Characterization of the Behavior of High Volume Fly Ash Concrete

Abstract

Fly ash is commonly used as a supplementary cementitious material (SCM) in the production of portland cement concrete. Concrete produced with high fly ash replacement levels is considered high volume fly ash (HVFA) concrete. HVFA concrete has many benefits, including reduced concrete production cost, reduced greenhouse gas emissions, and improved sustainability. Despite the advantages, there are several barriers that limit the use of HVFA concrete. One of the main limitations to the increased usage of HVFA concrete is the lack of contractor and transportation agency familiarity with the setting time and strength development of these concrete mixtures. For this research, a laboratory testing program was developed to examine the effect of fly ash type, fly ash dosage, cement chemical composition, and environmental conditions on the hydration development, setting times, and compressive strength development of HVFA concrete. Results from semi-adiabatic calorimetry were used to develop a hydration model for HVFA concrete. Finally, the ConcreteWorks software program was used to predict the in-place performance of selected HVFA concrete mixtures when placed in various transportation structures. It is concluded that HVFA concrete may be produced to have comparable setting times and early-age compressive strength development to conventional portland cement concrete when used for transportation infrastructure.