Direct Shear Test Equipment
Direct Shear test equipment from Karol-Warner is used to measure shear strength properties in samples of undisturbed or remolded soil. When conducting the direct shear test, typically three or more tests are ran to make up a series and are combined to determine strength properties such as Mohr strength envelopes.
A soil specimen is prepared by trimming the specimen into a Shear Box and placing it into the direct shear loading device, providing for wetting or draining of the sample. A vertical confining load is applied to consolidate the soil, then a horizontal shear load is applied, laterally displacing one-half of the Shear Box at a constant rate while measuring the required force and amount of displacement. For residual shear tests, the displacement direction is reversed and the force measured. Each machine is supplied with a drainage plate and water chamber.
- Direct Shear Machines (Pneumatic) are self-contained, tabletop shear testing machines designed for fast, precise application of vertical loads. The load set point is accurately maintained even during volume change as the sample is consolidated. Horizontal loads are controlled through the stepper motor and precision drive system, controlling strain forces to ±1%. Models are available using dial indicators for consolidation and shear displacement, or an all-digital model with capabilities for data output in ASCII format.
- Direct Shear Machines (Dead-Weight) use a dead-weight loading system with a 10:1 beam for applying the vertical load to the sample. Strain rate is adjustable and controlled to ±1% through the stepper motor. Standard versions have load cells with digital readout and use dial indicators to measure shear and vertical displacement. A digital model features transducers and a four-channel readout to measure and record consolidation, shear force, and displacement. The compact, self-contained units feature a built-in floor stand on heavy-duty casters.
- Direct / Residual Shear Data Acquisition Software records specimen information and real-time test data, calculate results and prepares reports following ASTM and AASHTO requirements.
- Shear Boxes are available for round or square direct/residual soil specimens in popular sizes. Anodized aluminum units are precision machined to hold specimens during testing and accurately apply shear forces.
- Direct Shear Accessories include Cutters and Extruders matched to individual Shear Box sizes for accurate and efficient trimming and removal of soil specimens.
- Slotted Weights & Weight Sets are required for use with Karol-Warner's Dead-Weight Direct and Direct / Residual Shear Machines and Dead-Weight Consolidation Load Frame. Weights are sold separately or in sets.
- Large Direct Shear Machines are built for specialized testing of large specimens of soil or soil with embedded geosynthetic material to ASTM D5321 and ASTM D6243 test methods. These units combine a pneumatic system with a larger, 12in (304.8mm) square sample for a test designed to replicate field conditions. Large Direct Shear Machines are offered in models with capacities of 45kN (10,000lbf) or 89kN (20,000lbf). Ergonomic features that allow handling and placement of the oversized shear rings are designed into the machines.
