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Many corrosion engineers will have encountered stress corrosion cracking (SCC) during their plant or field work, or while performing failure analyses. SCC is an insidious form of corrosion that often [...]

In this work, polyaniline-cellulose nanofiber (PANI-CNF) nanocomposites were prepared by in-situ polymerization of aniline on 2,2,6,6-tetramethyl1-piperidinyloxy (TEMPO) oxidized CNFs. Fourier transform infrared spectroscopy and transmission electron microscope demonstrate the successful polymerization of aniline on CNFs. The PANI-CNF nanocomposites were added as nanofillers to waterborne epoxy resin (WER) in different proportions. The composite coatings with different contents of PANI-CNFs were prepared by fabricating the mixture on the Q235 steel sheets. The corrosion resistance of different coatings was evaluated by potentiodynamic polarization and electrochemical impedance spectroscopy. The results confirmed that composite coatings containing 0.5% PANI-CNF exhibit the optimum anticorrosion behaviors and best corrosion resistance, which shows the lowest corrosion current density (1.788 * [10.sup.-7] A/[cm.sup.-2]) and highest corrosion potential (-0.458 V). In addition, PANI-CNF can significantly enhance the anticorrosion performance of WER coatings and maintain a high value even after 40 days of immersion in NaCl solutions. The above performances are attributed to the synergistic effect of the barrier effects and the passivation mechanism. Therefore, the bio-based composite materials developed in this work are promising in enhancing the corrosion protection of mild steel, which is essential for the sustainable development of waterborne coatings. KEYWORDS anticorrosive coating, cellulose nanofiber, nanocomposite, polyaniline, waterborne epoxy resin, 1 | INTRODUCTION Metals are very important and the most used materials in modern life and industry due to their competitive prices, good mechanical performances, and high recyclability. However, most [...]

From canoes to catamarans, aluminum is used for a variety of marine applications. Fishing boats, pontoon boats, ferries, oceangoing liners, and military vessels all benefit from the weight savings, corrosion [...]

Thermo-mechanically treated (TMT) reinforcing steel bars are extensively employed in RC buildings these days because of their superior thermal- and seismic-resisting characteristics, which enable them to sustain most of their strengths during earthquakes. The distinctive cross-sectional phase distribution (CSPD) of martensite, bainite, and pearlite in TMT rebars makes them outstanding. The current study examines the extent to which TMT reinforcing steel bars' mechanical properties deteriorate as a result of exposure to a combination of corrosion-induced CSPD damage and high temperatures. The research attempted to model an accidental fire in an aging structure with corroded members as a result of exposure to extreme environmental conditions. Heated residual tensile tests on rebar specimens subjected to various combinations of corrosion- induced damage and high temperatures were used in the experiment. The results show a significant loss in the key mechanical characteristics of reinforcing steel due to the superimposition of elevated temperature exposure on corrosion-induced damage to CSPD. Key words: TMT, corrosion-temperature combination, 1. Introduction One of the most common causes of deterioration of performance of structural elements is the corrosion of constructional and reinforcing steel. Various studies have investigated the impact of [...]

Cable corrosion is among one of the most common damage mechanisms in cable-stayed bridges. A finite element model of the long-span Stonecutters Cable-Stayed Bridge was built, and its dynamic behaviour was investigated considering localized groups of corroded cables. The reduction in cable cross-sectional area was used to simulate corrosion levels from 25% to 75% cross-sectional loss. The corroded cables were divided into two groups of four cables, arranged in symmetric and asymmetric distributions along both decks. Natural frequencies and mode shapes were compared with a reference case with no corrosion-damaged cables. A recorded wind load was applied on the deck to investigate the time-history response of the mid-span in lateral, vertical, and torsional directions. Frequency analysis was performed on the time-history response, and coupled motions at certain frequencies were observed for certain corrosion cases and were discussed. Key words: Stonecutters Cable-Stayed Bridge FEM, cable corrosion, wind-induced response, long-span bridge frequencies, 1. Introduction Cable-stayed bridges are widely used nowadays due to their lightweight structure, economic efficiency, and aesthetical appearance. However, these structures rely on high-strength cables, which transmit the loads from [...]

To study corrosion effects on real structures, three prestressed concrete (PC) girders salvaged from a decommissioned 27-year-old bridge in Alberta, Canada, were studied numerically and compared to experimental tests. Nonlinear finite element (FE) models were developed to simulate the degraded flexural and shear behaviour of PC girders. The FE models were used to infer the possible unknown deterioration conditions (i.e., forensic analysis) by comparing FE-predicted and experimental behaviour of the girders. Based on the developed FE models, comprehensive parametric studies considering various corrosion-induced deteriorations at a wide range of corrosion levels were also conducted. Insights gained from the parametric study assisted assessing other girders under similar conditions. It was found that corrosion defects, such as reinforcement area loss, prestress force loss, and bonding loss in the end anchorage, affect PC girder behaviour significantly and the developed FE models of corroded PC girders can assist girder condition assessment. Key words: prestressed concrete girder, corrosion-induced deterioration, finite element, parametric study, forensic analysis Dans le but d'etudier les effets de la corrosion sur les structures reelles, trois poutres en beton precontraint (BP) recuperees d'un pont desaffecte de 27 ans en Alberta, au Canada, ont fait l'objet d'une etude numerique laquelle a ete comparee a des essais experimentaux. Des modeles d'elements finis (EF) non lineaires ont ete mis au point pour simuler le comportement de flexion et de cisaillement degrade des poutres en BP. Les modeles d'EF ont ete utilises pour inferer les conditions de deterioration possibles (c.-a-d. analyse legale) en comparant le comportement des poutres predit par les modeles d'EF et obtenu des essais experimentaux. Sur la base des modeles EF developpes, on a egalement mene des etudes parametriques completes tenant compte de diverses deteriorations causees par la corrosion pour un large eventail de niveaux de corrosion. Les resultats de l'etude parametrique ont permis d'evaluer d'autres poutres dans des conditions similaires. On a constate que les defauts de corrosion comme la perte de surface des armatures, la perte de precontrainte et la perte d'adherence dans l'ancrage d'extremite ont une incidence importante sur le comportement des poutres en BP, et que les modeles d'EF developpes de poutres en BP corrodees peuvent aider a evaluer l'etat des poutres. [Traduit par la Redaction] Mots-cles : poutre en beton precontraint, deterioration causee par la corrosion, element fini, etude parametrique, analyse judiciaire, Introduction Prestressed concrete (PC) highway bridges represent integral parts of transportation networks in Alberta and across Canada. Their functionality and safety play important roles towards the socio-economic development. However, PC [...]