Concrete in a submerged zone is more resistant to reinforcement 

 corrosion than concrete in the tidal, splash, or marine atmospheric 

 zone where alternate wetting and drying permit a more rapid supply of 

 oxygen to the reinforcing steel. L 2 7 J 



The above discussion applies to the general mass of the concrete in 

 the structure. However, portions of the structure may be attacked by 

 corrosion for such reasons as cracked concrete due to impact or tensile 

 loading, or other electromotive forces whose driving forces are unknown. 

 OTEC structures will experience deep ocean pressures and extreme oxygen 

 gradients; the effects of these factors on corrosion are not known. L J 



High Strength Concrete . Ocean structures can utilize higher strength 

 concretes than are utilized conventionally. Field use of concrete with 

 compressive strength of 6,000 psi is common. For floating structures, higher 

 strengths (on the order of 8,000 to 12,000 psi) can result in thinner struc- 

 tural elements and thus lower weight and reduced draft. Minimum draft is 

 usually very important during construction and tow out. Significant cost 

 savings are realized during construction if auxiliary buoyancy structures 

 are not required. 



The state-of-the-art exists to produce high strength concretes, but 

 problems are encountered in developing quality assurance procedures for 

 proper field handling, placement, and curing. 



Saturated Concrete . The effect of partial and full saturation on 

 the compressive and tensile strength, modulus of elasticity, Poisson's 

 ratio, and creep rate of concrete is unknown. A limited study explored 

 the changes in compressive strength and quantity of seawater absorption 

 in concrete at various simulated ocean depths .L J It was found that 



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