Effect of environmental parameters on concrete carbonation. DURACON collaboration (Mexican results)

Abstract

This work is part of the DURACON Ibero-American project, aimed to characterize concrete durability under environmental conditions by natural exposure in two different atmospheres (marine and urban) for each of the 13 countries involved in the project. Specimens were exposed in 15 Mexican sites (9 urban and 6 marine atmospheres). Concrete specimens were 15 × 15 × 30 cm with two concrete mixes (water/cement ratios of 0.45 and 0.65). Six reinforced and six plain concrete specimens were placed on each exposure site. Environmental data was collected, including rainfall, relative humidity, time of wetness, temperature, wind velocity, and carbon dioxide/chloride concentrations in the atmosphere. Concrete resistivity, carbonation depth, and chloride concentrations in concrete were measured. Electrochemical characterization of the rebar was also performed by means of corrosion rates and half cell potentials. This investigation is focused on the effect of the environmental parameters inducing corrosion due to concrete carbonation during the first four years of exposure. A discussion regarding corrosion initiation period, with clear influence of the specific atmospheres tested, is also included.