Effect of phosphate on the hydration of alkali-activated red mud–slag cementitious material

Abstract The influence of sodium phosphate on the hydration of alkali-activated red mud–slag cementitious material (AARS) is studied through microcalorimeter, X-ray diffraction (XRD), and energy dispersive spectroscopy (EDS). It is shown that sodium phosphate decreases the hydration heat evolution and retards the hydration reaction of AARS effectively. A new phase is found to form in this system. The retarding mechanism is greatly attributed to the forming of this new phase. The composition of the new phase is identified and analyzed.