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Accelerated testing for chloride threshold of reinforcing steel in concrete

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Author: Polder, R.B. · Put, M. van · Peelen, W.H.A.
Type:article
Date:2017
Publisher: Springer International Publishing
Source:Lukovic, M.Hordijk, D.A., 2017 fib Symposium - High Tech Concrete: Where Technology and Engineering Meet. 12 June 2017 through 14 June 2017, 2066-2073
Identifier: 777346
doi: doi:10.1007/978-3-319-59471-2_236
ISBN: 9783319594705
Keywords: Architecture and Building · Chloride threshold · Critical chloride content · Reinforcement corrosion · Service life · Buildings and Infrastructures · 2015 Urbanisation · 2015 Fluid & Solid Mechanics · SR - Structural Reliability · TS - Technical Sciences

Abstract

Testing for the chloride threshold (also called critical chloride content) for corrosion initiation of steel in concrete has been found difficult and, at best, time consuming. Nevertheless, the chloride threshold is an important parameter in service life design of new structures and for evaluation of the remaining service life of existing structures. This paper reports on an accelerated test on mortar specimens that produces results within one week to a few weeks. It is based on accelerating chloride penetration by a mild electrical field while the steel potential is monitored. Upon corrosion initiation, specimens are sampled to obtain the chloride content that initiates corrosion. Results are reported of testing in CEM I (OPC) mortar on multiple specimens. Results for reference mortar are compared to specimens with application of a hydrophobic surface treatment. The results show that in reference CEM I mortar values for the critical threshold were obtained that agree well with previous experiments using the same method. This is taken as a validation of the method. The method is thought to be suitable for comparative chloride threshold studies of different binders, without or with corrosion inhibiting additions. Results for mortar with surface applied hydrophobic treatment, however, are unexpectedly low, which is taken to suggest that the method is not suitable for (e.g. surface treated) material with inhomogeneous electrolytic conduction. © Springer International Publishing AG 2018. Bam; Cement and Beton Centrum; et al.; Rijkswaterstaat - Ministry of Infrastructure and the Environment; Van Hattum en Blankevoort; VolkerInfra