Experimental and Energy Accounting Study on Waste Glass Powder Soil Stabilisation for Low-Carbon Mining Infrastructure

Stabilisation of weak subgrades in mining and infrastructure projects traditionally relies on cement and lime, leading to high embodied energy and carbon emissions. Although waste glass powder (GP) has been explored in previous studies, existing work has primarily focused on isolated mechanical or material characteristics, with limited emphasis on integrated performance metrics. This study addresses this gap by establishing a mechanical–energy–carbon evaluation framework for assessing GP as a low-carbon stabiliser for black cotton (BC) and kaolinite clay (KC) soils. Laboratory investigations were conducted to evaluate the index, compaction, strength, and swelling characteristics at GP dosages ranging from 0% to 20%. Results showed a marked decrease in liquid limit (from 76% to 61% for BC and 45% to 32% for KC) and optimum moisture content, accompanied by a concurrent increase in maximum dry density. Strength improved substantially, with UCS reaching 95 kN/m2 (BC) and 100 kN/m2 (KC) at 15% GP. CBR values increased threefold, while DFSI decreased by 45–75%, indicating improved volumetric stability. Energy accounting revealed an 80–85% lower embodied energy compared to cement, with carbon savings of approximately 52 kg CO2/t. The proposed Energy Performance Index confirmed superior strength per unit energy efficiency of GP. Valorising post-consumer glass aligns with circular economy principles and UN SDGs 9, 12, and 13, offering a low-carbon stabilisation strategy for energy-efficient mining operations.