Effects of delayed ettringite formation combined with alkali aggregate reaction on the hydrous transfer process in concrete
MARTIN ; LAPEYRERE ; TOUTLEMONDE
Type de document
COMMUNICATION AVEC ACTES INTERNATIONAL (ACTI)
Langue
anglais
Auteur
MARTIN ; LAPEYRERE ; TOUTLEMONDE
Résumé / Abstract
Delayed Ettringite Formation (DEF) and Alkali Aggregate Reaction (AAR) are both internal swelling processes that can affect concrete. They induce expansion, cracking and decrease of the mechanical properties and thus problems in terms of serviceability and safety for the corresponding structures. In the field, they are known to act frequently coupled. To deal with the affected structures, numerical tools are necessary to re-assess and predict their mechanical state. This implies to finely understand the mechanisms and to quantify the couplings between expansions and exposure parameters such as moisture which is one of the most influent. Thus, numerical tools often use a calculation of the hydrous state of the structure as an input data for the mechanical predictive calculations. Expansions may open cracks and are believed to modify the moisture transfer in the materials. Thus, computations of the hydrous state should be coupled to the mechanical calculations to take into account the evolution of the moisture transport. This paper provides preliminary experimental data to quantify the effect of expansion on the evolution of the moisture content and check if it should be implemented in the numerical tools. Tests were performed on specimens affected by DEF coupled with AAR or not and exposed to moisture gradients. Expansions, global and local water content and porosity were measured and then compared to predictive analyses with different assumptions.
