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ORIGINAL ARTICLE

Chloride migration measurement for chloride and sulfide contaminated concrete M. Decker . R. Grosch . S. Keßler . H. Hilbig

Received: 9 January 2020 / Accepted: 1 July 2020 Ó The Author(s) 2020

Abstract 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, DRCM is crucial to classify concretes for given applications and to enable full probabilistic service life prediction. To measure DRCM 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

Electronic supplementary material The online version of this article (https://doi.org/10.1617/s11527-020-01526-4) contains supplementary material, which is available to authorized users. M. Decker (&)  R. Grosch  H. Hilbig TUM Center for Building Materials and Material Testing, Baumbachstraße 7, 81245 Munich, Germany e-mail: [email protected] S. Keßler Helmut-Schmidt-University/University of the Federal Armed Forces Hamburg, Holstenhofweg 85, 22043 Hamburg, Germany

alternative oxidation agents are found and validated to overcome this problem. The new indicator mixtures with hydrogen peroxide (H2O2) or/and potassium persulfate (K2S2O8) 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. Keywords Rapid chloride/iodide migration  Sulfide  Iodine–starch reaction  Hydrogen peroxide  Potassium persulfate

1 Introduction The major reason for concrete structures to deteriorate is the chloride-induced reinforcement corrosion, for instance when the structure is located in marine environment or exposed to de-icing salts. The durability design of concrete structures is slowly moving from prescriptive to performance-based specifications. Consequently, suitable and reproducible test methods are required to characterize the chloride transport in concrete. These test methods should be usable for performance specifications and quality control. However, durability depends on deterioration processes, which need years to develop. Performance specifications require short term tests, lasting not more than some weeks, including preconditioning of the specimens. Otherwise, the approach is not practical

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nor acceptable for conformity control purposes, given the current pace of concrete construct