Developing Innovative Shotcrete as Rock Support for Underground Mining in Canada’s North

点击翻译按钮获取中文摘要

Shotcrete refers to a cement-based mixture projected pneumatically at high velocity towards the target substrate. Shotcrete has been widely used in underground mines as rock support; however, permafrost poses significant challenges to the design and use of shotcrete to support freshly excavated frozen rock/permafrost because the slow hydration of shotcrete mixture on frozen substrates leads to insufficient hardening and malfunctioning of the rock support system. This is unsafe as insufficient hardening may result in rockfalls and subsequent injuries or even fatalities of mine workers. For northern applications, the hydration of shotcrete must be accelerated to ensure adequate strength for rock support; however, excessive heat produced by shotcrete hydration and warm ventilation air within the mine causes thawing of the surrounding permafrost. Thawing is a serious problem because it triggers greenhouse gas emissions (i.e., methane) threatening global climate and it destabilizes the ground making underground operations unsafe.