Dépouillements

A tribute to Pietro Pedeferri's contribution to the knowledge on corrosion of steel in concrete and its prevention / Luca Bertolini in Materials and corrosion, Vol. 62 N° 2 (Fevrier 2011) 

Public ISBD [article]  in Materials and corrosion > Vol. 62 N° 2 (Fevrier 2011) . - pp. 96–97 Titre : A tribute to Pietro Pedeferri's contribution to the knowledge on corrosion of steel in concrete and its prevention Type de document : texte imprimé Auteurs : Luca Bertolini, Auteur Année de publication : 2011 Article en page(s) : pp. 96–97 Note générale : Génie Mécanique Langues : Anglais (eng) Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux DEWEY : 620.1 ISSN : 0947-5117 En ligne : http://acatalogue_2.biblio.intranet.enp.edu.dz/catalog.php?categ=serials&sub=ana [...] [article] A tribute to Pietro Pedeferri's contribution to the knowledge on corrosion of steel in concrete and its prevention [texte imprimé] / Luca Bertolini, Auteur . - 2011 . - pp. 96–97. Génie Mécanique Langues : Anglais (eng) in Materials and corrosion > Vol. 62 N° 2 (Fevrier 2011) . - pp. 96–97 Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux DEWEY : 620.1 ISSN : 0947-5117 En ligne : http://acatalogue_2.biblio.intranet.enp.edu.dz/catalog.php?categ=serials&sub=ana [...]

Ten-year results of galvanic sacrificial anodes in steel reinforced concrete / G. Sergi in Materials and corrosion, Vol. 62 N° 2 (Fevrier 2011) 

Public ISBD [article]  in Materials and corrosion > Vol. 62 N° 2 (Fevrier 2011) . - pp. 98–104 Titre : Ten-year results of galvanic sacrificial anodes in steel reinforced concrete Type de document : texte imprimé Auteurs : G. Sergi, Auteur Année de publication : 2011 Article en page(s) : pp. 98–104 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Cathodic  prevention  Concrete  durability  Galvanic  anodes  Steel  corrosion Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Zinc sacrificial anodes have been included in patch repairs to steel reinforced concrete structural elements suffering from corrosion since the mid-1990s. A number of these anode-containing repairs have been monitored with time. One of the first monitored sites was of a locally repaired cross beam of a bridge structure in Leicester, UK, which has now completed 10 years since its original repair and anode installation. This paper reviews the performance of the anodes installed at the Leicester site in terms of anode current output and steel reinforcement polarisation and corrosion rate over the period. It also presents results of analysis of recovered anodes exposed for 10 years which still show electrolyte continuity, uniform consumption of the zinc and coherent encasing mortar. The knowledge gained from the 10 year results has enabled the development of new, higher current output anodes, which are now trialled in this and other sites. DEWEY : 620.1 ISSN : 0947-5117 En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.201005707/abstract [article] Ten-year results of galvanic sacrificial anodes in steel reinforced concrete [texte imprimé] / G. Sergi, Auteur . - 2011 . - pp. 98–104. Génie Mécanique Langues : Anglais (eng) in Materials and corrosion > Vol. 62 N° 2 (Fevrier 2011) . - pp. 98–104 Mots-clés : Cathodic  prevention  Concrete  durability  Galvanic  anodes  Steel  corrosion Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Zinc sacrificial anodes have been included in patch repairs to steel reinforced concrete structural elements suffering from corrosion since the mid-1990s. A number of these anode-containing repairs have been monitored with time. One of the first monitored sites was of a locally repaired cross beam of a bridge structure in Leicester, UK, which has now completed 10 years since its original repair and anode installation. This paper reviews the performance of the anodes installed at the Leicester site in terms of anode current output and steel reinforcement polarisation and corrosion rate over the period. It also presents results of analysis of recovered anodes exposed for 10 years which still show electrolyte continuity, uniform consumption of the zinc and coherent encasing mortar. The knowledge gained from the 10 year results has enabled the development of new, higher current output anodes, which are now trialled in this and other sites. DEWEY : 620.1 ISSN : 0947-5117 En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.201005707/abstract

Early stage beneficial effects of cathodic protection in concrete structures / R. B. Polder in Materials and corrosion, Vol. 62 N° 2 (Fevrier 2011) 

