Iowa Department of Transportation
Iowa Highway Research Board
Chris Williamsrwilliam@iastate.edu email >
About the research
Low-volume rural roads are generally low funding priorities compared to the roads that are part of the National Highway System (NHS). Therefore, low-volume rural roads tend to deteriorate to a point where traditional pavement preservation and maintenance techniques no longer have the desired effect or sufficient funding is not available.
As a potential solution, the Iowa Department of Transportation (DOT) constructed 10 test sections with various base and surface treatments on a 13 mi low-volume asphalt road segment in northeast Iowa in 2013, which were studied as part of the first phase of this research project. The aim of the project was to develop holding strategies beyond pavement preservation as a solution to low-volume roads that are in poor condition when there are not resources available for a complete rehabilitation. Due to the success of this first phase, a second phase was proposed in 2018.
This second phase study focused on surface treatments and was intended to treat highly distressed composite pavements that have asphalt overlays on portland cement concrete (PCC) pavements. Eight test sections were constructed on US 65, between Hubbard and Zearing in Iowa. The holding strategies evaluated were a combination of cold in-place recycling with various surface mixes, 1 in. profile milling with various surface courses, 2.5 in. profile milling with interlayer and surface course, and double coats of microsurfacing with and without additional spot grinding.
Based on the evaluation of the test sections and follow-up surveys, recommendations are given regarding the selection of the most advantageous strategy for the conditions of the studied pavement.