Properties and microstructure of the hardened alkali-activated red mud-slag cementitious material

A new kind of alkali-slag-red mud cementitious (ASRC) material, with both high early and ultimate strength and excellent resistance against chemical attacks, has been developed by the introduction of composite solid alkali activator into slag-red mud mixture system. Tests on strength development and other properties such as resistance against carbonation, simulated seawater, diluted acid, sulfate solution and freeze and thaw cycles of the ASRC cement were carried out and the results were reported in this paper. Meanwhile, the microstructure of the hardened ASRC cement paste, such as porosity and pore size distribution, and morphological characteristics of the resultant cement stone were also analyzed with the aid of MIP, SEM, etc. The results showed that the hardened cement paste had almost integrated and very compacted structure, more appropriate pore structure and less coarse crystallized products, which were believed to be the physical reasons for its high early and ultimate strength and good resistance against chemical attacks. (C) 2003 Elsevier Ltd. All rights reserved.