Comparative Analysis of Global Standards in Accelerated Carbonation Testing of Concrete

Carbonation is one of the major causes of steel reinforcement corrosion, affecting the durability of concrete. Natural carbonation is a very long process; therefore, to predict the development of concrete carbonation, standards prescribe accelerated carbonation tests, in which specimens are exposed to carbon dioxide (CO₂) in a controlled environment. Although based on the same principle, global standards differ in methodology, e.g., different CO₂ concentrations, relative humidity or size of the specimens. Results of these tests might not be comparable with each other, and therefore, it is difficult to conclude which methodology most accurately predicts long-term carbonation. This diversity in standards highlights the need to study and compare them to identify similarities, differences, and the reasons behind these variations in accelerated carbonation tests worldwide. In this study, 12 standards from various regions were examined for differences in key parameters. Significant variations were found, largely due to climatic differences and testing objectives. A correlation was observed between CO₂ concentration and specimen surface area, and the study also noted that standards specifying higher CO₂ concentrations tend to have shorter test durations compared to those with lower CO₂ concentrations, aiming to accelerate the testing process. The study found that the ISO standard is applicable across diverse climatic conditions, as its flexible temperature and humidity ranges allow adjustment to local environments within the ISO limits.