Corrosion of Steel Bars with Respect to Orientation in Concrete

Abstract

Corrosion of steel bars (main steel and stirrup) with respect to the orientation in concrete is presented. A detailed study on macrocell and microcell corrosion of steel bars in concrete was conducted on horizontal and vertical steels, depending on the casting direction. The horizontal steel was divided into top and bottom halves. The study was conducted with chloride ions in concrete. Water-cement ratios were 0.5 and 0.7. The electrochemical investigations, microscopic, and physical observations of steel bars were performed. The laboratory investigations were verified with the long-term (23 year) exposure investigations on reinforced concrete beams. The study also focused on the influence of stirrup on macrocell formation of main steel, and corrosion of plain and deformed steel bars. It was concluded that orientation of steel bars has a significant influence on macrocell and microcell corrosion of steel bars in concrete. Formation of gaps under the horizontal steels cause significant corrosion. Stirrups play an important role in increasing macrocell corrosion of main steel. The deformed bar corroded more than the plain bar.