Durability of concrete structures: DURACON, an iberoamerican project. Preliminary results

This work presents preliminary results of the international project: "Effect of the environment on reinforced concrete durability: DURACON", which shows the physical, mechanical and chemical characterization of two different concrete mixtures prepared in the participating countries, as well as the environment to which the specimens are exposed. These results show the potentiality and probability of future reinforcement corrosion, depending on the type of mixture and the environment to which the structure is exposed. To that effect, concrete specimens, with and without reinforcement, were prepared for electrochemical and physical/mechanical/chemical testing using the existing materials in each participating country, following premises that enabled the preparation of similar concrete specimens. Two water/cement ratios (0.45 and 0.65) were selected, where the concrete with w/c = 0.45 had to have a minimum cement content of 400 kg m^-3, and the other with w/c = 0.65, a minimum compressive strength of 21 MPa. Ordinary Portland Cement (OPC), crushed coarse aggregate, and silica sand were used for concrete preparation. The specimens were exposed to several microenvironments including urban and marine conditions (at least two testing sites in each country), resulting into a total of 46 test sites distributed among 11 countries (Argentina, Bolivia, Brazil, Chile, Colombia, Costa Rica, Mexico, Spain, Uruguay, Portugal, and Venezuela). The environment was evaluated using ISO Standard 9223 and the concrete was characterized by measuring compressive strength, modulus of elasticity, total and effective porosity, and rapid chloride permeability according to ASTM standards, as well as resistance to water absorption, using the Fagerlund method. After 1-year exposure, some results of the corrosion potentiality and probability analysis of the reinforcement in several test sites based on environmental meteorochemical parameters show that, for specific microclimates like those in marine atmospheres, the most aggressive environment is that at Cabo Raso test site in Portugal, inducing the greater steel-corrosion probability. The least aggressive is the one at Valparaíso in Chile. It was also determined that Maracaibo, Venezuela, is the one that has the greatest probability of early rebar corrosion initiation by carbonation, with the test site at Cali, Colombia being the one that would induce the least corrosion probability.