Lignin-MgO Based Loess Stabilization Incorporating CO2 Mineralization

While increasing studies have incorporated carbonation into chemical stabilization of soils, a scarcity of research has focused on carbonation progress, carbonation effects on pH, dynamic properties, and brittleness of stabilized soils. None of these studies has been concerned with loess. To address these issues, this study proposes a novel and sustainable approach, which used lignin-MgO to integrate mineral carbonation into loess stabilization. This integrated approach enabled realizing mechanical property enhancement, alkalinity reduction, and CO2 sequestration. A comprehensive experimental program was conducted to evaluate the efficacy of this method. The results revealed that the proposed method could mineralize approximately 6% of CO2 relative to the dried mass of loess-binder mixture within 24 hours of carbonation; addition of CO2 reduced pH values in stabilized loess from 10.3 to 8.2, and carbonation increased the early strength of stabilized loess by 50%. Furthermore, addition of lignin was found to reduce the brittleness and improve the freeze-thaw durability of stabilized loess. Finally, based on comprehensive mineralogical and microstructural analyses, a conceptual model was proposed to explain the mechanisms of carbonation and stabilization for loess.