A new method is presented for measuring permeability evolution during
the rapid hydration phase of cement set. The method exploits the hydra
tion-induced pore pressure decline in the cement by using it as a driv
ing force for fluid dow and thus minimises damage to the delicate evol
ving matrix structure. This represents an improvement on traditional m
easurement techniques, where a pressure gradient is imposed on the sam
ple, which can cause much greater damage to the matrix. Cement is mode
lled as an elastic frame filled with a diffusing pore fluid, with flui
d consumption represented by an effective universal sink, or suction,
term. This sink term is proposed as a fundamental material property of
a setting cement, which is independent of curing conditions. Results
are compared with early-time measurements of permeability made using a
more conventional test scheme where water is forced through a sample.