EFFECT OF CARBONATION ON PROPERTIES OF ALKALI-ACTIVATED SLAG BINDERS

AAS binders activated by water glass (WG) and sodium hydroxide (NaOH) solution was used to investigate its carbonation properties. Carbonation product, carbonation shrinkage, and effect of carbonation on pore structure of AAS paste were studied. Compared with noncarbonated one, when AAS paste was carbonated, specific surface area and cumulative pore volume increased, and average pore diameter and most probable pore diameter reduced. As for carbonation product, the main form of CaCO3 is calcite, and the phases as vaterite and aragonite are lesser. The amount of aragonite and vaterite increases with the increase of carbonation age. During carbonation, the shrinkage only comes from the migration of Ca2+ from C-A-S-H gel and the increase of degree of polymerization (DP) of C-A-S-H gel. Carbonation process of AAS paste doesn't increase the dry shrinkage.