Advanced sustainable construction materials from hazardous iron ore treatment waste, concrete debris and lime production waste

It was developed new sustainable cement-less concretes from hazardous iron ore treatment sludge in composites with production/demolition debris and lime production waste with high mechanical and physical properties, corresponding to the Brazilian norms. Their axial resistance values on the 3rd day of hydration were until 2.34 MPa, on the 28th day up to 3.94 MPa, on the 180th day 8.40 MPa, and on the 365th day 10.22 MPa. The expanding coefficient on the 3rd day was until 2.13%, 2.51% on the 28th day, and on the 365th day 2.22%. Water absorption on the 28th day was 7.17–9.32% and decreases to 6.26–8.64% on the 90th day. All these characteristics correspond to the Brazilian norms. The physical–chemical processes of the materials’ structure formation included alkaline dissociation of solid particles’ surface, with sol appearing and densification until transition to gel. Long-lasting gel compaction and densification to stone-like condition made its structure similar to natural rock materials - silica, opal, obsidian, perlite, pumice, amber, flask, etc. They can be used for production of road bases, concrete blocks, and solid unburned bricks, among other sustainable construction materials. Their ​​axial resistance values on the 3rd day of hydration were until 2.34 MPa, on the 28th day up to 3.94 MPa, on the 180th day 8.40 MPa, and on the 365th day 10.22 MPa. The expanding coefficient on the 3rd day was until 2.13%, 2.51% on the 28th day, and on the 365th day 2.22%. Water absorption on the 28th day was 7.17–9.32% and decreases to 6.26–8.64% on the 90th day. The study of the structures’ formation processes using a complex of modern complementary methods (FRX, XRD, SEM-ED, LAMMA, leaching, and solubility of metals by AAS) showed the synthesis of sol–gel amorphous solutions, passing over time into a stone-like state similar to natural rock materials - silica, opal, obsidian, perlite, pumice, amber, flask, etc. Therefore, they can be used for production of road bases, concrete blocks, and solid unburned bricks. The greatest benefit from the application of the results obtained is the environment, considering the real possibility of using industrial waste as raw materials, applying an appropriate final destination, preventing possible contamination of the environment, and reducing the extraction of natural resources.