Public ISBD [article]  in Materials and corrosion > Vol. 62 N° 2 (Fevrier 2011) . - pp. 105–110 Titre : Early stage beneficial effects of cathodic protection in concrete structures Type de document : texte imprimé Auteurs : R. B. Polder, Auteur ; W. H. A. Peelen, Auteur ; B. Th. J. Stoop, Auteur Année de publication : 2011 Article en page(s) : pp. 105–110 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Cathodic  protection  Concrete  Numerical  modelling  Reinforcement  corrosion Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Over the last 25 years, cathodic protection (CP) of reinforced concrete structures suffering from chloride induced reinforcement corrosion has shown to be successful and durable. CP current causes steel polarisation, electrochemical reactions and ion transport in the concrete. CP systems are designed based on experience, which results in conservative designs and their performance is a matter of wait-and-see. CP systems can be designed for critical aspects and made more economical using numerical models for current and polarisation distribution. Previously, principles of numerical calculations for design of CP systems were reported. The results were satisfactory, except in terms of current density for active corroding systems. This was suggested to be due to neglecting beneficial effects of CP current flow. One of the beneficial effects is pH increase at the steel surface due to oxygen reduction. As the pH increases, the corrosion rate decreases and the current demand decreases. A simple model was set up for this transient process, suggesting that such effects should occur on the time scale of hours to days. This model was validated from start up data of a CP field trial system on part of a bridge. Field results confirmed the modelling proposed here. DEWEY : 620.1 ISSN : 0947-5117 En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.201005803/abstract [article] Early stage beneficial effects of cathodic protection in concrete structures [texte imprimé] / R. B. Polder, Auteur ; W. H. A. Peelen, Auteur ; B. Th. J. Stoop, Auteur . - 2011 . - pp. 105–110. Génie Mécanique Langues : Anglais (eng) in Materials and corrosion > Vol. 62 N° 2 (Fevrier 2011) . - pp. 105–110 Mots-clés : Cathodic  protection  Concrete  Numerical  modelling  Reinforcement  corrosion Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Over the last 25 years, cathodic protection (CP) of reinforced concrete structures suffering from chloride induced reinforcement corrosion has shown to be successful and durable. CP current causes steel polarisation, electrochemical reactions and ion transport in the concrete. CP systems are designed based on experience, which results in conservative designs and their performance is a matter of wait-and-see. CP systems can be designed for critical aspects and made more economical using numerical models for current and polarisation distribution. Previously, principles of numerical calculations for design of CP systems were reported. The results were satisfactory, except in terms of current density for active corroding systems. This was suggested to be due to neglecting beneficial effects of CP current flow. One of the beneficial effects is pH increase at the steel surface due to oxygen reduction. As the pH increases, the corrosion rate decreases and the current demand decreases. A simple model was set up for this transient process, suggesting that such effects should occur on the time scale of hours to days. This model was validated from start up data of a CP field trial system on part of a bridge. Field results confirmed the modelling proposed here. DEWEY : 620.1 ISSN : 0947-5117 En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.201005803/abstract

Stainless steel reinforcing bars – reason for their high pitting corrosion resistance / B. Elsener in Materials and corrosion, Vol. 62 N° 2 (Fevrier 2011) 

Public ISBD [article]  in Materials and corrosion > Vol. 62 N° 2 (Fevrier 2011) . - pp. 111–119 Titre : Stainless steel reinforcing bars – reason for their high pitting corrosion resistance Type de document : texte imprimé Auteurs : B. Elsener, Auteur ; D. Addari, Auteur ; S. Coray, Auteur Année de publication : 2011 Article en page(s) : pp. 111–119 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Alkaline  solutions  Concrete  Manganese  Passive  film  Pitting  corrosion  Reinforcement  Stainless  steels  XPS  surface  analysis Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In harsh chloride bearing environments stainless steel reinforcing bars offer excellent corrosion resistance and very long service life for concrete structures, but the high costs limit a more widespread use. Manganese bearing nickel-free stainless steels could be a cost-effective alternative. Whereas the corrosion behavior of stainless steels in alkaline solutions, mortar and concrete is quite well established, only little information on the reasons for the high pitting resistance are available. This work reports the results of pitting potential measurements in solutions simulating alkaline and carbonated concrete on black steel, stainless steel DIN 1.4301, duplex steel DIN 1.4462, and nickel-free stainless steel DIN 1.4456. Duplex and nickel-free stainless steels are fully resistant even in 4 M NaCl solutions with pH 13 or higher, the lower grade DIN 1.4301 shows a wide scatter between fully resistant and pitting potentials as low as +0.2 V SCE. In carbonated solutions with pH 9 the nickel-free DIN 1.4456 shows pitting corrosion at chloride concentrations ≥3 M. This ranking of the pitting resistance can be rationalized based on XPS surface analysis results: both the increase of the Cr(III)oxy-hydroxide and Mo(VI) contents in the passive film and a marked nickel enrichment beneath the film improve the pitting resistance. The duplex DIN 1.4462 shows the highest pitting resistance, which can be attributed to the very high Cr(III)oxy-hydroxide, to a medium Mo(VI) content in the film and to a nickel enrichment beneath the film. Upon time, the protective properties of the surface film improve. This beneficial effect of ageing (transformation of the passive film to a less Fe2+ containing, more hydrated film) will lead to higher pitting potentials. It can be concluded that short-term solution experiments give conservative results in terms of resistance to chloride-induced corrosion in reinforced concrete structures. DEWEY : 620.1 ISSN : 0947-5117 En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.201005826/abstract [article] Stainless steel reinforcing bars – reason for their high pitting corrosion resistance [texte imprimé] / B. Elsener, Auteur ; D. Addari, Auteur ; S. Coray, Auteur . - 2011 . - pp. 111–119. Génie Mécanique Langues : Anglais (eng) in Materials and corrosion > Vol. 62 N° 2 (Fevrier 2011) . - pp. 111–119 Mots-clés : Alkaline  solutions  Concrete  Manganese  Passive  film  Pitting  corrosion  Reinforcement  Stainless  steels  XPS  surface  analysis Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : In harsh chloride bearing environments stainless steel reinforcing bars offer excellent corrosion resistance and very long service life for concrete structures, but the high costs limit a more widespread use. Manganese bearing nickel-free stainless steels could be a cost-effective alternative. Whereas the corrosion behavior of stainless steels in alkaline solutions, mortar and concrete is quite well established, only little information on the reasons for the high pitting resistance are available. This work reports the results of pitting potential measurements in solutions simulating alkaline and carbonated concrete on black steel, stainless steel DIN 1.4301, duplex steel DIN 1.4462, and nickel-free stainless steel DIN 1.4456. Duplex and nickel-free stainless steels are fully resistant even in 4 M NaCl solutions with pH 13 or higher, the lower grade DIN 1.4301 shows a wide scatter between fully resistant and pitting potentials as low as +0.2 V SCE. In carbonated solutions with pH 9 the nickel-free DIN 1.4456 shows pitting corrosion at chloride concentrations ≥3 M. This ranking of the pitting resistance can be rationalized based on XPS surface analysis results: both the increase of the Cr(III)oxy-hydroxide and Mo(VI) contents in the passive film and a marked nickel enrichment beneath the film improve the pitting resistance. The duplex DIN 1.4462 shows the highest pitting resistance, which can be attributed to the very high Cr(III)oxy-hydroxide, to a medium Mo(VI) content in the film and to a nickel enrichment beneath the film. Upon time, the protective properties of the surface film improve. This beneficial effect of ageing (transformation of the passive film to a less Fe2+ containing, more hydrated film) will lead to higher pitting potentials. It can be concluded that short-term solution experiments give conservative results in terms of resistance to chloride-induced corrosion in reinforced concrete structures. DEWEY : 620.1 ISSN : 0947-5117 En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.201005826/abstract

