Experimental investigations concerning combined delayed ettringite formation and alkali aggregate reaction

Delayed Ettringite Formation (DEF) and Alkali-Aggregate Reaction (AAR) are both endogenous swelling processes that can affect concrete. They lead to a decrease of the mechanical properties, cracking and unexpected deformations and thus induce severe concerns in terms of structural integrity for affected structures. This paper describes an experimental investigation concerning the mechanical effects of DEF and AAR acting separately or simultaneously. The effect of the water supply conditions is investigated. Finally a quantitative model is proposed to account for swelling of materials affected by both DEF and AAR. with EDF (Electricité de France). Using large scale laboratory specimens, it aims to quantify at a macroscopic scale the mechanical effects of DEF and AAR acting separately or simultaneously (Martin et al. 2008). This paper proposes an experimental quantification of DEF and DEF-AAR processes in terms of kinetics and ultimate expansion in materials stored in various water supply conditions. To explain the macroscopic expansion of the materials, a quantitative model is proposed to describe the swellings of a material affected by DEF and AAR.