Alkali-activated slag modified by strongly basic anion exchange resin: Mechanical, microstructural, and durability studies

The durability issues of alkali-activated slag in chloride/sulfate environments limit its use in marine/saline regions. This study used 5 wt% NaOH solution to activate and prepare strongly basic anion exchange resin (SBAER) to enhance the chloride and sulfate corrosion resistance of alkali-activated slag. The effects of SBAER dosage on the mechanical properties and ion erosion behavior of the slag were systematically investigated. Results indicate that the sample containing 1.5 wt% SBAER exhibits the best performance, reducing the leaching rates of Cl - and SO 4 2- to 70.26% and 68.62% of those in the control group, respectively. As the SBAER dosage increases, the compressive strength of specimens at different ages first increases and then decreases. Analysis reveals that SBAER strongly adsorbs Cl - /SO 4 2- while releasing OH - to maintain a highly alkaline environment, thereby promoting hydration and densification, which inhibits the formation of harmful macropores. In addition, no visible cracks are observed on the surface of SBAER-treated samples. XRD and FT-IR analyses confirm that SBAER only adsorbs ions and does not alter the types of hydration products. Introducing SBAER as a functional modifier into alkali-activated slag materials effectively compensates for their insufficient corrosion resistance.