DEF coupled to thermal history : Recent Advances
TOUTLEMONDE ; KCHAKECH ; OMIKRINE METALSSI ; MARTIN
Type de document
COMMUNICATION AVEC ACTES INTERNATIONAL (ACTI)
Langue
anglais
Auteur
TOUTLEMONDE ; KCHAKECH ; OMIKRINE METALSSI ; MARTIN
Résumé / Abstract
Thermal history conditions susceptible of triggering Delayed Ettringite Formation (DEF), be it at early age due to uncontrolled heat curing or heat generation from hydration, or at a mature stage due to accidental or excessively hot service conditions, have deserved recent experimental investigations. Two concrete mixes with different
sulphates, alkalis and tri-calcium aluminates contents were considered. Expansion of specimens kept under watersaturated conditions after they have been submitted to 60 to 85°C treatments during one to several days have confirmed the risk of DEF occurrence when the specimens have been submitted for a sufficiently long duration to
a temperature higher than about 65°C. For a given concrete, parameters describing the sigmoid-shaped expansion curves may be determined from master curves as a function of the 'efficient' thermal energy provided. A pessimum effect related to the expansion amplitude has been quantitatively confirmed. It can be explained by the availability of sulphates on one hand, aluminates on the other hand, depending on the thermal history characteristics. Moreover, differences in the expansion kinetics might be consistent with the critical role of sulphates accessibility to pore water. These results shall improve DEF prevention through better tuned control of thermal history, especially at early age; it can also help in better managing affected structures.
