The Direct/Residual Shear, Standard Pneumatic, includes a load cell with digital readout to measure shear load and dial indicators for consolidation and shear displacement measurements.
Shear displacement tests determine direct and residual shear of consolidated drained and un-drained soils and give engineers valuable information for evaluating strength and stability of soils. The test is performed on a variety of soil types with either undisturbed or remolded soil samples. The specimens are carefully trimmed into a Direct Shear Box, which is split horizontally to allow individual movement of the upper and lower halves. A vertical confining load is applied to the specimen, and a horizontal shear force is applied to the lower half of the box. The upper half of the shear box remains stationary during testing. After shearing failure has occurred and force measurements have been determined, the direction of shear force can be reversed to determine residual shear values.
Tabletop units with pneumatic vertical loading use the patented CONBEL® loading system to apply confining pressures to the sample. Vertical loads are applied using two pneumatic pistons. A small, rolling diaphragm piston accurately applies light vertical loads of 4-100lbf (0.018-0.44kN) and the large diameter piston applies loads up to 1,500lbf (6.67kN). This design increases the sensitivity and accuracy of the light load system. Loading is controlled by setting the precision regulator to the desired pressure per the included calibration chart. Load settings are displayed digitally and are accurate to ±0.25%. Both pneumatic shear machines are completely self-contained units, and the need for loading weights is eliminated.
A stepper motor drive controls strain rates to ±1% from 0.0001-0.3in/min (0.0025-7.62mm/min), and is easily set with digital thumbwheels. Total shear capacity is 1,500lbf (6.67kN). A 2.5in (63.5mm) diameter stainless steel shear ring, porous stones, drainage plates and a water chamber constructed of Teflon coated, anodized aluminum for corrosion resistance are included.
Meets Test Methods:
ASTM D 3080