Specific mercury porosimetry for low-porosity materials

Modifications were made to a commercial porosimeter in order to measure very low open porosity in materials such as granites (porosity about 1%). A new measuring cell, i.e. the penetrometer, was designed with the highest possible sample holder capacity and with the capillary stem being of a smaller internal diameter than is standard. A specific computer software was also developed to take into account penetrometer distortions and granite and mercury compressions in order to correct the measured porosity values. This new apparatus was used successfully in measuring the porosity of granite from El Berrocal (Spain) as part of the European Commission Project `Rock Matrix Diffusion' (Contract No FI2W-CT91-0082). In particular, the experimental constraints were examined and the method validated by comparing the obtained results to porosities measured by water saturation.