The mechanical behavior of a high-strength, lightweight concrete made with expanded-shale aggregate was determined in the temperature range from 23°C (73°F) to −196°C (−320°F). High-strength, lightweight concrete is of particular interest for use in offshore cryogenic containment structures in which the concrete may be subjected to low temperatures and high-intensity cyclic loading simulating 20-year stormwave action. Values of compressive strength, tensile strength, and elastic modulus were determined, with moisture content and cyclic loading serving as key parameters. An evaluation was also made of the behavior of embedded strain gages at cryogenic temperatures. The results indicate that the lightweight concrete performed favorably under the test conditions, with the mechanical properties generally increasing at low temperatures with greater gains for higher moisture contents. Cyclic loading induced relatively minor fatigue damage in the concrete and should not affect the structural performance of an offshore containment structure.