Enhancement of mechanical and carbon sequestration properties of lightweight stabilized soil using ground granulated blast furnace slag, desulfurized gypsum, and CO2-foam

Carbon sequestration lightweight soil (CLS) represents a novel sustainable construction material developed by incorporating CO 2 foam into stabilized soils composed of industrial byproducts and high-water-content waste slurry. This strategy offers a dual-benefit solution, achieving material lightweighting alongside permanent carbon dioxide storage. This study evaluates the properties of CLS through a series of physicomechanical tests, as well as microstructural analyses. Results demonstrate that the integration of CO 2 foam enables a simultaneous enhancement of mechanical strength and reduction in bulk density. The UCS initially increases and then decreases with rising foam content, with an optimal dosage identified at 800 mL/kg. At this optimal content, CLS achieves high-performance metrics, including a 28-d UCS (uniaxial compressive strength) exceeding 2200 kPa, a substantial carbon sequestration capacity and higher durability. Microstructural analysis confirms that the enhanced strength originates from extensive carbonate mineralization, which fills pores and densifies the matrix. Scaling analysis underscores its substantial environmental potential: using CLS as a subgrade fill could sequester over 200 tons of CO 2 per kilometer of highway construction. Hence, CLS emerges as a high-performance, sustainable material that effectively integrates essential structural functionality with carbon sequestration, advancing the frontier of low-carbon infrastructure technology.