Geotechnical characterisation of neutralised red mud for use in civil engineering construction and manufacturing

Abstract

Red mud is a toxic by-product from the hot, caustic refining of bauxite to produce alumina, and is produced in the form of an aqueous slurry. It is typically thickened, and transported to a surface storage facility. The volume of red mud generated worldwide is increasing dramatically, leading to a massive amount of red mud to be stored annually. In order to alleviate the ongoing demand for the storage of red mud, means by which it may be used in civil engineering construction and manufacturing are being investigated. Its suitability for use demands that it's geotechnical and geochemical behaviour and parameters be better understood. The geotechnical characterisation of the red mud sample involved the determination of its as­supplied moisture content, specific gravity, particle size distribution, and Atterberg limits. The geochemical characterisation of the red mud sample involved the determination of its paste electrical conductivity, pH, chemistry and mineralogy, which also influence its mechanical behaviour and responses to external loading. The critical geotechnical parameters of red mud, such as compaction, shear strength, compressibility and permeability, also need to be determined, as a function of its moisture state. This paper describes the results of a series of geotechnical and geochemical characterisation and geotechnical parameter testing of a red mud sample to determine its applicability and potential uses in civil engineering construction and manufacturing applications