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 scanned electron microscopy, X-ray diffraction, and uniaxial tests. Carbonation experiments quantified CO2 fixation potential, with the formation of hydration and carbonation products, along with dynamic moisture content and pH conditions, playing 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 utilizing 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.

Constructing infrastructure on soft soils demands the implementation of ground improvement. This study proposed an eco-friendly method of stabilizing marine soil using a calcium carbide residue (CCR)-activated coal gangue (CG) geopolymer derived from industrial waste. Laboratory experiments were conducted to investigate the mechanical properties, durability performance, and stabilization mechanisms of stabilized marine soils under multiple wetting-dry cycles. The results highlighted the effectiveness of CG-CCR geopolymer by a content of 15% to achieve satisfactory strength gain over the engineering requirements. However, the largest decrease in strength (71.89%) was observed when the initial water content was beyond 1.5 times the liquid limit (LL). The optimum solution was proposed to have a geopolymer content of 15% or an initial water content of 1.25 & sdot;LL to exhibit the highest resistance to strength decay after 12 cycles. Compared with water intrusion, mass loss had a more significant effect on soil strength deterioration. The formation of noncrystalline or amorphous-phase reaction products effectively filled intergranular pores and reduced the void space between soil particles, improving the mechanical properties. The CG-CCR geopolymer was demonstrated to offer a promising solution for soil improvement in geotechnical engineering and waste reduction in industry as a soil stabilizer.