Improving the structure of the interfacial zone and its influence on the long-term behavior of mortars

The structure of the interfacial zone between cement paste and aggregate was improved by using a pretreated quartz aggregate on whose surface the hydraulic mineral ß-C₂S was directly formed. The composition and morphology of the structure of the interfacial zone was examined, and its influence was studied by comparisons between mortars made with pretreated quartz aggregate and with normal quartz aggregate. The results showed that the composition and morphology of the interfacial zone were substantially improved by the hydration of the mineral ß-C₂S of the pretreated quartz aggregate. The influence of the interfacial structure on the strength of mortars was related to structural development. It appears to be slight at early hydration, but significant at late hydration.