A Study on the Carbonation Rate of Concrete Exposed in Different Climatic Conditions

Abstract

Recently, the degradation of concrete has become a serious problem worldwide and one of the principle factors of degradation is the carbonation process. It is well established that environmental conditions affect the carbonation progress of concrete among the most important factors that can greatly affect the carbonation resistance of concrete are relative humidity (RH) and temperature. Carbonation has become a threat to concrete structures, especially in urban and industrial areas. Thus, it is necessary to have a proper design to maintain the structure's stability against degradation caused by carbonation. Therefore, this study was conducted to evaluate the effects of different environmental and climatic conditions on the carbonation rate of concrete. The specimens were prepared using OPC and fly ash (FA). After 28 days of air curing, specimens were exposed to different climate conditions under sheltered and un-sheltered conditions. The carbonation tests were conducted at the ages of 6 and 12 months. It was found that the carbonation rates were significantly influenced by the climate and environmental conditions; the specimens exposed to a relatively dry environment and low annual precipitations have shown higher carbonation during one-year exposure. Moreover, in unsheltered conditions, the annual precipitation significantly affects the carbonation rate of concrete. Furthermore, it was observed that a 20% replacement of FA does not enhance the carbonation resistance of concrete.