Influence of corrosion on prestress strands

Abstract

Corrosion on prestress strands affects their mechanical properties as well as the coefficient of friction in the surface strand/duct. In previous research on prestress beams, the authors have observed different coefficients of friction depending on the surface condition of the strands and wires used in investigation. Some of the strands used for the experiments were stored for some months in the laboratory and gained some rust on the surface. This was enough to influence the coefficient of friction in a noticeable manner. To study the influence of corrosion on the mechanical properties of prestress strands several samples were stored under different environmental conditions to produce various levels of corrosion. These samples were tested afterwards to determine the influence of corrosion on fatigue properties and the coefficient of friction. Apart from the coefficient of friction, light rust decreases none of the other studied mechanical properties of the strands and may even increase the bond characteristics. The presence of rust does not necessarily mean that the strands should be rejected. The work described in this paper was conducted to investigate the level of rust that could be considered acceptable and how corrosion influences some mechanical properties of prestressing strands.Key words: reinforced concrete, prestressed concrete, prestressed beams and girders, structural design, structural members, corrosion, fatigue, losses.