Corrosion resistance of low-nickel duplex stainless steel rebars / L. Bertolini in Materials and corrosion, Vol. 62 N° 2 (Fevrier 2011) 

Public ISBD [article]  in Materials and corrosion > Vol. 62 N° 2 (Fevrier 2011) . - pp. 120–129 Titre : Corrosion resistance of low-nickel duplex stainless steel rebars Type de document : texte imprimé Auteurs : L. Bertolini, Auteur ; M. Gastaldi, Auteur Année de publication : 2011 Article en page(s) : pp. 120–129 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Concrete  Critical  chloride  threshold  Low-nickel  duplex  stainless  steel  Reinforcement  Stainless  steels Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The use of stainless steel bars in reinforced concrete structures may be an effective method to prevent corrosion in aggressive environments where high amounts of chlorides may penetrate in the concrete cover. For an estimation of the service life of structures where stainless steel bars are used, the chloride threshold for these rebars should be defined, and the influence of chemical composition and metallurgical factors that may affect the corrosion resistance (strengthening, welding, etc.) should be assessed. To reduce the cost of stainless steel reinforcement, duplex stainless steels with low nickel content have been recently proposed as an alternative to traditional austenitic steels, even though, few results are available regarding their corrosion performance in chloride contaminated concrete. This paper deals with the corrosion resistance of low-nickel duplex stainless steel rebars (1.4362 and 1.4162) as a function of the chloride content. Comparison is made with traditional austenitic steels. An attempt to define a chloride threshold for the different stainless steels is made by comparing the results of several test procedures both in concrete and in solution. DEWEY : 620.1 ISSN : 0947-5117 En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.201005774/abstract [article] Corrosion resistance of low-nickel duplex stainless steel rebars [texte imprimé] / L. Bertolini, Auteur ; M. Gastaldi, Auteur . - 2011 . - pp. 120–129. Génie Mécanique Langues : Anglais (eng) in Materials and corrosion > Vol. 62 N° 2 (Fevrier 2011) . - pp. 120–129 Mots-clés : Concrete  Critical  chloride  threshold  Low-nickel  duplex  stainless  steel  Reinforcement  Stainless  steels Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The use of stainless steel bars in reinforced concrete structures may be an effective method to prevent corrosion in aggressive environments where high amounts of chlorides may penetrate in the concrete cover. For an estimation of the service life of structures where stainless steel bars are used, the chloride threshold for these rebars should be defined, and the influence of chemical composition and metallurgical factors that may affect the corrosion resistance (strengthening, welding, etc.) should be assessed. To reduce the cost of stainless steel reinforcement, duplex stainless steels with low nickel content have been recently proposed as an alternative to traditional austenitic steels, even though, few results are available regarding their corrosion performance in chloride contaminated concrete. This paper deals with the corrosion resistance of low-nickel duplex stainless steel rebars (1.4362 and 1.4162) as a function of the chloride content. Comparison is made with traditional austenitic steels. An attempt to define a chloride threshold for the different stainless steels is made by comparing the results of several test procedures both in concrete and in solution. DEWEY : 620.1 ISSN : 0947-5117 En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.201005774/abstract

Analysis of the relation between water and resistivity isotherms in concrete / M. C. Andrade in Materials and corrosion, Vol. 62 N° 2 (Fevrier 2011) 

