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• Corrosion Resistance Performance of Steel-Reinforced Engineered Cementitious Composite Beams

  M. Sahmaran, V. Li, C. Andrade

  Materials Journal (2008). Vol. 105 (3), pp. 243-250

  
  

  Abstract

  This paper presents the results of an experimental investigation on steel-reinforced engineered cementitious composite (ECC) beams subjected to accelerated corrosion by an electrochemical method. ECC is a micromechanically-based designed, high-performance, fiber-reinforced cementitious composite with high ductility and improved durability due to tight crack width. An accelerated corrosion test method, which was carried out by imposing a constant potential, was used to induce different degrees of corrosion into the reinforcement embedded in ECC prismatic specimens. Mortar specimens that have an equal compressive strength to the ECC specimens were also used as reference specimens. After inducing different degrees of accelerated corrosion, the cracks and the residual flexural load capacity of the test specimens and the mass loss of reinforcing bars embedded in specimens were determined. From the results of this study, it is concluded that due to its high tensile strain capacity and microcracking behaviors, ECC significantly prolonged the corrosion propagation period while enhancing the ability to maintain the load capacity of the beam. These performances of reinforced ECC (R/ECC) are expected to contribute substantially to improving infrastructure sustainability by reducing the amount of repair and maintenance during the service life of the infrastructure.

  Abstract
  This paper presents the results of an experimental investigation on steel-reinforced engineered cementitious composite (ECC) beams subjected to accelerated corrosion by an [...]

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• Hydrogen induced changes in structural properties of iron: Ab initio calculations

  A. Castedo, J. Sánchez, J. Fullea, C. Andrade, P. Andrés

  (2011). Advances in Modeling Concrete Service Life. RILEM Bookseries, Vol 3, pp. 79-84. Springer, Dordrecht

  
  

  Abstract

  We have used Ab initio calculations to study the structural changes produced by the inclusion of light impurities into pure bcc iron. In order to obtain a clear picture of the mechanics of the phase changes Bain’s pathway was studied in detail for pure iron. The position that hydrogen atoms tend to occupy at high densities favours octahedral sites inside the bcc matrix, producing an internal stress field that suggests a deformation that matches the prediction of martensitic transformation predicted by Bain’s pathway. We have used Density Functional Theory in order to optimize the structures studied, obtaining the enthalpy of the configuration as a function of c/a, allowing a better understanding of the dynamics of the process of phase changes.

  Abstract
  We have used Ab initio calculations to study the structural changes produced by the inclusion of light impurities into pure bcc iron. In order to obtain a clear picture of [...]

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

  L. Toro, C. Andrade, J. Fullea, I. Martínez, N. Rebolledo

  (2011). Advances in Modeling Concrete Service Life. RILEM Bookseries, vol 3, pp. 53-63. Springer, Dordrecht

  
  

  Abstract

  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.

  Abstract
  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 [...]

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

  N. Rebolledo, C. Andrade

  (2011). Advances in Modeling Concrete Service Life. RILEM Bookseries, vol 3, pp. 43-51. Springer, Dordrecht

  
  

  Abstract

  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.

  Abstract
  In marine environments, reinforcement corrosion develops due to the penetration of chlorides through the concrete pores. Initially the corrosion appears as localized attack, [...]

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• Corrosion Data Interpretation in Concrete Structures

  C. Andrade

  (2011). Advances in Modeling Concrete Service Life. RILEM Bookseries, vol 3, pp. 1-10. Springer, Dordrecht

  
  

  Abstract

  Concrete protects the steel embedded until carbonation front or the ­chloride threshold reaches the rebar. Then a corrosion process develops. In present paper the corrosion process is analyzed from its onset a definition of which is given. The techniques for its measurement are described and also are given a model for the corrosion propagation period as well as some alternatives to assume a value of the corrosion rate, even based in the values of the concrete resistivity. Finally, the functions of relation between the corrosion and the structural consequences are commented.

  Abstract
  Concrete protects the steel embedded until carbonation front or the ­chloride threshold reaches the rebar. Then a corrosion process develops. In present paper the corrosion [...]

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• From the instantaneous corrosion rate to a representative value

  C. Andrade, N. Rebolledo, F. Pedrosa

  ICCRRR 2012 (2012).

  
  

  Abstract

  Reinforcement corrosion develops due to the penetration of chlorides or of the carbonation front through the concrete pores and corrosion develops if enough moisture is present. However as the corrosion rate changes with temperature and the evolution of the corrosion itself, the representation may not be clear enough to be used for comparative purposes or for prediction of future evolution. 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 the adequate to establish a Representative annual average value for comparative purposes. The procedure is applied to concrete specimens and real size elements exposed to Madrid outdoor conditions.

