A Low-Carbon Composite Cementitious Material Manufactured by a Combined Process of Red Mud

In present study, the effects of varying dosages of combined red mud on the microstructure and hydration process of low-carbon composite cementitious material. The findings indicated a gradual decrease in the reactivity of RM, following a linear trend. The non-evaporable water content of the composite binder exhibited an initial increase followed by a subsequent decrease, with the optimal content identified at 10%, for RM content ranging from 10% to 90%, non-evaporable water decreases linearly. Optimal bending strength and compressive strength were achieved in the mortar when incorporating 10% of RM, reaching 8.56 MPa and 51.2 MPa at 28 days, respectively. The porosity was at its lowest when the RM content was added at 10%, but further increasing RM dosage was reversed. The pore size distribution aligned with the experimental findings on porosity. X-ray diffraction (XRD) analysis revealed the involvement of RM in the secondary hydration reaction, thereby enhancing the mechanical properties of low-carbon composite cementitious material. The optimal content of RM is suggested to be 10%, with a maximum recommended limit of 30%. The analysis has shown that red mud particles serve a dual purpose in low-carbon composite cementitious material. They enhance compactness by acting as fillers and promote cement hydration through surface activity, thereby enhancing mechanical properties, durability, and pore size distribution.