Recycling Treated Municipal Solid Waste Landfill in the Cementitious Mix: Sustainable and Modified Concrete

Abstract

Municipal solid waste landfill (MSWL) deposits, after extended periods of natural degradation, tend to stabilize and become largely inert, presenting an opportunity for their safe recovery and reuse. This study evaluates the suitability of processed MSWL fines as a partial replacement for manufactured sand (M-sand) in concrete. The excavated material underwent a simple water-washing treatment aimed at improving gradation, reducing impurities, and enhancing overall quality. Comprehensive physical, chemical, and leaching assessments, including the toxicity characteristic leaching procedure, were performed to establish its compliance with construction standards. The washed MSWL material exhibited physical characteristics comparable to M-sand, while microstructural analyses confirmed a cleaner, more refined matrix with the presence of beneficial mineral constituents. Concrete mixtures were prepared by substituting M-sand with 5%, 10%, 15%, and 20% washed MSWL by weight. Mechanical testing revealed notable performance enhancement, with the 15% replacement mix showing the maximum improvement: 20.17% in compressive strength; 10.48% in split tensile strength; and 9.05% in flexural strength relative to the control. Microstructural evaluations using X-ray diffraction, scanning electron microscope, and energy-dispersive X-ray, together with leachability tests, verified the stability and improved hydration characteristics of the modified concrete. Durability assessments, including resistance to acid and sulphate environments and rapid chloride penetration test, further substantiated its long-term performance, with all MSWL-based mixes classified under “negligible” chloride permeability. Overall, the results demonstrate that washed MSWL fines can be effectively integrated as a sustainable alternative to M-sand, contributing to enhanced mechanical and durability performance while offering a viable pathway for landfill waste utilization.