  A method is presented for the evaluation of the permeability-porosity
relationship in a low-permeability porous material using the results of a
single transient test. This method accounts for both elastic and non-elastic
deformations of the sample during the test and is applied to a hardened class G
oil well cement paste. An initial hydrostatic undrained loading is applied to
the sample. The generated excess pore pressure is then released at one end of
the sample while monitoring the pore pressure at the other end and the radial
strain in the middle of the sample during the dissipation of the pore pressure.
These measurements are back analysed to evaluate the permeability and its
evolution with porosity change. The effect of creep of the sample during the
test on the measured pore pressure and volume change is taken into account in
the analysis. This approach permits to calibrate a power law
permeability-porosity relationship for the tested hardened cement paste. The
porosity sensitivity exponent of the power-law is evaluated equal to 11 and is
shown to be mostly independent of the stress level and of the creep strains.
