Specific mercury porosimetry for low-porosity materials

Modifications were made to a commercial porosimeter in order to measure ver y low open porosity in materials such as granites (porosity about 1%). A ne w measuring cell, i.e. the penetrometer, was designed with the highest poss ible sample holder capacity and with the capillary stem being of a smaller internal diameter than is standard. A specific computer software was also d eveloped to take into account penetrometer distortions and granite and merc ury compressions in order to correct the measured porosity values. This new apparatus was used successfully in measuring the porosity of grani te from Er Berrocal (Spain) as part of the European Commission Project 'Roc k Matrix Diffusion' (Contract No FI2W-CT91-0082). In particular, the experi mental constraints were examined and the method validated by comparing the obtained results to porosities measured by water saturation.