Artículos sobre resistividad y durabilidad de hormigón / concreto
CEMENT and CONCRETE RESEARCH. Vol 23, pp. 724-742, 1993.
CALCULATION OF CHLORIDE DIFFUSION COEFFICIENTS IN CONCRETE FROM IONIC MIGRATION MEASUREMENTS
by C. ANDRADE, Institute "Eduardo Torroja" of Construction Sciences - CSIC - Madrid - Spain
Received July 21, 1992
A critical review is offered on the Rapid Chloride Permeability Test standardized by AASHTO, pointing out its limitations and errors but recognizing its contribution to the development of a simple and quick test for chloride migration.
Then another review is made on the electrochemical fundaments of the processes developed in concrete when an electrical field is applied and on the basic equations fo mass transport (Nernst-Plank and Nernst-Einstein) which can be applied to calculate ionic movements. The limitations and assumptions needed for a simplified resolution of these equations are presented, as well as numerical examples of calculation of the Effective Diffusion Coefficient of chlorides, Deff, in the steady state condition.
Finally, considerations on the possibility of calculation of Deff from simple resistivity measurements are also offered.
International Symposium: Advances in Concrete through Science and Engineering
CALCULATION OF INITIATION AND PROPAGATION PERIODS OF SERVICE LIFE OF REINFORCEMENTS BY USING THE ELECTRICAL RESISTIVITY
by C. Andrade Institute of Construction Science “Eduardo Torroja”, CSIC, Madrid, Spain
Presented at International Symposium: Advances in Concrete through Science and Engineering, March 22-24, 2004, RILEM, Evanston, Northwestern University-USA.
Reinforcement corrosion is attracting research interest in many areas due to the economical consequences of the damage generated by the process. Several proposals can be found on prediction of the time to reinforcement corrosion and service life duration. In present communication a proposal is made on using the electrical resistivity to calculate both the initiation and propagation periods. For the time period to corrosion onset, the electrical resistivity serves to model the porosity and its connectivity and therefore can be used to calculate transport processes. Due to the reaction of chlorides and carbon dioxide with cement phases, the resistivity has to be factorised by a “reaction factor”, r, accounting for it. Concerning the propagation period, the electrical resistivity is an indication of the moisture content of concrete and therefore, it has a relationship with the corrosion current. The service life can be
expressedwiththefollowingequation: tl =t1 +tp =x2ρes rClCO2 / k +P·ρ k
l i p es ClCO2 Cl,CO2 x ef corr
Based in it, minimum resistivity values can be established according to cover thickness and in function of exposure classes.
2nd International Symposium on Service Life Design for Infrastructure
ELECTRICAL RESISTIVITY AS MICROSTRUCTURAL PARAMETER FOR THE MODELLING OF SERVICE LIFE OF REINFORCED CONCRETE STRUCTURES
by Carmen Andrade, Institute od Construction Science "Eduardo Torroja", CSIC, Madrid, Spain Renata d'Andrea, Spanish Institute of Cement and its Applications, Madrid, Spain
4-6 October 2010, Delft, The Netherlands
There is an increasing interest in developing models for prediction of the service life regarding reinforcement corrosion. In present communication a proposal is made based on the electrical resistivity to calculate both the initiation and propagation periods as well as for predicting concrete aging related to durability and for measuring the efficiency of curing. The model is fundamented in that the Resistivity is a property depending on the concrete porous system and its degree of moisture, and the from its values in saturated conditions, it is possible to find relations between diffusivity and resistivity, then linking concrete microstructure and transport resistance.
The relation of resistivity and time is quantified through the square root law, either for chloride penetration as for carbonation. However some additional information is needed due to the reaction of chlorides and carbon dioxide with cement phases: the resistivity has to be factorised by a «reaction factor» accounting for it. Concerning the corrosion propagation period the relation between corrosion and resistivity is provided by an expression previously developed by one of the authors. Aging is introduced by measuring the evolution of the resistivity with time. The paper presents an example of application of the model. Finally it is mentioned that the concrete mix can be designed for a target resistivity and that this parameter can also be used as a performance parameter (Corrosion indicator). Being a measurement of resistivity a non destructive method, it can be as well used for on-site quality control.
Consejo Superior de Investigaciones Científicas
Approach to the effect of concrete resistivity in the corrosion of rebars in concrete
by C. ALONSO y C. ANDRADE lETcc/CSIC Serrano Galvache s/n, 28033-Madrid J. A. GONZALEZ Centro Nacional de Investigaciones l\/letalúrgicas MADRID/ESPAÑA
Fecha de Recepción: 22-VII-87
The concrete resistivity has been considered as a factor which affects the corrosion rate of the rebars. Untill now the only relation found has been stablished between potentials and resistivity for steel embedded in Chloride contaminated concrete.
In this paper a comparison between corrosion rate of rebars, determined from Polarization Resistance method, and Electrical Resistance data measured through the electronic compensation of the ohmic drop are given. The result for Icorr and Rohm has been measured for rebars embedded in mortar made with three different types of cement. The specimens were submited to an accelerated carbonation.
