vThere trouble occuri'ed from this source it was necessary to do some patch- 

 work on the concrete, clean off all the old paint if any, then apply some 

 kind of a coating such as an asphalt aluminum paint to seal the pores of 

 the concrete. In cases where anticipated trouble has not yet been experi- 

 enced a richer concrete mix is used to clean the coarse aggregate of its 

 loose and chalky coating and wash it in fresh water. Also where possible, 

 reinforcing steel is cleaned of heavy rust and dipped in a cement slurry 

 before being placed. In general, in areas like this resort is made also 

 to un-reinforced concrete wherever possible and placing electric conduits 

 in the concrete is avoided. 



By far the most of our trouble here, however, is ■ dth structures in direct 

 contact with the salt vrater. Even so, great advances have been made over 

 the troubles of the early twenties vrhen engineers labored under that mis- 

 guiding slogan of "concrete for permanence" and did not generally kno\v 

 what is knovm today about how to design, mix and place concrete for long- 

 term results. During the period mentioned a regular plethora of concrete 

 water front structure failures occurred and it seems navf on looking back 

 on that period, that a large part of the work was major repairs to such 

 structures due to the action of sea v;ater on the cement and the reinforce- 

 ment. Experiences here resulted in the .ureau's present very fine stand- 

 ard specifications for concrete work. .-hen the standards laid down in 

 these specifications are adhered to, good dense, durable water front 

 structures are possible anyvThere in the world. There still are troubles, 

 hovirever, but they are mostly very special troubles. Examples of these 

 special troubles are the growth or swelling of large mass poured tremie 

 concrete structures such as the Bureau's tv/o major graving docks at New 

 York which have increased in length in one case by about 10 inches since 

 they were completed about 6 or 7 years ago. Elaborate studies have been 

 made of this condition to determine its cause if possible and what the 

 effects of this growth are on the strength and usability of the structures. 

 The studies here have run into dead ends on all counts and nothing has been 

 found to account for the grovifth. Numerous borings vrere made and all indi- 

 cated satisfactory strength and normal chemical characteristics. Also 

 reinforcing and form steel .here exposed, showed no rusting even in one 

 suspect location v/here a trench was opened in the dock floor nearly to the 

 bottom of the dock. Different cements and aggregates were used on this 

 work of necessity at times and samples of similar materials, when analyzed, 

 gave us no clues to explore fui'ther. Hers is a problem wliich may or may 

 not be serious later although there is no indication novx th?t it v/ill be. 



In a somewhat similar dock at Ne?/port News, this same general problem 

 occurs and it is already definitely serious. In this case, marsh gas is 

 formed in the underlying materials and this works its ifay up through the 

 seasoning cracks in the concrete mass and by crystalline action is causing 

 the concrete abutment to s.vell and crack. No practicable solution has been 

 found to this problem either and therefore, the possibility is faced that 

 the abutment v/ill have to be rebuilt in say 25 to 30 years. On this part- 

 icular problem Terzagli v/as consulted by the Yard operator and it is under- 

 stood that he is still studying the problem. Other tremie concrete • '":.. ■:.':- 



D - 9 



