might be cracked due to flexing of the structure by the force of the 

 vaves. 



Procedures suggested to minimize the deterioration of reinforced 

 concrete should, in general, be applicable to concrete- jacketed steel 

 piles. Some pertinent precautionary measures suggested in Mather (1957) 

 from Warren (1956) for preventing deterioration of reinforced concrete 

 in coastal structures are: 



1. Careful selection of the cement. The most durable from the 

 standpoint of chemical composition were said to be those 

 with low tricalcium aluminate content, and the special 

 aluminous cements . 



2. Care with the aggregate, which must be tough and nonreactive 

 to cement; and careful grading of aggregates. 



3. High quality maximum density concrete. Rich mixtures - 1:1:3 

 or 1:1:2 were suggested. 



U. Restriction of all working stresses to reasonable values. 



5. Cover to be not less than 2 inches, preferably 3 inches; 

 and square edges on beams and piles to be avoided. 



6. Thorough curing in air before exposing to the tides or to 

 splash, to obtain a hard outer skin. 



7. Removal of mill scale from steel before installation. 



8. Water/cement ratio to be as low as possible, with correction 

 for the moisture content of the agregates. 



9. Special care in placing the concrete to avoid segregation, 

 particularly in underwater work. 



10. Use of vibrators to obtain maximum consolidation. 



The Corps of Engineers has conducted tests on over 2,500 concrete 

 specimens at exposure stations located at Treat Island (Eastport), Maine, 

 and St. Augustine, Florida. The tests were initiated in 1935- The con- 

 crete specimens were covered by seawater with the rising tides and ex- 

 posed to atmosphere at low tides. Conclusions from these tests as given 

 by Cook (1953) are as follows: 



1. The entrainment of properly regulated quantities of air is 



the most important factor in the improvement of the durability 

 of concrete under severe weathering conditions that has been 

 developed by these investigations. At Treat Island, well-made 

 concrete of good quality materials will not ordinarily with- 

 stand the exposure for more than one winter unless the concrete 

 contains the proper amount of entrained air. 



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