Exploring natural and accelerated carbonation of alkali-activated slag

The present study explores the natural and accelerated carbonation of alkali-activated slag. Six different activators of NaOH, Na₂SiO₃, Na₂CO₃, Na₂SO₄, CaO or MgO were used to make alkali-activated slag samples, and samples were accelerated-carbonated for 28 days or naturally-carbonated for 2 years. The types of calcium carbonate formed after carbonation varied depending on the activator and the carbonation condition. The stability of hydrotalcite-like layered double hydroxide was found to be underestimated when exposed to accelerated carbonation conditions, thus requiring caution when testing the durability performance of these materials under such conditions. CaCO₃ and the highly crosslinked aluminosilicate gel were the predominant carbonation products in both accelerated and natural carbonation, with the effects on the Al local environment differing between the carbonation conditions.