Accelerated carbonation of cement pastes partially substituted with fluid catalytic cracking catalyst residue (FC3R)

Accelerated carbonation tests have been carried out on Portland cement pastes and pastes partially substituted with a spent fluid catalytic cracking catalyst (FC3R) to investigate possible differences between the composition of FC3R/cement and plain cement matrices. Cement/FC3R pastes have been tested by thermogravimetry and X-ray diffraction analyses. This study has revealed that the incorporation of FC3R on pastes produces a significant reduction of the alkaline reserve and an increase in the quantity of cementing products such as hydrated calcium silicoaluminates. The carbonation of cement/FC3R pastes leads to the total consumption of the porlandite of the paste. Further carbonation will produce the capture of the calcium contained in the cementitious phases, yielding calcium carbonate and silica and alumina gel. The main product of the carbonation process is calcite, but vaterite has also been detected in the carbonated pastes. No major differences were observed between the composition of FC3R/cement and plain cement pastes after the carbonation that could add additional risk to carbonation processes of FC3R-containing binders.