Influence of Loading Cracks on the Carbonation Resistance of RC elements

Abstract

In reinforced concrete (RC) structures, carbonation induced corrosion is one of the most significant durability issues. A very important factor that affects the carbonation process is the appearance of cracks in RC structures. According to the current state of the art, cracks have not yet been considered as a parameter in carbonation models which are used for defining the service life of concrete structures. The main objective of this research is to analyse the influence of cracked concrete cover as reinforcement protection. The analysis was carried out using own experimental results and the application of available standards and novel predictions regarding carbonation depth. For that purpose, prismatic RC samples without cracks and with different crack widths (0.05, 0.10, 0.15, 0.20 and 0.30 mm) were made and subjected to accelerated carbonation. The influence of carbonation depth on the corrosion of cracked and uncracked samples was analysed by observing the reduction of the reinforcement cross section. The compressive and tensile stress influence on carbonation resistance was also evaluated. The conducted analysis showed that even with low crack widths (0.05 mm) the maximum carbonation depth was significantly higher compared with uncracked samples. It was also shown that reduction in the reinforcing bar cross section after 28 days of exposure to 2% CO2 was between 0.05% and 0.13%, depending on the crack width. The results showed that compressive stress increase had no significant effect in the carbonation depth of samples.