A Review on the Durability of Alkali-Activated Fly Ash/Slag Systems: Advances, Issues, and Perspectives

Alkali-activated materials (AAMs) have high potential as alternative binder to ordinary portland cement (OPC), because of their high performance beside lower CO2 emissions. While there is a general consensus about their strength advantages over OPC, there is a widespread debate regarding their durability. Some groups believe that the availability of wide scientific/technical background, together with the already-known OPC durability problems, are sufficient for their commercialization; however, others consider the durability of AAMs to be an unproven issue. This controversy represents one of the limitations facing their bulk applications. The present work provides an overview of the latest developments on durability of fly ash/slag-based AAMs with the aim to update recent findings regarding their behavior under aggressive conditions (sulfates, freeze–thaw, chloride, carbonation, acid, efflorescence). This review will provide a better understanding of the durability issues of AAMs, which will stimulate further research to develop the appropriate testing methods and help to promote their commercialization.