Compressibility, Durability and Strength of Coal Fly Ash–Carbide Lime–Sodium Chloride Blends

The use of waste materials in civil construction is a topic of great relevance today. Carbide lime (CL) and fly ash (FA) are wastes generated in industrial processes. The mixtures of fly ash and carbide lime can be used in various applications in civil engineering, such as: making artifacts (e.g., blocks), base and sub-base for pavement and ground improvement. The combination of the two residues promotes the pozzolanic reactions in the formation of a binder. However, these reactions are slow and can be accelerated with the addition of a small portion of salt (NaCl). In this sense, the present study verifies the behavior of compressibility, durability and strength of coal fly ash–carbide lime–sodium chloride blends. Test of unconfined compression strength, one-dimensional consolidation, wetting and drying cycles and X-ray diffraction was performed. Results demonstrate that the addition of salt promoted a rapid consumption of hydrated lime [Ca(OH)₂] which generated an improved mechanical behavior of ash stabilized with carbide lime.