The Mechanical Properties of an Interlocked Low-Porosity Aggregate

Synopsis If coarse grained marble is heated to around 6OO°C the anisotropy of thermal expansion of calcite causes almost complete separation at grain boundaries. The resulting material retains its shape and consists of a mass of crystals in contact, with a porosity of about 4%, very small direct tensile strength and the mechanical analysis and permeability to water of a sand. It may be regarded as a laboratory model of randomly jointed rock and perhaps of bad and broken rock in general. It has frequently been suggested that soil mechanics theory may be applied to such rock. This Paper examines the mechanical properties of the heated marble and shows that they different from those of soils. A small amount of confining pressure varies the triaxial strength rapidly, the initial slope of the Mohr envelope being of the order of 65° and the strength finally increasing to over 80% of that of the original rock. Young's modulus also increases with confining pressure but only to about 30% of that of original rock. ...