Measurement of CO₂ effective diffusion coefficient of cementitious materials

Abstract

The CO₂-effective diffusion coefficient is a key parameter in the modelling of carbonation of cementitious materials. It is usually deduced from empirical relationships determined by tests on mixtures made with Ordinary Portland Cement (OPC). These relationships are a priori non-valid for materials with high content of mineral additions, such as ground granulated blast furnace slag (BFS). In order to better understand the effect of composition on the CO₂ effective diffusion coefficient, a device was developed to measure this property. This study presents the developed protocol and the study carried out on dried cement pastes and limestone samples. The influence of several parameters was investigated: material nature, water/binder ratio, binder type (OPC or BFS). BFS pastes were found less diffusive than OPC pastes for the same porosity. CO₂ diffusion is strongly affected by the pore structure properties. Comparison with literature results is mixed. Effective diffusion coefficients determined in the present study are only of the same order of magnitude than coefficients measured through CO₂ diffusion tests.

Keywords:

• gas diffusion coefficient
• carbonation
• carbon dioxide
• ground-granulated blast furnace slag

Acknowledgements

The authors would like to acknowledge J.F. Meusnier for his help during the development of the experimental device. The authors  also acknowledge the Région Poitou-Charentes for funding the PhD Thesis of K. Namoulniara.

Disclosure statement

No potential conflict of interest was reported by the authors.