Sustainable material manufacturing from hazardous bauxite red mud in composites with clay slate waste and lime production waste

Abstract

The primary purpose of this study was to experimentally validate the possibility of using hazardous red mud (RM) from bauxite ore treatment and clay slate mining wastes (SW)—scraps of slabs and polishing sludge—as the main raw components in composites with poorly burned limestone as lime production wastes (LPW) here used as a binding additive. Mixtures of these components were homogenized, hydrated, and compacted with a compressive strength of 10 MPa. The incorporation of 15–30% LPW led to axial strength values of 4.7–12.8 MPa on the 28th curing day and 10.6–23.7 MPa on the 365th day. The results of XRF, XRD, AAS, and SEM with EDS, DTA-TGA, and LAMMA analyses showed that all mechanical properties of the developed materials were enhanced due to the synthesis of new formations, mainly amorphous and partly crystalline, during the microstructural densification of the composites. The developed materials can be used as road base and airfield runways, levee cores, industrial and municipal waste dumps, building foundations, and production of tiles, bricks, and blocks. The most important contribution of this study is the convincing experimental evidence of an efficient engineering solution to the ecological problems of three types of industrial enterprise, without the use of expensive traditional market materials such as Portland cement or commercial lime, preventing the accumulation of large amounts of these wastes in industrial dumps. Furthermore, it would significantly reduce nature’s irreversible destruction by quarries of natural raw material like clay, sand, and crushed stone.