When structural lightweight aggregate concrete was first employed a number of people had serious reservations regarding its durability. Since concrete which contains voids and capillaries soon deteriorates, they believed that lightweight aggregate particles which also contain voids would also result in concrete suspectable to weathering. The fallacy in their reasoning was that the voids in lightweight aggregates were minute and did not contribute to deterioration any more than do the air bubbles in air-entrained concrete. Still, the notion persisted and it took a number of years for it to be dispelled. One of the factors which helped for it to eradicate this misconception was a 7,500 tanker, christened Selma, built in Alabama in 1919 of expanded shale lightweight concrete. The ship was built out of concrete because of a lack of steel during World War I. After 3 years of highly satisfactory service transporting crude oil from Tampico to Texas Gulf Coast refinery ports, the Selma was struck by a large, heavy tug. Because no one could offer a guaranteed means of repairing the large crack that resulted from the collision the vessel was stripped, towed out into Galveston Bay and sunk. In 1953 it was decided to investigate the effect on the lightweight concrete of 34 years' continuous exposure to these stringent conditions. Samples of the concrete were cut from the hull above the mean high-water line (exposed to sea water and salt air) and below the low-water line (exposed to sea water). Specimens were also taken from the compartment ribs which had been exposed to salt air only. The extensive examination of the Selma revealed that the lightweight expanded shale aggregate concrete had weathered its severe exposure test in fine shape. Not only had the concrete not deteriorated, but it had actually made substantial gains in strength. This investigation coupled with the many other field and laboratory tests which have been carried out on expanded shale and slate aggregate concrete have proven beyond a doubt that great durability can be achieved.