Evidence of stabilised peat as a net carbon sink

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 CO2, because the binder takes in CO2 from the atmosphere and any CO2 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 CO2 intake rate. The studies revealed that an increase in cement content and a larger surcharge contributed to a larger CO2 intake rate. These rates decreased logarithmically with time, and surcharge was found to be less influential over time. The CO2 intake rate reduced when the atmospheric CO2 concentration reduced, and the replacement of cement with ground granulated blast-furnace slag had a negative effect on the CO2 intake rate due to its lower carbonation potential. Furthermore, a high water table resulted in a decrease in the CO2 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.peer-reviewe