<p> The growing demand for concrete in the construction sector has led to an increased necessity to extract raw materials, resulting in the depletion of natural resources. In order to conserve these natural resources, the current study was conducted to assess the viability of employing silico-manganese slag, a byproduct generated during the manufacturing of silico manganese alloy, as coarse aggregate in concrete. The study examines the mechanical and durability characteristics of M25 grade concrete using silico manganese slag as a replacement for coarse aggregate at different levels: 20%, 40%, 60%, 80%, and 100%. The concrete samples underwent analysis to assess their various mechanical properties, and all the replacement levels achieved the target strength of 25&#xa0;MPa. Even though there are slight variations in strength among the various mixes, SM 100 shows a compressive strength of 28.16&#xa0;MPa, higher split tensile strength, flexural strength, and workability. Considering this performance along with the greater utilization of SiMn slag, SM 100 is acknowledged as the optimum mix. Durability of the materials was assessed by considering parameters such as water absorption, chloride ion permeability, exposure to high temperatures, and susceptibility to sulphate attack. The durability tests also demonstrate that employing 100% slag (SM 100) as a coarse aggregate for concrete construction is effective in the long run. Scanning electron microscopy and energy-dispersive X-ray spectroscopy analysis are conducted to study the microstructural behaviour and elemental composition, which shows a dense and globular structure in SM100 compared to normal concrete. A life cycle analysis is also carried out to understand the environmental impact of utilization of SiMn slag in concrete as a replacement of coarse aggregate.</p>