Public ISBD [article]  in Materials and corrosion > Vol. 62 N° 2 (Fevrier 2011) . - pp. 130–138 Titre : Analysis of the relation between water and resistivity isotherms in concrete Type de document : texte imprimé Auteurs : M. C. Andrade, Auteur ; F. Bolzoni, Auteur ; J. Fullea, Auteur Année de publication : 2011 Article en page(s) : pp. 130–138 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Concrete  Isotherms  Moisture  Resistivity Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Concrete is a porous material, that contains an alkaline solution, whose pore network enables mass transport from the exterior. The concrete as composite material is quasi an insulator when it is dry and presents relatively low resistivities, in the order of few kΩ cm when it is fully saturated. Concrete resistivity reflects the degree of saturation and is therefore a useful indicator of the risk of chemical attack and of reinforcement corrosion. The dependence of resistivity on the degree of saturation has been studied, yet this subject has still not been fully elucidated. The present paper studies the evolution of concrete drying from the end of curing in order to analyze the water and resistivity isotherms. Four concrete mixes (w/c = 0.4 and 0.7 after 3 and 7 days of curing wrapped in plastic sheets) have been prepared and submitted to conditions of isothermic water desorption in controlled atmospheres with relative humidity (RH) of 55, 65, 75, 85, 95%. Resistivity measurements were simultaneously carried out which enabled to identify for the four mixes the water content and the RH which gives resistivity values higher than 105 Ω cm. The radii of water-filled pores calculated from Kelvin's law were found to be smaller than those calculated by integrating the mercury intrusion porosimetry (MIP) accumulated intrusion curve with the water lost during conditioning at different RHs. The water content measurement that seems to be most adequate for comparison with resistivity values is the volumetric fraction. DEWEY : 620.1 ISSN : 0947-5117 En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.201005777/abstract [article] Analysis of the relation between water and resistivity isotherms in concrete [texte imprimé] / M. C. Andrade, Auteur ; F. Bolzoni, Auteur ; J. Fullea, Auteur . - 2011 . - pp. 130–138. Génie Mécanique Langues : Anglais (eng) in Materials and corrosion > Vol. 62 N° 2 (Fevrier 2011) . - pp. 130–138 Mots-clés : Concrete  Isotherms  Moisture  Resistivity Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Concrete is a porous material, that contains an alkaline solution, whose pore network enables mass transport from the exterior. The concrete as composite material is quasi an insulator when it is dry and presents relatively low resistivities, in the order of few kΩ cm when it is fully saturated. Concrete resistivity reflects the degree of saturation and is therefore a useful indicator of the risk of chemical attack and of reinforcement corrosion. The dependence of resistivity on the degree of saturation has been studied, yet this subject has still not been fully elucidated. The present paper studies the evolution of concrete drying from the end of curing in order to analyze the water and resistivity isotherms. Four concrete mixes (w/c = 0.4 and 0.7 after 3 and 7 days of curing wrapped in plastic sheets) have been prepared and submitted to conditions of isothermic water desorption in controlled atmospheres with relative humidity (RH) of 55, 65, 75, 85, 95%. Resistivity measurements were simultaneously carried out which enabled to identify for the four mixes the water content and the RH which gives resistivity values higher than 105 Ω cm. The radii of water-filled pores calculated from Kelvin's law were found to be smaller than those calculated by integrating the mercury intrusion porosimetry (MIP) accumulated intrusion curve with the water lost during conditioning at different RHs. The water content measurement that seems to be most adequate for comparison with resistivity values is the volumetric fraction. DEWEY : 620.1 ISSN : 0947-5117 En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.201005777/abstract

Impedance spectroscopy: An efficient tool to determine the non-steady-state chloride diffusion coefficient in building materials / I. Sanchez in Materials and corrosion, Vol. 62 N° 2 (Fevrier 2011) 

Public ISBD [article]  in Materials and corrosion > Vol. 62 N° 2 (Fevrier 2011) . - pp. 139–145 Titre : Impedance spectroscopy: An efficient tool to determine the non-steady-state chloride diffusion coefficient in building materials Type de document : texte imprimé Auteurs : I. Sanchez, Auteur ; M. P. Lopez, Auteur ; J. M. Ortega, Auteur Année de publication : 2011 Article en page(s) : pp. 139–145 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Chloride  migration  Concrete  microstructure  Diffusion  coefficient  Impedance  spectroscopy  In  situ  measurement Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : One of the most important problems of reinforced steel concrete in marine environments is the corrosion of the reinforcing bars. Most of the times, this corrosion is a consequence of the local destruction of the passive layer formed on the surface of the embedded steel, due to the arrival of chlorides present in the environment. Many efforts have been made to determine the chloride diffusion coefficient in concrete structures, both using natural diffusion methods, and accelerated migration methods. This coefficient determines the velocity of ingress of chlorides, and as a consequence the life time of the structures. In this work it is presented the possibility of using the technique of impedance spectroscopy, that is, very simple to use and requires no chemical or conductivity measurement, to determine the value of the non-steady-state diffusion coefficient. This technique, together with the equivalent circuits proposed for the interpretation of the measurements, allows the determination of the chloride saturation of a concrete or mortar sample. Pores of the material that are initially filled with water have high resistivity, and as the chlorides penetrate into the sample the value of the resistivity decreases. This diminution can be determined in situ, and permits the calculation of the diffusion coefficient saving experimental time and efforts. The results have been obtained both with concrete and mortar samples, and using different cement types. DEWEY : 620.1 ISSN : 0947-5117 En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.201005775/abstract [article] Impedance spectroscopy: An efficient tool to determine the non-steady-state chloride diffusion coefficient in building materials [texte imprimé] / I. Sanchez, Auteur ; M. P. Lopez, Auteur ; J. M. Ortega, Auteur . - 2011 . - pp. 139–145. Génie Mécanique Langues : Anglais (eng) in Materials and corrosion > Vol. 62 N° 2 (Fevrier 2011) . - pp. 139–145 Mots-clés : Chloride  migration  Concrete  microstructure  Diffusion  coefficient  Impedance  spectroscopy  In  situ  measurement Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : One of the most important problems of reinforced steel concrete in marine environments is the corrosion of the reinforcing bars. Most of the times, this corrosion is a consequence of the local destruction of the passive layer formed on the surface of the embedded steel, due to the arrival of chlorides present in the environment. Many efforts have been made to determine the chloride diffusion coefficient in concrete structures, both using natural diffusion methods, and accelerated migration methods. This coefficient determines the velocity of ingress of chlorides, and as a consequence the life time of the structures. In this work it is presented the possibility of using the technique of impedance spectroscopy, that is, very simple to use and requires no chemical or conductivity measurement, to determine the value of the non-steady-state diffusion coefficient. This technique, together with the equivalent circuits proposed for the interpretation of the measurements, allows the determination of the chloride saturation of a concrete or mortar sample. Pores of the material that are initially filled with water have high resistivity, and as the chlorides penetrate into the sample the value of the resistivity decreases. This diminution can be determined in situ, and permits the calculation of the diffusion coefficient saving experimental time and efforts. The results have been obtained both with concrete and mortar samples, and using different cement types. DEWEY : 620.1 ISSN : 0947-5117 En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.201005775/abstract

