Numerical approach for concrete carbonation considering moisture diffusion

Abstract

Carbonation is a common type of concrete deterioration, which can cause various physicochemical changes that adversely affect the performance of reinforced concrete structures. The reinforced concrete structures can be considerably damaged by the reinforcement corrosion caused by the neutralization of concrete under carbonation. This study introduces a numerical analysis approach to examine concrete carbonation with calcium hydroxide (Ca(OH)2), which decreases the alkalinity of concrete. Carbonation analysis is performed by considering the diffusion of carbon dioxide (CO2) and moisture, which play influential roles in the carbonation reaction. A detailed formulation process is established to apply the theoretical equations to the numerical analysis by considering the mentioned influential factors. Further, appropriate modification factors are applied to the numerical analysis under various environmental conditions. The proposed numerical analysis is verified by comparing the carbonation front depths with those obtained from the experimental results via thermogravimetric analysis. Furthermore, a carbonation experiment is conducted using a phenolphthalein solution, and the results are compared with those of the numerical analysis. The experimental carbonation front depth obtained using a phenolphthalein solution is half of that obtained using numerical analysis, which is consistent with the result obtained by other researchers in previous studies. These observations indicate that the proposed numerical analysis considering CO2 and moisture diffusion sufficiently simulates concrete carbonation.