Evidence of Stabilized Peat as a Net Carbon Sink: Fid-Bau Portal

Evidence of Stabilized Peat as a Net Carbon Sink

Duggan, Alan R. / McCabe, Bryan A. / Goggins, Jamie / Clifford, Eoghan

Mass stabilization, a ground improvement solution used for construction in peatlands, involves mixing suitable dry binders into the peat, increasing strength and stiffness and reducing permeability. A previous pilot study of the carbonation process in stabilized peat showed that it could be a net sink of ${CO}_{2}$ , because the binder takes in ${CO}_{2}$ from the atmosphere and any ${CO}_{2}$ released by oxidized peat due to carbonation. In this study, a closed-chamber method was applied to stabilised peat specimens over a 6 month period to assess the factors affecting ${CO}_{2}$ intake rate. The studies revealed that an increase in cement content and a larger surcharge contributed to a larger ${CO}_{2}$ intake rate. These rates decreased logarithmically with time, and surcharge was found to be less influential over time. The ${CO}_{2}$ intake rate reduced when the atmospheric ${CO}_{2}$ concentration reduced, and the replacement of cement with ground granulated blast-furnace slag had a negative effect on the ${CO}_{2}$ intake rate due to its lower carbonation potential. Furthermore, a high water table resulted in a decrease in the ${CO}_{2}$ intake rate. These laboratory results have highlighted that dry soil mixing has a minimal on-site impact in environmental terms, allowing geotechnical engineers to make more informed decisions on the suitability of this technique for construction projects.