Grant: Alliance Grants

Alkali-silica reaction (ASR) is a concrete deterioration mode that negatively impacts infrastructures' serviceability in Canada and worldwide. The deterioration takes the forms of cracking, disruption and reduced structure serviceability. Moreover, the cracks can promote more types of deterioration, including reinforcement corrosion and freezing/thawing damage. In recent years, concerns have arisen that current standard aggregate screening tests could underestimate the reactivity of stones used as aggregate in concrete, imposing a risk on new infrastructures. The main objectives of this proposed research are: (i) examine the true ASR reactivity of selected aggregates in Ontario where current screening test methods might not be adequate in evaluating them. The examination will be carried out using different sampling methods and analytical techniques that can help explain the results of the screening tests and (ii) propose simple, sustainable, and economical preventive measures that could be used with marginally reactive aggregates to produce structures that are safe from the ASR viewpoint. The second objective benefits Canada significantly as structure owners like the Ministry of Transportation Ontario (MTO) may find themselves obligated to use aggregates of low reactivity due to limited aggregate sources and to void hauling aggregates from locations far from the construction sites. The outcomes of this research will help the Ministry and other structure owners develop their standards of practices, including sampling methods and frequency, and aggregate testing.