Carbon Sequestration Capacity of Stabilized Soft Clays with Recycled Binders

This study estimates the CO₂ sequestration capacity of Malmi clay stabilized with various recycled binders tested in laboratory conditions. Carbonation experiments were performed on stabilized samples using an autoclave and a carbonation chamber. Results revealed that the rate of carbonation differs significantly when carbonation is performed using a carbonation chamber or an autoclave. After 1 day in room temperature, the carbonated-stabilized samples were kept in the carbonation chamber for 13 days or in the autoclave for 5 days. Additionally, the reference samples were cured for 14 and 28 days to estimate the effect of CO₂ sequestration capacity on curing time. Further, thermogravimetric analysis (TGA) was used to measure the CO₂ intake. The findings indicated that the CO₂ sequestration capacity of carbonated-stabilized soil for the recycled binders ranged from 2.8 % to 4.1 % of dry mass of the mixture. The CO₂ intake was found to be 4.1 %, 3.5 %, 3.0 %, and 2.8 %/dry mass of the mixture for cement type I (CEMI), cement type III (CEMIII), GTC (gypsum + slaked lime + CEMIII), and biomass fly ash + CEMII (BFA + CEMII) stabilized clay, respectively. Ultimately, GTC binder was found to have the greatest potential to be carbon negative. The present study shows that it may be potential to create stabilization technique, which can be carbon negative especially by using recycled binder materials.