The occurrence of two-tone structures in room-temperature cured cement pastes

It is generally accepted that high-temperature steam cured concretes, or concretes otherwise exposed to high temperatures during early hydration, can be recognized by the subsequent presence of "temperature relics" in the form of banded or layered hydration rims displaying two-tone or sometimes three-tone appearance in backscatter SEM. We have found (and illustrate) populations of such supposed indicators of high-temperature curing in various small specimens that have been cured entirely at room temperature. Accordingly, we suggest that such banded structures may arise in other ways, and their presence does not necessarily indicate that high-temperature curing has occurred. (C) 1998 Elsevier Science Ltd.