Performance of reactive magnesia cement formulations containing fly ash and ground granulated blast-furnace slag

This study investigated the performance of carbonated reactive MgO cement (RMC) and sealed MgO-SiO2 (RMS) concrete formulations. Fly ash (FA) and ground granulated blast-furnace slag (GGBS) replaced half of the binder component in each system. The assessment of hydration mechanisms via isothermal calorimetry was supported by performance evaluation involving the measurement of permeable pores and compressive strength. Samples were also studied via x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and field emission scanning electron microscopy (FESEM). The formation of a continuous carbonate network was responsible for the strength development of RMC samples, whereas hydrate phases such as M-S-H were observed in RMS samples. Partial replacement of RMC with GGBS led to similar performances under carbonation. RMS samples revealed comparable strengths to PC-based samples, highlighting the potential of MgO-SiO2 binders to be used in similar applications without requiring any special curing conditions. (C) 2019 Elsevier Ltd. All rights reserved.