9f83f8b1d3 This is the reason why, the most favourable conditions to the penetration of carbon dioxide correspond to a relative humidity of about 65%. Moist or wetting condition of concrete can influence the results of half-cell potential method, or it is important to assure the sufficient wetting of concrete to complete the setup for valid half-cell potential measurement. In a rather porous and wet concrete, these products migrate through the cover and can stain the concrete surface. The mechanism by which chlorides promote corrosion is not entirely understood, but the most popular theory is that chloride ions penetrate the protective oxide film easier than do other ions, leaving the steel vulnerable to corrosion. Steel 7. You will receive a link and will create a new password via email. The production steps that transform iron ore into steel add energy to the metal. Table 4: Techniques to protect concrete from corrosion. - a first stage involves the transfers of aggressive agents (mainly carbon dioxide and chloride) of water and of oxygen, inducing the corrosion initiation (depassivation of reinforcement), - a stage of corrosion growth, leading to concrete damage, to spalling, cracks, etc. At the high pH, a thin oxide layer forms on the steel and prevents metal atoms from dissolving.
However, only water-soluble chlorides promote corrosion; some acid-soluble chlorides may be bound within aggregates and, therefore, unavailable to promote corrosion. To interpret HCP data, factors such as variation in moisture content, chloride content, and concrete electrical resistance are required to be considered as all these parameters have a significant influence on the readings. Figure 2: Cracks formation. shows that as the corrosion proceeds, the concrete will spall away completely to expose the steel. b) The ingress of chlorides 2. No other contaminant is documented as extensively in the literature as a cause of corrosion of metals in concrete than chloride ions. So, the pH is about 9 for the pore solution of a concrete deteriorated by carbonation. Methods to Protect Structures from Corrosion. Chlorides dissolved in water can permeate through sound concrete or reach the steel through cracks.
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