Quality Control . Quality control procedures for concrete were ad- 

 vanced significantly by the requirements of concrete nuclear reactor 

 containment vessels. t* J Quality control is rigorous today; however, a 

 major flaw still exists. The basic approach in concrete quality control 

 is to inspect constituent materials and batching, mixing, and placing 

 equipment before use to prevent problems. Concrete is sampled at time of 

 casting and the samples tested several days later for strength. This 

 procedure is archaic and should be replaced by a method of testing con- 

 crete for its quality just prior to casting. It is quite important for 

 structures resisting hydrostatic load to have concrete of uniform strength 

 and elastic modulus. The quality of the concrete needs to be known before 

 it is placed in the structure and not after. Technological development 

 in testing fresh concrete is advancing. The United States Army's Construction 

 Engineering Research Laboratory recently held a conference on rapid test- 

 ing of fresh concrete; the state-of-the-art was summarized for techniques 

 to determine the water and cement content of fresh concrete. L J Present 

 methods using chemical-mechanical or nuclear analyses are available for 

 field use. They require about 15 minutes to analyze fresh concrete for 

 water or cement content. However, limited field use was reported. 

 Operation 



Although the North Sea structures have not yet undergone inspections, 

 such inspections are required by law and will be conducted in the future. 

 Therefore, by the time OTEC structures are placed in service, substan- 

 tial advancements in the state-of-the-are of inspection, maintenance, and 

 repair of concrete ocean structures will have occurred. 



27 



