Avoiding & mitigating alkali-aggregate reaction (AAR) in concrete structures

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Alkali-aggregate reaction (AAR) is one of the main processes affecting the durability of concrete infrastructure in Canada and worldwide. Over the years, several approaches and recommendations, including a comprehensive variety of laboratory test procedures, have been developed around the world to assess the potential alkali-reactivity of concrete aggregates and the effectiveness of preventive measures (e.g. control of the cement & concrete alkali content, use of supplementary cementing materials, etc.) before their use in the field. Despite some issues with some test procedures (e.g. long-term duration, alkali leaching, long-term correlation with field structures, evaluation of concrete mixtures, etc.) and the constant need for improvement in the various standards/protocols, the majority of experts agree that, in general, it is now possible to build new concrete infrastructure with minimum or even calculated/limited risk of AAR. However, there is currently no consensus about the most efficient method(s) (e.g. surface treatments for moisture control, chemical treatments, strengthening, stress relief, etc.) that should be implemented, and when, for the rehabilitation of AAR-affected concrete structures/structural members. In this context, a number of engineers and researchers around the globe have been trying to develop appraisal techniques and tools that are capable of either halting/mitigating further AAR development in service or at least appraising the current damage degree (diagnosis) and the potential of future distress (prognosis) of affected aging structures, both essential steps in selecting efficient rehabilitation methods and optimum application periods for critical aging infrastructure affected by AAR. In this context, this research project, in collaboration with Kryton, aims to evaluate existing commercial products and develop new product(s) for preventing and/or mitigating (i.e. physically, chemically or both) concrete deterioration caused by AAR in its initial, moderate and advanced phases. The scientific benefit of this CRD is very clear through the evaluation/development of current/new products for avoiding & mitigating AAR in the field. Moreover, Kryton will benefit from the collaboration and exchange with uOttawa researchers to appraise, develop and implement new products to the Canadian and global civil engineering market.