Table 1. Test Description 



Sphere 

 No. 



Depth 

 (ft) 



P /P- " 

 •^s' im 



Concrete 

 Water- 

 proofed 



Comments 



1 



5,075 



0.83 



Yes 



clock inside sphere 



2 



4,875 



0.80 



Yes 



clock inside sphere 



3 



4,330 



0.72 



Yes 



clock inside sphere 



4 



4,185 



0,81 



No 



clock inside sphere 



5 



4,100 



0.78 



No 



clock inside sphere 



6 



3,875 



0.70 



No 



clock inside sphere 



7 



3,725 



0.58 



Yes 





8 



3,665 



0.60 



Yes 





9 



3,295 



0.62 



No 





10 



3,190 



0.56 



No 





11 



3,140 



0.50 



Yes 





12 



2,790 



0.55 



No 





13 



2,635 



0.41 



Yes 





14 



2,440 



0.44 



Yes 





15 



2,300 



0.43 



No 





16 



2,120 



0.40 



No 





17 



1,980 



0.38 



b 



steel reinforcement in walls 



18 



1,840 



0.36 



b 



steel reinforcement in walls 



Sustained pressure-to-short-term implosion pressure ratio. 



One hemisphere is waterproofed while the other hemisphere is not 

 waterproofed. 



exposed to ambient conditions. Chemical 

 composition changes of the concrete will be 

 determined by comparing x-ray diffraction patterns 

 with those of the concrete at age 20 months. 



FABRICATION 



Concrete hemisphere sections were cast in a steel 

 mold and the following day were removed from the 

 mold. Twelve 6 x 12-inch-long control cylinders and 

 one 14 X 18 X 18-inch control block of concrete were 

 also cast with each hemisphere. 



Moist-curing of the hemisphere, six control 

 cylinders, and the control block was accomplished by 

 wrapping the specimens in wet burlap and then in 

 polyethylene film: the remaining six control cylinders 

 were placed in the fog room. Moist-curing continued 

 for 28 days at ambient temperature inside an open 

 building followed by 28 days of room-curing condi- 

 tions, and then on-land field-curing conditions. 



After several weeks of field curing, the 

 hemispheres were prepared for assembly into spheres. 

 The equatorial edges were ground flat by using a large "^ 

 steel plate, and silica carbide grit and water as the 

 cutting agent. A titanium hull penetration at the apex 



