Suitability of alkali activated slag/fly ash (AA-GGBS/FA) concretes for chloride environments: Characterisation based on mix design and compliance testing

Ground granulated blast furnace slag (GGBS) and fly ash are two of the most common industrial by-products used as precursors in an alkali activated material (AAM). Alkali-activated systems with fly ash as the sole precursor often require elevated temperature curing, while if made with GGBS alone can lead to flash setting, low workability and high degree of drying shrinkage. This article presents data from a range of GGBS/Fly Ash blends designed to avoid elevated temperature curing whilst achieving desirable fresh properties. Further, the suitability of such blended concrete for their use in chloride environments is outlined with the help of diffusivity testing and binding assessment. The results show that while attractive engineering properties can be achieved, chloride ingress in the AA-GGBS/FA concretes studied here with ≥20% fly ash is moderate to high. Reduction in pH resulting from the long term exposure to chloride solution also affected the ability of the binder to chemically or physically binding chlorides.