Evaluation of the Mechanical and Environmental Performance of Biofuel Co-Product-Stabilized Unpaved Roads

Project status

In progress

Start date: 09/01/16
End date: 08/31/17


Principal investigator:

Co-principal investigators:

About the research

More than 50 percent of roadways in Iowa are unpaved. The performance and long-term sustainability of these roads are dependent on the quality of the surfacing material, which varies considerably with location. Frequent maintenance and rehabilitation of unpaved roads becomes very expensive for Iowa counties. Therefore, it is very important to construct these roads with materials that can sustain their performance for a considerable amount of time with less maintenance.

This problem can be addressed economically in locations that are close to sources of considerable amounts of biofuel co-products (BCPs). Recent research by the Institute for Transportation shows that BCPs can be used effectively as a stabilization material for fine-grained soils.

This project investigates improving the long-term performance of unpaved roads by adding BCPs to unpaved road surfacing materials. This study will focus on the improvement of geotechnical and environmental performance of unpaved roads stabilized with BCPs. This research will include both geotechnical and environmental laboratory experiments.

Geotechnical laboratory tests will include index properties, resilient modulus, permanent deformation, and hydraulic conductivity. Laboratory samples will be subjected to environmental conditions (freeze-thaw cycling) during testing. The toxicity characteristics leaching procedure (TCLP) and shake extraction tests (often referred to as the water leach test) will be performed on BCP-stabilized unpaved road test specimens to characterize their environmental suitability.

In addition, field lysimeters will be installed to monitor the leachate properties of the BCP-stabilized roadways to collect leachate from the field test sections. Environmental analyses will include measurements of pH, electrical conductivity (EC), oxidation-reduction potential (Eh), and metal, sulfate, and carbonate concentrations.



  • Iowa Department of Transportation
  • Iowa Highway Research Board
  • Midwest Transportation Center