Tortuosity quantification of fly ash concrete considering interfacial transition zone

For concrete materials, durability is closely related to the mass transport property. The tortuosity of concrete material is an important factor accounting for the transport property. In this paper, the tortuosity of concrete is studied by mercury intrusion porosimetry and permeation tests in order to consider the existence of aggregate induced in the interfacial transition zone (ITZ). Tortuosity gained through the corrugated pore structure model and the Katz–Thompson model are compared and analysed to quantify the tortuosity of fly ash concrete. The ITZ was observed by scanning electron microscopy. The results show that the effect of aggregate should be considered when studying the tortuosity of concrete materials. With an aggregate value fraction of 43.8%, when considering the ITZ around coarse aggregate, concrete tortuosity is 1.29–16.18 times higher than that of the mortar matrix.