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Rock Test Hammer - RockSchmidt
Concrete Test Hammer - SilverSchmidt

The RockSchmidt is the world’s most advanced rebound hammer fully adapted specifically to the extremely varied rock testing applications.

The RockSchmidt incorporates statistical methods based on ASTM and ISRM recommendations and provides the user with the freedom to define his own statistical process for determining a rebound number.

Type N with standard impact energy ist most suited to field testing.
Type L with low impact energy as specified by ASTM for testing cores.


The features of the hammer make it ideal for rock testing applications:

  • Impact Angle Independence: The rebound value is independent of the impact direction.
  • Optimized for Field Work: Tighter sealing against dirt and dust intrusion for longer life. Significantly lighter and more ergonomic than the classic Schmidt hammer.  A large number of readings can be saved and downloaded later to a PC.
  • Preset Statistics: Statistics methods recommended by ISRM and ASTM are implemented into the hammer for automatic calculation of the rebound number. The option is also there to define a user specific statistics method.
  • Unconfined Compressive Strength: ISRM recommends a correlation between UCS and the rebound value based on the formula
    UCS = aebR (where R is the rebound value). A correlation in this format may be defined in the PC software and downloaded onto the RockSchmidt.
  • E-Modulus: ISRM recommends a correlation between elastic modulus and the rebound value based on the formula Et = cedR  (where R is the rebound value). A correlation in this format may be defined in the PC software and downloaded onto the RockSchmidt.
  • Weathering Grade: Impacting on the same location twice can be used to correlate to weathering grade. The ISRM recommended method has been included in the device.
  • Geomorphological applications which investigate the bulk hardness properties of a rock outcrop
  • Prediction of weathering grades
  • Correlation to Unconfined (or Uniaxial) Compressive Strength (UCS)
  • Correlation to Young’s Modulus
  • Prediction of penetration rates for tunnel boring machines and rotary drum cutters
  • Testing on cores and blocks
  • Determing uniaxial compressive strength with RockSchmidt
Product Variations

Type N: Standard impact energy, 2.207 Nm. Recommended for field work. For core testing ISRM recommend that cores should be at least moderate strength (>80 MPa) and at least T2 size (≥ 84mm).

Type L: Low impact energy, 0.735 Nm. Recommended impact energy in the ASTM D 5873 standard for testing of cores. ISRM recommend for testing on cores of moderate strength and above of at least NX size (≥ 54mm).

Applicable Standards

The following standards and guidelines apply to rock

  • ASTM D 5873 – Standard Test Method for Determination of Rock Hardness by Rebound Hammer Method. (Applicable for UCS between 1 MPa and 100 MPa.)
  • ISRM – Aydin A., ISRM Suggested method for determination of the Schmidt hammer rebound hardness: Revised version. Int J Rock Mech Mining Sci (2008), DOI:10.1016/j.ijrmms.2008.01.020.
Technical Data

Technical Data

Impact energy (N) 2.207 Nm, (L) 0.735 Nm
Spring extension 75 mm (2.95")
Plunger radius 25 mm (0.98"
Dimensions of housing 55 x 55 x 250 mm (2.16" x 2.16" x 9.84")
Weight 570 g
Memory Data  
No. of impacts in a series Maximum 99
Memory capacity dependent on length of test series
Example 400 series with 10 values per series
Example 200 series with 20 values per series
Electrical data                          

Display 17 x 71 pixels; graphic
Battery lifetime >5000 impacts between charges
Charger connectionUSB type B (5V, 100 mA)
Environmental conditions  
Operating temperature 0 to 50°C
Storage temperature -10 to 70°C



  • Standard 2-year limited warranty on electronic parts of the concrete test hammer
  • Optional extended warranty periods up to 3 additional years