{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,25]],"date-time":"2026-06-25T13:34:59Z","timestamp":1782394499844,"version":"3.54.5"},"reference-count":62,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2018,9,14]],"date-time":"2018-09-14T00:00:00Z","timestamp":1536883200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Both the free chloride concentration and the pH of the concrete pore solution are highly relevant parameters that control corrosion of the reinforcing steel. In this paper, we present a method to continuously monitor these two parameters in-situ. The approach is based on a recently developed electrode system that consists of several different potentiometric sensors as well as a data interpretation procedure. Instrumented mortar specimens containing different amounts of admixed chlorides were exposed to accelerated carbonation, and changes in free chloride concentration and pH were monitored simultaneously over time. The results revealed the stepwise decrease in pH as well as corresponding increases in free chlorides, resulting from the release of bound chlorides. For a pH drop of about 1 unit (from pH 13.5 down to pH 12.5), the free chloride concentration increased up to 1.5-fold. We continuously quantified the ratio Cl\u2212\/OH\u2212 that increased steeply with time, and was found to exceed a critical corrosion threshold long before carbonation can be detected with traditional indicator spray testing, even at admixed chloride contents in the order of allowable limits. These results can strongly influence the decision-making in engineering practice and it is expected to significantly improve condition assessments of reinforced concrete structures.<\/jats:p>","DOI":"10.3390\/s18093101","type":"journal-article","created":{"date-parts":[[2018,9,14]],"date-time":"2018-09-14T10:57:59Z","timestamp":1536922679000},"page":"3101","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":23,"title":["Development of a Novel Methodology to Assess the Corrosion Threshold in Concrete Based on Simultaneous Monitoring of pH and Free Chloride Concentration"],"prefix":"10.3390","volume":"18","author":[{"given":"Yurena Segu\u00ed","family":"Femenias","sequence":"first","affiliation":[{"name":"Institute for Building Materials (IfB), ETH Z\u00fcrich, Stefano-Franscini-Platz 3, 8093 Zurich, Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2603-4757","authenticated-orcid":false,"given":"Ueli","family":"Angst","sequence":"additional","affiliation":[{"name":"Institute for Building Materials (IfB), ETH Z\u00fcrich, Stefano-Franscini-Platz 3, 8093 Zurich, Switzerland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Fabrizio","family":"Moro","sequence":"additional","affiliation":[{"name":"Lafargeholcim Research Center, 95, rue du Montmurier, BP 15, 38291 Saint-Quentin Fallavier, France"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Bernhard","family":"Elsener","sequence":"additional","affiliation":[{"name":"Institute for Building Materials (IfB), ETH Z\u00fcrich, Stefano-Franscini-Platz 3, 8093 Zurich, Switzerland"},{"name":"Department of Chemical and Geological Sciences, University of Cagliari, 09100 Monserrato (CA), Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2018,9,14]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"2787","DOI":"10.1016\/j.jeurceramsoc.2011.11.012","article-title":"Concrete: An eco material that needs to be improved","volume":"32","author":"Flatt","year":"2012","journal-title":"J. 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