Cylinder Testing Details

 Nine cylinders (three control and six grid) were tested in displacement control

mode in order to capture the post peak behavior of the specimens.

 The smallest rate that the MTS loading frame could handle was approximately 0.06

in. per minute that resulted in a load rate of approximately 106 psi per second. This load

rate was approximately two times higher than the maximum load rate allowed by ASTM

C39 (ASTM 2001). Typical load head movement rate and load rate curves from the

control cylinders can be seen in Figs 3-6 and 3-7 respectively. The same load head

movement rate was used for all cylinder specimens tested in displacement control mode.

 0.12


 0.09


 S0.06


 0.03


 0.00
 0 20 40 60 80 100
 Time (sec)

Figure 3-6. Typical load head movement rate for control cylinders

 For the cylinder specimens to be tested in displacement control the 500 kip loading

frame was used. Two Linear Variable Displacement Transducers (LVDTs) were used to

continuously record the length change of the specimens as load was applied. The two

LVDTs were placed on opposing sides of the cylinder to determine the average length

change of the cylinder specimen (Fig. 3-8).