Optimizing Asphalt Mixture Designs for Low-Volume Roads of Minnesota

Project summary:

The state of Minnesota has a large number of low-volume asphalt roads. As the traffic volumes of these roads are usually low, the pavement failure is typically not traffic load-related, rather mostly driven by environmental factors such as oxidation, freeze-thaw, and seasonal and daily temperature variations. These environmental factors create block cracking, moisture damage, thermal cracking (transverse cracking), and potholes in low-volume roads. Ironically, the asphalt mixtures for such low-volume roads are usually designed based on a procedure that was actually developed for high-volume roads which fails by load-related distresses (e.g., rutting and fatigue cracking).

The objective of this proposed research study is to develop a mixture design guideline for producing durable asphalt mixtures for the low-volume roads of Minnesota. The study includes several tasks, such as (i) a literature search and an online survey to gather information on the existing mixture design practices of Minnesota and other nearby cold-climate states, (ii) a distress survey on a few selected low-volume roads and collection of field cores to understand typical distresses and field densification of asphalt in the low-volume roads, (iii) design and performance testing of various asphalt mixtures, and (iv) development of a guideline on asphalt mixture design for low-volume roads. The study will propose a "go-to" mixture design and a recommendation will be made on the range of minimum effective binder content (Pbe).