The relation between Icorr and Rohm is quite similar in all the cases and suggests that the concrete electrical resistivity may be a controling factor of the corrosion rate of the rebars.
Journal of Advanced Concrete Technology Vol. 15, 278-289, June 2017 / Copyright © 2017 Japan Concrete Institute
Relationship of Apparent Electrical Resistivity Measured by Four-Probe Method with Water Content Distribution in Concrete
by Hiroshi Minagawa1*, Shintaro Miyamoto2 and Makoto Hisada3
Received 8 April 2016, accepted 30 May 2017
The electrical resistivity of concrete is an important value for designing electrochemical anti-corrosive methods or a durability indicator of reinforced concrete structures. It is well known that the four-probe method (the Wenner method) can be useful one for non-destructive evaluation of electrical resistivity. However, it has been pointed out that the measured results must be identified as an apparent value including the effect of water content gradient in concrete. In order to consider the engineering property of apparent electrical resistivity, this study evaluated the water content gradient dependency of the measured results by experimental approach and numerical analysis with FEM. As a result, this study explained the mechanism about the probe spacing dependency of apparent electrical resistivity of concrete with water content gradient in depth direction. Moreover, it was pointed out that the apparent electrical resistivity of concrete with water content gradient was correlated with the electrical resistivity at a depth about equal to the probe spacing, and measuring apparent electrical resistivity does not necessarily mean that the four probe method can evaluate the electrical resistivity of the immediate surface of concrete in dry conditions. In addition to this, it was recommended to compare the apparent electrical resistivities measured by several distance of the probe spacing in order to clarify the presence or absence of the effect of the water content gradient in concrete.
Revista ALCONPAT, 8 (1), 2018: 1 – 15
Service life analysis of reinforced concrete structure under uniform corrosion through ANN model coupled to the FEM
by E. F. Felix, T. J. Rodrigues Balabuch, M. Corrêa Posterlli, E. Possan, R. Carrazedo (2018)
Recepción: 24/08/2017 | Aceptación: 18/12/2017 | Publicación: 31/01/2018
The present work intends to analyze and numerically model the corrosion process, estimating the service life of concrete structures. The modelling process was divided in two stages, initiation and propagation. The modeling of the initiation phase was carried out by Artificial Neural Networks (ANN), and the modeling of the propagation phase was done by means of Finite Element Method (FEM). The results show the efficiency of the model generated by the coupling of ANN to the FEM to analyze and study the durability of reinforced concrete structures under uniform corrosion, and the numerical model applicability to estimate the service life of reinforced concrete structures.
Keywords: reinforced concrete; reinforcement corrosion; service life; Artificial Neural Networks; Finite Element Method.
13th International Congress on the Chemistry of Cement. 13th ICCC
Setting and hydration evolution monitored by resistivity and ultrasonic velocity
Andrade C. and Rebolledo N., Instituto Eduardo Torroja de Ciencias de la Construcción (CSIC) Madrid, Spain
Madrid, July 2010
Cement hydration and setting can be studied from numerous perspectives. One present trend is based in the use of non destructive techniques as the analysis of the evolution of the ultrasonic pulses with time from cement mixing with water. There are two main methods and equipments which have been recently developed: the impulse-echo and the flight time or velocity of the sound waves. Regarding resistivity, it has been used some decades ago for the identification of the setting time and the conductivity has been used for the study of the pore solution chemistry. In this study is presented the joint analysis of both ND techniques applied to an ordinary Portland cement. In the case of the sonic pulse, the technique of velocity or flight time has been used. The results show the suitability of the sonic flight time to monitor the dynamic modulus of the material and through the resistivity, the formation of the pore network and in consequence of the mechanical strength. Then both techniques jointly analyzed are promising for the prediction to longer terms of the strength, porosity and likely of other hydration events.
Originality
The simultaneous use of resistivity and ultrasonic pulses. There are very few data. It is original their comparison to the advance of hydration and not only to the setting.
Chief contributions
The possibility to predict long term strength and durability from very early NDT results.
Keywords: electrical resistivity, ultrasonic waves, setting time and hydration
XVII: ERMCO CONGRESS
ASSESSMENT OF CONCRETE DURABILITY OF NEW PANAMA CANAL LOCKS THROUGH THE USE OF RESISTIVITY
C. Andrade (1), N. Rebolledo (1), F. Tavares (1), R. Pérez (2), M. Baz (2) (1) IETcc-CSIC-Spain; e-mail address (andrade@ietcc.csic.es) (2) GUPC: Grupo Unidos por el Canal (Sacyr); e-mail address (rafael.perez@GUPC.PA)
Istambul, Turkey
Panama Canal connects the Pacific Ocean and the Caribbean Sea, being a crucial shortening in the world navigation and international trade. Now 100 years old, the canal is insufficient for the new large boats. New parallel locks are being built by a consortium “Grupo Unidos por el Canal”, GUPC, whose engineering division is headed by the firm Sacyr, S.A. The concrete on the new structure is reinforced as an anti-seismic precaution. In its specifications, the Panama Canal Authority, ACP, requires a 100-year service life for the so called marine concrete, defined to mean conformity with the 1000-coulomb electrical charge set out in ASTM 1202 and application of a reliable method for calculating service life.
