Deep geological disposal designs for nuclear waste often include an engineered barrier to protect
the
waste canisters
and prevent leakage
. The long
-
term safety of the re
pository relies on studies of the buffer
material
.
Oedometer tests
provide values of
de
sign parameters
for
numerical simulations.
A
newly
-
developed
oedometer with automated suction control is presented to assist in the investigation of
the coupled hydro
-
me-
chanical
-
volumetric behaviour of an expansive clay, namely a natural sodium bentonite.
The displacement
-
controlled device was developed to apply suction
over a range of
1
0 MPa to 300 MPa
using a divided
-
flow
humidity
-
generator. The device allows the application of combined stress and suction states, and continuous
stress paths of constant vo
lume, stress or suction. The development of the new oedometer is described. Results
obtained during the preliminary tests are evaluated through comparison with experimental data from similar
tests found in the literature. The current method benefits from c
ontinuous control of suction with servo
-
control
of relative humidity using calibrated capacitance hygrometers. The system self
-
compensates for minor temper-
ature changes and therefore the requirement for thermal insulation is not as crucial as in vapour equ
ilibrium
methods.