Abstract
The Leeb hardness test (LHT with test value of L D ) is a rebound hardness test, originally developed for metals, that has been correlated with the Unconfined Compressive Strength (test value of σ c ) of rock by several authors. The tests can be carried out rapidly, conveniently and nondestructively on core and block samples or on rock outcrops. This makes the relatively small LHT device convenient for field tests. The present study compiles test data from literature sources and presents new laboratory testing carried out by the authors to develop a substantially expanded database with wide-ranging rock types. In addition, the number of impacts that should be averaged to comprise a “test result” was revisited along with the issue of test specimen size. Correlation for L D and σ c for various rock types is provided along with recommended testing methodology. The accuracy of correlated σ c estimates was assessed and reasonable correlations were observed between L D and σ c . The study findings show that LHT can be useful particularly for field estimation of σ c and offers a significant improvement over the conventional field estimation methods outlined by the ISRM (e.g., hammer blows). This test is rapid and simple, with relatively low equipment costs, and provides a reasonably accurate estimate of σ c .
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Acknowledgements
The authors would like to acknowledge the financial support of the Saudi Arabian Cultural Bureau in Canada scholarship. BGC Engineering Inc. provided access to their collected LHT data. Mr Jesse Keane assisted with much of the laboratory testing, and his help was appreciated. The manuscript was kindly edited by Judy MacLean. Furthermore, we would like to thank the journal’s anonymous reviewers for their effort and constructive comments.
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Corkum, A.G., Asiri, Y., El Naggar, H. et al. The Leeb Hardness Test for Rock: An Updated Methodology and UCS Correlation. Rock Mech Rock Eng 51, 665–675 (2018). https://doi.org/10.1007/s00603-017-1372-2
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DOI: https://doi.org/10.1007/s00603-017-1372-2