Study of Carbonation and Diffusion in Concrete with Supplementary Cementitious Materials

The reduction of carbon dioxide (CO2) emissions from cement production by the additionof supplementary cementitious materials (SCM’s) has garnered significant interest. To predict the CO2 uptake of systems with SCM’s, an experimental setup for measuring the effective diffusion coefficient of CO2 in concrete was developed. A MATLAB script was written to calculate the diffusion coefficient through curve-fitting of Fick’s second law. Six mixtures which represented a ternary binder composition varying in quantity of Portland cement, fly ash, and portlandite were tested after 1, 4, and 7 days of curing. CO2 uptake was measured by X-ray diffraction (XRD) and thermogravimetric analysis (TGA). Porosity and pore saturation were measured by solvent exchange. Results of the experimental diffusion setup were consistent with these tests, and changes in methods to increase the setup’s reliability are discussed