Active thin sections to study syneresis

Thin sec:ions an made from hardened products. To achieve information on the very early hydration process of cementitious composites, one would need an "active thin section," i.e., a thin section of a cement paste that is hard ening while under investigation. In our research, it has been possible to c onstruct such active thin sections. Using ordinary light microscopy it is p ossible to observe water movement and volume changes on hydrating specimens of about 100-mu m thickness. This research is part of a larger project to investigate the formation of the interfacial transition zone. We believe th at a process called syneresis might play an important role. Syneresis is th e contraction of a gel under the expulsion of a liquid. This is addressed i n the second part of this paper. This phenomenon is studied using active th in sections. (C) 1999 Elsevier Science Ltd. All rights reserved.