Date of Award

12-2012

Document Type

Thesis

Degree Name

Master of Engineering (ME)

Legacy Department

Civil Engineering

Advisor

Poursaee, Amir

Committee Member

Putman , Bradley J

Committee Member

Rangaraju , Prasad Rao

Abstract

Reinforced concrete is a structure material made up of concrete with relatively lower tensile strength containing reinforcements with higher tensile strength and better ductility, which are embedded into fresh concrete to resist tensile stress in certain regions of concrete. Steel reinforced concrete is most widely used around the world in civil engineering structures, water conservancy and highway construction due to its durability strength and reasonable cost.
However, reinforced concrete structures such as bridges and parking lots slabs inevitably experience variable loads and constant degradation from the aggressive environments, such as marine and deicing salts. Therefore, it is imperative to study the synergic impact of different types of loadings and exposure to chloride ions on the corrosion of steel rebars. Clear understanding of such processes assists improving the resiliency of the structures and helps extending the service life of the constructions by modifying the design codes of structural steel, which will thus improve the durability and safety of next generation of sustainable infrastructures. In addition, it is necessary to understand the fundamental mechanism of steel passivation and depassivation processes in concrete under stresses, then more reliable and robust service life modeling tools can be made to help engineers predict the state and performance of rebar in concrete structures.
Hence, in order to obtain detailed understanding of the effect of both tensile and compressive stresses on passive film and the depassivation process, experiments were performed on steel immersed in concrete simulated pore solution under different types and degrees of loadings. Simulated concrete pore solution was chosen in order to obtain the results in a reasonable time frame required for this project. Several electrochemical measurement techniques were used. Besides, Mott-Schottky technique was utilized to investigate the semi-conductive behavior of the passive film, which is formed on the surface of the steel rebars. Results indicate that steel specimens in chloride free pore solution under tensile loadings passivate more rapidly compared to those under compressive loadings. However, the situation in chloride contaminated solution is different and steel under tensile stress exhibit more corrosion than that under compressive stress and no load.

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