Synergistically Using Bauxite Residue (Red Mud) and Other Solid Wastes to Manufacture Eco-Friendly Cementitious Materials

Abstract

Bauxite residue (red mud) is a solid waste resulting from the aluminum production industry. Disposal or landfill of the red mud (RM) poses irreversible environmental problems; therefore, it is compelling to find practical solutions that can mitigate the negative environmental problems of RM stacking storage. In the past decades, although the recycling of RM has achieved significant progress, challenges remain from both academic and practical perspectives. Previous studies have demonstrated that all the aluminosilicate-based solid wastes have pozzolanic activity, and thus can be considered as resources to manufacture eco-friendly cementitious materials to relieve the carbon emission burden. Therefore, combining RM and other solid wastes to manufacture green cementitious materials has become a promising route to alleviate the burden of environmental pollutions. However, challenges from the fluctuation of the chemical compositions, inert activity, heavy metals stabilization, efflorescence, the side effects of the second pollutions from solid wastes, the hydration process, and mutual interaction mechanisms between the various types of solid wastes are still unclear, especially for multi-components RM-based cementitious materials. This review article summarizes the state of the art of mechanical properties, microstructure characterization methodologies, and hydration process and mechanisms of RM along with other solid wastes. The main challenges and future research trends are discussed. This article attempts to summarize the details of the RM recycling technologies that are beneficial to readers in understanding the background knowledge and research methodologies of eco-friendly cementitious materials.

The Precursors Used for Developing Geopolymer Composites for Circular Economy—A Review

“…Improper storage of these wastes can lead to air, soil, or water contamination, leading to a negative impact on the environment. In addition to this waste, there are other examples like glass [4] and bauxite waste [5]. Figure 1 shows the main stages of the circular economy.…”

Experimental Study on the Strength and Microstructure of Red Mud-Based Silty Sand Modified with Lime–Fly Ash

“…Although the global average rate of RM use is 15%, it is just 4% in China. The resource utilization rate of RM is significantly lower than the average of other forms of industrial solid waste [3,4]. RM is a solid waste containing high levels of alkalinity, heavy metals, and radioactivity.…”

Contribution to Understanding of Synergy between Red Mud and Common Supplementary Cementitious Materials

“…Although red mud, due to its lack of reactive silica, exhibits lower reaction than fly ash or slag, the idea of its use in construction materials is still present, also in synergy with other SCMs in cementitious or alkali-activated binders. [ 12 , 15 , 16 , 17 ]. High alkali content in red mud can promote hydration of Portland cement [ 12 ] and could help activate SCMs such as slag, fly ash or limestone.…”