Accelerated Expansion Test: UK

Abstract

This test method determines the variability of long term dimensional changes in sets of mature concrete cores as they take up moisture by capillary absorption. The dimensional changes are initially due to normal swelling (shrinkage recovery) of concrete from measured increased moisture availability. The moisture then leads to the slow swelling of any pre-existing gel from AAR and, in the longer term, to further AAR reaction with swelling of its gel. The swelling due to AAR is a measure of the “free residual expansion potential” which can arise in the cored concrete at a rate depending on the in-situ moisture and the temperature. The “free” expansion will be modified in the structure by the effects of stress and reinforcement restrain acting in three distinct directions.