The effect of pozzolans and slag on the expansion of mortars cured at elevated temperature - Part I: Expansive behaviour

The expansive behaviour of heat-cured mortars containing pozzolans and slag was investigated. In most cases, the addition of any amount of these materials to the mixture typically reduced the long-term expansion, slowed the rate of expansion, and delayed the onset of expansion. However, the efficacy of a particular pozzolan or slag in controlling expansion may depend on its Al2O3 content. Metakaolin, which contains a high amount of reactive Al2O3, was the most effective at controlling expansion at relatively low cement replacement levels. Slag and fly ash, which are also sources of Al2O3, were also effective at suppressing expansion at higher replacement levels. Silica fume was less effective at controlling expansion at conventional replacement levels, and even at higher replacement levels expansion may only be delayed. (C) 2002 Elsevier Science Ltd. All rights reserved.