Industrial byproduct Iron ore tailings as ecofriendly materials in the utilization of cementitious composites

Iron ore tailings (IOT)-industrial byproducts-are un-floating minerals in the flotation process of raw ore. Their large stockpiles and low utilization rates have become pressing challenges. This study provides a cleaner production solution for the potential usage of IOT as ecofriendly fine aggregates in the cementitious composite. The mechanical properties, carbonation resistance, and freeze-thaw (F-T) cycle resistance of iron ore tailings cementitious composites (IOTCC) with different IOT replacement ratios were evaluated rigorously. The porefluid distribution and pore-three-dimensional distribution of IOTCC were investigated using nuclear magnetic resonance (NMR) and industrial computer technology (CT). The micro-morphologies of the IOTCC was characterized using scanning electron microscopy (SEM). Finally, the environmental impact of IOTCC was assessed. Results indicated that, compared to ordinary cementitious composites, the IOTCC exhibited the most remarkable mechanical properties, carbonation resistance, and F-T resistance, and had the lowest porosity as well as a denser, more homogeneous interfacial transition zone (ITZ) between the fine aggregate and the matrix under a IOT replacement ratio of 25 %. This was further confirmed by SEM observations. The porosities of the IOTCC decreased faster in the early stage of carbonization than in the subsequent stage. Otherwise, the porosities of the IOTCC increased with increasing number of F-T cycles. The gradual increase in the number of larger pores and deteriorated pore morphology was the main factor affecting their F-T resistance. The life cycle assessment further indicated that the IOT could help reduce environmental overload. The successful application of IOT as ecofriendly materials will further promote the sustainable development of the construction industry.