Currently, traditional vertical barrier materials are associated with large carbon footprints and high costs (in some regions) due to the widespread use of Portland cement and sodium-based bentonite materials. In recent years, a new technology of Carbonized Reactive Magnesia Cement (CRMC) has gradually been developed to sequester CO2 using Eco-cement. The application prospects of CRMC in vertical barrier materials are explored in this study. The changes in flowability of Reactive Magnesia Cement (RMC) slurry and the unconfined compressive strengthen (UCS) and permeability characteristics of CRMC treated soils are investigated. The results show that the fluidity of RMC slurry decreases further with the increase of MgO substitute cement content. For RMC slurry meeting the fluidity requirements, UCS increased rapidly in the early period (3 h) after carbonization, reaching 348.33 kPa, and the hydraulic conductivity k decreased (k < 1 x10(- 7) cm/s) in the later period (14d), and the final hydraulic conductivity reached 6.13 x 10(- 8) cm/s (28d). The pores of the material are filled with a large number of hydration products and carbonates, which alters the pore size distribution structure of the material. This is the reason for the mechanical properties and permeability performance of CRMC treated soils. The overall results of this study well demonstrate that CRMC treated soils, as a new, environmentally friendly, and cost-effective material, have great potential in the construction of vertical barriers.

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.

Carbon dioxide fluxes between ecosystems of the Earth are presented. It was shown that intensifying its absorption of terrestrial ecosystems by 3.2% would prove sufficient to neutralize carbon dioxide emissions from the combustion of fossil fuels and cement production. It was shown that Polish forests absorb 84.6 million tons of CO2/year, that is 26% of emissions from fossil fuel combustion and cement production, while agricultural crops absorb 103 million tons of CO2/year. Total carbon dioxide sequestration by forests and agricultural crops amounts to 187.5 million tons of CO2/year, which is tantamount to 59% of emissions from fossil fuel combustion and cement production. Forestation of marginal soils would further increase carbon dioxide absorption in Poland by 20.6 million tons of CO2/year. Moreover, if plants were sown in order to produce green manure - instead of leaving soil fallow - sequestration could still be boosted by another 6.2 million tons of CO2/year.