An Assessment of the Leaching Behavior of Coal Fly Ash as a Supplementary Cementitious Material for Precast Concrete Applications

Among widespread use of concrete as a building material, production of Portland cement remains one of the greatest producers of CO2 emissions (Huntzinger, 2009). Therefore, it is important to seek out sustainable alternatives to Portland cement for concrete manufacture. Coal fly ash, a byproduct of coal combustion for energy production, has the potential to replace some volume of Portland cement as a Supplementary Cementitious Material (SCM). Use of coal fly ash has the capability to reduce overall CO2 emissions associated with concrete manufacture and decrease the need for disposal of the combustion byproduct (Li, 2022). Coal fly ash contains inorganic contaminants that, if allowed to leach into the surrounding environment, may adversely affect environmental health (Bhatt, 2019). This study intends to examine the leaching behavior of coal fly ash, and to infer how concrete containing coal fly ash as a SCM may perform in the natural environment using the EPA Leaching Environmental Assessment Framework (LEAF). The EPA LEAF approach aims to quantify leaching behavior in various scenarios that represent naturally occurring conditions using four tests: pH-Dependent Liquid-Solid Partitioning, Liquid-Solid Ratio Dependent Up-Flow Percolation, Rate of Mass Transfer, and Liquid-Solid Dependent Liquid-Solid Partitioning (EPA, 2017).