Properties and microstructure of blended cement containing activated iron tailings powder

To solve the environmental problem of iron tailings, the preparation of green binding materials using iron tailings powder (ITP) shows bright prospects. However, the low activity of ITP limits its use as supplementary cementitious materials in large amounts. In this work, the activity of ITP treated for different milling times and at different sintering temperatures was studied, as well as the effects on the properties and microstructure of blended cement. It was found that ITP has a filling effect and provides additional nucleation sites. Additionally, ITP exhibits pozzolanic activity and consumes more hydration products at the later stage, which promotes the formation and deposition of C-S-H. All of these factors are related to the specific surface area (SSA) of the ITP and provide the conditions for cement paste densification, laying a foundation for the strength of cement blended with ITP. In summary, the activity of activated ITP is related to its SSA. It takes a long time for ITP to show pozzolanic activity. Activated ITP undergoes a secondary reaction to form a hydration product. The environmental impact and cost of pure cement pastes were higher than those of the cement–ITP pastes.