Effects of Alternative Wetting and Drying on the Development of Delayed Ettringite Formation

Similarly to Alkali Aggregate Reaction, Delayed Ettringite Formation (DEF) is highly affected by moisture. Understanding quantitatively the coupling between moisture and expansion is mandatory to be able to predict the field behavior of concrete exposed to variable water supply by using results of laboratory tests performed in controlled conditions. This paper presents an experimental investigation that consists in exposing concrete specimens to wetting/drying cycles. To be more representative of field exposure, the wetting duration was set to relatively short periods. For the concrete mixes investigated, the tests showed that not only the kinetics of expansions but also their final magnitude is affected by the water-supply history. Some preliminary assumptions are proposed to explain this phenomenon.