Sustainable Ground Improvement of Sandy Soils Through Artificial Cementation: An Integrated Numerical Investigation of Mechanical Behaviour and Foundation Performance

This study investigates the sustainable optimisation of cement-treated calcareous sandy soils using an integrated finite-element framework that links material-scale mechanical behaviour to foundation-scale response. Experimentally derived shear-strength parameters obtained from drained triaxial tests on sands treated with 1%, 2%, and 4% Portland cement were incorporated into COMSOL Multiphysics simulations to evaluate stress–strain behaviour, plastic deformation, displacement response, and bearing capacity under strip-footing loading conditions. The results demonstrate that artificial cementation substantially enhances soil behaviour by increasing apparent cohesion and limiting plastic deformation. Bearing capacity increased from 816.64 kPa for untreated sand to 5684.64 kPa, 8981.64 kPa, and 13,431.64 kPa for soils treated with 1%, 2%, and 4% cement, respectively. Concurrently, footing displacement and plastic strain development decreased progressively with increasing cement content. Cement stabilisation also improved stress distribution beneath the foundation and confined failure zones to smaller regions surrounding the footing, indicating enhanced foundation stability. To evaluate environmental performance, a quantitative embodied carbon assessment framework incorporating the Carbon Efficiency Index (CEI) and Carbon Intensity Index (CII) was developed. The results indicate that although the 4% cement treatment achieved the highest bearing capacity, the engineering benefit obtained per unit of embodied carbon decreased with increasing cement dosage. The 1% cement treatment exhibited the highest carbon efficiency, whereas the 2% cement treatment provided the most favourable balance between geotechnical improvement and environmental efficiency. The proposed framework integrates finite-element-based foundation analysis with embodied carbon assessment, establishing a direct relationship between soil-strength enhancement, foundation response, and carbon efficiency. The findings demonstrate that substantial improvements in bearing capacity can be achieved without proportionally increasing environmental impacts, supporting performance-based optimisation and sustainable ground-improvement design for sandy soils in arid regions.