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Herein, micro iron ore tailings (micro-IOTs) were prepared by wet-grinding and applied to improve sulphoaluminate cement (SAC) performance. The physicochemical properties of micro-IOTs were investigated by particle size analysis, XRD, and XPS. The hydrates trait and the hydration mechanism of micro-IOTs-SAC composite were studied by XRD, TGA, MIP, and SEM. The results demonstrated that micro-IOTs with an average grain diameter of 517 nm could be obtained by wet-grinding. The setting time of SAC gradually decreased with increasing micro-IOTs content. By adding 2% micro-IOTs, the compressive strengths of SAC pastes were enhanced about 22% and 10% at 4 h and 28 d, respectively. Moreover, the addition of micro-IOTs accelerated ettringite precipitation and changed its morphology, resulting in early strength improvement of the binary system. And increased later strength by micro-IOTs was closely related to the high content of AH 3 , fine pore structure, and high hydration degree of SAC. The findings suggested one new approach to utilize iron ore tailings in cementbased materials.

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