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Decreased Corrosion Initiation Time of Steel in Concrete due to Reinforcing Bar Obstruction of Diffusional Flow

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Coupled Multi-Electrode Investigation of Crevice Corrosion of 316 Stainless Steel and NiCrMo Alloy 625

Crevice corrosion is currently mostly studied using either one of two techniques depending on the information desired. The first method involves two multicrevice formers or washers fastened on both sides of a sample plate. This technique provides exposure information regarding the severity of crevice corrosion (depth, position, frequency of attack) but delivers little or no electrochemical information. The second method involves the potentiodynamic or potentiostatic study of an uncreviced sample in a model crevice solution or under a crevice former in aggressive solution where crevice corrosion may initiate and propagate and global current is recorded. However, crevice corrosion initiation and propagation behavior is highly dependent on exact position in the crevice over time. The distance from the crevice mouth will affect the solution composition, the pH, the ohmic potential drop and the true potential in the crevice. Coupled multi-electrode arrays (MEA) were used to study crevice corrosion in order to take in account spatial and temporal evolution of electrochemistry simultaneously. Scaling laws were used to rescale the crevice geometry while keeping the corrosion electrochemical properties equivalent to that of a natural crevice at a smaller length scale. one of the advantages was to be able to use commercial alloys available as wires electrode and, in the case of MEA, to spread the crevice corrosion over many individual electrodes so each one of them will have a near homogeneous electrochemical behavior. The initial step was to obtain anodic polarization curves for the relevant material in acid chloride solution which simulated the crevice electrolyte. using the software Crevicer{trademark}, the potential distribution inside the crevice as a function of the distance from the crevice mouth was determined for various crevice gaps and applied potentials, assuming constant chemistry throughout the crevice. The crevice corrosion initiation location x{sub crit} is the position where the potential drops to E{sub Flade}. Figure 1 illustrates the resulting x{sub crit} vs. G scaling laws for 316 Stainless Steel in 1 M HCl at 50 C. The coupled multi-wire array is composed of one hundred identical 316 Stainless Steel wires in a five by twenty formation inserted in a groove of a 316 Stainless Steel rod such that the ends of the wires are flush mounted with the rod. The 100 wires are coupled electrically through in-line zero resistance ammeters. The diameter of the wires (250 {micro}m) was chosen so that x{sub crit} (critical initiation distance from the crevice mouth) and the expected zone of crevice corrosion (predicted from the scaling law) would be larger than the radius of a single wire. The array created a flush mounted planar electrode with the surface/volume ratio obtained in planar crevices. The observation of the current evolution as a function of position inside and outside the crevice as function of time was made possible as illustrated in Figure 2 in 0.6 M NaCl at 50 C.

F. Bocher, Francisco Presuel-moreno, John R. Scully 2006Report

Publications

Assessment of the Corrosion Protection of Seven Wire Steel Strand Provided by Flexible Fillers

Decreased Corrosion Initiation Time of Steel in Concrete due to Reinforcing Bar Obstruction of Diffusional Flow

Long-Term Corrosion Behavior of Reinforced Concrete: Impact of Supplementary Cementitious Materials and Reservoir Size under Accelerated Chloride Ingress

Marine Atmospheric Corrosion of Additively Manufactured Stainless Steels

Computational and Experimental Investigation of Cathodic Protection Distribution in Reinforced Concrete Marine Piling

MODELING OF CREVICE CORROSION STABILITY AND STIFLING

Steel Activation in Concrete Following Interruption of Long Term Cathodic Polarization

Corrosion Propagation of Dry-Cast Reinforced Concrete Pipes Exposed to Simulated Field Environments

Characterization of Chloride thresholds in Florida coastal concrete bridge substructures : final report, February 11, 2009.

Literature Review of Commercially Available Alloys That Have Potential as Low-Cost, Corrosion-Resistant Concrete Reinforcement

Protection of Reinforced Concrete Bridge Substructures Using Submerged Bulk Anodes

Environmental Suitability of Weathering Steel Structures in Florida - Material Selection, Phase 2.

Steel Activation in Concrete Following Interruption of Long-Term Cathodic Polarization

Characterization of Various Corrosion Resistant Rebars Embedded in Concrete after 20 Years of Exposure

Concrete Pipe - Electrochemical Cell, Phase II

Preliminary Results of Surface Resistivity Readings (Wenner Method) on Field Marine Substructures as a Mean to Assess Concrete Permeability

Corrosion Behavior of Reinforcing Steel Embedded in Fly Ash Concrete

Diffusion vs. concentration of chloride ions in concrete : [summary].

Coupled Multi-Electrode Investigation of Crevice Corrosion of 316 Stainless Steel and NiCrMo Alloy 625

A Long-Term Experimental Study on Evaluating Corrosion Currents in Reinforced Concrete for Marine Structures