Evaluation of damage in concrete from structures affected by internal swelling reactions – A case study

Abstract Nowadays, a significant number of concrete infrastructures are affected by internal swelling reactions (ISR). The most common in Portugal are the alkali-silica reaction (ASR) and the internal sulphate reaction (DEF). Existing knowledge does not allow for a complete assessment of the actual condition of an ISR-affected structure and an accurate prediction of the mechanical properties deterioration and, consequently, of the period during which the structure will effectively perform its function. To help surpassing this situation, research is being conducted at LNEC to contribute to the establishment of a method for a more accurate determination of the current level of ISR progression and of the deterioration of the concrete mechanical properties. This paper aims at contributing to the ongoing discussion of this topic and, therefore, presents the methodology followed to assess the condition of the concrete from an ISR-affected motorway underpass in Portugal. It includes a comprehensive experimental campaign, performed to concrete cores, to allow for an adequate diagnosis and prognosis of the ISR development. The results evidenced the utility of such a methodology on the appraisal of the actual expansion level attained to date in concrete from ISR-affected structures.