Performance and sustainability overview of sodium carbonate activated slag materials cured at ambient temperature

Abstract

The production of Portland cement (PC) which is the main binder in conventional cementitious materials contributes about 7% to the world’s anthropogenic carbon dioxide emission. As the demand for PC is expected to increase significantly in the coming years, it is imperative to find other environmentally friendly alternatives. Alkali-activated binders (AABs) obtained by alkali activation of aluminosilicate precursors are viable alternatives for PC as they possess lower embodied carbon and energy compared to PC. However, the conventional activators (i.e. sodium silicate and sodium hydroxide) are corrosive, expensive and have a high environmental footprint. These limitations have resulted in impractical and expensive applications of such binders on a large scale. On the other hand, sodium carbonate, which is less corrosive, cheaper and available naturally in the environment can be used as a sustainable alternative to sodium silicate and sodium hydroxide. In a quest to propel the application of sustainable binders, this study was undertaken to explore the properties of slag activated with sodium carbonate at ambient temperature. The effect of sodium carbonate dosage on the fresh, mechanical and durability properties are discussed. A simplified sustainability assessment of concrete made with different binders was also carried out and the results showed that the sodium carbonate activated slag concretes are a sustainable alternative to PC concrete to achieve a cleaner environment. • Sodium carbonate was used as an activator in alkali-activated slag systems. • Sodium carbonate activated slag can be used as an alternative to Portland cement. • Materials made with sodium carbonate activated slag exhibited good properties. • Sodium carbonate is more eco-friendly compared to sodium silicate/hydroxide.