Mechanical performance and sustainability assessment of copper slag mortar for masonry structures

The need to utilize industrial by-products effectively to meet the increasing demands for sustainable building materials, to decrease dependence on natural resources and maintain structural integrity has necessitated an evaluation of the potential of copper slag (CS), a by-product from copper smelting, as a fine aggregate substitute in 1:6 (M2) mortar and subsequently as a building material for masonry construction. The study evaluated mortar mixes containing 0–100% CS substitution for their fresh properties, compressive strength, and microstructure. The brick masonry prism samples prepared using CS-containing mortars were analyzed for compressive strength, masonry efficiency, and modulus of elasticity (MOE). A sustainability-oriented evaluation was conducted through the analysis of embodied energy (EE) and associated costs. Predictive modeling was also used to compare the experimental data to that predicted using existing empirical models. The results showed that increased levels of CS resulted in significantly increased workability due to the CS's smooth surface texture and low water absorption. At the replacement level of 25% CS content was determined to be the optimal level for producing a mortar with the highest compressive strength. The masonry prism specimens prepared with 75% CS-mortar demonstrated the greatest increase in compressive strength, masonry efficiency, and MOE compared to all other masonry prism specimens. Furthermore, significant decreases in EE and material cost were observed with each increase in CS content. The novel contribution of this study is the comprehensive, multi-scale approach that integrates mortar performance, masonry efficiency, microstructural mechanisms, sustainability metrics, and predictive modeling into a single experimental program, thereby providing reliable data to support the use of resource-efficient masonry construction methods.