Abstract
Cemented rockfill (CRF) is being used to backfill primary and secondary stopes at the Eagle Mine, an underground nickel and copper mine operated by Lundin Mining. The National Institute for Occupational Safety and Health (NIOSH) is partnering with Eagle Mine and researching the advancement of mine backfill QA/QC guidelines through batching and strength testing method studies, specifically through investigation of existing methods that best determine in-situ properties of CRF. As part of this collaborative research, NIOSH researchers traveled to Eagle Mine and worked with mine staff to trial multiple 6-inch QA/QC CRF cylinder preparation methods including ASTM C31, ASTM C1435, and a drop hammer compaction method to identify which method can best correlate to the in-situ strength of CRF placed underground with the least operator bias and highest confidence. A total of sixty 6-inch cylindrical samples of CRF were cast in accordance with the three cylinder preparation methods at the mine and cured underground. The samples were later transported to the SMRD laboratory to determine the strength and elastic properties of the CRF. The data collected from this study will help identify which test cylinder method provides consistent density and strength results that can better correlate with in-situ density of CRF.