Document Details

Document Type : Thesis 
Document Title :
Corrosion and Corrosion Inhibition of Reinforcing Steel in Simulated Concrete Pore Solution Containing Chloride Ions
تآكل وثتبيط تآكل حديد التسليح في محلول مماثل لمحلول مسام الخرسانة يحتوي على أيونات الكلوريد
 
Subject : Faculty of Science - AL Faisaliah Campus > Sciences Faculty for Girls - Department of Chemistry 
Document Language : Arabic 
Abstract : Steel in concrete is generally in a passive state because concrete is alkaline, since it contains high concentrations of soluble calcium, sodium and potassium ions. Generally, metal corrosion cannot be prevented in environments containing active ions like chloride. The presence of chloride ions leads to breakdown the passive film on the metal surface that may result eventually in pitting of the rebar. In the present thesis corrosion and corrosion inhibition of reinforcing steel (RS) in simulated concrete pore (SCP) solution without and with chloride ions were investigated using electrochemical measurements (electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP)) under different conditions such as immersion time, chloride ion concentration and solution temperature. The results revealed that the corrosion rate stimulated at certain concentration of Cl- ions called the chloride threshold level ( ). The latter was found to vary depending on the immersion time as well as the technique used for measurements. EIS measurements showed that the was about 0.1M at zero h and 24 h of immersion time and directly related to the polarization resistance (Rp). While PDP measurements presented two different values for the , these are 0.05M and 0.25M at zero h and 24 h, respectively and powerfully related to the corrosion current density ( ) as well as the pitting potential ( ). Electrochemical data for RS corrosion in SCP without and with 0.1M Cl- ions at different temperatures (20-50 oC) revealed that the corrosion reaction was activated with increasing solutions temperature and hence obeys Arrhenius equation. Thermodynamic parameters ( and A) for RS corrosion were estimated and discussed. The effect of addition of tarragon aqueous extract (TAE) on the corrosion behavior of RS without and with 0.1M Cl- ions was investigated at two different periods of immersion time (zero h and 24 h).It was found that that inhibition efficiency increased with increase in TAE concentration and reached a maximum value at certain concentration after which it decreases with further increase in TAE concentration. The maximum inhibition efficiencies of 84.53% and 91.78% were obtained in SCP solution containing 4.5 g.L-1 and 2.5 g.L-1 of TAE at zero h and 24 h immersion, respectively. While they are 52.52% and 82.25% in SCP solution with 0.1M Cl- containing 3.5 g.L-1 of TAE at zero h and 24 h immersion, respectively. The acceleration behavior was detected at lower TAE for all cases studied except that for inhibited SCP solution at 24 h immersion. The effect of temperature on the inhibitory action of TAE without and with 0.1M Cl- ions also studied at zero h immersion and the results illustrated that the decreased as the temperature increased, which seems to indicate a physical absorption mechanism. The value of determined in inhibited SCP solution without and with 0.1M Cl- is higher than that for uninhibited solutions, and this result confirmed the physical adsorption process. The inhibition efficiency of TAE against corrosion of RS in the studied solutions was discussed based on its constituents. 
Supervisor : Prof. Ehteram A. Noor 
Thesis Type : Master Thesis 
Publishing Year : 1437 AH
2016 AD 
Co-Supervisor : Dr. Aisha H. Al-Moubaraki 
Added Date : Wednesday, January 27, 2016 

Researchers

Researcher Name (Arabic)Researcher Name (English)Researcher TypeDr GradeEmail
دلال ابراهيم المسعوديAl-Masoudi, Dalal IBRAHIMResearcherMaster 

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