Evaluation of different techniques for the diagnosis & prognosis of Internal Swelling Reaction (ISR) mechanisms in concrete

Aging concrete structures affected by Internal Swelling Reactions (ISR) may be quite difficult to manage. Over the past years, several tools were developed to provide diagnostic and prognostic assessment of concrete structures, especially those affected by Alkali-Aggregate Reaction (AAR). Among those tools, the Stiffness Damage Test (SDT), Damage Rating Index (DRI) and Residual Expansion (RE) seem to be promising. However, the comprehensive and complementary character of the prior tools in assessing different mechanisms other than AAR was barely verified, which significantly reduces their use for engineering purposes. This paper presents the overall condition assessment of a concrete structural member affected by coupled AAR and Delayed Ettringite Formation (DEF) through the use of the above techniques. Results show that the three procedures were similarly capable of providing the current damage degree (i.e. quantitative diagnosis), enabling the estimation of the concrete expansion attained to date. Finally, although theoretically different, the test procedures seem to have a somehow complementary character, and could potentially be used together in the understanding of ISR progress, damage generation and future prognosis.