Concrete Carbonation under Wide Range of Conditions

In urban and industrial areas with high CO2 concentration, carbonation is the main deterioration mechanism affecting service life of concrete structures. A mathematical model for carbonation of concrete is proposed. This model can cover many parameters affecting the carbonation rate of concrete. The input data for this model include physical and chemical characteristics of Portland cement and mineral admixtures, water/cement ratio, aggregate/cement ratio, maximum aggregate size, curing condition (period, temperature, relative humidity), preconditioning (period, temperature), CO2 concentration, exposure time and the ambient conditions. A new model to predict the degree of pozzolanic activity of mineral admixtures has been proposed. Moreover, by monitoring the total weight loss during drying-wetting process and study on pore structure of various mix proportions, the effect of preconditioning and mineral admixtures on saturation degree and drying rate of concrete was studied. Natural carbonation of concrete was carried out to verify the modeling. The proposed carbonation model can predict the carbonation depth of concrete under wide range of conditions.