Any of these LVDT's can be used as feedback signals for the closed loop control. The system is designed to compensate for the effects of the moving masses of the machine on the load measurements during testing because these effects can be relatively high compared to the load measurements. Repeated shear at constant height. Repeated shear at constant stress ratio. Simple shear at constant height.
Frequency sweep at constant height.
Identical SST's were purchased for the five Superpave Centers located in the United States.