Corrosion assessment and restoration strategies of reinforced concrete buildings of the cultural heritage / L. Bertolini in Materials and corrosion, Vol. 62 N° 2 (Fevrier 2011) 

Public ISBD [article]  in Materials and corrosion > Vol. 62 N° 2 (Fevrier 2011) . - pp. 146–154 Titre : Corrosion assessment and restoration strategies of reinforced concrete buildings of the cultural heritage Type de document : texte imprimé Auteurs : L. Bertolini, Auteur ; M. Carsana, Auteur ; M. Gastaldi, Auteur Année de publication : 2011 Article en page(s) : pp. 146–154 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Reinforced  concrete  structures  Carbonation  Cultural  heritage  Durability  Inspection  Restoration Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Since the beginning of the 20th century, in Italy as in many other countries, reinforced concrete (RC) became one of the most popular construction materials and it was used for buildings, monuments, infrastructures, etc. Several of these structures, although of recent formation, have now been included in the cultural heritage, because of their architectural or social relevance. As a consequence of the typical urban or rural exposure conditions of these buildings, they often suffer damage due to carbonation-induced corrosion of reinforcement, such as concrete spalling or cracking or rust stains that may affect the serviceability of structures. Furthermore, chloride-induced corrosion of reinforcement, may also concern buildings exposed to de-icing salts or marine environments. Due to strict requirements related to the preservation of the original materials and texture, the repair of structures that belong to the cultural heritage cannot rely on the conventional repair technique, based on the replacement of carbonated concrete. Therefore, the conservation of RC buildings of the cultural heritage is a challenge, since it requires the development of specific strategies aimed at finding the best compromise between, on one hand, the restoration of structural safety and the prevention of future damage and, on the other hand, the preservation of the original materials and surfaces. This paper analyses the results of inspections carried out on several buildings, built in Italy throughout the 20th century in different micro- and macro-climates, with the aim of showing their peculiarities with regard to steel corrosion and the selection of restorations strategies. DEWEY : 620.1 ISSN : 0947-5117 En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.201005773/abstract [article] Corrosion assessment and restoration strategies of reinforced concrete buildings of the cultural heritage [texte imprimé] / L. Bertolini, Auteur ; M. Carsana, Auteur ; M. Gastaldi, Auteur . - 2011 . - pp. 146–154. Génie Mécanique Langues : Anglais (eng) in Materials and corrosion > Vol. 62 N° 2 (Fevrier 2011) . - pp. 146–154 Mots-clés : Reinforced  concrete  structures  Carbonation  Cultural  heritage  Durability  Inspection  Restoration Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Since the beginning of the 20th century, in Italy as in many other countries, reinforced concrete (RC) became one of the most popular construction materials and it was used for buildings, monuments, infrastructures, etc. Several of these structures, although of recent formation, have now been included in the cultural heritage, because of their architectural or social relevance. As a consequence of the typical urban or rural exposure conditions of these buildings, they often suffer damage due to carbonation-induced corrosion of reinforcement, such as concrete spalling or cracking or rust stains that may affect the serviceability of structures. Furthermore, chloride-induced corrosion of reinforcement, may also concern buildings exposed to de-icing salts or marine environments. Due to strict requirements related to the preservation of the original materials and texture, the repair of structures that belong to the cultural heritage cannot rely on the conventional repair technique, based on the replacement of carbonated concrete. Therefore, the conservation of RC buildings of the cultural heritage is a challenge, since it requires the development of specific strategies aimed at finding the best compromise between, on one hand, the restoration of structural safety and the prevention of future damage and, on the other hand, the preservation of the original materials and surfaces. This paper analyses the results of inspections carried out on several buildings, built in Italy throughout the 20th century in different micro- and macro-climates, with the aim of showing their peculiarities with regard to steel corrosion and the selection of restorations strategies. DEWEY : 620.1 ISSN : 0947-5117 En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.201005773/abstract

Effect of concrete carbonation process on the passivating products of galvanized steel reinforcements / T. Bellezze in Materials and corrosion, Vol. 62 N° 2 (Fevrier 2011) 

