ABSTRACT
Two spray on polymer membranes were trialed at Junction mine as a potential replacement for mesh. The membranes trialed were a polyurethane material called Mineguard™ and an acrylic based polymer membrane Everbond Mark II. The polymers were trailed underground in a development heading and at the brow of a long hole stope. A series of performance tests were also conducted on surface, which included pull tests on steel plates which had been sprayed over with membrane and strength tests of concrete and rock cores which had been coated with membrane.
The underground trials showed that the membranes were easy to apply and the logistics of spraying could be easily managed. The trials also showed that Mineguard™ had problems adhering to rock if it were wet or dusty and that Everbond II was unable to set in areas where ground water was flowing.
The surface plate tests showed that Mineguard™ could be used to replace mesh as a structural surface restraint but Everbond II was unable to sustain the necessary high loads. The core tests showed that both membranes prevented the explosive failure of the porphyry rock cores and increased the post failure strength of the concrete cores.
