Multi-scale investigation of the formation and breakdown of passive films on carbon steel rebar in concrete

Numerical investigation of the effects of cracking and embedded reinforcement on surface concrete resistivity measurements using Wenner probe

“…Although it is highly unlikely to have concrete with resistivity comparable to steel, some areas such as cracks might have significantly lower resistivity compared to bulk concrete. Cracks filled with moisture and ions could have very low resistivity reaching to values in the order o f 10'3 Q-m (Ghods, 2010). Thus, an attempt was made to investigate how variations in the resistivity o f concrete with respect to the rebar might influence measurements using the Wenner probe.…”

“…This condition leads to an electrolyte that has the capability of carrying electrical current within and across the crack. Experiments by Ghods (2010) showed that conductivity o f such electrolyte could cover a wide range from 0.04 Q-m to 2 Q-m depending on the type and concentration o f ions present.…”

“…-18: Variation in resistivity measurement fo r different crack widths for Ch -40 mm, a = 50 mm, 0 = 90°.5.3.7 Effect o f concrete resistivityThe last influential parameter affecting the electrical resistivity measurements on concrete with conductive crack present is the ratio between the resistivity o f concrete and contents filling the crack. Resistivity o f the crack is affected by the water content inside the crack and the type o f ions and minerals mixed with the water filling the crack.Resistivity o f crack content varies based on the type o f ions present and their concentration(Ghods, 2010) Ghods (2010). reported typical pore solutions available inside concrete have electrical resistivity ranging from 0.04 Q-m to 2 Q-m.…”

Electrochemical and microscopic investigation of the passivation and depassivation processes of iron and steel in simulated concrete pore solutions

“…(1) The nanoscale passive film studies that were carried out by Ghods (2010) investigated passive films in three stages: (a) after passivation, (b) after exposure to low concentrations of chloride after passivation, and (c) after exposure to high concentrations of chloride after passivation. Therefore, these studies only provided instantaneous information about the passive film and depassivation process.…”

“…The reduction in oxygen K edge energy at 0.5 keV shows thinning of the oxide film. Chlorine and sodium are detected 198 XV111 List of Tables Table 3.1: Synthetic pore solutions used in the electrochemical investigation (Ghods, 2010) 69 Table 3.2: Samples used in the electrochemical investigation 73 billion dollars. In Canada, a country where corrosion is a serious problem due to the excessive use of de-icing salts, a large portion of the overall bridge maintenance cost is due to the corrosion of carbon steel reinforcement in concrete structures.…”