(56f) Wall Friction Tests On Limestone Using An Annular Shear Cell

Limestone is a commodity material in many economic sectors including the chemical and agricultural industries where large quantities are transported, stored and handled. Although nominally calcium carbonate, the properties of limestone, as quarried, are influenced by its geological origins which affect its mineralogy and overall chemical composition.

In a campaign of experiments to measure the flow parameters of three different limestones, using an annular shear cell, we have logged shear stress measurements over extended periods of time for a number of different normal stresses. Our data are indicative of stick-slip friction, and also suggest that the method of filling the trough of the annular shear cell has a strong influence on the form of the shear-stress/time record.

Results are presented for an algal Oligocene limestone containing small amounts of quartz and mica, an Oligocene sandy coquina, and an Ordovician marble containing small amounts of mica; the size distributions of each were similar.