Tunnel piperoof grouting
An underground drill jumbo is an example of percussive drilling. The first mechanized percussive drill was invented in 1844 using compressed air to apply the percussive load to strike the drill. Photo: AcademyBlasting.com
About the Author: Kevin Yanik
Kevin Yanik is editor-in-chief of Pit & Quarry. He can be reached at 216-706-3724 or kyanik@northcoastmedia.net.Subscribe to Pit & Quarry
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