Mechanistic evaluation of sustainable soil stabilization using calcium-rich oil well drilling waste

Sustainable reuse of oil-well drilling waste (DW) offers a promising approach to soil stabilisation and waste management. This study investigates calcium-rich DW (5% and 10%) to improve four cohesive soils through chemical, microstructural, geotechnical, and leaching analyses. The high CaO content (≈48%) promotes physicochemical modification and cementitious reactions, reducing plasticity, swelling, and hydraulic conductivity while improving strength and bearing capacity. Unsoaked CBR increased by up to 328%, UCS nearly doubled after 28 days, and swelling pressure decreased by up to 80%. Limited leaching under the tested conditions suggests potential environmental benefits. However, the relatively high LOI of Soil C (12.57%) introduces uncertainty about calcium availability. Overall, calcium-rich DW demonstrates potential as a sustainable stabiliser for fine-grained soils.