Appendix C 

 MOISTURE CONTENT OF CONCRETE SAMPLES 



Tests were conducted on concrete 

 fragments from ocean-cured spheres and 

 blocks, on-land-cured blocks, and fog- 

 cured cylinders to determine the relative 

 free moisture contents associated with 

 the different curing environments. 

 These data were obtained by drying 

 specimens in a 50% RH, 70F environment 

 for li- months and then at 130F (55C) for 

 3 weeks. The data are presented in Table 

 C-1 and Figure C-1. 



Moisture contents for the continu- 

 ously fog-cured cylinders, ocean-cured 

 blocks, and uncoated ocean-cured sphere 

 were similar. The concrete in the coated 

 ocean-cured sphere had a lower moisture 

 content, and the on-land field-cured 

 block had a still lower moisture content. 



The moisture content of the con- 

 crete in the coated spheres represents 

 the condition of the concrete after the 

 spheres were tested in the pressure 

 vessel. The spheres in the ocean 

 probably had a lower moisture content. 

 This conclusion can be presented because 

 of an observation made during test. Prior 



to tests in the pressure vessel, the 

 interior volume of the sphere was filled 

 with water for the purpose of measuring 

 the change in volume of the sphere 

 during pressurization. The interior sur- 

 face of the sphere was not coated. For 

 Sphere no. 13, the specim.en had water in 

 its interior for about 16 hours, at which 

 time it was observed that additional 

 water had to be added to completely fill 

 the interior again. A certain quantity of 

 water was absorbed by the dry concrete 

 before the test. For Sphere no. 11, water 

 was in contact with the dry concrete for 

 only about ^- hours. 



In addition to drying some samples, 

 other samples from the ocean-cured 

 blocks and coated sphere wall were 

 saturated in a pressure vessel. When the 

 water gained was added to the water 

 lost, the total water content for the 

 blocks was about 5.13% by weight, and 

 for the coated sphere wall, it was about 

 5.55% by weight. The average water 

 content was 5.3'f% by weight, which 

 represents an average void volume in the 

 concrete of 12.5%.. 



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