(a) The four underwater-curing epoxies tested adhered 

 well to sandblasted steel and to a variety of protective coatings. 



(b) In general, the bonds formed by these epoxies lost 

 no strength after the specimens were submerged for 6 months in flowing 

 seawater. 



(c) The bonded specimens with protecting coatings 

 failed under applied stress in four different ways and under forces 

 differing widely in magnitude. 



(d) The foiir underwater-curing epoxies were similar in 

 formulation; the major differences were in types and amounts of added 

 fillers. 



(e) In these tests, none of the four proprietary epoxies 

 performed significantly better than the others. 



(f ) The underwater-curing epoxies tested can be used 

 successfully to make underwater repairs to abrasion damage to recently 

 applied protective coatings and to protect bare steel. 



Table X gives the force required to break the bond between the four 

 underwater-curing epoxies and other protective coatings. The results of 

 these tests indicate that the underwater-curing epoxy coatings may be 

 of considerable value for patching other types of coatings. The cost, 

 however, may prohibit its use as a primary coating on most types of 

 marine structures . 



Polyamide- and amine-cured epoxy resin systems tested on steel in 

 seawater performed quite well with the exception of systems Uo, Ul and 68 

 shown in Figure 11a. System 88 in this test was giving- good protection 

 to the steel after 9 years of exposure in seawater (Alumbaugh and 

 Brouillette, I966). An epoxy coating system tested on mooring buoys was 

 rated to be in "good" condition after 2 years of service (Drisko, I965). 

 See Table VIII. The coating was 'also rated good after 5 years of service 

 (Drisko, 196b). 



(9) Urethane . Very little test data was found for urethane 

 coatings. However, one report (Drisko, I965) rated a urethane coating 

 "good-fair" after nearly 2 1/2 years exposure on a mooring buoy in sea- 

 water at San Diego, California. See Table VIII. The same coating rated 

 fair-poor after nearly 5 1/2 years of exposure (Drisko, I968). Tests 

 by the U.S. Naval Civil Engineering Laboratory (Alumbaugh and Brouillette, 

 1966), indicated that, based on their condition after 5 to 6 years of 

 exposure, urethane coatings should rate quite high for protecting steel 

 piling. The urethane system affording the best protection except in the 

 abrasion zone was applied over a vinyl primer. 



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