Effects of temperature, humidity and CO2 concentration on carbonation of cement-based materials: A review

For in situ reinforced concrete structures, carbonation has been considered as a risk that needs to be inhibited for the past decades; while a pronounced carbonation in early age concretes is now regarded as a good method to reduce carbon footprint for civil engineering industry, and needs to be promoted. Therefore, a thorough understanding on controlling the extent of carbonation in various types of concretes and at different stages needs to be delivered, so as to meet the opposite demands in various cases. By controlling environmental conditions, including temperature, humidity and CO2 concentration, different degrees of carbonation can be achieved. However, even though significant amount of carbonation works have been carried out, there is still a lack of a unified conclusion and summary discussion on the impacts from external factors. In this review, impacts of temperature, humidity, CO2 concentration and their coupling effects on carbonation of concretes are summarised, aiming to facilitate promotion and inhibition of the process in practice. Meanwhile, future perspectives to gap the current research status and precise carbonation control are raised.