Strength development and microstructure of hardened cement paste blended with red mud

Abstract

Red mud was activated to be a mineral admixture for Portland cement by means of heating at different elevated temperatures from 400 °C to 700 °C. Results show that heating was effective, among which thermal activation of red mud at 600 °C was most effective. Chemical analysis suggested that cement added with 600 °C thermally activated red mud yielded more calcium ion during the early stage of hydration and less at later stage in liquid phase of cement water suspension system, more combined water and less calcium hydroxide in its hardened cement paste. MIP measurement and SEM observation proved that the hardened cement paste had a similar total porosity and a less portion of large size pores hence a denser microstructure compared with that added with original red mud.

Keywords

thermal treatment / activation / red mud / cement / microstructure / strength

References

[1] Liang Hua. Recent Trend of the Research on the Utilization of Red Mud[J]. World Nonferrous Metals, 1999, (3): 32–34

[2] Jiao Zhanzhong, Xing Guo, Wang Huamin. Preparation of Brick from Red Mud without Steam Curing or Sintering[J]. Lightweight Metal, 1996, (6): 16–19

[3] Wang P., Li G., Liu S. Study on Preparation of Ceramsite Using Industrial Solid Wastes[J]. Chinese Mineral Industry, 2003, 12(12): 74-77.

[4] Zhang Qinghe, Zhuang Jianming, Wang Longqian. Present Status of the Utilization of Red Mud and Its Application in Plastics Manufacture[J]. Multipurpose Utilization of Mineral Resources, 1994, (1): 37–40

[5] Pan Z., Yang N., Masuda T., . Changes of Physicochemical Properties of ALC Powder-Ca(OH)₂ Mixtures by Heating Treatment[J]. Inorganic Materials, 1998, 5(11): 498-503.