Use of grounded iron ore tailings (GIOTs) and BaCO3 to improve sulfate resistance of pastes

Novel methods are explored to improve sulfate resistance for cement pastes by using grounded iron ore tailings (GIOTs), BaCO3 and both of them. Experiments were conducted on a plain cement paste and six blended cement pastes with different contents of GIOTs and BaCO3. All the pastes were exposed to two kinds of external sulfate attacks (a 5 wt.% Na2SO4 solution and a 5 wt.% MgSO4 solution). The effect of additions on the sulfate resistance of pastes was assessed by compressive strength, expansion and Vickers hardness. Mercury Intrusion Porosimetry (MIP), X-ray diffraction (XRD), Scanning Electron Microscope (SEM) and Energy Dispersive Spectrometer (EDS) were performed to clarify mechanisms of BaCO3 and GIOTs on sulfate resistance of pastes. As the results shown, both BaCO3 and GOITs can improve the capacity of pastes against to external sulfate attack. Pastes with interaction of BaCO3 and GIOTs present the highest sulfate resistance level under the both sulfate attacks.