Class F Fly Ash Assessment for Use in Concrete Pavements

Project Details









Konstantin Sobolev, Mohamadreza Moini, Rani Pradoto, Marina Kozhukhova, Ismael Flores-Vivian, Scott Muzenski, Habib Tabatabai, Hani H. Titi


Wisconsin Department of Transportation


Admixtures, Compressive strength, Durability, Fly ash, low cement concrete, superplasticizer, Supplementary cementitious materials



Project description

The Wisconsin Department of Transportation (WisDOT) currently specifies Class C fly ash for use as a partial replacement for portland cement in concrete pavements. Class F fly ash sources were eliminated from WisDOT specifications in the 1990’s due to high values of loss on ignition (LOI) which led to difficulties in establishing and maintaining a proper entrained air void system in the concrete used in paving applications. A recent study that looked at the use of Class F fly ash demonstrated its potential usage in WisDOT specifications. However, WisDOT needs more evaluation with regard to durability testing. Specifically, research is needed to evaluate the feasibility of expanding current specifications to allow for use of Class F fly ash in concrete paving applications with southern Wisconsin aggregates. In order for Class F fly ash to be a viable alternative as a supplemental cementitious material, its use must produce mixes that meet current performance standards with respect to strength (including early strength) and durability, when compared with a commonly used Class C fly ash. The main objective of this study is to evaluate whether the locally available Class F fly ash from Elm Road Generating Station, operated by WE Energies and located in Oak Creek, Wisconsin, will provide satisfactory performance in concrete pavement, in comparison with a Class C fly ash from Columbia Energy Center currently in use. The study will also provide mix design guidance related to acceptable proportions of Class F fly ash that can be used in paving applications without negatively impacting performance. The performance evaluation of optimized concrete included workability (slump), air content, compressive strength, freezethaw and salt scaling resistance in accordance with the relevant AASHTO or ASTM standards. Finally, the reported research recommended the selection of fly ash for low-slump concrete with reduced cementitious material content intended for paving applications.