Valorization of marble waste in mortar partial replacement of ciment

Abstract

Industrial marble processing activities generate massive volumes of discarded fragments, causing severe environmental challenges when left unmanaged. Upcycling these residues into construction materials offers an innovative solution that reduces waste and lowers the carbon footprint of building components. This dissertation investigates the incorporation of thermally activated marble powder (TAMP) into cement mortars and evaluates its effects on mechanical and fresh-state performance. The marble waste was manually collected, cleaned, ground, and thermally activated at 900°C for one hour. The experimental program was carried out using a standard Portland-limestone cement (CEM II/A-L 42.5 N, NA 442) mixed with local sand. Mortar mixtures were prepared with varying TAMP contents (0%, 5%, 10%, and 15% by weight of cement). Fresh properties were analyzed through consistency and Vicat setting time tests. Compressive strength was assessed at 3, 7, and 28 days using prismatic specimens, while flexural tensile strength and durability metrics (water absorption and mass loss) were measured at later ages. The results showed that the inclusion of 5% TAMP maintained excellent mechanical performance, retaining 98% of the 28-day control compressive strength. While higher substitution dosages (10% and 15%) experienced an early-age strength drop at 3 days due to binder dilution, their 28-day compressive values recovered past a structurally viable 31 MPa. Furthermore, the 10% and 15% mixes achieved a 3.9% and 3.5% increase in flexural strength, respectively, due to the micro-filler effect that densified the matrix and reduced capillary water absorption to 6.27%. In contrast, the 15% mix showed a higher mass loss under environmental exposure, highlighting performance limits at elevated dosages. This study demonstrates the technical feasibility of recycling marble fragments in mortar, offering a dual benefit: environmental protection through waste valorization and optimized material performance.