Nuria Rebolledo

Corrosion Characterization of Reinforced Concrete Slabs with Different Devices

Abstract There are few works undertaken to verify the accuracy of corrosion measurements. In general, it is assumed that potentiostats are correctly fabricated and then efforts are made to check th...

Influence of humidity and temperature on the corrosion of reinforced concrete prisms

Reinforcement corrosion is one of the major durability problems that need to be solved in order to extend the service life of a structure. It is influenced, on one hand, by the concrete itself, sound or polluted (chlorinated or carbonated), and on the other hand, by the environmental conditions (controlled or outdoor). To explore the influence of temperature and humidity, electrochemical characterisations (potential, linear polarisation resistance and corrosion rate) were carried out on reinforced concrete prisms. A database of more than 3000 values has been delivered. The results enabled us to deduce that both parameters have influences on each other. Moreover, considering the four concretes, the corrosion order obtained in controlled conditions may be different from the one obtained in outdoor conditions. La corrosion des armatures est un problème majeur dans la durabilité du béton qui doit être résolu afin d’augmenter la durée de vie des structures. Elle dépend, d’une part, de la nature du béton (sain ou pollué (chloruré ou carbonaté)) et, d’autre part, des conditions environnementales (contrôlées ou naturelles). Afin d’étudier l’influence de la température et de l’humidité, des caractérisations électrochimiques (potentiel, résistance de polarisation linéaire, courant de corrosion) ont été réalisées sur des prismes en béton armé. Une base de données, avec plus de 3 000 valeurs, a été constituée. Les résultats montrent que les deux paramètres interagissent l’un sur l’autre. De plus, l’ordre de corrosion obtenu dans des conditions contrôlées peut être différent de celui observé dans des conditions naturelles.

Reinforced Concrete Durability in Marine Environments DURACON Project: Long-Term Exposure

This paper presents the results, after a long-term evaluation in marine environments, from an Ibero-American project called “Effect of the environment on reinforcement durability” (DURACON). This p...

From corrosion rate to accumulated corrosion depth or loss in cross section of reinforcements

In marine environments, reinforcement corrosion develops due to the penetration of chlorides through the concrete pores. Initially the corrosion appears as localized attack, but when the chlorides arrive in high quantities, it extends to the bar surfaces which corrode entirely. In numerous previous studies, the detection of corrosion and its evolution have been monitored by means of measuring and presenting the variation of corrosion rate over time. This representation can be used to deduce when corrosion initiates on a steel bar and how it evolves with time. However, as the corrosion rate changes with temperature and the corrosion process itself evolves, this representation may not be clear enough to be used for comparative purposes. The present work proposes a parallel use of accumulated corrosion depth, which is obtained by the integration of each age of the corrosion rate-time curve. This kind of representation enables the determination of corrosion depth at each age and appears more appropriate for comparative purposes. The procedure is applied to concrete specimens that have been in contact with natural sea water from the Mediterranean Sea for 20 years. The specimens are prepared with different binders in different proportions for purposes of comparison.

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 du...

Steel Corrosion in a Chloride Contaminated Concrete Pore Solution with Low Oxygen Availability

It is commonly mentioned that in concrete chloride induced corrosion is controlled by the oxygen content in such a manner that in water saturated conditions no oxygen will be present and thus no corrosion can develop. In the present paper, experimentation has been made in low oxygen availability “pore” solutions with several amounts of chlorides. These situations may represent the case of a water saturated concrete. The results indicate that at very low oxygen contents, i.e. almost negligible because complete removal is very difficult, corrosion may develop in presence of chlorides. The presence or absence of corrosion is influenced by the amount of chloride, its corrosion potential and the steel surface condition.

Generic Modelling of Propagation of Reinforced Concrete Damage

Reinforced concrete may suffer rebar corrosion but also other types of attack to the material integrity. When these processes develop actively at significant rate, they usually manifest through cracking of concrete cover, expansions and efflorescences and they are named, for the sake of the service life calculation, as “propagation” periods. The most known generic model is that of reinforcement corrosion published by Tuutti with two time- phases: corrosion initiation and propagation, that is, during the penetration of aggressive substances no damage is produced until achieving the aggressive front the rebar level, where the oxides formed provoke the cracking of the cover. This result into a horizontal line regarding the damage level followed with a continuous increase when the external sign of deterioration are visible. The other most frequent attacks are: alkali-silica reaction or sulfate attack, acid or leaching by pure waters and frost attack. In present communication, although of complex mechanisms as corrosion is, it is shown that all these propagation periods can be linearized in order to be made “generic” and with the possibility to be considered too as a two-period service life model. Some examples are commented, in particular that of reinforcement corrosion which is modelled through a constant rate or with a bilinear trend.

Concrete Carbonation in Mexico and Spain: DURACON Project, Four Year Evaluation

This work is part of the DURACON Ibero-American project, which seeks to characterize concrete durability under environmental conditions, based on reinforced concrete sample exposure in at least two different atmospheres (marine and urban), for each of the 11 countries in the project. Specimens were exposed to the environmental conditions of 13 Mexican sites (8 urban and 5 marine atmospheres). Concrete specimens were 15 x 15 x 30 cm, with 6 rebars each, and three concrete covers (15, 20 and 30 cm). Two concrete mixtures were used with water/cement ratios of 0.45 and 0.65, respectively. Six reinforced and six plain concrete specimens were placed on each exposure site. Environmental data was collected on each exposure site, including rainfall, relative humidity, time of wetness, temperature, wind velocity, and carbon dioxide/chloride concentrations. Corrosion rates and potentials, as well as concrete resistivity were measured in the reinforced samples. Carbonation depths were measured on the plain ones. The present work focused on the measurements of environmental parameters during the first two years of exposure to analyze the potentiality and the probability of carbonation-induced corrosion, and the evaluation of the corrosion initiation period for the reinforcing steel on the 13 Mexican exposure sites.