  Values of water permeability for cementitious materials reported in the
literature show a large scatter. This is partially attributed to the fact that
materials used in different studies are different. To eliminate the effects of
cements, specimen preparation, curing conditions and other batch effects, this
study employs a long cylindrical cement paste to prepare all specimens for a
variety of permeability determination methods, such as beam bending,
sorptivity, Katz Thompson and Kozeny Carman equations. Permeabilities
determined by these methods are then used in a moisture transport model.
Compared with the measured mass loss curves, we found that permeability
determined by the beam bending method provides much closer results to the
measured ones than other methods. The difference results from that the
saturated specimen is used in the beam bending method while specimens in other
methods are dried (or rewetted). As already shown in the literature, the
microstructure of the dried or rewetted specimens is altered and different to
the original microstructure of the water saturated specimens.
