Accelerated corrosion testing was used to compare the behavior of conventional reinforcing steel in concrete with two types of coated reinforcement; hot dip galvanized and fusion bonded epoxy coated. Galvanized steel resisted chloride concentrations in concrete some 2.5 times higher than caused corrosion of uncoated black steel in equivalent conditions. The period over which the zinc coating sacrificially protected the base steel and delayed corrosion was about 4-5 times the period for the initiation of corrosion of black steel in concrete. The zinc also provided localized protection over a distance of about 8 mm to the steel exposed at cut ends of galvanized bars. A half-cell potential model is proposed for the prediction of the remaining life of galvanized reinforcement in concrete. Epoxy coated bar was largely unaffected by corrosion, though at isolated points of damage to the coating and especially at cut ends of bars which were not repaired, localized attack on the exposed steel occurred in the same time interval as for uncoated steel with corrosion proceeding along the bar under the coating. Repairs to cut ends of epoxy coated bars did not substantially delay corrosion of the base steel.

Subject
Zinc rich coatings, Black steel, Galvanized coatings, Epoxy coatings, Salt spray corrosion testing, Steel, Corrosion protection, Zinc, Chlorides, Half cell potential, Concrete, Reinforcement, Electrode potential
Keywords:
concrete, reinforcement, corrosion, galvanizing, epoxy coating, corrosion testing, half-cell potential, chloride concentration, weight loss
© 1993 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).
1993
Association for Materials Protection and Performance (AMPP)
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