The Effect of Bayer Red Mud Blending on the Mechanical Properties of Alkali-Activated Slag-Red Mud and the Mechanism

In this paper, Bayer red mud and ground granulated blast furnace slag were formed into three different ratios (7:3, 5:5 and 3:7) of alkali-activated cementitious materials (AASR) using a water glass solution as the alkali activator. By studying the compressive strength of different red mud content, the effect of Bayer red mud content on the mechanical properties of AASR was analyzed. The influence mechanism of red mud content on the mechanical properties of AASR was revealed by the variation of micro-porosity, connected porosity, Isothermal calorimetry, XRD, FTIR, and BSE/EDS testing techniques. The results show that the compressive strength of the specimens at the same age decreases with the increase of red mud content. On one hand, the addition of red mud makes the connected porosity in the AASR system increase, and the densification of the slurry structure decreases; on the other hand, the inert minerals in red mud participate in the hydration reaction to a lesser extent, the overall hydration reaction process becomes lower, and the generation of hydration products providing strength decreases.