ABSTRACT
Fundamental to understanding and controlling the durability of cement-based systems is the relationship between microstructure and transport properties, particularly ionic diffusivity and hydraulic permeability. While our understanding of cement paste microstructure and interfacial zone contributions has improved considerably over the past few years, largely due to advances in nondestructive methods and modelling, there is a demonstrated need for improved laboratory and field techniques for determining diffusivity and permeability. This work provides an overview of existing and emerging techniques for measuring or predicting the transport properties of cement-based materials. Although a major focus will be impedance spectroscopy, alternative methods will also be considered, including solvent exchange kinetics, mercury intrusion porosimetry, nuclear magnetic resonance, microstructure-based modelling, and the more conventional permeameter and rapid chloride penetration techniques. The applicability of the NemstEinstein (diffusivity) and Katz-Thompson (permeability) equations to cement-based materials will be considered. Ramifications for rapid testing and field testing of concrete will also be discussed. Keywords: Diffusivity, impedance spectroscopy, mercury intrusion porosimetry, modelling, nuclear magnetic resonance, permeability, solvent exchange, transport properties.
