The effect of different cathodic potentials applied to the X70 pipeline steel immersed in acidified and aerated synthetic soil solution under stress using a slow strain rate test (SSRT) and electrochemical impedance spectroscopy (EIS) was studied. According to SSRT results and the fracture surface analysis by scanning electron microscopy (SEM), the steel susceptibility to stress corrosion cracking (SCC) increased as the cathodic polarization increased (Ecp). This behavior is attributed to the anodic dissolution at the tip of the crack and the increment of the cathodic reaction (hydrogen evolution) producing hydrogen embrittlement. Nevertheless, when the Ecp was subjected to the maximum cathodic potential applied (−970 mV), the susceptibility decreased; this behavior is attributed to the fact that the anodic dissolution was suppressed and the process of the SCC was dominated only by hydrogen embrittlement (HE). The EIS results showed that the cathodic process was influenced by the mass transport (hydrogen diffusion) due to the steel undergoing so many changes in the metallic surface as a result of the applied strain that it generated active sites at the surface.

Se propone la inclusión de perfiles de PET pretensados como fibras de refuerzo en elementos estructurales. Los perfiles de PET se colocan en una matriz de fibra unidireccional y bidireccional pretensada ligeramente que podría tener ventajas en miembros estructurales hechos de concreto en algunas aplicaciones especificas, por ejemplo, soporte estructural para barreras de seguridad vial. Una máquina universal se usa para probar perfiles de PET con diferentes anchos, nudos e incluso otras condiciones. Se elige el perfil de PET deseado y la mezcla de concreto se diseña según el codigo ACI. Los perfiles de PET pretensados se incluyen en moldes de madera con forma de vigas y, posteriormente, se estima la resistencia a la flexión. Finalmente, se presentan los resultados de las pruebas experimentales para perfiles de PET como refuerzo estructural de vigas hechas de concreto bajo flexión pura. Finalmente, se usa un modelo probabilístico para estimar la contribución de PET en términos de excedencia del módulo de ruptura.

In this work the corrosion kinetics of X80 steel immersed in synthetic seawater was analyzed using the electrochemical noise technique in static condition at room temperature and atmospheric pressure. An arrangement of three electrodes was used in an electrochemical cell, with two nominally identical working electrodes (X80 steel) and a saturated calomel electrode (SCE) as reference one. The results obtained were used to calculate the localization index (LI), which indicated that the corrosion process has a localized character. The optical micrographs confirmed the attack morphology of the corrosion process. Also, the corrosion rate values for X80 steel obtained from Noise Resistance (Rn) increase and decrease as exposure time elapses. The above is attributed to the rupture and subsequent regeneration of the corrosion products film adsorbed onto the metal surface.

The damage caused by atmospheric pollutants, chlorides, and sulfates, is evident in historical metallic monuments. Therefore, it is vitally important to analyze these interactions to ensure adequate conservation. The electrochemical behavior was studied using Linear Polarization Resistance (LPR) and Electrochemical Impedance Spectroscopy (EIS) of quaternary bronze with an artificially formed patina with CuSO4 representing a historical metal exposed in the atmosphere and thus obtaining information about its degradation process during a determined time. The results show that charge and mass transfer processes were carried out by varying the resistances of the patinas during the weeks that they were exposed, reaching to observe a diffusive and metastable process due to the formation of corrosion products that lead to an increase in the resistance of charge transfer.

In the present work, contribution of supplementary cementitious materials (SCM) such as sugarcane bagasse ash (SCBA) and fly ash (FA) in the reduction of the corrosion phenomenon in AISI 1018 carbon steel as reinforcement during 24 hours of concrete setting was studied. The design of ternary concrete systems was carried out according to ACI 211.1 method. Ash percentages were 10 and 30% of SCBA and FA combined. During the electrochemical study, corrosion potential (Ecorr ) and electrochemical noise (EN) of AISI 1018 carbon steel was monitored. Time series of current and potential, as well as the corrosion current density (icorr), noise resistance (Rn), localization index (LI) and corrosion rate (Vcorr) were analyzed. Results show that concretes added with SCBA and FA presented a better anticorrosion behavior, especially ternary concrete system added with 10% of combined ash, corrosion rate decreased 55% against the reference concrete.