Alkali-Activated Slag Concrete After 5 Years of Alkali-Silica Reaction

Cement is one of the most widely adopted building materials in the world, due to versatility, efficiency, and cost. Cement production, however, is a big contributor to \(CO_{2}\) emissions worldwide. Alternatives are available, based on recycled building materials, industrial by-products, natural minerals, among others, but these are not always as cost-effective and durable as Portland Cement. The processes responsible for the long-term degradation of concrete, made from Portland Cement or otherwise, include corrosion, carbonation, binder-aggregate reactions, sulfate attack among others. This work assesses the long-term durability of alkali-activated alternative binders, namely slag, as compared to regular Portland Cement in concrete under Alkali-silica reaction conditions. Six mix designs were chosen for this study, two using Portland Cement as the binder, and four with slag as the alkali-activated precursor. Out of the four slag mix designs, two used slags from a Canadian source as the primary binders, and two used slag from an European source. Concrete samples were kept at 38 ℃ and 100% RH for 5 years. The performance was investigated by length measurements, microscopic investigations, and chemical analyses using SEM-EDS equipment. It was found that ASR gel chemistry may change over time, both for OPC and Alkali-activated Slag concrete.