A major, 3 1/2 year study was funded by a consortium of oil companies on high strength lightweight aggregate concrete for arctic applications [8]. This study indicated that not all lightweight aggregates could be used for offshore structures because of limiting strength of the aggregate or because of high water absorptions that adversely affected freezing and thawing durability and constructability. Testing for the Hibernia Platform indicated that replacing 50% of the normal weight aggregate (by volume) with expanded slate aggregate most closely approximated the project criteria for the modified normal density concrete. The following table presents results from this testing [9]: