Interaction of DEF and AAR, a review
- Authors
- Publication Date
- Jan 01, 2021
- Source
- Portail Documentaire MADIS
- Keywords
- License
- Unknown
- External links
Abstract
AAR and DEF can lead to the development of severe cracking in structures. Both reactions are often associated with high cement content mixes: AAR because of the increased availability of alkalis, DEF because the heat of cement hydration can lead to temperatures over 65 ?C, above which sulphates lead to the delayed formation of expansive ettringite. High cement content mixes, favoured by contractors for early strength gain and workability, also lead to increased early age thermal and shrinkage cracking. This cracking becomes increasingly complex as it is enlarged by the swelling from AAR and/or DEF, which later impose their own characteristics, modified by constraints from stress and reinforcement. The paper considers AAR and DEF at the scale of the interaction of paste with aggregate, as observable petrographically and from changed physical properties. Examples of large scale laboratory tests on beams further clarify the interactions which are also illustrated by reference to major structures which have suffered AAR, DEF and combined AAR/DEF damage.
