A series of laboratory tests were conducted to investigate the possibility of using sulfur iron ore tailings (SIOT) in GGBS-metakaolin based alkali-activated mortar (AAM) as grouting material. The results indicate that increasing SIOT content leads to a longer setting time of the mortar. This leads to the activation of SIOT particles within the mortar, thereby creating a denser microstructure. The X-ray diffraction (XRD) patterns reveal more pronounced peaks associated with the calcium-aluminosilicate-hydrate (C-A-S-H) network in specimens containing 25 % and 50 % SIOT and 10 % MK. These specimens demonstrate superior sulfate resistance, freeze-thaw resistance, and reduced drying shrinkage. The compressive strengths decrease nonlinearly with higher SIOT content, likely due to a reduction in calcium ions (Ca²⁺) which impedes the formation of the C-A-S-H network. While the compressive strengths exhibit minimal variation between 3 and 7 days of curing, there is a significant increase after 28 days. The ratios between compressive and flexural strengths of the mortar specimens exceed 4.5. Poorly crystallized gypsum was observed in the XRD patterns, resulting from the interaction between sulfates from SIOT and Ca²⁺ from GGBS, which may influence the overall performance of the mortar.