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Dredged marine soils (DMS) have poor engineering properties, which limit their usage in construction projects. This research examines the application of reactive magnesia (rMgO) containing supplementary cementitious materials (SCMs) to stabilize DMS under ambient and carbon dioxide (CO2) curing conditions. Several proprietary experimental tests were conducted to investigate the stabilized DMS. Furthermore, the carbonation-induced mineralogical, thermal, and microstructural properties change of the samples were explored. The findings show that the compressive strength of the stabilized DMS fulfilled the 7-d requirement (0.7–2.1 MPa) for pavement and building foundations. Replacing rMgO with SCMs such as biochar or ground granulated blast-furnace slag (GGBS) altered the engineering properties and particle packing of the stabilized soils, thus influencing their performances. Biochar increased the porosity of the samples, facilitating higher CO2 uptake and improved ductility, while GGBS decreased porosity and increased the dry density of the samples, resulting in higher strength. The addition of SCMs also enhanced the water retention capacity and modified the pH of the samples. Microstructural analysis revealed that the hydrated magnesium carbonates precipitated in the carbonated samples provided better cementation effects than brucite formed during rMgO hydration. Moreover, incorporating SCMs reduced the overall global warming potential and energy demand of the rMgO-based systems. The biochar mixes demonstrated lower toxicity and energy consumption. Ultimately, the rMgO and biochar blend can serve as an environmentally friendly additive for soft soil stabilization and permanent fixation of significant amounts of CO2 in soils through mineral carbonation, potentially reducing environmental pollution while meeting urbanization needs.

Application of 3D printing in building projects can enhance construction efficiency and productivity. Rheological properties play a key role in defining the suitability of different cement-based mixes for digital construction. In this study, the rheological behavior of the MgO-SiO 2 system involving metakaolin (MK) as the silica source was thoroughly investigated. Mixes with two different MgO/MK ratios (1 and 1.5) were prepared and evaluated for their hydration process, solid phase analysis, and dispersion stability of suspension particles by utilizing isothermal calorimetry, zeta potential, XRD, and TG-DTG analyses. Results revealed that the median differential viscosity (μ diff), dynamic yield stress (τ d), and static yield stress (τ s) of M50-MK50 were considerably greater than those of M60-MK40. The increase of τ s over time adhered to the linear structuration model within 60 min of hydration. The small amplitude oscillatory shear (SAOS) test findings indicated that M50-MK50 paste had a larger storage modulus. Although the printed structure of M50-MK50 closely approximated the intended dimensions of the design, notable instability was evident in the first and third layers from bottom to top. Microscopic analysis revealed that the formation of a modest number of hydration products in the early stage, the tendency of the system to agglomerate due to the smaller particle size of MK, and the irregular morphology of MK are significant variables influencing the rheological behavior of the MgO-MK mixes. [ABSTRACT FROM AUTHOR]