Durability of alkali activated slag in a marine environment: Influence of alkali ion

The durability of alkali-activated steel electric arc furnace slag (EAFS) in a marine environment was evaluated with respect to the chemical composition of the alkaline activator. Two different alkaline activators have been used: a mixture of NaOH and Na2SiO3 solutions (Na-activator), as well as a mixture of KOH and K2SiO3 solutions (K-activator). The obtained results gave the insight into the influence of alkaline activator chemistry on the compressive strength and durability of alkali-activated slag (AAS), which was exposed to the damaging seawater environment. The porosity of AAS was found to be the most important factor with regards to the strength and durability of these materials in marine environment. Sodium based alkali-activated slag (Na-AAS) displayed lower porosity and higher compressive strength compared to potassium based AAS (K-AAS). Lower porosity and thus a lower rate of water uptake by AAS matrix, i.e., the lower sorptivity was exhibited by the Na-AAS when compared to K-AAS. Hence, Na-AAS exhibited better durability in a marine environment.