Concrete maintains the steel passivated unless a chloride proportion above the threshold or the carbonation front reach rebar position. When corrosion develops, several key aspects of the composite bar-concrete composite action are affected which compromises the structural stability and safety. The relative premature failure by steel corrosion of structures has increased the interest to incorporate to the standards for the calculation of the time to corrosion. These models in general identify the end of service life with the starting of bar corrosion, either by chlorides or by carbonation. Additionally, from the publications of the project Duracrete, funded by the EU, probabilistic treatments have been applied to steel depasivation which is associated to a serviceability limit state, SLS. Thus, fib Model Code (MC2010) recommends a probability of failure of 10% for the calculation of the time to corrosion. However, this recommendation leads to incoherences because, on one hand, the chloride threshold is not a fixed value and the carbonation front affects first to the external face of the bar developing a progressive perimetral damage and, on the other hand, the consideration of the limit state as a SLS, with so low fixed failure probability, introduces some degree of contradiction with the classical definition of the SLS. This is because, while the SLS is defined as the not fulfilling of the design prescriptions, any structural design performance changes just at the moment of steel depassivation. Additionally, no treatment on how to consider the damaged section or corrosion propagation model is usually given in the MC2010 or other standard and then, how to verify the classical SLS and ULS is undefined. Present work introduces new perspectives from a probabilistic point of view on the subject by, 1) first treating statistically the depassivation step, 2) second by introducing a corrosion propagation model and quantifying the corrosion limit states and 3) by the calculation of the depassivation probability which results dependent on the rate of the deterioration process itself. The whole exercise stresses the need to not consider a fixed value (10%) associated to a SLS the probability of corrosion, but to consider it a limit state of “corrosion initiation” following ISO 2394. The value of the adequate probability of corrosion would be dependent on the consequences of the failure and on the rates of chloride ingress, of carbonation or of steel corrosion. Associating a steel corrosion rate to the chloride diffusion coefficient or the carbonation ingress, the probability of depassivation can be calculated for a limit state of cover cracking of around 0.3 mm of crack width (corresponding to a bar diameter loss of 100 mm).
C. Andrade is Research Professor of the CSIC at the institute of Construction sciences “Eduardo Torroja”. Her “h” Index is 41. She has received several international awards in recognition of her research and training work (R. N. Whitney Prize 2013 by NACE and Robert L’Hermite Medal 1987 to young scientists from RILEM and “Manuel Rocha” of the Presidency of Portugal” among other).
She was appointed in 2003 Doctor Honoris Causa by the University of Trondheim, Norway, in 2006 from the University of Alicante. She is the author of about 300 papers in journals indexed and 160 in national magazines. She has presented over 250 communications to national conferences and more than 650 International.
She has published over 150 book chapters and has awarded several national and international patents and registered trademarks. She is co-author of 14 patents having 5 in exploitation and has participated in around 250 industrial contracts. In 2013 she promoted with other partners a start-up called “safety and Durability Engineering”. She was Principal Investigator of the Project Consolider-SEDUREC (Safety and Durability of Structures) in collaboration with the Polytechnic University of Madrid and the Center for Numerical Methods (CIMNE) of Barcelona approved within the Ingenio-2010 Spanish Research Program. Also has organized courses and seminars and lectured in Spain and several foreign countries, among which can be mentioned the Chair SEDUREC with 8 editions in South America.
She was Director of the Institute of Construction Sciences Eduardo Torroja (CSIC) for the periods 1985-1988 and 1993-2003; has participated in Standarization Committees at national, European and International level and has been President of several international organizations related to her specialty (UEAtc, RILEM, WFTAO and Liaison Committee which brings together the Associations: CIB, FIB, IABSE, IASS, RILEM and ECCE). She has also been Vice-chairman of the Promotion Area for the Industrial Development of the Iberoamerican Program CYTED. In the field of training she has supervised 31 doctoral theses and supervises another 10 that are in progress and about 31 Masters (or equivalent) Degrees.
She is Honour Director of “Advanced Courses of IETcc” organized annually by her Institute and is Coordinator of the official Master SEDUREC of CSIC-UIMP (International University Menendez Pelayo) approved by the ANECA (Agency of University Evaluation and Accreditation) of Spain. She is a member of several editorial boards of journals included in the SCI. She was member two years of the Jury of the Price “Principe de Asturias” on Science and Technology. From 2006-2008 she was Director General of Technological Policy at the Ministry of Education and Science of Spain. From 2008-2012 she was Adviser to the Secretary of State for Universities, Secretary of State for Research and to the Secretary General for Universities.