Course 2 - Dams affected by concrete swelling reactions: diagnosis, prediction and rehabilitation

António Lopes Batista is a civil engineer, PhD, principal researcher and head of the Concrete Dams Department of LNEC (Portugal). He developed his professional activity in LNEC since 1986, in the following fields related with concrete and masonry dams: i) analysis and interpretation of the observed behavior, using mathematical modelling; ii) instrumentation, monitoring and inspection; and iii) deterioration and rehabilitation, particularly the concrete dams affected by swelling reactions. He is responsible for the team that monitors the behavior of around 70 large Portuguese concrete and masonry dams. He was also involved in studies of large dams abroad, namely in Mozambique, Angola, Brazil and Peru. He was the chairman of the 16th International Conference on Alkali-Aggregate Reaction in Concrete (ICAAR-2020-2022). The most common chemical reactions of internal origin in concrete that cause expansion can be grouped into two main types: alkali-silica reactions (ASR) and internal sulphatic reactions (ISR). Both reactions require water to develop, making concrete dams particularly vulnerable structures. The structural effects of these swelling reactions are difficult to manage, as there are no fully effective methods to either mitigate the development of the reactions themselves or to repair the deteriorated structures. Over the past few decades, engineering has developed a set of measures that, when applied judiciously, allow for limiting, in many cases, the adverse effects of these reactions. In the case of severely damaged structures, a range of rehabilitation techniques can be employed to restore structural performance and extend the useful lifespan of dams. In dams equipped with well-designed monitoring systems, the proper handling of observation elements, such as monitoring data, and inspection and specific tests results, helps quantify the structural effects of these reactions. Adequate modeling of the expansion development and its structural consequences makes it possible to assess the safety of the structures, predict their future behavior, and guide the study of the best intervention solutions when needed. The keynote lecture will discuss the role of observation and modeling in supporting studies and decisions to manage the functionality, safety, and durability of affected dams. Several examples of dams with this pathology, from both Portugal and around the world, will be presented to illustrate the topic.