About the research
More than 50% of roadways in Iowa are classified as unpaved. The performance and long-term sustainability of such roads are dependent on the quality of the surfacing material, which varies considerably by location. The large, unbound particles form an unstable road surface that becomes rough, developing potholes and corrugations as the “floating” material is scattered by vehicles or washed away by rain. As a result, such roads require more frequent maintenance and reconstruction, which becomes very expensive for Iowa counties. Therefore, it is important to construct unpaved 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).
Loess soil was mixed with four different biofuel co-products: lignosulfonate, glycerin bottoms, crude glycerine, and glycerin 95. The soil was mixed with 4, 8, 12, and 16% BCP by weight. Results of the study showed that lignosulfonate improved the unconfined compressive strength (UCS) of the loess soil to some extent, while such trends were not observed for the mixtures prepared with glycerin products. Leaching tests focused on the pH and leaching of metals such as Cr, Al, Fe, As, and Zn from soil mixtures. The addition of the BCP did not influence the pH of the loess soil, and none of the mixtures leached metals that were above the detection limit of the equipment. These results indicate that BCPs do not pose any environmental threat when used as a dust control or stabilizing agent in unpaved roads.
Iowa Department of Transportation
Iowa Highway Research Board ($40,000.00)
Midwest Transportation Center
Contract Number: DTRT13-G-UTC37