Influence of Chloride on the Compressive Strength of Reinforced Concrete Columns

Abstract

Cementitious material with silica fume, the degree of chloride-induced corrosion, and the type of external strengthening. A water-to-binder ratio of 0.65 was used. Specimens were sized 20×20×80 cm and cured for 28 days before being subjected to accelerated corrosion using an impressed current method adapted from the NT Build 356 standard, with 5% sodium chloride solution and a constant voltage of 18 volts applied for durations of 1, 4, and 8 days. Strengthening was performed using carbon fiber reinforced polymer (CFRP) sheets, followed by axial compression testing until failure.The results showed that the electrical current decreased as the silica fume content increased. This is attributed to the extremely fine particles of silica fume filling the pores within the concrete, increasing its density and reducing the conductivity of the medium used to accelerate corrosion. Consequently, columns with silica fume exhibited lower corrosion rates and better compressive strength retention. Regarding CFRP strengthening, both partial and full wrapping methods were effective in enhancing load capacity. However, failure modes differed: partial wrapping led to sudden failure at the mid-height—where no confinement was provided—while full wrapping helped confine the material and delay failure. When the tensile limit of the CFRP was exceeded, rupture of the confining material occurred, leading to structural failure.