RESISTANCE OF MATERIALS TO MARINE BIOLOGICAL ATTACK 1115 



IV. SOIL BURIAL 



Since this phase of the test program is yet to be started no extended 

 coverage is possible in this paper, except to point out the reason for its 

 inclusion. There is some evidence in the results of the marine exposure 

 tests at the Laboratories that the general order of susceptibility of ma- 

 terials to marine microorganisms is the same as it is to terrestrial micro- 

 organisms. This observation has also been supported in discussions with 

 some other investigators. The current program at the Laboratories 

 offers an excellent opportunity to compare the performance of a wide 

 range of materials in the two environments. If a correlation pattern can 

 be established, considerably more data in the literature can be brought 

 to bear on the problem. Perhaps at a later date it will be possible to 

 present data comparing material performance in the laboratory soil- 

 burial test and marine-type tests. 



V. MARINE EXPOSURE 



5.1 Marine Borer Tests 



The Laboratories, in cooperation with the William F. Clapp Labora- 

 tories, Inc., Duxbury, Massachusetts, is conducting the marine borer 

 tests. This phase of the program was initiated in 1954 and involves the 

 natural exposure of specimens at two locations — ■ Wrightsville Beach, 

 North Carolina, and Daytona Beach, Florida. These tests are aimed 

 primarily at obtaining information on marine borer attack; however, the 

 samples are exposed in such a way that information is obtained on micro- 

 biological activity as well. In addition, valuable data is obtained on the 

 purely physical and chemical effects of the environment on the materials. 



Wrightsville Beach and Daytona Beach were selected as test sites 

 because of the severe and diversified borer activity present in the two 

 areas. At present, more than fifty different materials are exposed at the 

 two locations. Represented are plastics, elastomers and natural organic 

 materials. All of the materials which have been put through the BOD- 

 type test, or are still to be included, are represented in the marine borer 

 portion of the test program. Where possible, test specimens are made in 

 solid rod or tube form about one inch in diameter and three feet long 

 to simulate cable shape. In the case of fibers and tapes, samples are 

 wrapped on |-inch diameter Lucite rods 3 feet long. These rods are as- 

 sembled in racks of about 26 rods each. An untreated, southern pine 

 two by four, susceptible to borer attack, is fitted around the samples at 

 midpoint, where it functions as a bait piece to lead the organisms into 

 direct contact with each test rod. Of course, where there is no bait piece 



