Durability of carbonated MgO concrete containing fly ash and ground granulated blast-furnace slag

This study investigated the durability of carbonated reactive MgO cement (RMC) concrete containing fly ash (FA) and ground granulated blast-furnace slag (GGBS) under conditions involving exposure to sodium chloride, sodium sulfate, freeze-thaw cycling and seawater for up to 6 months. RMC samples were compared in terms of their performance to Portland cement (PC) samples. Changes in sample structure were analyzed by XRD, TGA and SEM. Amongst all the conditions used, sulfate attack led to the most obvious reduction (10.7-17.8%), whereas seawater had the lowest influence (5.8-6.9%) on strength at 6 months. RMC samples revealed a better performance over PC samples in sulfate attack and freeze-thaw cycling, which was associated with the stability of their phases under aggressive environments. Addition of FA and GGBS improved the durability of RMC concrete by enabling denser microstructures and formation of phases that were stable under the tested conditions. (C) 2018 Elsevier Ltd. All rights reserved.