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This paper presents the development of Bauxite residue (red mud) based cement composite mortar blocks for applications in pavement construction. The experimental techniques considered include the structural, thermal, morphological and microscopy analysis of the raw bauxite and red mud samples calcined at 800 °C. Composite mortar blocks of different batch formulations were produced and their physicochemical properties were investigated. The results show that the compressive strength of the as-prepared composite mortar blocks increased by ∼40% compared to the type M mortar strength of ∼2500 N/mm2. The load bearing applications of the composites are discussed to influence the adoption of the calcined red mud as supplement in the production of low-cost Portland cement based composite mortar blocks for the construction industry.

Brazil is one of the world greatest aluminum producer and also comprises a large industrial sector dedicated to the production of alumina (Al2O3) by the traditional Bayer process. During this process an insoluble residue, known as red-mud, is generated and normally discarded. A possible use for the red mud is its incorporation into clay ceramics. Indeed, this has been a solution not only for the red mud but also for residues of different industrial segments. The common clay, like the kaolinite, versatility allows the incorporation of several types of residues. The red mud, in addition to compounds like silica and alumina that are compatible with clays, is also composed of iron, sodium, calcium and other elements that confer important characteristics to ceramic products. Thus, the present work investigated the incorporation of up 60 wt% of distinct red muds, one as processed, in natura, and the other calcined at 900 °C, into clay ceramics. Both red muds act as inert materials without improving the pure clay ceramic properties.

Abstract: This paper studies the effect of 5wt% red mud particles addition to sol–gel films applied on AA2024-T3 aluminium alloy. The red mud powder was dried or calcined, previously to added to the sol–gel film, in order to analyzed the effect of the thermal activation. The RM particles were characterized using several techniques; x-ray diffraction (XRD), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results confirm that the thermal treatment leads to several phase transformations which affect to gibbsite, Al(OH)3, boehmite, AlO(OH), and goethite, FeO(OH), species. The anti-corrosion properties were evaluated by salt pray test and electrochemical impedance spectroscopy (EIS) techniques. Both types of studies indicate increased protecting properties of the sol–gel films doped with calcined red mud particles. Although the inhibition mechanism is not well-established, it must be related to the formation of reactive species during the heat treatment, which can evolve to mixed aluminium oxides in contact with the electrolyte. [Copyright &y& Elsevier]