Public ISBD [article]  in Materials and corrosion > Vol. 62 N° 2 (Fevrier 2011) . - pp. 155–160 Titre : Effect of concrete carbonation process on the passivating products of galvanized steel reinforcements Type de document : texte imprimé Auteurs : T. Bellezze, Auteur ; G. Roventi, Auteur ; E. Barbaresi, Auteur Année de publication : 2011 Article en page(s) : pp. 155–160 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Characterization  of  passivation  products  Concrete  carbonation  process  Corrosion  in  concrete  Galvanized  steel  Potential  and  corrosion  rate  measurements Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The composition of passivating products on galvanized steel reinforcement in concrete during carbonation was studied. Cube-shaped concrete specimens were manufactured with Portland 52.5 R cement and reinforced with hot-dip galvanized steel sheets obtained from pure Zn and Zn[BOND]Sn[BOND]Bi[BOND]Ni alloy bath. The concrete specimens were exposed to air curing for 28 days and then to the carbonation chamber. Corrosion rate and potential measurements were performed both during the curing in air and exposure in a carbonation chamber. At defined periods of time, some concrete specimens were broken and the galvanized steel sheets were submitted to XRD, SEM observations and EDX analysis. The growth of the passivation products was evaluated by integrating the diffraction peaks. XRD analysis and SEM observations show that the layer of calcium hydroxyzincate (CaHZn), formed on the galvanized sheets during the air curing, is destroyed by the concrete carbonation process. However, potential measurements indicate that the galvanized steel always remains in the passive state. X-ray diffractometry was not able to identify the new passivating product; EDX maps suggest the presence of zinc carbonates. DEWEY : 620.1 ISSN : 0947-5117 En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.201005776/abstract [article] Effect of concrete carbonation process on the passivating products of galvanized steel reinforcements [texte imprimé] / T. Bellezze, Auteur ; G. Roventi, Auteur ; E. Barbaresi, Auteur . - 2011 . - pp. 155–160. Génie Mécanique Langues : Anglais (eng) in Materials and corrosion > Vol. 62 N° 2 (Fevrier 2011) . - pp. 155–160 Mots-clés : Characterization  of  passivation  products  Concrete  carbonation  process  Corrosion  in  concrete  Galvanized  steel  Potential  and  corrosion  rate  measurements Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The composition of passivating products on galvanized steel reinforcement in concrete during carbonation was studied. Cube-shaped concrete specimens were manufactured with Portland 52.5 R cement and reinforced with hot-dip galvanized steel sheets obtained from pure Zn and Zn[BOND]Sn[BOND]Bi[BOND]Ni alloy bath. The concrete specimens were exposed to air curing for 28 days and then to the carbonation chamber. Corrosion rate and potential measurements were performed both during the curing in air and exposure in a carbonation chamber. At defined periods of time, some concrete specimens were broken and the galvanized steel sheets were submitted to XRD, SEM observations and EDX analysis. The growth of the passivation products was evaluated by integrating the diffraction peaks. XRD analysis and SEM observations show that the layer of calcium hydroxyzincate (CaHZn), formed on the galvanized sheets during the air curing, is destroyed by the concrete carbonation process. However, potential measurements indicate that the galvanized steel always remains in the passive state. X-ray diffractometry was not able to identify the new passivating product; EDX maps suggest the presence of zinc carbonates. DEWEY : 620.1 ISSN : 0947-5117 En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.201005776/abstract

Evaluation of deterioration in reinforced concrete structures by AE technique / E. Proverbio in Materials and corrosion, Vol. 62 N° 2 (Fevrier 2011) 

Public ISBD [article]  in Materials and corrosion > Vol. 62 N° 2 (Fevrier 2011) . - pp. 161–169 Titre : Evaluation of deterioration in reinforced concrete structures by AE technique Type de document : texte imprimé Auteurs : E. Proverbio, Auteur Année de publication : 2011 Article en page(s) : pp. 161–169 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Acoustic  emission  b-value  analysis  Concrete  Damage  evaluation  Intensity  analysis  Prestressed  concrete Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Acoustic emission (AE) technique is gaining increasing interest for applications in civil engineering. AE indeed is a passive nonintrusive technique that can be applicable either in structural health monitoring (global evaluation) and in defect localization (local evaluation). The most promising application of such a technique seems to be however in the evaluation of growing defects. Defects such as cracks and delamination can be caused by reinforcement corrosion as well as by other concrete deterioration mechanisms (alkali silica reaction, sulphate attack, etc.) as well as originating from improper concrete casting, curing or structure setting. Damage severity can be evaluated by means of the intensity analysis (IA) through the use of different indexes such as ‘Load Ratio’, ‘Calm Ratio’, ‘Felicity Ratio’ or ‘Historical Index’. Damage evolution analysis along time could be however significantly improved by adopting some procedure already used in the field of geophysics and earth science. Among various parameters, the most significant one is the b-value which is derived from the amplitude distribution data of AE following the methods used in seismology. Several application examples applied to prestressed concrete structures are reported in the paper. DEWEY : 620.1 ISSN : 0947-5117 En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.201005735/abstract [article] Evaluation of deterioration in reinforced concrete structures by AE technique [texte imprimé] / E. Proverbio, Auteur . - 2011 . - pp. 161–169. Génie Mécanique Langues : Anglais (eng) in Materials and corrosion > Vol. 62 N° 2 (Fevrier 2011) . - pp. 161–169 Mots-clés : Acoustic  emission  b-value  analysis  Concrete  Damage  evaluation  Intensity  analysis  Prestressed  concrete Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Acoustic emission (AE) technique is gaining increasing interest for applications in civil engineering. AE indeed is a passive nonintrusive technique that can be applicable either in structural health monitoring (global evaluation) and in defect localization (local evaluation). The most promising application of such a technique seems to be however in the evaluation of growing defects. Defects such as cracks and delamination can be caused by reinforcement corrosion as well as by other concrete deterioration mechanisms (alkali silica reaction, sulphate attack, etc.) as well as originating from improper concrete casting, curing or structure setting. Damage severity can be evaluated by means of the intensity analysis (IA) through the use of different indexes such as ‘Load Ratio’, ‘Calm Ratio’, ‘Felicity Ratio’ or ‘Historical Index’. Damage evolution analysis along time could be however significantly improved by adopting some procedure already used in the field of geophysics and earth science. Among various parameters, the most significant one is the b-value which is derived from the amplitude distribution data of AE following the methods used in seismology. Several application examples applied to prestressed concrete structures are reported in the paper. DEWEY : 620.1 ISSN : 0947-5117 En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.201005735/abstract

