Materials and Structures

, 51:138 | Cite as

Testing of concrete by rebound method: Leeb versus Schmidt hammers

  • Konstantin KovlerEmail author
  • Fengzhe Wang
  • Boris Muravin
Original Article


Hardness is considered as an important property of concrete; it can be used to estimate compressive strength of concrete in situ. The classic Schmidt rebound hammer is the most popular nondestructive method to measure concrete surface hardness, while the Leeb rebound hammer has been extensively studied in geological and metallographic fields over decades, and its use for testing concrete is almost not known. The national and international standards for the measurement of hardness are reviewed. Concrete made different w/c ratios (0.33, 0.4 and 0.5) were tested by both methods. The simple linear correlation between rebound numbers (both Schmidt and Leeb) and concrete compressive strength are proposed. Schmidt rebound number was differently correlated with compressive strength for concretes with different w/c ratios, while the Leeb rebound numbers were more consistent and could be applied in predicting concrete compressive strength within 10% error for all w/c ratios. It was also concluded that Schmidt test can be considered as a semi-destructive method, because of significant strength reduction (in average by 10.5 MPa) that was observed after application of Schmidt hammer impact on specimens, while the Leeb rebound test procedure did not result in any damage of concrete. This difference can be explained by the dramatic difference in impact energy of the two hammers (2207 and 11 N·mm - for Schmidt rebound hammers of N-type and Leeb hammers of D-type, respectively). Moreover, the classic Schmidt rebound hammer is not recommended to be used on the concrete specimens, which are aimed for compressive tests at early age (less than 3 days) or when expected compressive strength is less than 7 MPa. These constraints do not apply to lower impact Leeb rebound devices, which can be considered as perfectly invasive (non-destructive). At the same time, as expected, Leeb rebound test is sensitive to the surface conditions, such as carbonation and surface moisture.


Concrete Nondestructive tests Schmidt rebound hammer Leeb rebound hammer Compressive strength Hardness 



The authors thank to Mr. Boris Gershengoren and Mr. Elhanan Itzhak for their valuable assistance in conducting the experiments.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.


