Concrete Carbonation in Ibero-American Countries DURACON Project: Six-Year Evaluation

Concrete carbonation data from 16 test sites in 9 countries (Bolivia, Chile, Colombia, Costa Rica, Mexico, Spain, Uruguay, Portugal, and Venezuela) were compared to identify concrete performance due to carbonation at natural exposure conditions after almost six years of exposure. This research is part of the DURACON project (“Effect of the environment on reinforcement durability”), a long-term Ibero-American project intended to correlate the influence of urban and marine meteorochemical parameters on the performance of reinforced concrete structures. Environmental parameters were measured following the ISO 9223 standard. Concrete was physically characterized by the results of compressive strength, elastic modulus, total and effective porosity, and water absorption resistance (Fagerlund method) laboratory tests. Concrete specimens (with and without steel reinforcement bars—rebars) were prepared for electrochemical and physical/mechanical/chemical tests using materials available in each country. Concrete composition was kept similar between specimens by following strict preparation protocols. Two water/cement (w/c) ratios were used: 0.45 w/c ratio concrete had a minimum cement content of 400 kg/m3; and 0.65 w/c ratio concrete had a minimum 28-day compressive strength of 210 kg/cm2. Materials were type I Portland cement, siliceous sand, and crushed rock as coarse aggregates (13-mm maximum nominal size). After six years of exposure, corrosion potentiality and probability analysis of the reinforcement at the different sites indicated the concrete prepared in Venezuela to have the highest probability of experiencing carbonation-induced reinforcement corrosion. The concrete prepared at the Cali, Colombia, site had the lowest probability. Carbonation aggressiveness was found to be highest at tropical sites, with the Venezuela sites exhibiting the most aggressive conditions among the participating countries.