Thin Spray-On Liners (TSLs) have been the subject of much international research, laboratory testing and underground trials over the past 20 years and yet their fully functional and widely justifiable application in mining has yet to be achieved. While the explanation for this is partly technical, it is also clear that proving and communicating the operational and economic case for why a mine should change from mesh or shotcrete liners to a TSL is not a trivial matter. Evidence must be presented and communicated effectively, that is both obvious and compelling for a mine operator. The paper describes recent work carried out and directed towards this end, with funding from CAMIRO's Deep Mining Research Consortium and additional support from 3M Canada and ABB Canada. Future plans are also presented to demonstrate the performance of a new 3M composite TSL/yielding bolt support system in underground trials where the substrate rock is intended to fail through a number of mining-induced mechanisms.
Underground rock support typically comprises two or more basic components: a sur-face liner of screen or shotcrete, together with various configurations of rockbolts working with the surface liner. Shotcrete in mining has evolved over the last 25 years to become a mainstay liner component, but is challenged by its brittle nature and lack of yielding capacity in seismically active and/or strongly deforming ground, as well as by material handling issues. This statement alone may be seen as the original motiva-tion for seeking a tough or yielding alternative to shotcrete in the form of a thin spray-on (deformable) liner, or TSL. Here "thin" implies that it would have an order of magnitude less material volume and thus a significant reduction in material handling issues compared to shotcrete, particularly in the context of deep mining.