Figure B-1. Cylinder specimen 

 being removed from mold. 



Figure B-2. Specimen partly 

 assembled inside polyethy- 

 lene tent. 



The specimens were moist-cured in this manner untU assembled for 

 test. During assembly (Figure B-2) a tent of polyethylene film was 

 used to maintain a high relative humidity environment around the speci- 

 men to minimize shrinkage cracking. Keeping the cylinder in the moist 

 environment assured the test conductors that the concrete was in a 

 "wet" condition at the time of the implosion test. 



Assembly 



The procedure to assemble a specimen for test (Figure B-3) began 

 by placing the cylinder on the bottom end-closure, which was a flat 

 steel plate. The top end-closure was a steel ring. The top and bottom 

 closures were held together by eight chains, post-tensioned to precom- 

 press the concrete by 20 psi (0.14 MPa) when the structure was sub- 

 merged in water in the pressure vessel. 



41 



