Environment-Friendly Cementless Concretes from Hazardous Metallurgical Wastes

This chapter presents the results from the study of new compositions of construction materials developed from hazardous, highly alkaline (pH = 13.5) sludge of red mud from bauxite tailing (52–78 wt. %), ground-cooled converter slag (20%–45%) and lime production waste (LPW) (2%) to develop new cementless concrete-like construction materials and study the structure formation processes of the new composites during their hydration and strengthening processes. The axial compressive strength increased progressively over time, reaching 1.8 MPa at 3 days, 3.4 MPa at 7 days, 6.2 MPa at 14 days, and 11.2 MPa after 365 days of hydration. The linear expansion coefficient ranged from 0.3% to 3.64%, while the water absorption (WA) coefficient varied between 1.8% and 9.31%. The processes of the materials structure formation were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), atomic absorption spectroscopy (AAS) and laser micro-mass analysis (LAMMA) methods. The solubility and leaching of metals by the AAS method showed the compliance of the new compositions with Russian sanitary standards.