Hostname: page-component-7c8c6479df-ws8qp Total loading time: 0 Render date: 2024-03-29T13:29:20.448Z Has data issue: false hasContentIssue false

Monitoring the Electrochemical Response of Chloride Sensors Embedded in Cement Paste

Published online by Cambridge University Press:  27 March 2015

F. Pargar
Affiliation:
Faculty of Civil Engineering and Geosciences, Delft University of Technology, Section of Materials and Environment, Stevinweg 1, 2628 CN Delft, The Netherlands.
D.A. Koleva
Affiliation:
Faculty of Civil Engineering and Geosciences, Delft University of Technology, Section of Materials and Environment, Stevinweg 1, 2628 CN Delft, The Netherlands.
E.A.B. Koenders
Affiliation:
Faculty of Civil Engineering and Geosciences, Delft University of Technology, Section of Materials and Environment, Stevinweg 1, 2628 CN Delft, The Netherlands.
K. van Breugel
Affiliation:
Faculty of Civil Engineering and Geosciences, Delft University of Technology, Section of Materials and Environment, Stevinweg 1, 2628 CN Delft, The Netherlands.
Get access

Abstract

This work presents the electrochemical behavior of Ag/AgCl electrodes (chloride sensors) in cement paste environment, monitored over a period of 180 days via open circuit potential (OCP) readings and electrochemical impedance spectroscopy (EIS). The EIS response indicates modification of the sensors’ morphology, in particular alteration of the AgCl layers, as a result of continuous chloride penetration into the bulk matrix towards the vicinity of the sensor/cement paste interface. A gradual shift to more cathodic OCP values and stabilization at approximately -1mVSCE to 2mVSCE was observed at the end of the test, reflecting chloride content of 820mM to 930mM in the pore solution surrounding the sensors, which differs 5-10% from the chloride concentration in the external solution. The water soluble chloride content in the cement pate, as destructively measured wet chemically by Volhard method and photometry, was in the range of 1100mM - 1300mM i.e. about 30-50% more than the chloride concentration in the external solution. This difference of maximum 50% in the recorded chloride levels is attributed to the fact that the sensors “read” the average amount of free chloride at the interface sensor/cement paste, while the destructively measured water soluble chloride reflects the average free (with possible contribution of physically bound chloride) in the total volume of analyzed cement paste. It can be concluded that for the conditions of this experiment, more reliable free chloride content is measured via the sensors’ readings. Hence, if chloride thresholds for corrosion initiation are to be determined, the sensors’ readings will be more representative and accurate if compared to destructive water soluble chloride determination.

Type
Articles
Copyright
Copyright © Materials Research Society 2015 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

Pargar, F., Koleva, D.A., Koenders, E.A.B., van Breugel, K., 13th International conference on Durability of Building Materials and Components (DBMC 2014), Sao Paulo, Brazil, (2014).Google Scholar
Angst, U., Elsener, B., Larsen, C. K., Vennesland, O., Vol. 40(3), p. 561573, (2010).CrossRefGoogle Scholar
Angst, U., Larsen, C. K., Vennesland, O., Elsener, B., Proceeding International Conference on Concrete Solutions, Padua, Italy (2009).Google Scholar
Angstand, U., Vennesland, O., Materials and Corrosion, Vol. 60(8), p. 638643, (2009).CrossRefGoogle Scholar
Pargar, F., Koleva, D.A., Koenders, E.A.B., van Breugel, K., proceeding of 1st International conference on Ageing of Materials and Structures (AMS'14), pp. 542547, (2014).Google Scholar
Koleva, D.A., PhD Thesis, Delft University Press, Delft, the Netherlands, (2007).Google Scholar
Arya, C., Buenfeld, N.R., Newman, J.B., Cement and Concrete Research, Vol. 17(6), p. 907918, (1987).CrossRefGoogle Scholar
Ramachandran, V.S., Seeley, R.C., Polomark, G.M., Vol. 17(4), p. 285289, (1984).CrossRefGoogle Scholar
Liao, K., Chang, P., Peng, Y., Yang, C., Cement and Concrete Research, Vol. 34(6), p. 977989, (2004).CrossRefGoogle Scholar