Micromorphology of the Interfacial Zone Around Aggregates in Portland Cement Mortar

Abstract

Scanning electron microscopy showed that micromorphological features of the interfacial zone, which occur next to glass slide “model aggregates” occur also in mortars made with standard Ottawa silica sand. These features included formation of a duplex film on the sand‐grain surfaces, development of large well‐formed Ca(OH) 2 crystals at intervals near the interface with their c axes roughly parallel to it, development of stacked‐platelet secondary Ca(OH) 2 in open spaces immediately adjacent the duplex film, and hydration leading to the presence of hollow‐shell hydration grains (Hadley grains) in the interfacial region.