Limestone calcined clay cements (LC3) produced with iron ore tailings and ceramic waste: Hydration, mechanical performance and rheology

The search for suitable raw materials for limestone calcined clay cement (LC3) production becomes crucial for enabling its global production. In this work, LC3 with calcined kaolinitic iron ore tailings (CCT) and ceramic tile waste (CW) as replacements for natural calcined clay (CC) were produced. Rheology, hydration (isothermal calorimetry), and hardened properties (phase assemblage and compressive strength) were evaluated. We found that CC led to the highest yield stress and viscosity, while its partial/total replacement with CW and CCT improved LC3 fresh performance. Replacing CC with CW did not affect sulfate balance, while CCT reduced it by 1.0 wt%. CCT showed the highest chemically bound water (TGA) and AFm presence (XRD) at 1 day, correlating with higher calorimetry heat up to 3 days. However, this did not translate into higher early-age compressive strength due to aluminate phase reactions and higher porosity of the CCT-containing hardened paste. Nonetheless, LC3 produced with CW or CCT met 40/42.5 standard cement strength classes.