some of the common distresses.