Institute for Transportation

About the research

This study assessed the long-term performance of four aggressively rehabilitated gravel road test sections whose roadway cross-sectional profiles were rebuilt by recovering material from the ditches to restore the proper widths, elevations, and slopes of the roadways and the proper profiles of the drainage ditches. Two of the rehabilitated test sections were constructed with an enzymatic chemical soil stabilizer, while the other two were not. For each pair of test sections, one was constructed using smooth-tired compaction, while the other was constructed using sheepsfoot compaction. A fifth control section was also studied to establish a baseline that was representative of the surrounding roads in the project area.

Overall, this study demonstrated the effectiveness of aggressively rehabilitating gravel roads that had been lowered, widened, and flattened by decades of heavy traffic. Rebuilding the roadway cross sections improved the drainage capacity of the test sections relative to the much flatter control section. The enzymatic soil stabilizer showed measurable benefits in terms of strength, stiffness, and surface distresses. The benefits were greatest in the first year after construction but then decreased somewhat by the end of the second year. With additional field testing and observation, it could be determined whether the latter decrease was a temporary trend or whether the rehabilitation and stabilization will produce continued benefits over time.