A Kansas State University (KSU) civil engineer is working to develop a new version of concrete, using just the right mix of ingredients to to make it stronger, and to reduce the carbon footprint of this ubiquitous building material. The surprising ingredient is something that must ordinarily be dealt with as a waste product: the byproducts of biofuel production.
With some 7 billion cubic meters of concrete poured every year, it is easily the most-used industrial material, and one that also carries a rather large carbon footprint – one which adds up to somewhere between 3 and 8% of our total global carbon dioxide emissions. Making this material less resource-intensive by substituting another ingredient, and one which must be disposed of anyway, for part of the portland cement may be a step toward a greener concrete mix.
The researcher, Feraidon Ataie, a doctoral student in civil engineering, focused on the byproducts that come from the production of cellulosic ethanol, which yields an inedible byproduct, called high-lignin residue, and has found some success by using the byproducts from rice and wheat straw and corn stover biofuel production.
“With the cellulosic ethanol process, you have leftover material that has lignin and some cellulose in it, but it’s not really a feed material anymore. Your choices of how to use it are a lot lower. The most common choices would be to either burn it for electricity or dispose of the ash.” – Kyle Riding, KSU assistant professor of civil engineering
Researchers found that not only is it possible to replace part of the materials with a greener alternative, but that it also made a stronger product. They added high-lignin ash byproduct to a concrete mix (replacing 20% of the cement), and a chemical reaction between the ash and the cement served to make the resulting concrete 32% stronger.
The results of the research are encouraging for both the biofuels production industry and the future of building materials, as this process could help lower the carbon footprints of each, as well as decreasing costs:
“This has the potential to make biofuel manufacture more cost effective by better using all of the resources that are being wasted and getting value from otherwise wasteful material and leftover materials. It has the potential to improve the strength and durability of concrete. It benefits both industries.” – Riding