Surfaces of quartz tailings were modified in laboratory through calcining 850℃ for lh with carbide slag.The mineral phase, chemical compositions and the microstructure of the modified quartz tailings were analyzed by X-ray diffraction (XRD), scanning electron microscopy(SEM) and backscattered electron microscopy(BSEM).Meanwhile, the chemically combined bonding water content of hydrated modified quartz tailings and the strength of blended cement pastes and mortars containing unmodified and modified quartz tailings were measured.The microstructures of fractured blended cement pastes were investigated.The results show that the modified quartz tailing particle consists of a β-C2S layer and inert core.Hydration of β-C2S can generate CSH gel which densified the interface zone and enhanced the bonding strength between particles of quartz tailings and cement paste.Consequently, the strength of cement pastes and mortars with modified quartz tailings are improved effectively.