Bolt Anchorage with Gypsum-Plaster Water Capsule Cartridges

摘要

Full-column anchored resin bolts were first used in underground mines in 1972. In the mid-1970's, Bureau of Mines investigators began looking for a substitute for resin because of its short supply and rapidly increasing price. The investigators selected accelerated gypsum plaster, which becomes gypsum when mixed with water. The Bureau received a patent for a system combining water capsules (wax-encapsulated water) with plaster into cartridges resembling resin cartridges. This report presents the results of tests conducted by the Bureau on the plaster, the water capsules, and their combined use in cartridges. The tests were designed to determine how the gypsum-plaster water capsule bolting system performs and what happens in the hole while the bolt is being inserted through the cartridge. The test results indicate that water capsule plaster cartridges are a workable alternative to resin cartridges under normal or dry conditions.