Carbon dioxide use in beneficiation of landfilled coal ash for hazardous waste immobilization

Abstract Landfilled coal fly ash and supplementary minerals were processed into a hydraulic cement binder via input of mechanical energy at ambient temperature in the presence of carbon dioxide (CO 2 ) (considered as a gaseous raw material). An experimental program was conducted with the purpose of optimizing the raw materials formulation for achieving a desired balance of cement chemistry for CO 2 capture, compressive strength and heavy metals immobilization qualities of the cement hydration products. The optimum formulation was found to complement high levels of CO 2 capture with desired material properties offered by the hydration products. Insight into the structure of hydration products was gained by evaluating their chemical bond structure and thermogravimetry attributes.