Influence of Cracks on the Carbonation Resistance of Recycled Aggregate Concrete

Abstract

The use of recycled concrete aggregate (RCA) for the production of new concrete can be a promising eco-efficient solution. However, replacement of natural aggregate (NA) with RCA influences concrete’s durability performance. One of major durability problems worldwide is carbonation-induced corrosion, given that a large number of infrastructural objects are exposed to a CO2-rich environment. There are many factors that affect carbonation process, but possibly the most important one is the appearance of cracks in reinforced concrete (RC) structures. Currently, the cracks have not yet been considered as a parameter in carbonation model which is used for defining the service life of RC structures. The objective of this research was to analyse the influence of cracked concrete cover as a good reinforcement protection. In order to ensure a sustainable application of recycle aggregate concrete (RAC), an analysis was performed on RAC with 100% replacement of coarse NA with RCA. The analysis was carried out using own experimental results and the application of existing fib Model Code 2010 carbonation depth prediction model derived for NA concrete. For that purpose, prismatic RC samples without cracks and with different crack width (0.05 mm, 0.10 mm, 0.15 mm, 0.20 mm and 0.30 mm) were made and subjected to accelerated carbonation. The compressive and tensile stress influence on carbonation resistance was evaluated as well as reinforcing bar corrosion at crack position. The conducted analysis showed that even with low crack widths (0.05 mm) the maximum carbonation depth was significantly higher compared with the uncracked samples. The results showed that compressive stress increase had no significant difference in the carbonation depth of samples.