Concrete Properties at Ocean Depths

The results of three studies are reported herein on seawater absorption and compressive strength of 6-in. x 12-in. (152-mm x 305-mm) concrete control cylinders subjected to simulated ocean conditions, and on the long-term permeability of concrete spheres in the ocean at depths to 4,200 ft (1,280 m). The first study determined that seawater absorption of field-dry concrete was 2.36% by weight after exposure to a pressure head of 550 ft (168 m) for 84 days. The second study determined that the uniaxial compressive strength of concrete saturated and tested under a pressure head of 20,000 ft (6,100 m) decreased by 10% when compared with the compressive strength of fog-cured concrete. Concrete under 1 ft and 500 ft (0.3 m and 152 m) pressure heads had a compressive strength similar to that of fog-cured concrete. The third study reports interim data from an ongoing 10-yr investigation of the permeability of concrete spheres placed in the ocean.