Comparison between chloride ion threshold and electrochemical measurements for reinforcement corrosion

Title: Comparison between chloride ion threshold and electrochemical measurements for reinforcement corrosion
Author(s): O. de Rincón
Paper category : conference
Book title: Third International RILEM Workshop on Testing and Modelling Chloride Ingress into Concrete
Editor(s): C. Andrade and J. Kropp
Print-ISBN: 2-912143-48-9
e-ISBN: 2912143578
Publisher: RILEM Publications SARL
Publication year: 2004
Pages: 361 - 380
Total Pages: 20
Nb references: 20
Language: English

Abstract: The present paper shows a comparison of electrochemical evaluation and chloride-ion threshold for reinforcement corrosion in mortar mixtures with additives (silica fume and fly ash), exposed to a marine environment for three years. To do so, test specimens with a w/c ratio of 0.58, 100% workability and a design compressive strength of 40 MPa were prepared. The mixes were prepared with 5, 10 and 15% w/w silica fume, and 5, 10, 12.5, 15 and 17.5% w/w fly ash based on cement content. In all, a total of 342 test specimens, 6 per each condition, were prepared. During the first 16 months, the specimens were exposed 5 days a week for 8 hours in a saline chamber. For the rest of the three-year period, they were partially submerged in saline water (at 3.5% NaCl). Electrochemical techniques used: potentials measurements, with linear polarization to evaluate the corrosion rate. Electrochemical behavior was determined by running potentiodynamic cyclic polarization curves. All the results indicate that more than 4000 ppm of free chloride ions (cement basis), are needed to destroy the passive film. The effect of silica fume on corrosion rate reduction was confirmed after three years' exposure to the saline environment. It was also shown that the addition of fly ash for low silica fume contents (<10%) has an effect on reducing the corrosion rate. The best results were obtained with the 15% silica fume mix.

Online publication: 2002-12-15
Publication type : full_text
Public price (Euros): 0.00
doi: 10.1617/2912143578.024