Waste Valorization Pathways for the Development of Advanced Inorganic Materials

Currently, the large amount of waste and the by-products of technological processes represent a significant problem for the environment. The limited storage capacity, as well as the uncontrolled disposal of waste or industrial by-products in landfills, represent growing concerns for environmental protection. The recovery of waste can be done for the purpose of formulating new alkaline-activated inorganic materials, obtained from precursors such as fly ash, blast furnace slag, silica fume, glass powder, etc. In this study, material formulations were designed using fly ash, furnace slag and silica fume, in order to evaluate their influence on the mechanical and chemical performances of the inorganic materials obtained by KOH attack at ambiental temperature. The obtained materials present advanced mechanical characteristics (compressive strength, flexural strength, adhesion to the substrate) as well as high durability, due to the formation of compact and chemically stable structures. The samples with the addition of slag show a consistent increase in compressive strength, with values over 70 MPa ​at 28 days, thus confirming the essential role of slag as an active binder. Regarding chemical resistance, slag-based formulations showed improved resistance in acidic environments, with maximum mass losses of 4%. According to the results obtained, it can be concluded that the type of precursor influences the nature of the reaction gel formed and, implicitly, the overall strength of the material. The use of wastes for the development of inorganic materials with high properties and applications in the construction industry represents a promising research direction.