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Investigation of the Effect of Chlorine ion Concentration on Corrosion of Steel Reinforcement in Concrete

Hajian, Morteza | 2021

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 54303 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Afshar, Abdollah
  7. Abstract:
  8. Today, in our beloved country of Iran and other parts of the world, reinforced concrete structures are used in large industrial projects, in some cases we see their very early failure even before the time of operation. This issue in the southern coasts of the country due to special weather conditions (humidity and high temperature) and the existence of the offensive ions such as chlorine and sulfate in seawater are more important and we always face with severe corrosion of reinforcement and reduced service life of concrete structures in these areas. Despite this, little research has been done on the reliability of concrete facilities in the vicinity of the Caspian Sea in the north of the country and the Persian Gulf and comparing the situation of these two areas in relation to each other. In this study, in order to study the reliability of concrete, to investigate the rate of corrosion of reinforced steel in the concrete environment at similar concentrations of Caspian Sea water (1.2%) and the Persian Gulf and other seas and oceans of the world (3.5%) at different intervals, various studies have been performed and for this purpose polarization tests, impedance electrochemical spectroscopy and weight loss have been used. Also, images prepared by scanning electron microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDS) were used to study corrosion levels and elemental analysis of corrosion products. It is worth mentioning that in addition to the above, in order to estimate the life of concrete structures in the vicinity of the areas mentioned above, the chlorine ion penetration profile from the outermost wall to the reinforcement and also the chlorine ion penetration coefficient to concrete at different concentrations and time intervals, has been evaluated. It is worth noting that the results of all the above methods were logically related to each other. The amount of critical chloride concentration after which corrosion continues with a significant amount is equal to 0.1% by weight of the concrete. This means that if the amount of chlorine reaches this amount, the service life of the structure is over. This criterion is reached in sodium chloride solutions of 1.2 and 3.5% in 90 and 60 day intervals, respectively
  9. Keywords:
  10. Reinforced Concrete ; Corrosion Resistance ; Chlorine ; Critical Chloride Concentration ; Penetration Profile ; Reinforced Concrete Structures

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