Improving Roads with Ethanol Co-products
Iowa鈥檚 soil is great for growing corn. But it鈥檚 not so great for building roads. Soil around the Midwest is mostly soft clay and till deposited by glaciers, said Halil Ceylan, an Iowa State assistant professor of civil, construction and environmental engineering. It鈥檚 hardly the bedrock engineers would like for a good, solid roadbed.
And so the soil under Iowa鈥檚 roads often has to be mixed with chemicals that bind and stabilize soil particles. That improves soil strength. And that makes for better roads.
While stabilizing soils for road construction is standard practice around the Midwest, there are limits to its effectiveness. Ceylan said costs can be high and current practices only work with certain soil types and site conditions. So civil engineers are always looking for better, cheaper and more efficient ways to get the job done.
That has Ceylan and Kasthurirangan Gopalakrishnan, a research scientist in civil, construction and environmental engineering, experimenting to see whether lignin, a co-product of producing ethanol from plant fibers, could be a good soil stabilizing agent.
Their research is partially supported by a $93,775 grant from the Grow Iowa Values Fund, a state program that promotes economic development. The Iowa Highway Research Board, Grain Processing Corp. of Muscatine and Iowa State鈥檚 Office of Biorenewables Programs are also supporting the project.
Using lignin to stabilize soil make sense. Lignin is the glue that holds plant fibers together. It鈥檚 the tough stuff that allows corn plants to stand up to a summer thunderstorm. But there鈥檚 not a lot of value in it when it鈥檚 removed from corn stalks, switchgrass or other biomass feeding the production of cellulosic ethanol.
As researcher Andy Aden of the National Renewable Energy Laboratory in Colorado recently told National Geographic magazine, 鈥淭he old joke is you can make anything from lignin but money.鈥�
Ceylan said previous Iowa State studies of lignin from the paper-making industry found it to be a cementing agent that could be of value for soil stabilization. But nobody has determined if that鈥檚 also the case for lignin from ethanol production.
Ceylan thinks it will be.
鈥淚t is expected that the lignin derived from lignocellulosic biorefineries will see similar success, if not better,鈥� he wrote in his proposal for a Grow Iowa Values Fund grant.
To find out, Ceylan and his research team will head to the soils engineering lab in Iowa State鈥檚 Town Engineering Building where they鈥檒l prepare soil samples containing various percentages of lignin. The mixtures will be tested and evaluated for strength, stability and other properties.
The researchers hope they come up with a new technology that鈥檚 good for road builders, good for drivers, good for the environment and good for the cellulosic ethanol industry.
The research could also be a big help to the people who build and maintain Iowa鈥檚 roads, especially as ethanol plants increase truck traffic through rural areas.
鈥淲hen I talk to county engineers they鈥檙e very concerned about increased traffic,鈥� Ceylan said. 鈥淩oads are designed according to traffic forecasts and suddenly there is a lot more truck traffic. This can be a cause of distress to the highway system. But, maybe we can also get the benefit of soil and road stabilization from these plants.鈥�
Source: Iowa State University
