INTRODUCTION 



At Navy establishments, many of the structures that must be wholly 

 or partly immersed in the ocean are made of concrete [1]. These include 

 wharfs, piling, seawater intakes for desalination plants and power 

 stations, floating docks and barges, LST landing ramps, undersea plat- 

 forms, and numerous other structures. After prolonged exposure in the 

 sea, the concrete structures usually become covered with a dense growth 

 of marine organisms. Over 2,000 species of plants and animals have been 

 identified in the fouling community [2]. Mussels, barnacles, oysters, 

 tubeworms, bryozoans, sea squirts, kelp, and brown algae are some of the 

 organisms most frequently found. Once they become attached, the sessile 

 fouling organisms are difficult to remove. They must be removed by 

 sandblasting or scraping. 



Fouling growth interferes with the function of many concrete marine 

 structures. Most notably, fouling organisms interfere with the opera- 

 tion of desalination plants and coastal power stations [3] . Dense 

 marine growth in concrete intake pipes interferes with the flow of 

 seawater. Fouling growth in the condenser tubes reduces their heat- 

 transf erring capacity and dislodged mussels often block the tubes. 

 Fouling organisms on the surface of concrete structures are hazardous to 

 Navy divers. The sharp edges of calcareous barnacles may cut the skin 

 or tear the suits of divers who brush against them. Furthermore, 

 fouling is unsightly; and by its shear bulk, it can restrict the useful- 

 ness of almost any waterfront structure, including an increase in weight 

 and reduction of the freeboard of floating structures. 



The objective of the investigation described in this report was to 

 develop a concrete that would resist the attachment of fouling organisms 

 for long periods of exposure in the ocean. A concrete was sought that 

 could not only be used as the primary construction material but that 

 could also be used as a protective antifouling covering for purposes 

 such as lining a concrete intake pipe [4]. It was visualized that the 

 lining would be replaced when its antifouling properties had been 

 depleted. 



The approach chosen was to prevent the attachment of fouling 

 organisms to concrete by means of toxic chemicals. Several problems 

 were encounted. Merely brushing chemical agents on the surfaces of the 

 concrete would not be adequate because the agents would soon be washed 

 off. Impregnating concrete with toxic chemicals is next to impossible 

 once the cement has set . Adding a toxic mixture to the cement and 

 aggregate before they have been mixed might interfere with the curing of 

 the concrete, especially if the toxic agent is an oil. 



