Galvanic cathodic protection (GCP) of reinforced concrete offers important advantages of simplicity, lower cost, and lack of cumbersome monitoring and maintenance procedures. But since GCP of reinforced concrete structures is relatively new, there is a general lack of long-term test results. This paper presents test data for the application of zinc anodes activated by a combination of lithium nitrate and lithium bromide in indoor test blocks, large outdoor test slabs, and field trials, all operational from 5 to nearly 8 years.

Protective current delivered by GCP in indoor test blocks declined from about one mA to about 0.04 mA after 8 years on-line, but cathodic polarization of steel remained high throughout the period. Polarization of steel bars in outdoor test slabs were >100 mV at most test points after 3¼ years, and at 50% of test points after 5 years on-line. Polarization was more difficult to achieve after 5 years on-line in a field trial where chloride contamination and corrosion rates of steel were much higher, but even then, little increase in concrete delamination was noted over the test period.

Subject
Electric current, Concrete repair, Cathodic protection, Rebar, Zinc anodes, Slabs, Anodic current, Steel, Electric potential, Polarization, Delamination, Concrete, Anodes
Keywords:
anodes, cathodic protection, concrete, concrete patch repair, corrosion, lithium chemicals, reinforcing steel, zinc
© 2008 Association for Materials Protection and Performance (AMPP). All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means (electronic, mechanical, photocopying, recording, or otherwise) without the prior written permission of AMPP. Positions and opinions advanced in this work are those of the author(s) and not necessarily those of AMPP. Responsibility for the content of the work lies solely with the author(s).
2008
Association for Materials Protection and Performance (AMPP)
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