Textural and Mineralogical Controls on Microwave-Induced Cracking in Granites
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ORIGINAL PAPER
Textural and Mineralogical Controls on Microwave‑Induced Cracking in Granites Marion Nicco1 · Elizabeth A. Holley1 · Philipp Hartlieb2 · Katharina Pfaff3 Received: 19 November 2019 / Accepted: 26 June 2020 © Springer-Verlag GmbH Austria, part of Springer Nature 2020
Abstract Microwave irradiation has been considered as a potential method for weakening rock in mining and civil engineering applications, and numerous studies have demonstrated the strength-reducing effects. SEM-based automated mineralogy provides new opportunities to examine the mineralogical controls on microwave-induced cracking. This study employed a combined approach of optical microscopy and automated mineralogical analysis of scanning electron microscopy to investigate the roles of mineralogy and texture in microwave-induced cracking of granitic rocks. Most rocks on Earth, such as granite, are composed of relatively weak microwave absorbing minerals, compared to those tested in prior investigations on ores. This study examined three types of natural granite specimens, selected for their varying proportions of weak microwave absorbers (albite, amphibole, biotite, orthoclase, and quartz), and their contrasting textures (perthitic, granophyric and oikocrystic) and grain sizes (fine and coarse grained). Microwave irradiation experiments at 3.2 kW and 2.45 GHz led to the generation of macroscopically and microscopically visible cracks and lower P-wave velocities after irradiation. The optical investigations revealed that coarse-grained (1–5 mm) granites developed extensive networks of narrow cracks; whereas, fine-grained (
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