Influence of floor volume ratio on determining the TOEFL slopes of the potentiodynamic polarization curve and the Stern Gray constant coefficient

نوع: Type: thesis

مقطع: Segment: masters

عنوان: Title: Influence of floor volume ratio on determining the TOEFL slopes of the potentiodynamic polarization curve and the Stern Gray constant coefficient

ارائه دهنده: Provider: Mobin Ahmadi

اساتید راهنما: Supervisors: Dr Ebrahim Ghiasvand

اساتید مشاور: Advisory Professors: Dr Mohammad Mehdi Rastegar

اساتید ممتحن یا داور: Examining professors or referees: Dr Javad Taherinezhad & Dr Seyed Mehdi Hoseinian

زمان و تاریخ ارائه: Time and date of presentation: 2024

مکان ارائه: Place of presentation: سالن کنفرانس

چکیده: Abstract: Abstract: With the increase of global warming, the construction sector is trying to find an alternative to ordinary concrete due to its high dead weight and thermal conductivity. Also, a large number of pores in concrete foam reduces heat and sound absorption and as a result makes the structure suitable for all weather conditions. It requires the use of reinforcement in this type of concrete. The presence of a large percentage of air bubbles in the vicinity of the armature can adversely affect its electrochemical behavior and endanger the formation of a passive layer. Electrochemical methods have been used by previous researchers to evaluate the corrosion rate and the development of the oxide film layer in steel buried in concrete and simulated pore fluid solution. One of the methods of analyzing the corrosion mechanism of metal in concrete is done by measuring and drawing the cathodic and anodic polarization curves, and a part of these curves which is a straight line is called TOEFL region. The value of the potentiodynamic polarization resistance, which represents the resistance of the armature against oxidation, is obtained from the slope of the potential versus current curve at the point of zero current, and at the end, the potentiodynamic polarization curve can be used to estimate the corrosion rate and corrosion current density. In this research, first, 5 designs with the same water-to-cement ratio but with different percentages of the floor were determined for conducting tests, and after determining their mixing plan, they were made in the laboratory and cured for 28 days (4 weeks) in a humid environment. Corrosion of steel buried in concrete including half pile test, linear polarization test and potentiodynamic polarization test after placing the samples of all designs in the corrosive medium containing sodium chloride with a concentration of 5% has been done in weekly and dry cycles. Results The results of the tests show that the probability of corrosion of mortar with 50% foam after one week in a sodium chloride environment is more than 90%, and also the results of half-pile in floor concrete with 50% foam after 5 weeks are always more than other designs. It is from 200%. The electrode buried in the base mortar in the corrosive solution of sodium chloride is inactive after 11 weeks. With the increase in the percentage of floor in the plans, the OCP value decreases and the difference in OCP between the plans increases with the passage of time. In each period of the potentiodynamic test, with the increase in the percentage of foam in the mortar, the anodic and cathodic slopes increase. The changes of the anodic and cathodic slopes in the base mortar do not have a predictable trend with the passage of time and are variable in a fixed interval. The changes in the Stern-Gray coefficient In the design with base mortar, it is stable in 11 weeks and does not change. The changes of Stern-Gray coefficient with respect to time are always downward in all designs with floor mortar.

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