Study on the Carbonation Properties of Fly Ash Concrete by the New Rapid Carbonation Experimental System

Carbonation is one of the most important factors of the concrete deterioration resulting in the steel corrosion in concrete. Nevertheless, the experimental data for the study of the concrete carbonation have not been sufficiently accumulated because the carbonation of concrete is a long-term phenomenon. In this study, the newly-developed rapid carbonation test by the usage of the vacuum equipment has been used to observe the carbonation behaviors of concretes made of portland cement and of fly-ash cement. Experimental results showed that concretes with 0.45 and 0.6 w/c had the carbonation depth of 103% and 138%, respectively, comparing to that of 0.4 w/c. The carbonation depths calculated by an analytical model were deeper than the experimental results and the deviations increased with the increase of the water to cement ratio. It was also observed that the carbonation depth rapidly increased with the increase of fly-ash replacement. Consequently, the rapid carbonation test provided experimental results in a shorter time than the conventional carbonation tests, and it is expected that these experimental data and the further study by the new rapid carbonation test will contribute to the future studies of concrete carbonation.