Abstract
Kelly Habib, Isaac Vennes, Hani Mitri
This project focuses on Soundless Explosive-Free Chemical Demolition Agents (SCDA) as a potential replacement of explosives for underground mining. SCDA are cementitious powdery substances with quicklime (CaO) as primary ingredient that expands during the moist curing process which results in high expansive pressure when the CaO hydration reaction occurs in a confined borehole space. SCDA are currently used for rock fracturing in construction projects to demolish old concrete foundations, and in dimension stone quarries for block splitting. The use of SCDA for rock fragmentation is considered an environmentally friendly method as it is noise and vibration free and does not produce greenhouse gas emissions usually associated with blasting with explosive energy. For underground mining applications, it would not necessitate additional ventilation and it would not produce rock damage or overbreak caused by blasting.
SCDA have never been attempted before in underground mines. The presence of high in-situ stress and high host medium stiffness of the rock mass is perceived to limit the initiation and propagation of rock fractures induced by SCDA. This paper will report the results of a laboratory investigation aimed at quantifying the effects of borehole diameter, host stiffness and load on the fracturing performance of SCDA. A series of experiments was carried out on granite rock blocks under no load and under uniaxial loading. Finally, the influence of ambient temperature and humidity on SCDA performance is investigated. This work is part of a multi-phase project which aims to develop a sound methodology for fragmenting hard rock in underground mines with SCDA.