Film-Forming Property of Cement Paste with Red Mud as a Supplementary Cementitious Material

Abstract

Red mud has been used as a supplement substitute material in the fabrication of concrete. However, the influence mechanism of red mud on the film-forming performance of cement paste is still unclear. In this study, red mud with different substitution rates (by cement mass) was added to cement paste to investigate the influence of red mud on the film-forming performance. The addition of red mud increased the cohesiveness and reduced the fluidity of cement paste. It showed that low fluidity reduced the film thickness of cement paste, and the film thickness decreased gradually with the increase of red mud substitution. Moreover, thermogravimetric analysis, X-ray diffraction, and scanning electron microscopy results demonstrated that red mud promotes the hydration process of cement by providing hydration nucleation sites, making the interfacial transition zone denser, which is important for improving the mechanical properties of cement paste. It is expected that this study improves the application of red mud in concrete.