Documents disponibles écrits par cet auteur

Modelling of reinforcement corrosion – geometrical effects on macrocell corrosion / J. Warkus in Materials and corrosion, Vol. 61 N° 6 (Juin 2010) 

Public ISBD [article]  in Materials and corrosion > Vol. 61 N° 6 (Juin 2010) . - pp. 494–504 Titre : Modelling of reinforcement corrosion – geometrical effects on macrocell corrosion Type de document : texte imprimé Auteurs : J. Warkus, Auteur ; M. Raupach, Auteur Année de publication : 2010 Article en page(s) : pp. 494–504 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : concrete;  corrosion;modelling;  reinforcement;  simulation Résumé : Reinforcement corrosion is still the most frequent reason for damage of concrete structures. It can be caused by carbonation or the ingress of chlorides. In cases of localized contaminations with chlorides, macrocells with very high corrosion rates can be established. Thereby the resulting macrocell current is dependent on many different boundary conditions like driving voltage, concrete resistivity and the geometrical arrangement of anode and cathode. In order to investigate macrocell corrosion, the herein presented research work was carried out by laboratory experiments and additionally by numerical analyses. First the numerical simulations were calibrated by laboratory measurements and thereafter, a numerical parameter study was carried out to increase the available database and identify the impact of changes in single parameters. As the focus is on geometrical effects, all laboratory specimens and numerical models were designed to represent practical conditions with diverse geometrical arrangements, e.g., slabs or beams with localized depassivations. In addition, parameters like concrete resistivity, driving voltage and cathode to anode surface area ratios have been varied. Thereafter, all results were used to derive cell factors for a simple macrocell current estimation. The present status of the project will be presented and discussed. En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.200905437/abstract [article] Modelling of reinforcement corrosion – geometrical effects on macrocell corrosion [texte imprimé] / J. Warkus, Auteur ; M. Raupach, Auteur . - 2010 . - pp. 494–504. Génie mécanique Langues : Anglais (eng) in Materials and corrosion > Vol. 61 N° 6 (Juin 2010) . - pp. 494–504 Mots-clés : concrete;  corrosion;modelling;  reinforcement;  simulation Résumé : Reinforcement corrosion is still the most frequent reason for damage of concrete structures. It can be caused by carbonation or the ingress of chlorides. In cases of localized contaminations with chlorides, macrocells with very high corrosion rates can be established. Thereby the resulting macrocell current is dependent on many different boundary conditions like driving voltage, concrete resistivity and the geometrical arrangement of anode and cathode. In order to investigate macrocell corrosion, the herein presented research work was carried out by laboratory experiments and additionally by numerical analyses. First the numerical simulations were calibrated by laboratory measurements and thereafter, a numerical parameter study was carried out to increase the available database and identify the impact of changes in single parameters. As the focus is on geometrical effects, all laboratory specimens and numerical models were designed to represent practical conditions with diverse geometrical arrangements, e.g., slabs or beams with localized depassivations. In addition, parameters like concrete resistivity, driving voltage and cathode to anode surface area ratios have been varied. Thereafter, all results were used to derive cell factors for a simple macrocell current estimation. The present status of the project will be presented and discussed. En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.200905437/abstract

Protection of the opposite reinforcement layer of RC-structures by CP – results of numerical simulations / M. Bruns in Materials and corrosion, Vol. 61 N° 6 (Juin 2010) 

Public ISBD [article]  in Materials and corrosion > Vol. 61 N° 6 (Juin 2010) . - pp. 505–511 Titre : Protection of the opposite reinforcement layer of RC-structures by CP – results of numerical simulations Type de document : texte imprimé Auteurs : M. Bruns, Auteur ; M. Raupach, Auteur Année de publication : 2010 Article en page(s) : pp. 505–511 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : cathodic  protection;  concrete  repair;  current  distribution;  numerical  simulation Résumé : If cathodic protection (CP) is applied to reinforced concrete structures the anode is usually attached at the concrete surface closest to the corroding reinforcement in order to minimise voltage and protection current that is required. In specific circumstances an anode installation at the concrete surface next to the corroding reinforcement is not practicable, i.e. due to difficult access. In such cases it would be helpful to know whether it is possible to protect the reinforcement by an anode being installed at the opposite surface of the structural element. The question is: does the second reinforcement layer obtain sufficient current to be effectively protected? Since a general answer to this question is not possible because the distribution of protection current depends on several parameters like the geometry and amount of the reinforcement, concrete resistivity, the polarisation behaviour and geometry of corroding and passive zones, a 3 D-FEM model of the current and potential distribution was developed and its accuracy was verified by laboratory results. This paper presents the model itself as well as the results of parameter studies carried out to show the impact of the reinforcement distribution, the concrete resistivity and the polarisation behaviour of the reinforcement on the current distribution within the reinforcement. En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.200905584/abstract [article] Protection of the opposite reinforcement layer of RC-structures by CP – results of numerical simulations [texte imprimé] / M. Bruns, Auteur ; M. Raupach, Auteur . - 2010 . - pp. 505–511. Génie mécanique Langues : Anglais (eng) in Materials and corrosion > Vol. 61 N° 6 (Juin 2010) . - pp. 505–511 Mots-clés : cathodic  protection;  concrete  repair;  current  distribution;  numerical  simulation Résumé : If cathodic protection (CP) is applied to reinforced concrete structures the anode is usually attached at the concrete surface closest to the corroding reinforcement in order to minimise voltage and protection current that is required. In specific circumstances an anode installation at the concrete surface next to the corroding reinforcement is not practicable, i.e. due to difficult access. In such cases it would be helpful to know whether it is possible to protect the reinforcement by an anode being installed at the opposite surface of the structural element. The question is: does the second reinforcement layer obtain sufficient current to be effectively protected? Since a general answer to this question is not possible because the distribution of protection current depends on several parameters like the geometry and amount of the reinforcement, concrete resistivity, the polarisation behaviour and geometry of corroding and passive zones, a 3 D-FEM model of the current and potential distribution was developed and its accuracy was verified by laboratory results. This paper presents the model itself as well as the results of parameter studies carried out to show the impact of the reinforcement distribution, the concrete resistivity and the polarisation behaviour of the reinforcement on the current distribution within the reinforcement. En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.200905584/abstract