In present paper some of the designed concrete mixes and their performance are described. As an alternative to the ASTM 1202 test, resistivity measurements and natural chloride diffusion tests were proposed. Additionally the service life calculation was made through a program with a numerical model. The relationship between electrical charge and resistivity values is discussed, along with the variation in these parameters over time, the chloride diffusion values and the «age factor” proved to have an even more critical effect on predictions than the diffusion coefficient. The use of the resistivity is a very practical manner to control concrete production due to its non-destructive character.
Keywords: concrete, chlorides, resistivity, diffusion.
Hindawi Advances in Materials Science and Engineering Volume 2017, Article ID 8453095
Electrical Resistivity of Concrete for Durability Evaluation: A Review
Pejman Azarsa and Rishi Gupta Department of Civil Engineering, University of Victoria, Victoria, BC, Canada
Received 17 October 2016; Revised 30 March 2017; Accepted 2 May 2017; Published 31 May 2017
Degradation processes in reinforced concrete structures that affect durability are partially controlled by transport of aggressive ions through the concrete microstructure. Ions are charged and the ability of concrete to hold out against transfer of ions greatly relies on its electrical resistivity. Hence, a connection could be expected between electrical resistivity of concrete and the deterioration processes such as increase in permeability and corrosion of embedded steel.Through this paper, an extensive literature review has been done to address relationship between concrete electrical resistivity and its certain durability characteristics. These durability characteristics include chloride diffusivity and corrosion of reinforcement as these have major influence on concrete degradation process. Overall, there exists an inverse or direct proportional correlation between these parameters.
Evaluated results, from measuring the concrete electrical resistivity, can also be used as a great indicator to identify early age characteristics of fresh concrete and for evaluation of its properties, determination ofmoisture content, connectivity of themicropores, and even condition assessment of in-service structures. This paper also reviews and assesses research concerning the influential parameters such as environmental conditions and presence of steel rebar and cracks onmeasuring electrical resistivity of concrete.Moreover, concrete resistivity concept, application, and its various measurement techniques are introduced.
US Department of Transportation, Federal Highway Administration
Resistivity Testing for Long Term Durability of Concrete
Findings from the FHWA Mobile Concrete Trailer (MCT)
FHWA-HIF-18-037
One of the major forms of environmental attack for concrete structures is chloride ingress due to salt water or deicing chemicals. Chloride ingress leads to corrosion of the reinforcement and subsequent reduction in strength, serviceability, and aesthetics of the structure. To mitigate this issue, designing concrete mixtures to resist chloride ingress and verifying mix properties during construction are key activities.
Traditional Test: Electrical Indication of Concrete’s Ability To Resist Chloride Ion Penetration test (AASHTO T 277 /ASTM C 1202), more commonly referred to as the Rapid Chloride Permeability Test (RCPT), is the most widely used test method by state agencies for this purpose. This test measures the number of coulombs that pass through a 2” concrete specimen. This is a surrogate test for concrete permeability in that the number of coulombs passed is directly proportional to the permeability of concrete. One of the drawbacks with the RCPT test method is the time and labor required to run the test (approximately 2 days to prepare the test specimens and 6 hrs. to perform the test).
Benefits of using this Technology
➢ A very quick test
o 2 minutes to perform
➢ Non-destructive
o Allows for testing at different ages and specimens can be used for other tests
➢ Easy to use and handle
o Does not require use of chemicals
o Tests can be performed by one person.
➢ Economical (when compared to RCPT)
o Cost savings of more than 90% due to reduction in testing time, labor, and equipment costs (Reference 1).
➢ Time Savings
o Tests can be run earlier than 56 days to verify if 56 days specified minimum resistivity is achieved.
➢ Allows for greater number of measurements
o Statistically more robust data.
Revista de la Asociación Latinoamericana de Control de Calidad, Patología y Recuperación de la Construcción ISSN: 2007-6835
Service life design and modelling of concrete structures – background, developments, and implementation
M. G. Alexander University of Cape Town, Southafrica
FHWA-HIF-18-037
The paper presents an international overview of current knowledge and progress in service life design and modelling of concrete structures. It explores why service life modelling is needed, and indicates that modern demands for longevity, durability, and sustainability of concrete structures cannot be fulfilled without service life modelling. It addresses the current approaches to durability design and specification and concludes that a move to performance-based approaches is imperative for progress to be made.
Examples from international experience are cited to illustrate progress that has been made. Lastly, the paper discusses ways of moving forward, recognizing that the philosophical bases are already in place in the form of general code formulations, but which need to be converted into useful approaches
Keywords: service life modelling, performance-based specifications, concrete durability, durability indicators, model code.
