Reinforcement corrosion of circular concrete columns under sustained load

Abstract

This paper presents the results of an experimental study of the axial capacity of circular spirally-reinforced concrete columns that were subjected to accelerated corrosion while sustaining a constant compressive service load. Two sets of columns of five columns each were designed with different spiral pitch to investigate the effect of concrete confinement on the corrosion propagation. Columns with non-confining spiral reinforcement had only their longitudinal reinforcing steel corroded, whereas in the other set of specimens, the spiral reinforcement was corroded and isolated from the vertical reinforcing steel. The cracking initiation, pattern, and widening of the concrete cover were monitored for a period of 4-10 months, and relations obtained between the crack widening and propagation and the elastic shortening of the column and steel mass loss were established. After the accelerated corrosion period, eight columns were tested to failure under either concentric or eccentric load; the vertical deformation, cracking pattern and failure type were monitored and recorded. The failure of specimens with non-confining spiral reinforcement was characterized by sudden crushing of the concrete and longitudinal reinforcement buckling, with a reduction in load capacity of 30-40%. Columns with confinement reinforcement failed in a ductile manner by progressive spalling of the concrete cover, maintaining their load capacity in spite of the corroded spiral reinforcement.