Chloride migration measurement for chloride and sulfide contaminated concrete

Reinforcement corrosion is major reason for concrete structures deterioration. Chlorides from external sources such as seawater and de-icing salts penetrate in the concrete and as soon as a critical threshold reaches the reinforcement level corrosion processes start. Therefore, the characterization of the chloride ingress resistance in form of the rapid chloride migration (RCM) coefficient, D RCM is crucial to classify concretes for given applications and to enable full probabilistic service life prediction. To measure D RCM of chloride-contaminated concrete, a rapid iodide migration test was developed using iodide as penetration ion and an iodine–starch reaction for penetration depth indication. This indicator mixture has the disadvantage that it is not applicable on sulfide containing concretes such as ground granulated blast furnace slag concretes. In this paper, the reason for the unsuitability of this indicator is examined and alternative oxidation agents are found and validated to overcome this problem. The new indicator mixtures with hydrogen peroxide (H 2 O 2 ) or/and potassium persulfate (K 2 S 2 O 8 ) as oxidation agents are not only insensitive to sulfide contamination but are also applicable to common concrete compositions and could replace the existing indicator universally.