Influence of Blended Cements on the Service Life of Reinforced Concrete Structures against Carbonation Induced Corrosion

Corrosion due to carbonation is a major factor in reducing the service life of reinforced concrete structures exposed to the environment. The problem is more pronounced in concretes that are made with composite cements. In this case, both the total percentage of pozzolanic materials and their type play an important role. In this work, the effect of three different cements on the carbonation of concrete is examined. Concretes with different w/c ratios were prepared using one ordinary Portland cement (CEM I 42.5N) and two blended cements - CEM II (A-M) 42.5N and CEM II (B-M) 42.5N. The depth of carbonation after curing in a carbonation chamber with a carbon dioxide concentration of 2% was measured. Service life of reinforced concrete structures was calculated using the model referred to in FIB MC 2010 for structures exposed to different environmental conditions. The results show that blended cements increase the vulnerability of concretes against carbonation and reduce the service life of reinforced concrete structures exposed to environmental conditions typical of those of the Mediterranean countries. In order to overcome this problem, it is suggested to increase the initial wet curing period of the casted concrete.