Cenocell is a patented concrete material that is manufactured without the addition of Portland cement. It is produced from a chemical reaction involving fly ash, bottom ash, or flue-gas desulfurization gypsum with organic and inorganic chemicals. It was invented by Mulalo Doyoyo and Paul Biju-Duval at the Georgia Institute of Technology. It is generally known as "cementless concrete". Fly ash, bottom ash, and gypsum are unwanted pollutants that are byproducts mainly of coal combustion in power generation, cement production, pulp and paper manufacturing, and mining operations. In addition to its role as an environmental-friendly construction material, it is as strong as concrete at lower specific gravity. Its tensile strength is one third of its compressive strength. The tensile strength in traditional concrete is around one tenth. That means that the material requires less reinforcement.