Antifouling Concrete . Development work on antifouling concrete by 

 using toxic- impregnated aggregate needs to be conducted. High strength 

 concretes with sufficient antifouling properties for long-term effec- 

 tiveness need to be developed. The long-term effectiveness of the mixes 

 may be improved by use of more viscous chemical solutions. Higher strengths 

 may be obtained by using chemicals that do not interfere with the hydration 

 or bonding processes of the portland cement. Tests need to be conducted on 

 specimens having surface areas of several square feet and exposed to ocean 

 sea conditions. 



The bond strength of antifouling concrete when cast against normal 

 concrete needs to be investigated. It is envisioned that antifouling 

 concrete could be used as an overlay coating to normal concrete. It is 

 unlikely that antifouling concrete would be used for the entire wall- 

 thickness. 



Lightweight Concrete . Research to determine the behavior of light- 

 weight concrete for use in ocean structures -in particular, pressure- 

 resistant structures -should be conducted. The permeability and seawater 

 absorption characteristics need to be determined. Some tests for compres- 

 sive strength, tensile strength, and modulus of elasticity of partially 

 saturated lightweight concrete should be conducted. 



Advanced development work on new lightweight aggregates would be 

 beneficial. Aggregates that show small seawater absorption values and pro- 

 duce concretes of compressive strength of greater than 5,000 psi would find 

 application in OTEC structures. Due to the additional cost of lightweight 

 concrete compared to normal weight concrete, it is unlikely that the entire 



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