Title: Chloride Threshold Levels, Corrosion Rates and Service Life for Cracked High-Performance Concrete

Author(s): K. Pettersson and P. Sandberg

Publication: Symposium Paper

Volume: 170

Issue:

Appears on pages(s): 451-472

Keywords: Chlorides; corrosion; cracking (fracturing); high-performance concrete.

DOI: 10.14359/6836

Date: 7/1/1997

Abstract:
Factors affecting the chloride threshold level and the active corrosion rate are reviewed, with a special emphasis on the effect of macro cracks in high performance concrete. It was found that while the initiation time in uncracked high performance concrete may be more than a hundred years, reinforced high performance concrete is likely to crack, reducing the initiation time substantially as compared with uncracked concrete. Measurements of long term corrosion rates in cracked high performance concrete indicate however, that initially high corrosion rates decrease rapidly to very low corrosion rates, in the same range as for the passive corrosion rate in uncracked concrete. Therefore the initiation time for cracked high performance concrete may be very short, but the propagation time can be very long before any critical damage will occur. As a consequence, it seems more appropriate to define the service life for cracked high performance concrete as the time to reach a certain degree of corrosion damage, instead of using the (unpredictable) initiation time.