Relationships between permeability and pore structure of hardened cement paste

Abstract

Synopsis A description is given of a steady-state method of measuring the permeability of hardened cement paste. The method takes advantage of the applied hydrostatic pressure in sealing truncated conical disc specimens at hydraulic gradients up to 150000. Relationships between saturated permeability and pore structure parameters, as determined by drying at 105°C and mercury intrusion porosimetry, are presented for hardened cement pastes of differing water/cement ratios and times of hydration. It was found that there is no unique relationship between permeability and porosity, though well defined trends were evident for the effect upon permeability of time of hydration at constant water/cement ratio. Similar trends were found between permeability and surface area at constant time of hydration. A broad-banded relationship was evident between permeability and hydraulic radius for all the grouped results. Reasonably close agreement was found between the structural parameter from hydraulic radius theory and the permeability, though with some discrepancies at low permeabilities.