Carbonation of Portlandite in low humidity environments

Computer study of Portlandite carbonization reaction was made using density functional theory (DFT). Also an experimental investigation of Portlandite carbonization was performed at low relative humidity (40%). Two cycles of a change of regime from chemical control to diffusional control of carbonation were observed within the first 74 h of carbonation. The first cycle of chemical and diffusional control belongs to reactions in the surface, whereas the second cycle belongs to reactions in solution. Thus, the end of the first regime of diffusional control marks a transition from a surface reaction to a reaction in solution. These results show that, even in environments with low humidity, carbonation can occur as a surface reaction and finally become a reaction in solution. This may also lead to new applications of carbonation for the design of structural materials.

Author: A. Funk, K.M. Salah Uddin, A. Wetzel, B. Middendorf

Section: Science and production

Keywords: carbonization, portlandite, kinetics, diffusion