The G. M. Idorn International Symposium on Durability of Concrete, sponsored by the ACI Committee 201 on Durability, was held at the 1990 annual ACI Convention in Toronto, Ontario, Canada. This symposium was dedicated to Dr. G. M. Idorn in view of his many decades of relentless dedication to the subject of improving concrete durability. A total of 32 paper are included in this publication.

The volume has been divided into 4 parts, which all deal with the durability of cover. Part 1 covers durability aspects in relation to effects of environment on placement. Part 2 covers effects of composition. Part 3 deals with the assessment of durability, and in Part 4, various case histories are given.