Abstract: This paper presents fracture response of alkali-activated slag (AAS) mortarswith up to 30% (by volume) of slag being replaced by waste iron powder whichcontains a significant fraction of elongated particles. The elongated ironparticles act as micro-reinforcement and improve the crack resistance of AASmortars by increasing the area of fracture process zone (FPZ). Increased areaof FPZ signifies increased energy-dissipation which is reflected in the form ofsignificant increase in the crack growth resistance as determined fromR-curves. Fracture response of notched AAS mortar beams under three-pointbending is simulated using extended finite element method (XFEM) to develop atool for direct determination of fracture characteristics such as crackextension and fracture toughness in particulate-reinforced AAS mortars.Fracture response simulated using the XFEM based framework correlates well withexperimental observations. The comprehensive fracture studies reported hereprovide an economical and sustainable means towards improving the ductility ofAAS systems which are generally more brittle than their conventional ordinaryportland cement counterparts.