POROSITÀ E PERMEABILITÀ DELLE CALCARENITI DI PIETRA CADUTA

In the “Pietra Caduta” area, a wide covering, about 50 m thick, of Plio-Pleistocene “Calcareous Tuffs” (Calcarenite di Gravina), rests on a Mesozoic carbonate basement. From the bottom towards the top of the calcarenite formation, rather fine-grained calcarenites are succeeded by medium-grained and, finally, coarse calcarenites and calcirudites, the latter with an isoclinal stratification. The quarries were initially worked underground at a shallow depth, and later, up to the present day, open cast. Along the walls three main varieties have been found of which the most utilized and valued is the fine-grained one. The physical and mechanical parameters of these varieties have been studied with particular attention to the characteristics of porosity and permeability. The comparative analysis of the data obtained from geotechnical laboratory tests, mercury microporosymetry, and computerized analysis of the digital images of microphotos has made it possible to obtain detailed information on the distribution of pores and their influence on the water retention properties of these rocks.