Effect of red mud (bauxite residue) as cement replacement on the properties of self-compacting concrete incorporating various fillers

A huge transformation in the cement and concrete industry needs to be made to reduce the environmental pollution, especially carbon dioxide, in order to take consistent steps towards sustainable development. Concrete production has been increasing in the past decades and this is now one of the biggest concerns of researchers who follow a sustainable development approach. The use of waste materials in concrete production is a proven alternative to reduce the consumption of natural resources. On the other hand, red mud (RM), granite (GP) and marble (MP) waste powders, whose disposal has adverse environmental effects, have become environmental concerns in industrial areas. In light of these issues, employing alternatives to benefit from such valuable local waste materials, rich in silica, alumina, and ferric oxide, can be a great help to the environment. In this study, to evaluate the efficiency of using these materials in self-compacting mixes, the fresh and mechanical parameters were first determined, and then experiments on waste mixes produced with varying percentages of RM (2.5%, 5%, 7.5%, and 10%) as partial replacement of cement, besides using GP and MP as filler replacement (at 100%), were performed. Although application of RM negatively influenced the fresh properties, it was observed that a low level of RM incorporation along with MP and GP enhanced the mechanical properties of self-compacting concrete (SCC), e.g. a mix made with 2.5% of RM and 100% of GP can increase the compressive strength by 19% compared to that of the control mix. Depending on the local characteristics of RM, these conclusions are expected to apply to many locations worldwide. (C) 2019 Elsevier Ltd. All rights reserved.