Physical and mechanical characteristics of the gravina calcarenite (southern Italy)

Abstract

One of the most important problems in designing engineering works is the knowledge of the strength parameters of the rock masses. Beside the soil-structure interaction, a satisfactory performance of structures requires that rock mass properties such as deformation modulus, intact rock and global rock mass strengths and shear strength parameters are reliably defined. The studied Calcarenite of Gravina, is a calcarenitic rock outcropping in the area of the town of Matera (Southern Italy). It is a natural soft rock, mainly used since prehistoric times as building and dimension stone, considered durable although air pollution and water weathering markedly reduce the mechanical properties both at short and long term. Consequently, locally existing cliffs may be affected by erosive phenomena and, even, by unexpected collapses resulting from complex hydro-chemo-mechanical processes. This paper presents the evaluation of the Calcarenite of Gravina physical and mechanical properties, using laboratory tests on intact rock samples collected in seven different locations. From a macroscopic point of view, calcarenites are highly porous materials showing the presence of three main components: calcareous grains, micrite matrix and sparite cement. Dry and saturated calcarenite samples have been tested according to the ISRM suggested methods at room temperature (~20°). As the studied Calcarenite cannot be considered homogenous rocks, being characterized by largely scattered pore sizes, further research on the effect of porosity on mechanical properties, mainly strength and deformability is needed and still ongoing.