The interfacial transition zone in alkali-activated slag mortars

Abstract

The interfacial transition zone (ITZ) is known to strongly influence the mechanical and transport properties of mortars and concretes. This paper studies the ITZ between siliceous (quartz) aggregates and alkali-activated slag (AAS) binders in the context of mortar specimens. Backscattered electron (BSE) images generated in an environmental scanning electron microscope (ESEM) are used to identify unreacted binder components, reaction products, and porosity in the zone surrounding aggregate particles, by composition and density contrast. X-ray mapping is used to exclude the regions corresponding to the aggregates from the BSE image of the ITZ, thus, enabling analysis of only the binder phases,..