  Abstract
  Reinforcement corrosion develops due to the penetration of chlorides or of the carbonation front through the concrete pores and corrosion develops if enough moisture is present. [...]

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• Corrosión y protección de armaduras

  C. Andrade

  Informes de la Construcción (1982). Vol. 33 (339), pp. 33-41

  
  

  Abstract

  La investigación en el campo de la corrosión de armaduras ha ido siempre muchos años con retraso respecto de los avances conseguidos en otros campos de la corrosión del acero, principalmente por la dificultad que supone el manejo de un electrólito (fase acuosa) que está encerrado en los poros de una estructura pétrea que dificulta el seguimiento visual de los procesos. Electrólito que evoluciona constantemente en el tiempo debido a la progresiva hidratación del cemento y, por lo tanto, no presenta una composición definida y fácilmente reproducible en todos sus componentes.

  Abstract
  La investigación en el campo de la corrosión de armaduras ha ido siempre muchos años con retraso respecto de los avances conseguidos en otros campos de [...]

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• Determinación electroquímica cuantitativa de la velocidad de corrosión de un acero de construcción. Evaluación de la susceptibilidad al ataque por picaduras. Parte II: Ensayos en mortero

  C. Andrade, J. González

  Materiales de Construcción (1978). Vol. 28 (169), pp. 49-62

  
  

  Abstract

  El estudio del efecto de un determinado aditivo sobre la corrosión de las armaduras, o el de un hormigón con fisuras, o sometido a ambientes marinos o, en fin, de cualquier factor o circunstancia calificada como agresiva, suele exigir un laborioso y extenso programa de trabajo que contemple todas las posibilidades por las que puedan pasar las armaduras y el hormigón que las contiene. En éste, como en tantos otros campos de la tecnología, es importante la búsqueda de métodos de ensayo acelerados, que sean a la vez de lo más representativos posible una ayuda para economizar esfuerzo y materiales.

  Abstract
  El estudio del efecto de un determinado aditivo sobre la corrosión de las armaduras, o el de un hormigón con fisuras, o sometido a ambientes marinos o, en fin, [...]

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• Corrosión de armaduras embebidas en hormigón carbonatado

  C. Andrade, S. Algaba, J. González

  Materiales de Construcción (1981). Vol. 31 (181), pp. 45-53

  
  

  Abstract

  Los componentes ácidos de la atmósfera, en particular el CO₂, pueden neutralizar (carbonatar) el electrólito que llena los poros del hormigón y las fases del clínker, transformándolos en variedades del CO₃Ca. La carbonatación no sólo modifica la estructura de la pasta de cemento y por lo tanto sus propiedades, sino que también tiene una influencia decisiva sobre la velocidad de corrosión de las armaduras (1) (2). En un reciente informe del Comité 12-CRC de la RILEM (3) se afirmaba que: "si se exceptúa la corrosión causada por Cl^-, actualmente se está de acuerdo en que la carbonatación del hormigón es la condición esencial para la corrosión de las armaduras". (Aquí se debería añadir que esto se aplica a los hormigones simplemente armados, pues en los pretensados también es muy peligroso el fenómeno conocido como corrosión bajo tensión). La carbonatación puede desencadenar el proceso de corrosión, debido a que el descenso de pH que provoca hace posible el paso de las armaduras del estado pasivo al activo. La velocidad de ataque depende, sin embargo, de otros factores externos: un contenido mínimo de humedad en el medio ambiente que garantice la existencia del electrólito en los poros del hormigón, y un libre acceso de O₂ hasta la superficie metálica para que pueda producirse la semirreacción catódica. Numerosos autores están de acuerdo con estos puntos, pero sin aportar pruebas cuantitativas de los mismos. Es objeto principal de este trabajo contribuir a llenar este vacío.

  Abstract
  Los componentes ácidos de la atmósfera, en particular el CO₂, pueden neutralizar (carbonatar) el electrólito que llena los poros [...]

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• La agresividad ambiental y la durabilidad de las estructuras de hormigón

  B. Perepérez, E. Barberá, C. Andrade

  Informes de la Construcción (2012). Vol. 38 (388), pp. 17-24

  
  

  Abstract

  The deterioration of concrete structures is the result of the interaction between them and the environment. In this study, comments are made on the most decisive environmental factors and their interactions. Special reference is made to the corrosion of the reinforcements and also to the different proposals of classification of the aggressiveness. El deterioro de las estructuras de hormigón es el resultado de la interacción entre ellas y el medio ambiente. En el presente trabajo se comentan los factores ambientales más determinantes y sus interacciones, con especial referencia a la corrosión de las armaduras, así como diferentes propuestas de clasificación de la agresividad.

  Abstract
  The deterioration of concrete structures is the result of the interaction between them and the environment. In this study, comments are made on the most decisive environmental [...]

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