Rock core samples were assembled as

Rock core samples were assembled as shown in Figure 1. The rock sample is ground for parallel and perpendicular conditions per ASTM standards. The samples were right circular cylinders of Westerly granite, nominally 3.8 cm in diameter, 8 cm in length and weighing between 250 and 260 g and were oven dried for a week at 50∘C prior to testing. Acoustic emission transducer buttons were glued directly to the sample along a diameter near the sample midheight. The sample was sandwiched between alternating layers of pressed metal fiber mesh and steel spacers to assure gas flow accessibility along the core ends. The sample is then jacketed to keep confining fluid out of the pore volume. Specimens were jacketed first with a thin layer of UV cure urethane which adheres tightly to the rock surface inhibiting gas flow along the rock surface. A sleeve of polyolefin shrink tube was placed over the first layer of UV cure urethane, and then encapsulated in another layer of UV cure urethane. This jacketing procedure has proved successful in avoiding jacket leaks during rock fracture events.