STUDY ON THE STRENGTH CHARACTERISTICS OF CARBONATED RED MUD CONCRETEM. JOTHILINGAM AND PRATHEEBA PAUL
Red mud is a waste material generated by the Bayer Process widely used to produce alumina from bauxite throughout the world. Depending on the raw material processed, 1 - 2.5 tons of red mud is generated per ton of alumina produced. The main chemical constituents of red mud are Al2O3 (16.35%), SiO2 (7.99%), CaO (9.06%), MgO (0.45%), Fe2O3 (42.33%), TiO2 (5.99%), Na2O (4.6%) and LoI (10.2%). It indicates that percentage of CaO is very less hence it has no cementitious properties but when it reacts with water and cement it starts gaining cementitious properties. Also percentage of silica available contributes to strength. It can be used as a partial replacement for cement up to 20% and the compressive strength and split tensile strength are comparable with conventional concrete. Curing water analysis concluded that pH was in alkaline range due to alkaline nature of Red mud since NaOH is used in Bayer process. Chlorides and Sulphates are within the permissible limit. Heavy metal concentrations in curing water is below the detectable limit whereas Fe, Na and Al are detectable and non-hazardous. Further an attempt has been made to conduct carbonation test on Red mud concrete to evaluate its mechanical properties. The obtained results are compared with the conventional concrete in this paper.
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