Engineering Landfill Liners for SDGs 6, 11, and 13: Comparative Consolidation Performance of Bentonite–Sand, Bentonite–Fly Ash, and Bentonite–Marble Dust Mixtures

Adhering to the Sustainable Development Goals (SDGs) for clean water and sanitation (SDG 6), sustainable cities and communities (SDG 11) and climate action (SDG 13) calls for landfill containment systems that are environmentally robust and resource-effective. Traditional B–S liners are highly dependent on natural sand (which is a limited resource) and contribute to the environmental footprint of waste disposal infrastructure. The compaction characteristics of B–FA and B–MD mix are also evaluated in the present work as an environmentally friendly alternative low hydraulic conductivity material to the traditional B–S liner, since it encourages circular use of materials leading to lesser resource extraction. For the purpose of simulating the effects of loading in a landfill setting, laboratory consolidation tests were performed on the B–S, B-FA and B-MD mixtures with different bentonite contents between 0 and 40% at intervals of 5%. Key consolidation parameters such as compression index, swelling index, coefficient of consolidation and settlement behaviour were evaluated on a systematic basis to assess the compressibility, stability and suitability for long-term use of each liner system. The results show that industrial wastes including FA and MD have a significant potential to improve the consolidation of bentonite-based liners and, therefore, achieve the same or superior consolidation parameters as traditional sand mixtures but with less use of virgin materials. The comparison demonstrates preferred mixes which promote integrity, controlled settling and low yield that afford for liner reliability. The inclusion of industrial waste materials in engineered landfill liners serves for groundwater protection and leachate containment (SDG 6), contributes to sustainable urban waste management infrastructure (SDG 11) and material engineering adapted for climate through waste valorization with lower GHG emission values towards carbon intensity reduction (SDG 13). These results offer a defensible basis on which to develop sustainable EBSs in support of the Sustainable Development goals.