Experimental study on the preparation of cementitious materials from iron ore tailings by activation

Studies have shown that iron tailings (IOT) have potential activity and can be used to prepare cementitious materials to replace cement.The purpose of this study was to evaluate the effects of different activation methods, activation time and activator types on the properties of IOT cementitious materials.Different mechanical activation time (0.5 h, 1 h, 1.5 h, 2 h, 2.5 h, 3 h), different mechanical-chemical activation time (0.5 h, 1 h, 1.5 h, 2 h, 2.5 h, 3 h) and different activator content sodium sulfate (NS) (0.5%, 1.0%, 1.5%), desulfurized gypsum (DG) (0.5%, 1.0%, 1.5%) and metakaolin (MK) (5%, 10%, 15%) were used for activation. The compressive strength, flexural strength, frost resistance and sulfate resistance of active IOT cementitious materials were analyzed and discussed. The results show that the performance of cementitious materials can be significantly improved after IOT activation, and the performance is significantly improved when 10 % metakaolin is activated by mechanical-chemical coupling for 1.5 h. In addition, after 28 days of curing, the mechanical activation (1.5 h), mechanical-chemical coupling activation (NS-1%-1.5 h, DG-1%-1.5 h, MK-10%-1.5 h) were compared with the baseline grou (XRD, SEM). The results show that under the action of mechanochemical coupling activation, IOT can increase the specific surface area, improve the surface energy and activity, increase the degree of participation in hydration reaction, promote the formation of a large number of acicular ettringite(AFt) and hydrated calcium silicate (C-S-H) gels, and improve the pore structure of hydration products, resulting in a denser microstructure, thereby improving mechanical properties.