Engineers Use Biofuel Byproducts to Make Stronger, Greener Concrete

Civil engineers at Kansas State University are testing the idea of using the byproducts of cellulosic ethanol production as partial replacement for cement to make concrete. They say that it can reduce the concrete's carbon footprint and make the concrete more rigid.

The researchers are exploring the use of leftover material from production of cellulosic ethanol, which is biofuel produced from non-food biomass such as wood chips, grass straw and other agricultural residue. The leftover from cellulosic ethanol process contains lignin and some cellulose and this material is typically burned to generate electricity or disposed as ash. The researchers found that high-lignin ash mixed with portland cement formed a chemical reaction that made the concrete more rigid. The experiment showed that replacing 20 percent of the cement with cellulosic leftover after burning increased the strength of the concrete by 32 percent.

According to the KSU engineers, the potential of cellulosic ethanol byproduct to increase the durability of concrete will not only reap value added benefits for both the ethanol and concrete industry but also for the environment. They say that concrete production is rampant and cement production requires lot of energy. While making concrete is less energy intensive than making steel or other building materials, it potentially contributes between 3 to 8 percent to global carbon dioxide emissions since it is the most widely used industrial material after water. By using alternative materials such as the leftover lignin ash, dependence on cement and hence the carbon footprint of concrete materials can be reduced.