Institute for Transportation

About the research

A significant amount of waste ash in the United States does not meet the necessary specifications for construction and other uses, and power plants are searching for a way to dispose of surplus waste ashes.

To address this issue, this research aimed to treat waste ashes using CO₂ injection in order to modify their properties and enable their beneficial use in concrete. The main tasks of the study were to (1) optimize the carbon treatment procedure (pressure, moisture, and time) for the selected waste ashes, (2) determine the effects of the carbon treatment on the properties of the ashes (surface chemistry, morphology, pore structure, etc.), (3) evaluate the effects of carbon-treated ashes on the properties of cement composites such as paste and mortar (set time, flowability, hydration, strength, etc.), and (4) quantify CO₂ sequestration and assess the benefit-to-cost potential of the carbon-curing treatment. Findings indicate that certain types of waste ashes can increase the decarbonation of cement and concrete providing a use for the waste ashes and promoting sustainability.