The aim of this research was the characterization of the porous system and pore size distribution by both
polarisation optical microscopy and scanning electron microscopy using digital image processing. The
three stones studies belong to the Miocene age and are found in the Ebro basin: Ayerbe, Uncastillo and
Alcañiz sandstones. These sandstones have an historical importance in the architectural heritage of Aragon.
The results obtained from digital image analysis have been crosschecked with the results obtain by hydric
tests. The results have demonstrated that image analysis is an important and objective tool for textural
studies of natural stone. In addition, pore spectra can be used to estimate physical parameters.
Porosity governs strength physical-mechanical characteristics, chemical behaviour and hydraulic conductivity.
Therefore, the study of both geometry and pore size distribution are indispensable for understanding the
future behaviour of natural stone