Guidelines development for sustainable use of reactive/marginal/recycled aggregates in concrete construction

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Aggregate composition and properties largely affect the mechanical and durability performance of concrete. The shortage in quality materials, the increasing pressure for new construction and the application of sustainable development practices will result in an increased use, in concrete construction, of aggregates with deleterious/marginal properties or resulting from recycling/industrial processes. On the other hand, a large number of concrete structures built in the 1950-1970's are in alarming conditions resulting from different pathologies, including deleterious aggregate reactions. Because of the tight financial situation in the public sector and ever-increasing social needs, a large number of ageing structures will require remedial work for extending their service life. The objective of my research is thus to contribute to sustainability by resolving concrete durability issues resulting from deleterious aggregate reactions in concrete infrastructure. In the Research Theme A, investigations will be carried out to 1) better understand the mechanisms involved in deleterious aggregate reactions, 2) improve QC tests for concrete aggregates, and 3) develop better guidelines/standards to design long-lasting structures with such aggregates. Cores will be extracted from existing field test specimens made with reactive aggregates, with and without preventive measures, and that were stored on different exposure sites across North America and Europe. The cores will then be subjected to full microstructural/mechanical characterization. Additional field test specimens will be manufactured with reactive recycled concrete aggregates and sulphide-bearing aggregates, with/without supplementary cementing materials, for long-term field performance monitoring; in parallel, concrete specimens will be cast and subjected to conventional and new laboratory test procedures for improving field and laboratory performance correlations. In Research Theme B, field inspection protocols and laboratory methodologies will be optimized for quantifying the current condition and the potential for future deterioration of concrete infrastructure (notably mass concrete) affected by deleterious aggregate reactions. Various structures that were previously treated for deterioration mitigation purposes will be inspected and recommendations developed on the best measures to apply to extend the service life of ASR-affected structures. The strength and originality of the proposed research program relate on the availability of long-term field performance data for validating new test procedures for QC of concrete aggregates, a strong network of collaborators on the national/international scenes, an history of successful implementation of the research into guidelines & standards, and most favourable work/training environment for the research team, including a wide array of HQP.