The performance of coil-coated materials after 5 years of outdoor exposure in the Netherlands

Abstract

The performance level of a selection of commercially available coil-coated materials had to be established as part of a larger investigation, to serve as a basis for comparisons in the rest of the project. The collected data can also provide useful references for other applications. The mechanical properties, the artificial durability tests and the condition of the materials after 2 years of outdoor exposure have been discussed in an earlier article. This article will discuss the condition of the 13 tested systems after 5 years of outdoor exposure in the Netherlands. It also addresses some questions concerning the `reliability' of artificial durability tests. Durability varies across the range of tested materials. So far, both weathering resistance and corrosion resistance are excellent for three out of 13 tested coil-coated materials and at least good for nine out of 13 tested coil-coated materials. The other four materials are good to excellent with regard to one of these aspects (either weathering or corrosion) but are classified as `fair' with respect to the other durability aspect. No coil-coated materials are classified as just `fair' for both aspects of durability. A few job-coated materials are included in the program as reference materials. They are classified as having fair to excellent corrosion resistance, but limited resistance to weathering. The outdoor exposure will be extended to a total duration of 10 years. More accurate information on long-term durability will then become available. The assessment of the durability of materials using artificial weathering and corrosion tests is often unreliable. Poor materials can be accepted and perfectly satisfactory materials can be rejected by selecting materials on the basis of such tests. The relevance of test methods and requirements in existing performance specifications with respect to actual, practical performance should be improved.