Choosing the proper maintenance strategy when scoping a coatings project is difficult, and potentially costly if incorrect procedures are utilized. This is especially true for steel bridges with millions of square feet of coated surface to be repaired and coated. For the last 30 years, bridge coating maintenance has been dominated by the desire to remove lead coatings from existing structures, followed by the application of Zinc/Epoxy/Urethane or other modern coatings systems. These modern coating systems are now reaching the age where major maintenance is required, and the decision must be made regarding how much coating to retain, and what methods will be used to clean and paint. This paper presents results of field and laboratory testing of alternative approaches to maintaining an Organic Zinc/Epoxy/Urethane bridge coatings system.

Maintenance alternatives evaluated during this project include degrees of power tool cleaning (e.g., SSPC-SP 3, SSPC-SP-15, and SSPC-SP-11), spot/sweep blasting (SSPC-SP 18) and a near white metal blast (SSPC-SP 10). In addition to alternative surface preparation techniques, the relative value of spot zinc versus spot epoxy priming during maintenance painting were evaluated. (Spot zinc refers to painting of zinc primer to areas of localized bare steel).

Data and knowledge presented in this paper will allow for other maintainers and owners of steel structures decide proper maintenance strategies for their bridges.

Subject
Test methods, Coating inspection, Zinc rich coatings, Water, Photography, Surface preparation, Steel, Rust, Power tool cleaning, Maintenance, Epoxies, Bridges, Steel grit
© 2022 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).
2022
Association for Materials Protection and Performance (AMPP)
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