FINE FRACTION OF IRON ORE TAILINGS AS MINERAL ADDITION IN SELF-COMPACTING MIXTURES
Name: MARCELLY PIRES DE SOUSA RAMOS CIPRIANO
Publication date: 08/02/2024
Examining board:
Name |
Role |
|---|---|
| ALEXANDRE LIMA DE OLIVEIRA | Examinador Externo |
| AUGUSTO CESAR DA SILVA BEZERRA | Examinador Externo |
| PAULO RICARDO DE MATOS | Examinador Externo |
| RUDIELE APARECIDA SCHANKOSKI | Presidente |
Summary: compressive and flexural strength, ultrasonic pulse velocity, void index, scanning electron microscopy, and mercury intrusion porosimetry (MIP). Isothermal calorimetry was also conducted on pastes to evaluate the cement hydration kinetics. It was found that the SCMs anticipated the induction period compared to the reference, with minimal impact on its duration. Otherwise, the heat release was most affected, with LF increasing it by 8%, 14%, and 17% at 10%, 20%, and 30% content, and MF rising it by 9%, 13%, and 22%. Mortars with SCMs showed improved spreading compared to the reference, with MF enhancing it by approximately 8%, 10%, and 15% at 10%, 20%, and 30% replacements, surpassing limestone filler at the same levels. MF, at 10%, 20%, and 30% replacements, reduced V-funnel times by around 30%, 31%, and 27% respectively compared to LF. At 28 days, mortars with MF showed around 6%, 4%, and 2% higher compressive strength than mLF at 10%, 20%, and 30% substitutions respectively. The mortar with 20% of MF incorporation had a cement index almost 13% lower than the reference mixture, implying a reduction of 65 kg of cement and the incorporation of 133 kg of tailing for a mortar with a strength of 50 MPa. MIP results showed that this same mixture had a pore volume >200 nm 50% smaller than that with 20% of LF, with a slightly lower total porosity. Overall, the use of the fine fraction of iron ore tailings as SCM in self-compacting mixtures is feasible for contents up to 30% and environmentally advantageous compared to the use of LF.
