Humectant use in the cathodic protection of reinforced concrete
- Albany Research Center, USDOE
- not a DOE author
The use of humectants to improve the thermal-sprayed zinc anode performance during the cathodic protection (CP) of reinforced concrete is examined. A humectant is a hygroscopic material. It is applied onto the surface of the zinc anode to keep the concrete-anode interface moist and a good conductor. The thermodynamics of humectants are discussed. Laboratory results are presented on the effects of using LiBr and LiNO{sub 3} as humectants in galvanic (GCP) and impressed current (ICCP) systems, in high and low relative humidities, and on new and previously electrochemically aged CP systems. LiNO{sub 3} and LiBr promoted more effective CP performance. Both improved the performance of aged slabs, suggesting that application of humectants onto existing CP systems would be of benefit. Microscopy showed that humectant-treated slabs develop the same cement-reaction zone-zinc anode structures as untreated slabs. Microscopy of LiBr-treated slabs revealed that the highest concentration of bromide was in the reaction zone. In GCP tests, LiBr was more effective than LiNO{sub 3}. In accelerated ICCP tests, LiNO{sub 3} was more effective than LiBr. It was surmised that bromide could be oxidized in the high-voltage accelerated ICCP tests. At the lower impressed currents of most installed ICCP systems, LiBr may perform as well as or better than LiNO{sub 3}.
- Research Organization:
- Albany Research Center, Albany, OR (US) (US)
- Sponsoring Organization:
- Oregon Department of Transportation (ODOT) (US) (US)
- OSTI ID:
- 760034
- Report Number(s):
- DOE/ARC-2000-003; ARC CRADA No. 0961; Corrosion 2000 paper no. 812
- Country of Publication:
- United States
- Language:
- English
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