  1. 1.
    Schmidt E (1950) Rebound hammer for concrete testing (Der Beton-Prüfhammer). Schweizerische Bauzeitung. 15:378–379Google Scholar
  2. 2.
    Schmidt E (1975) Method and apparatus for testing hardness of specimens. US Patent 38,799,82AGoogle Scholar
  3. 3.
    Williams RBG, Robinson DA (1983) The effect of surface texture on the determination of the surface hardness of rock using the Schmidt hammer. Earth Surf Process Landf 8:289–292. CrossRefGoogle Scholar
  4. 4.
    Hack R, Huisman M (2002) Estimating the intact rock strength of a rock mass by simple means. In: Engineering geology for developing countries, proceedings 9th congress, international association for engineering geology and the environment. Durban, South Africa, pp 16–20Google Scholar
  5. 5.
    Sumner P, Nel W (2002) The effect of rock moisture on Schmidt hammer rebound: tests on rock samples from Marion Island and South Africa. Earth Surf Process Landf 27:1137–1142. CrossRefGoogle Scholar
  6. 6.
    Demirdag S, Yavuz H, Altindag R (2009) The effect of sample size on Schmidt rebound hardness value of rocks. Int J Rock Mech Min Sci 46:725–730. CrossRefGoogle Scholar
  7. 7.
    Viles H, Goudie A, Grab S, Lalley J (2011) The use of the Schmidt Hammer and Equotip for rock hardness assessment in geomorphology and heritage science: a comparative analysis. Earth Surf Process Landf 36:320–333. CrossRefGoogle Scholar
  8. 8.
    Leeb D (1979) Dynamic hardness testing of metallic materials. NDT Int 12:274–278CrossRefGoogle Scholar
  9. 9.
    Anan S (1997) Application of rebound hardness tester to rock material: an attempt to material classification by Equotip hardness testing. In: Proceeding conference on the Japan Society of Engineering Geology, Chugoku-Shikoku Dist., pp 15–18Google Scholar
  10. 10.
    Frank S, Sommer J (1986) Standardization of the Leeb hardness testing method. Krautkrämer GmbH, HürthGoogle Scholar
  11. 11.
    Verwaal W, Mulder A (1993) Estimating rock strength with the equotip hardness tester. Int J Rock Mech Min Sci 30:659–662. CrossRefGoogle Scholar
  12. 12.
    Borggren K, Tønder P, Lorentzen MS, Hansen JV, Auerkari P (1999) Comparison of portable hardness testers—performance with ideal samples (NT TR 424 - Part 2). FORCE Institute, CopenhagenGoogle Scholar
  13. 13.
    Borggren K, Tønder P, Lorentzen MS, Hansen JV, Auerkari P (1999) Comparison of portable hardness testers—performance with non-ideal samples and cases (NT TR 424 - Part 3). FORCE Institute, CopenhagenGoogle Scholar
  14. 14.
    Kawasaki S, Tanimoto C, Koizumi K, Ishikawa M (2002) An attempt to estimate mechanical properties of rocks using the Equotip hardness tester. J. Jpn Soc Eng Geol 43:244–248. CrossRefGoogle Scholar
  15. 15.
    Kompatscher M (2004) Equotip-rebound hardness testing after D. Leeb. In: Proceedings, conference on hardness measurement theory and application in laboratories and industries, pp 11–12Google Scholar
  16. 16.
    Aoki H, Matsukura Y (2008) Estimating the unconfined compressive strength of intact rocks from Equotip hardness. Bull Eng Geol Environ 67:23–29. CrossRefGoogle Scholar
  17. 17.
    Yılmaz NG (2013) The influence of testing procedures on uniaxial compressive strength prediction of carbonate rocks from Equotip hardness tester (EHT) and proposal of a new testing methodology: hybrid dynamic hardness (HDH). Rock Mech Rock Eng 46:95–106. CrossRefGoogle Scholar
  18. 18.
    Coombes MA, Feal-Pérez A, Naylor LA, Wilhelm K (2013) A non-destructive tool for detecting changes in the hardness of engineering materials: application of the Equotip durometer in the coastal zone. Eng Geol 167:14–19. CrossRefGoogle Scholar
  19. 19.
    Alberti AP, Gomes A, Trenhaile A, Oliveira M, Horacio J (2013) Correlating river terrace remnants using an Equotip hardness tester: an example from the Miño River, northwestern Iberian Peninsula. Geomorphology 192:59–70. CrossRefGoogle Scholar
  20. 20.
    Wilhelm K, Viles H, Burke Ó (2016) Low impact surface hardness testing (Equotip) on porous surfaces—advances in methodology with implications for rock weathering and stone deterioration research. Earth Surf Process Landf 41:1027–1038. CrossRefGoogle Scholar
  21. 21.
    Greene GW (1954) Test hammer provides new method of evaluating hardened concrete. J Proc 249–256Google Scholar
  22. 22.
    Kolek J (1958) An appreciation of the Schmidt rebound hammer. Mag Concr Res 10:27–36CrossRefGoogle Scholar
  23. 23.
    Goudie AS (2006) The Schmidt Hammer in geomorphologlical research. Prog Phys Geogr 30:703–718. CrossRefGoogle Scholar
  24. 24.
    Katz O, Reches Z, Roegiers J-C (2000) Evaluation of mechanical rock properties using a Schmidt Hammer. Int J Rock Mech Min Sci 37:723–728. CrossRefGoogle Scholar
  25. 25.
    Szilágyi K, Borosnyói A, Zsigovics I (2015) Understanding the rebound surface hardness of concrete. J Civ Eng Manag 21:185–192. CrossRefGoogle Scholar
  26. 26.
    Yılmaz I, Sendır H (2002) Correlation of Schmidt hardness with unconfined compressive strength and Young’s modulus in gypsum from Sivas (Turkey). Eng Geol 66:211–219. CrossRefGoogle Scholar
  27. 27.
    Dinçer I, Acar A, Çobanoğlu I, Uras Y (2004) Correlation between Schmidt hardness, uniaxial compressive strength and Young’s modulus for andesites, basalts and tuffs. Bull Eng Geol Environ 63:141–148. CrossRefGoogle Scholar
  28. 28.
    Cargill JS, Shakoor A (1990) Evaluation of empirical methods for measuring the uniaxial compressive strength of rock. Int J Rock Mech Min Sci Geomech Abstr 27:495–503. CrossRefGoogle Scholar
  29. 29.
    Hannachi S, Guetteche MN (2012) Application of the combined method for evaluating the compressive strength of concrete on site. Open J Civ Eng 2:16. CrossRefGoogle Scholar
  30. 30.
    Malhotra V, Carino N (2003) Handbook on nondestructive testing of concrete, 2nd edn. CRC Press, Boca Raton. CrossRefGoogle Scholar
  31. 31.
    Aydin A, Basu A (2005) The Schmidt hammer in rock material characterization. Eng Geol 81:1–14. CrossRefGoogle Scholar
  32. 32.
    Bieniawski ZT (1989) Engineering rock mass classifications: a complete manual for engineers and geologists in mining, civil, and petroleum engineering. Wiley, HobokenGoogle Scholar
  33. 33.
    Momber AW (2004) Deformation and fracture of rocks loaded with spherical indenters. Int J Fract 125:263–279. CrossRefGoogle Scholar
  34. 34.
    Aydin A (2009) ISRM Suggested method for determination of the Schmidt hammer rebound hardness: revised version. Int J Rock Mech Min Sci 46:627–634. CrossRefGoogle Scholar
  35. 35.
    ASTM C5873-14, Standard Test Method for Determination of Rock Hardness by Rebound Hammer Method (2014).
  36. 36.
    ASTM C805/C805M-13a, Standard test method for rebound number of hardened concrete (2013).
  37. 37.
    EN, 12504-2:2012 Testing Concrete In Structures—Part 2: Non-destructive Testing—Determination of Rebound Number (2012)Google Scholar
  38. 38.
    ACI Committee 211 (1991) Standard practice for selecting proportions for normal, heavyweight, and mass concrete (ACI 211.1-91). Man Concr Pract 1–38Google Scholar
  39. 39.
    BS EN, 12390-3:2009 Testing Hardened Concrete (2009) Compressive strength of test specimens.
  40. 40.
    Crawford GI (1997) Guide to nondestructive testing of concrete, FHWA-SA-97-105, Technical ReportGoogle Scholar
  41. 41.
    Non Destructive Assessment of Concrete Structures: Reliability and Limits of Single and Combined Techniques, State-of the-Art Report of the RILEM Technical Committee 207-INR. In: Breysse D. Springer (2012)Google Scholar

Copyright information

© RILEM 2018

Authors and Affiliations

  1. 1.Faculty of Civil and Environmental EngineeringTechnion - Israel Institute of TechnologyHaifaIsrael
  2. 2.Integrity Diagnostics Ltd.NetanyaIsrael

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