Institute for Transportation

About the research

The overall pavement condition of Iowa’s highway network has been deteriorating in the past decade due to aging facilities, increasing traffic, and lack of financial resources. Due to insufficient funding, rehabilitation or reconstruction is delayed for low-volume roads in need of repairs. Some lower cost treatments, which may have shorter life expectancies in comparison to traditional rehabilitation or reconstruction methods, have been considered inappropriate for use with severely deteriorated pavements. However, these treatments could be applied to “hold” these pavements in an acceptable condition until funding for rehabilitation or reconstruction is available. Such holding strategies would likely increase the flexibility in allocating funds and improve the overall condition of the highway network in Iowa.

In order to develop treatments that can be used to fulfill the goal of a holding strategy, nine test sections were constructed on a 13 mile low-volume asphalt road segment in 2013. Proposed holding strategy treatments using various combinations of thin and ultrathin asphalt overlays, in-place recycling technologies, and chip seals were applied to remedy the poor surface conditions of the pavements. A series of pavement condition surveys, in situ and laboratory material tests, and surface characterizations were performed to evaluate the structural and functional performance of the test sections.

Based on the performance of the test sections, the life expectancies of the various treatments were estimated and lifecycle costs were analyzed. The lifecycle cost analysis results indicate that 8 of the 10 proposed treatments can be used as candidate holding strategy treatments to address conditions that are like the test. The other treatments had lower cost-effectiveness for these test sections compared to traditional pavement rehabilitation methods.  However, they could be more cost effective in circumstances that are better matched to their advantages.