CARBONATION MODEL OF HARDENED CONCRET SUBJECTED TO HIGH-PRESSURE CO₂ ENVIRONMENT

Abstract

In this study, modeling based on Fick's laws of diffusion, hydration reaction formula, and carbonation reaction formula was done to determine the progress of carbonation of hardened concrete and to estimate the coefficient of carbonation rate and the mass change rate, by using concentrated CO₂ under high-pressure CO₂ environment. For comparison of this model, hardened ordinary concrete with different compressive strength, mix proportions and curing age is subjected to concentrated CO₂ gas under a pressure of 0.5MPa and 1.0MPa respectively, using a high-pressure injection chamber and evaluated for the carbonation depth, coefficient of carbonation rate, and mass change rate for immobilization of CO₂ by concrete. As a result, it was found that the coefficient of carbonation rate and the mass change rate calculated by the model was roughly in good agreement with the experimental results, and the carbonation progress can be estimated using the proposed model. In addition, the actual test results suggest that the degree of carbonation and coefficient of carbonation rate may decrease as the carbonation progresses, and it is necessary to further study the mechanism of the progress of carbonation under high-pressure CO₂ environment.