Investigation on the interfacial transition zone in ternary blended cement based composites with respect to curing age and water binder ratio

Though discussed a lot, the interfacial transition zone (ITZ), the linking phase between aggregate and bulk paste, still undertakes ambiguity on its knowledge. In this paper, the intention is borne to investigate the influence of curing age and water binder (w/b) ratio in blended hydration systems, where due to the more complex interaction between cementitious particles, such two factors are more pronounced compared to the hydration of plain cement. In particular, Portland cement, blast furnace slag and limestone filler are blended as binders for the cementitious composites. The designed w/b ratio is 0.3, 0.4, and 0.5, respectively. Two curing ages, i.e., 28 and 56 days are discussed. Hardened microstructures are characterized with regard to ITZ and bulk paste based on the BSE-SEM image analysis. Results indicate that ITZ is alleviated as hydration proceeds. When the w/b ratio increases, more porous ITZ are found. However, the extent of ITZ seems not affected by the curing age and w/b ratio.