Unsaturated Consolidation Testing

Product Code : Unsat CRS, Unsat Rowe

Unsaturated one dimensional consolidation can be performed to define the Stress Dependant Soil Water Characteristic Curve (SDSWCC). Vertical stress is applied under K0 conditions whilst pore water and pore air pressure are precisely controlled.

The GDS range allows for various options to perform SDSWCC testing.  The Rowe and Barden cell is the choice for a direct axial stress controlled unsaturated consolidation system. Alternatively a CRS cell (Constant Rate of Strain) can be used with either a 10kN or 50kN load frame. Whether using a Rowe and Barden cell or the CRS cell, each is supplied modified from the standard saturated version with a high air entry porous disc installed in the base.

Key features Benefits to the user
Direct control of both Matric Suction and Axial Stress: It is now generally accepted that unsaturated soil behaviour is governed by two independent stress state variables, i.e. net stress and matric suction (Fredlund and Morgenstern, 1977).
Axis translation technique:Matric suction is controlled up to either 500kPa or 1500kPa (depending on the air entry value chosen) by controlling pore air and pore water pressure directly. 
Fully controllable axial load / stress / displacement / strain:
The Stress Dependant Soil Water Characteristic Curve (SDSWCC) is possible due to the precise control over the axial stress. This poses an advantage over the traditional pressure plate extractor in which no external stress is applied and volume change of the soil specimen is assumed to be zero.
Fixed ring K0 conditions:
K0 conditions ensure there is no lateral deformation, therefore sample volume can be calculated directly from the axial deformation recorded.
Upgrade Options:
Both the Rowe and Barden and CRS type apparatus, even if first supplied for fully saturated testing only, can be upgraded to an unsaturated version at any time.