These devices feature the exclusive Karol-Warner CONBEL™ system for loading the large soil or soil/geosynthetic samples. The specimens are mounted in a two-piece shear box assembly, divided in half horizontally. The bottom half is held securely in place and a vertical confining force is applied. Horizontal force is then directed against the upper half of the box to shear the specimen. Shear loads are applied using two pneumatic pistons. Initial loads are applied using a small diameter rolling diaphragm piston, for greater accuracy and sensitivity of lighter loads, up to 4.4kN (1,000lbf) of force. The larger piston generates loads up to 45kN (10,000lbf), or 90kN (20,000lbf) depending on unit selected. Horizontal shear rate from 0.0508—5.08mm (0.002—0.2in) per minute is easily set with thumbwheels on the control panel. Limit switches control the home position and limit total horizontal displacement to 102mm (4in).
Vertical loading is controlled through a precision regulator, using the included calibration chart to set the required pressure. Loads are displayed to two decimal places on the digital readout, and are accurate to ±0.25%. Consolidation and shear displacement are measured by Linear Variable Displacement Transducers. Shear load is measured from a load cell attached to the water chamber. The four-channel readout displays all these values while directing data in ASCII format through the mini USB serial port to the user’s computer.