A study on characteristics of interfacial transition zone in concrete

The aim of this study was to observe the behavior of the interfacial transition zone (ITZ) of high-performance concrete that was under curing in saturated lime water. From the Scanning Electron Microscope (SEM), it was found that the pores and hydration products at the ITZ, within 100 mum between the paste and aggregate, permuted each other during the early hydration stage, and then appeared as a large lump or strip. They gradually became irregular and small lumps for the further curing age. At the curing age of 56 days, the pores almost concentrated within an area of 0-15 mum from the aggregate edge. The hydration products were much denser with the increase in its distance from the aggregate edge. (C) 2004 Elsevier Ltd. All rights reserved.