The application of sacrificial zinc anodes to cathodic protection of reinforced bridge decks is described. Two systems, one based on commercial strip anodes, the other on a custom-fabricated perforated zinc sheet are compared. For the closest strip spacing polarized potentials indicate a potential shift of from 200-300 mv more negative than native potentials. For the perforated zinc sheet potential shifts greater than -400 mv have been observed. Current densities approach 20 mA/m2 (2 mA/ft2) during warm, moist periods. This is close to the value needed to supply adequate protective current based on results of polarization ("E log I") tests carried out on the structure under similar climatic conditions. The magnitude of the protective current is found to correlate with the internal resistance of the system, which in turn is lowest during periods of high internal moisture and relatively high ambient temperatures.

Subject
Electric current, Galvanic anodes, Cathodic protection, Zinc anodes, Current densities, Anodic current, Transportation, Steel, Electric potential, Highways, Zinc, Polarized potential, Instant off potential
© 1981 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).
1981
Association for Materials Protection and Performance (AMPP)
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