Organic substances as inhibitors for chloride-induced corrosion in reinforced concrete / M. Ormellese in Materials and corrosion, Vol. 62 N° 2 (Fevrier 2011) 

Public ISBD [article]  in Materials and corrosion > Vol. 62 N° 2 (Fevrier 2011) . - pp. 170–177 Titre : Organic substances as inhibitors for chloride-induced corrosion in reinforced concrete Type de document : texte imprimé Auteurs : M. Ormellese, Auteur ; F. Bolzoni, Auteur ; L. Lazzari, Auteur Année de publication : 2011 Article en page(s) : pp. 170–177 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Chloride-induced  corrosion  Concrete  Critical  chloride  threshold  Inhibitor Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Corrosion inhibitors are used to prevent chloride-induced corrosion in reinforced concrete structures. Since performance of commercial organic inhibitors is only partially satisfactory, a 7-year long research has been carried out in order to set-up a new organic inhibitive mixture, able to prevent chlorides-induced corrosion. A first screening, by means of potentiodynamic polarisation test in alkaline synthetic pore solution, was performed on 80 organic compounds, mainly primary and tertiary amines, aminoalcohols, carboxylates compounds and aminoacids, in order to select the best inhibiting substances. The nine best inhibitive organic substances were selected for long-term tests: 2 amines (dimethylethanolamine and triethylentetramine), 4 aminoacids (aspartate, asparagine, glutamate and glutamine) and 3 carboxylates compounds (tartrate, benzoate and EDTA). Potentiostatic polarisation and free corrosion tests in synthetic pore solution were performed, as well as tests in concrete exposed to accelerated chlorides penetration. Five years of tests allow estimating the efficiency of the substances in preventing chlorides-induced corrosion, in term of influence on chlorides penetration and on critical chlorides threshold. DEWEY : 620.1 ISSN : 0947-5117 En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.201005763/abstract [article] Organic substances as inhibitors for chloride-induced corrosion in reinforced concrete [texte imprimé] / M. Ormellese, Auteur ; F. Bolzoni, Auteur ; L. Lazzari, Auteur . - 2011 . - pp. 170–177. Génie Mécanique Langues : Anglais (eng) in Materials and corrosion > Vol. 62 N° 2 (Fevrier 2011) . - pp. 170–177 Mots-clés : Chloride-induced  corrosion  Concrete  Critical  chloride  threshold  Inhibitor Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Corrosion inhibitors are used to prevent chloride-induced corrosion in reinforced concrete structures. Since performance of commercial organic inhibitors is only partially satisfactory, a 7-year long research has been carried out in order to set-up a new organic inhibitive mixture, able to prevent chlorides-induced corrosion. A first screening, by means of potentiodynamic polarisation test in alkaline synthetic pore solution, was performed on 80 organic compounds, mainly primary and tertiary amines, aminoalcohols, carboxylates compounds and aminoacids, in order to select the best inhibiting substances. The nine best inhibitive organic substances were selected for long-term tests: 2 amines (dimethylethanolamine and triethylentetramine), 4 aminoacids (aspartate, asparagine, glutamate and glutamine) and 3 carboxylates compounds (tartrate, benzoate and EDTA). Potentiostatic polarisation and free corrosion tests in synthetic pore solution were performed, as well as tests in concrete exposed to accelerated chlorides penetration. Five years of tests allow estimating the efficiency of the substances in preventing chlorides-induced corrosion, in term of influence on chlorides penetration and on critical chlorides threshold. DEWEY : 620.1 ISSN : 0947-5117 En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.201005763/abstract

Influence of two specific inhibitors on steel corrosion in a synthetic solution simulating a carbonated concrete with chlorides / C. Monticelli in Materials and corrosion, Vol. 62 N° 2 (Fevrier 2011) 

