PSI - Issue 77

João Custódio et al. / Procedia Structural Integrity 77 (2026) 447–456 João Custódio, et al. / Structural Integrity Procedia 00 (2026) 000–000

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Fig. 3. View of the new Alto Ceira dam. The old dam is visible in the background.

6. Final remarks Internal swelling reactions can reduce the service life and cause operational disruptions or the decommissioning or demolition (partial or total) of vital infrastructures (e.g., dams, bridges, viaducts, harbours). Despite existing specifications and guidelines, adequate prevention of the harmful development of ASR and DEF is still sometimes overlooked in new construction in Portugal and other countries. Therefore, raising awareness among construction stakeholders remains necessary. Due to the severe consequences that ASR and DEF can have on these infrastructures, the early identification of structures where they may potentially develop, the early detection of signs of these phenomena in existing structures, and adequate maintenance (e.g., drainage systems) are crucial. Proper prevention and management of these reactions can save millions of euros spent both publicly and privately: on avoidable, inadequate, or ineffective rehabilitation works; on the unnecessary or avoidable decommissioning of structures; on the unnecessary or avoidable reconstruction and/or demolition of structures; on legal disputes; on implementing alternatives to address the inoperability of such structures. Finally, several fundamental questions still need to be addressed, such as acquiring large-scale alternative supplementary cementitious additions to prevent ASR and DEF with costs and performance comparable to traditional ones, which are becoming less available or are already not available in some countries, translating laboratory test results to long-term field performance in different environmental service conditions, and effectively mitigating ASR and DEF in existing structures. Analyses of the structural behaviour of affected structures are based on mathematical modelling, which also requires further development. References AASHTO (2017). AASHTO R 80-17 Standard practice for determining the reactivity of concrete aggregates and selecting appropriate measures for preventing deleterious expansion in new concrete construction. Washington, DC, USA: American Association of State and Highway Transportation Officials (AASHTO). ACI (2008). ACI 221.1R-98 (Reapproved 2008) Report on Alkali-Aggregate Reactivity. Farmington Hills, MI: American Concrete Institute (ACI). ACI (2023). ACI PRC-201.2-23 Durable Concrete - Guide. Farmington Hills, MI, USA: American Concrete Institute (ACI). ACI (2025). ACI Concrete Terminology (ACI CT-25). Farmington Hills, MI: American Concrete Institute (ACI). AFNOR (2021). FD P18-464:2014 Béton. Dispositions pour prévenir les phénomènes d'alcali-réaction. Paris: Association Française de Normalisation (AFNOR). ASTM (2023). ASTM C1778-23 Standard Guide for Reducing the Risk of Deleterious Alkali-Aggregate Reaction in Concrete. West Conshohocken, PA: ASTM International. Batista, A. L. (2022). Monitoring the deterioration processes of Portuguese dams affected by concrete internal swelling reactions (in Portuguese). Revista Portuguesa de Engenharia de Estruturas, Série III, n.º 18 , 43-64. BRE (2002). Information Paper 1/2002 Minimising the risk of alkali-silica reaction: alternative methods. Garston, Watford, UK: Building Research Establishment Limited (BRE). BRE (2004a). Digest 330 Part 1 Alkali-silica reaction in concrete. Background to the guidance notes. Garston, Watford, UK: Building Research Establishment Limited (BRE). BRE (2004b). Digest 330 Part 2 Alkali-silica reaction in concrete. Detailed guidance for new construction. Garston, Watford, UK: Building Research Establishment Limited (BRE).