Experimental Investigation of Marine Soil Stabilization with Recycled Aggregates and MgO: Implications for CO<sub>2</sub> Sequestration

Dredged marine soils are increasingly recognized as a valuable resource amidst growing environmental concerns and the need for sustainable waste recycling. This study presents an innovative soil stabilization technique combining recycled aggregate (RA) and magnesium oxide (MgO), with a dual focus on enhancing soil properties and promoting carbon dioxide (CO2) sequestration. The stabilizing effects of RA and MgO were evaluated independently and synergistically under varied curing conditions and durations, with microstructural and mechanical properties analysed using scanning electron microscopy (SEM), X-ray diffraction (XRD), and uniaxial tests. Carbonation experiments quantified CO2 fixation potential, demonstrating that the formation of hydration and carbonation products, in conjunction with the dynamic moisture content and pH conditions, played a significant role in enhancing the structural reinforcement of the soil. The combined RA-MgO treatment achieved superior mechanical stability (1.28-3.02 MPa) and a CO2 sequestration capacity of up to 11 g/kg without compromising performance. This study highlights the dual environmental and structural benefits of utilising RA and low-content MgO for marine soil stabilization, offering a sustainable pathway to reduce carbon emissions, promote waste recycling, and support resilient infrastructure development.