Public ISBD [article]  in Materials and corrosion > Vol. 62 N° 2 (Fevrier 2011) . - pp. 178–186 Titre : Influence of two specific inhibitors on steel corrosion in a synthetic solution simulating a carbonated concrete with chlorides Type de document : texte imprimé Auteurs : C. Monticelli, Auteur ; A. Frignani, Auteur ; A. Balbo, Auteur Année de publication : 2011 Article en page(s) : pp. 178–186 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Carbonation  Chloride  Corrosion  inhibitor  EIS  analysis  Synthetic  solution Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The present research aims at studying two corrosion inhibitors, that is sodium 2-amino-benzoate (2AMB) and sodium glycero-phosphate (GPH), in a synthetic solution simulating the composition of the pore solution in a carbonated concrete, containing chlorides. Tests have been performed to verify if the simultaneous use of the two substances is compatible and if their addition can efficiently hinder the corrosion attack in the presence of both chlorides and carbonation. The synthetic solution has been prepared by bubbling carbon dioxide through a saturated (and filtered) solution of Ca(OH)2, containing 0.1 M NaCl, in order to reach pH 7. Polarization curve recording and EIS technique have shown that, after an induction period of about 24 h, the highest inhibiting efficiencies are obtained by mixtures of the two additives at the concentration of 0.05 M, which still produce high inhibiting efficiencies (87%) at the end of 120 h immersion. At the end of this exposure period, also more diluted symmetric mixtures (0.025 and 0.01 M) exhibit comparable efficiencies. The analysis of EIS spectra gives interesting information concerning the inhibiting mechanism of the studied mixture. DEWEY : 620.1 ISSN : 0947-5117 En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.201005764/abstract [article] Influence of two specific inhibitors on steel corrosion in a synthetic solution simulating a carbonated concrete with chlorides [texte imprimé] / C. Monticelli, Auteur ; A. Frignani, Auteur ; A. Balbo, Auteur . - 2011 . - pp. 178–186. Génie Mécanique Langues : Anglais (eng) in Materials and corrosion > Vol. 62 N° 2 (Fevrier 2011) . - pp. 178–186 Mots-clés : Carbonation  Chloride  Corrosion  inhibitor  EIS  analysis  Synthetic  solution Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : The present research aims at studying two corrosion inhibitors, that is sodium 2-amino-benzoate (2AMB) and sodium glycero-phosphate (GPH), in a synthetic solution simulating the composition of the pore solution in a carbonated concrete, containing chlorides. Tests have been performed to verify if the simultaneous use of the two substances is compatible and if their addition can efficiently hinder the corrosion attack in the presence of both chlorides and carbonation. The synthetic solution has been prepared by bubbling carbon dioxide through a saturated (and filtered) solution of Ca(OH)2, containing 0.1 M NaCl, in order to reach pH 7. Polarization curve recording and EIS technique have shown that, after an induction period of about 24 h, the highest inhibiting efficiencies are obtained by mixtures of the two additives at the concentration of 0.05 M, which still produce high inhibiting efficiencies (87%) at the end of 120 h immersion. At the end of this exposure period, also more diluted symmetric mixtures (0.025 and 0.01 M) exhibit comparable efficiencies. The analysis of EIS spectra gives interesting information concerning the inhibiting mechanism of the studied mixture. DEWEY : 620.1 ISSN : 0947-5117 En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.201005764/abstract

Evaluation of the corrosion inhibition of salts of organic acids in alkaline solutions and chloride contaminated concrete / T. Pastore in Materials and corrosion, Vol. 62 N° 2 (Fevrier 2011) 

Public ISBD [article]  in Materials and corrosion > Vol. 62 N° 2 (Fevrier 2011) . - pp. 187–195 Titre : Evaluation of the corrosion inhibition of salts of organic acids in alkaline solutions and chloride contaminated concrete Type de document : texte imprimé Auteurs : T. Pastore, Auteur ; M. Cabrini, Auteur ; L. Coppola, Auteur Année de publication : 2011 Article en page(s) : pp. 187–195 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Corrosion  inhibitors  Localized  corrosion  Reinforced  concrete  Sodium  lactate  Steel Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper summarizes the results of testing on salts of organic acids for evaluating their use as inhibitors of rebar corrosion in chloride-contaminated concrete. Initially a screening based on electrochemical tests in alkalinized calcium hydroxide solutions was performed on a number of carboxylic acid salts with different number of carbon atoms in the chain and carboxylic groups, also covering substances with hydroxyl and amine group substituents. The screening was completed by testing on carbon steel rebars in concretes with chlorides and substances added at 1:1 molar ratio, focused on sodium lactate, sodium oxalate and sodium borate for comparison. The monitoring of free corrosion potential and linear polarization resistance of steel bars have confirmed significant inhibition only for lactate. Corrosion was only restricted to occluded zones where the access of substance was limited by disadvantageous geometry, producing shallow attacks. Results of further tests in saturated calcium hydroxide solution are reported in order to assess the inhibition ability of lactate as a function of its content, chloride content and pH. DEWEY : 620.1 ISSN : 0947-5117 En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.201005789/abstract [article] Evaluation of the corrosion inhibition of salts of organic acids in alkaline solutions and chloride contaminated concrete [texte imprimé] / T. Pastore, Auteur ; M. Cabrini, Auteur ; L. Coppola, Auteur . - 2011 . - pp. 187–195. Génie Mécanique Langues : Anglais (eng) in Materials and corrosion > Vol. 62 N° 2 (Fevrier 2011) . - pp. 187–195 Mots-clés : Corrosion  inhibitors  Localized  corrosion  Reinforced  concrete  Sodium  lactate  Steel Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper summarizes the results of testing on salts of organic acids for evaluating their use as inhibitors of rebar corrosion in chloride-contaminated concrete. Initially a screening based on electrochemical tests in alkalinized calcium hydroxide solutions was performed on a number of carboxylic acid salts with different number of carbon atoms in the chain and carboxylic groups, also covering substances with hydroxyl and amine group substituents. The screening was completed by testing on carbon steel rebars in concretes with chlorides and substances added at 1:1 molar ratio, focused on sodium lactate, sodium oxalate and sodium borate for comparison. The monitoring of free corrosion potential and linear polarization resistance of steel bars have confirmed significant inhibition only for lactate. Corrosion was only restricted to occluded zones where the access of substance was limited by disadvantageous geometry, producing shallow attacks. Results of further tests in saturated calcium hydroxide solution are reported in order to assess the inhibition ability of lactate as a function of its content, chloride content and pH. DEWEY : 620.1 ISSN : 0947-5117 En ligne : http://onlinelibrary.wiley.com/doi/10.1002/maco.201005789/abstract

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