Quantification of tortuosity of mortar matrix and concrete with different fly ash content considering interfacial transition zone

For concrete materials, durability is closely related to mass transport property. The tortuosity of concrete material is an important factor to account for transport property. In this paper, tortuosity of concrete is studied by experiments of MIP and permeation test to consider the exist of aggregate which induce in the interfacial transition zone. Tortuosity gained through corrugated pore structure model (CPSM) and Katz-Thompson model is compared and analyzed to quantify the tortuosity of fly ash concrete. Interfacial transition zone (ITZ) was observed by scanning electron microscope. The results show that the effect of aggregate should be considered when studying the tortuosity of concrete materials. With aggregate value fraction of 43.8%, when considering ITZ around coarse aggregate, concrete tortuosity is 1.29-16.18 times higher than the mortar matrix.