Surface Analysis and Electrochemical Behavior of Zinc Composite Layers, Incorporating Polymer Nano-Micelles

This study presents a comparative investigation of the corrosion behavior of zinc (Zn) and nano-composite zinc (ZnC) galvanic layers on a steel substrate in 5% NaCl solution as a corrosion medium.Design and ConstructionCivil Engineering and Geoscience

Steel Corrosion in Mortar Specimens, Deteriorated by Chloride Ingress: Electrochemical Study Using AC and DC Methods and Microscopic Analysis of the Steel/Mortar Interface

Design and ConstructionCivil Engineering and Geoscience

The Impact of Core-Shell Micelles on Steel Properties and Microstructural Characteristics in Reinforced Mortar after Corrosion and Cathodic Prevention

Design and ConstructionCivil Engineering and Geoscience

Conventional and Pulse Cathodic Protection of Reinforced Concrete: Electrochemical Approach and Microstructural Investigations

Design and ConstructionCivil Engineering and Geoscience

Composition and Morphology of Product Layers in the Steel/Cement Paste Interface in Conditions of Corrosion and Cathodic Protection in Reinforced Concrete

The present study explores the formation of corrosion products on the steel surface in reinforced concrete in conditions of corrosion and subsequent transformation of these layers in conditions of cathodic protection (CP). Of particular interest was to investigate if the introduced pulse CP (as cost- effective alternative of CP) will lead to similar (or even better) transformation of the product layers on the steel surface, compared to conventional techniques. Qualification and quantification of the studied layers was performed using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray analysis (EDAX), visualization of morphology and products distribution was achieved using environmental SEM (ESEM).Delft University of Technolog

Conventional and Pulse Cathodic Protection of Reinforced Concrete: Electrochemical Approach and Microstructural Investigations

An improved cathodic protection (CP), based on pulse regime was investigated in reinforced concrete, compared to conventional CP. Both regimes used CP current in the range of 2 to15 mA/m2. A voltage-to-current converter maintained the pulse current, the latter adjusted with duty cycle of 12% to 50 % and frequency of 500 Hz to 1 kHz. The efficiency of the improved CP was evaluated by means of electrochemical methods and microstructural investigation of the bulk concrete matrix, the steel/paste interface and the steel surface. The combination of techniques provides a detailed understanding of the electrochemical phenomena associated with corrosion and protection processes. The pulse CP achieves sufficient protection of the steel reinforcement and is less detrimental to the bulk concrete matrix. In this sense, pulse CP is able to minimize the negative side effects and to ensure better performance and protection in reinforced concrete.Delft University of Technolog

Electrochemical and Microstructural Studies in Reinforced Mortar, Modified with Core-Shell Micelles

This work reports on monitoring chloride-induced corrosion in reinforced mortar specimens, with and without addition of polymeric nano-aggregates in the mortar mixture. The investigation is a novel approach to control steel corrosion in reinforced concrete, hereby reporting the preliminary results, related to one of the main objectives: studying the influence of admixed polymer nano-aggregates (in the form of PEO113-b-PS218 core-shell micelles with a very low concentration of 0.006 wt.% per mortar weight) on the corrosion behavior of the steel reinforcement, compared to reference, micelles-free mixtures.Design and ConstructionCivil Engineering and Geoscience

Application of Electrochemical Impedance Spectroscopy in the Evaluation of Corrosion and Cathodic Protection in Reinforced Concrete

The electrochemical behavior of steel reinforcement in conditions of corrosion and cathodic protection (CP) was studied, using electrochemical impedance spectroscopy (EIS) and compared to reference (non-corroding) conditions. Polarization resistance (PR) method and potentio-dynamic polarization (PDP) were employed as well, in addition to AC 2 pin electrical resistance monitoring, thus deriving a comparison of the involved parameters. It was found out that EIS is readily applicable for evaluating electrochemical behavior of the steel surface not only for corroding or passive state, but also in conditions of CP, although the interpretation of derived parameters is not straightforward and is related to the properties of the product layers, formed on the steel surface in the different conditions. The evaluation of the electrochemical behavior of the steel surface, should take into account the crystallinity, morphology and composition of the surface layers, which were investigated by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX).Delft University of Technolog

Corrosion Performance of Composite Galvanic Coatings with Variable Concentration of Polymeric Nanoaggregates and/or Cr(III) Conversion Layers

This paper reports on the corrosion performance of composite zinc layers (~ 8µm) on a steel substrate, considering the influence of nano-aggregates and Cr(III) conversion layers, compared to control (only Zn layers) conditions. The main factors, influencing the corrosion performance of Zn in this study are: a) the effect of two concentrations of polymeric nano-aggregates (0.1g/l and 0.3g/l PEO113-b-PS218 core-shell micelles in the starting electrolyte); b) the effect of Cr(III) conversion layers on both pure Zn and composite Zn layers. For most of the hereby investigated time intervals i.e. treatment in aerated 5% NaCl from 2h until 120h, the composite coatings present higher corrosion resistance, especially within longer treatment. Corrosion current densities are similar to Zn, however, anodic currents are significantly lower. After treatment in NaCl, the composite Zn coatings present a more homogenous product layer, formed as a result of the presence of the nano-aggregates. The additional Cr(III) treatment does not significantly improve the corrosion resistance of the composite coatings for the hereby investigated time intervals.Design and ConstructionCivil Engineering and Geoscience

Hybrid Composite Aggregates for Superior Corrosion Performance of Low-Carbon Steel in Model Solutions

Design and ConstructionCivil Engineering and Geoscience