The determination of chloride threshold concentrations using different supplementary cementing materials in steel-reinforced concrete

grantor: University of TorontoThe ingress of chloride ions from de-icing salts or marine environments causes depassivation of the protective film surrounding the embedded steel surface. This consequently leads to corrosion of the steel reinforcement. The prevention or postponement of the initiation phase of corrosion is important to the serviceability and longevity of a structure. This maybe achieved through the use of better quality concretes containing supplementary cementing materials (SCMs). The study undertaken investigates the influence of SCMs on chloride ingress and corrosion in reinforced concrete. The experiments were conducted on steel-reinforced concrete beams containing ordinary portland cement with and without various supplementary cementing materials. Two water-cement ratios were used; w/cm = 0.6 and 0.5. Concrete quality was determined using rapid chloride permeability and resistivity tests. Macro-cell, corrosion potential and linear polarisation techniques were used to determine the onset of corrosion activity, as the beam specimens were continuously ponded with a 3% sodium chloride solution. Upon corrosion initiation, beams were removed and frozen prior profile grinding and chemical analysis to determine the chloride concentration at the steel-concrete interface.M.A.Sc