Stachiw 



time intervals. 



TESTING PROCEDURE - The testing of the concrete spheres under 

 hydrostatic pressure was conducted in the pressure vessel of the 

 Deep Ocean Simulation Laboratory. The spheres were either placed in 

 a retaining cage prior to testing or were attached to end closure 

 (Figure 10) so that they would not float in the vessel and strike 

 the end closure when the vessel was filled with water. The vessel 

 was pressurized by air-operated, positive-displacement pumps that 

 raised the pressure inside the vessel at a predetermined rate 

 until implosion occurred. Pressure and temperature sensors located 

 inside the pressure vessel permitted recording of these two para- 

 meters on a strip chart recorder. Upon implosion of the concrete 

 spheres, manifesting itself by a loud noise, the end closure was 

 removed and the fragments of the concrete structure were inspected, 

 (Figure 11). 



DISCUSSION OF TEST RESULTS 



PHASE I 



SHORT-TERM STRENGTH OF DRY CONCRETE SPHERES - The average 

 ultimate compressive strength of the concrete spheres under hydro- 

 static loading has been found to be approximately 487o higher than 

 for the 3 x 6-inch solid control cylinders tested under standard 

 conditions (Table 1). 



Table 1. Implosion Pressure, Calculated Maximum Stress in 

 Dry Concrete Spheres; and Average Compressive 

 Strength of Test Cylinders Associated With These 

 Spheres. 



11 stress calculated with Equation 1 (Figure 2), 



227 



