THE OCCURRENCE OF 2-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 hydra tion, can be recognized by the subsequent presence of ''temperature re lics'' in the form of banded or layered hydration rims displaying two- tone or sometimes three-tone appearance in backscatter SEM. We have fo und (and illustrate) populations of such supposed indicators of high-t emperature curing in various small specimens that have been cured enti rely at room temperature. Accordingly, we suggest that such banded str uctures may arise in other ways, and their presence does not necessari ly indicate that high-temperature curing has occurred. (C) 1998 Elsevi er Science Ltd.