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The water permeability of both pastes and mortars was measured using the permeability cell
designed and built by Hearn and Mills . The permeability cell allows monitoring of both
inflow and outflow by sensing the movement of pistons in calibrated cylinders as well as
measuring the driving pressure and outflow pressure by means of pressure transducers. The
outflow pressure is caused mainly by the friction of the piston in the outflow cylinder. The inflow
pressure was applied by dead loading of the piston and
was maintained at the lowest
range that would still yield results. The pressure transducers
were calibrated by means of vacuum
and a mercury manometer. The confining pressure of the sample was applied by a silicone rubber
cylinder constrained by a stainless steel cylinder. The axial confining force was applied by screw
For each test, two 35-mm thick disks were cut from each specimen cylinder immediately after
demolding. These specimens were vacuum saturated for 24 hours according to the procedure
described by ASTM C 1202-91 . The earliest age at the start of the test was 44 hours.
After saturation, the mass and dimensions of each specimen were measured. The specimens were
then inserted into the permeability cells. The system was evacuated and filled with de-aired water.
Typically, measurements were made over the course of 200-300 hours.