Evidence of Stabilized Peat as a Net Carbon Sink

Abstract

Mass stabilisation, a ground improvement solution used for construction in peatlands, involves mixing suitable dry binders into the peat to create a homogenous mass, that strengthens and stiffens the peat. A previous pilot study of the carbonation process in stabilised peat showed that it can be a net sink of CO2, as the binder takes in CO2 from the atmosphere and any CO2 released by oxidised peat due to carbonation. In this study extensive laboratory experiments were undertaken to investigate the key factors affecting the CO2 intake rate. A closed chamber method was applied over approximately 6 months to stabilised peat to calculate this rate. The studies revealed that both an increased cement content and a larger surcharge contributed to a larger CO2 intake rate. These intake rates decreased logarithmically with time, and surcharge was found to be a less dominant factor in influencing the CO2 intake rate over time. It was observed that the CO2 intake rate declined when a decrease in CO2 concentration occurred, 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, and the consideration of the factors affecting flux rates will allow geotechnical engineers to make more informed decisions on the suitability of this technique for construction projects. Table 5-Boundary conditions for input variables for sensitivity analysis for Studies A and B Study A Study B

Effect of Biochar Filler on the Hydration Products and Microstructure in Portland Cement–Stabilized Peat

“…The carbonation reaction in concrete is diffusion limited, it only occurs on surfaces exposed to a source of CO2 (Haselbach 2009). Labile Carbon in peat is one source that has been shown to promote the carbonation reaction (Duggan, et al 2019). SEM analysis demonstrate that another important source is biochar.…”