Microstructure Evolution in Ordinary Portland Cement–Metakaolin–Red Mud-Based Ternary Blended Cement

The microstructure plays a vital role in governing the physical, chemical and strength properties of cement. Hence, microstructure analysis has been carried out by replacing 0% to 14% of the mass of ordinary Portland cement with metakaolin and red mud of different ratios. Studies have also been carried out to understand the effect of blending on the pH of cement paste and its influence on the setting time. The normal consistency of cement and red mud mix is found to be proportional to the percentage of replaced red mud and is attributed to the presence of finer particles in red mud. The cement paste without any addition has the lowest water requirement (28.5%) compared to the cement with metakaolin and red mud. The study shows that the strength of OPC having 80:20 MK:RM blend is high and is attributed to the pozzolanic reaction of MK and the RM particles which imparts filler effects to the concrete.