MANHATTAN, Kan. — At Kansas State University (KSU) in Manhattan, civil engineers are researching a way to reduce concrete’s carbon footprint while making it stronger. The key ingredient: biofuel byproducts.
Concrete is made from portland cement, water and aggregate, and the world uses about 7 billion cubic meters of concrete each year, according to a statement by the University.
“Even though making concrete is less energy intensive than making steel or other building materials, we use so much of it that concrete production accounts for between 3 to 8 percent of global carbon dioxide emissions,” said Kyle Riding, KSU assistant professor of civil engineering, in a statement.
To reduce the carbon dioxide emissions set off from concrete productions, researchers are looking for environmentally friendly materials that can replace the portland cement. So far, they found success with byproducts of biofuels made from corn stover, wheat straw and rice straw.
“It is predicted that bioethanol production will increase in the future because of sustainability,” said Feraidon Ataie, KSU doctoral student in civil engineering, in a statement. “As bioethanol production increases, the amount of the byproduct produced also increases. This byproduct can be used in concrete.”
The researchers are focusing on byproducts from cellulosic ethanol production, which creates biofuel produced from inedible materials such as wood chips or wheat straw. This is different from other bioethanols, which use corn or grain to make biofuel. Cellulosic ethanol’s byproduct is perceived as less valuable than corn ethanol’s byproduct (distiller’s dried grains), which can be used as cattle feed.
When researchers added the high-lignin ash byproduct (created from cellulosic ethanol production) to cement, the chemical reaction made the cement stronger. After testing the finished concrete material, researchers found that replacing 20 percent of the cement with cellulosic material after burning increased the strength of the concrete by 32 percent.
“The utilization of this byproduct is important in both concrete materials and biofuel production,” Ataie said. “If you use this in concrete to increase strength and quality, then you add value to this byproduct rather than just land filling it. If you add value to this byproduct, then it is a positive factor for the industry. It can help to reduce the cost of bioethanol production.”
This research has been published in the American Society of Civil Engineer’s Journal of Materials in Civil Engineering and was funded by more than $210,000 from the National Science Foundation. The researchers also collaborated with the University of Texas, North Carolina State University and the National Renewable Energy Laboratory in Golden, Colo.