Multiphase Sphere Modeling of High-Volume Fly Ash Concrete: Freezing-Thawing Performance

Replacing more than 50% of the cement in concrete with fly ash produces high-volume fly ash (HVFA) concrete, which likely reduces the life-cycle cost and environmental footprints of concrete. In cold climates, the susceptibility of HVFA concrete to freezing-thawing cycles is a durability concern if no appropriate measures are taken. This study modeled the degradation of dynamic modulus of elasticity of HVFA concrete during the freezing-thawing cycles. A four-phase sphere composite model considering the unhydrated fly ash particles in HVFA concrete is proposed to interpret the change in dynamic modulus of elasticity. The modeled values were in good agreement with the measured values; therefore, this model sheds new light on the deterioration of HVFA concrete caused by freeze/thaw damage cycles. Parameter analysis clarified the influence of the key factors in this model.