Concrete Test Hammer - Schmidt OS-120
Concrete Test Hammer - Schmidt OS-120

The Schmidt OS-120 Pendulum Hammers are designed to test on softer material such as light weight concrete, gypsum boards, fresh concrete and the mortar of joints in brickwork. Their unique design allows easy to handle measurements on vertical and horizontal surfaces.

Schmidt OS-120 is the only rebound hammer worldwide working with the pendulum system, thus it must not be loaded on the test surface. The larger plunger surface on the Schmidt OS-120PT allows tests on soft concrete starting with a compressive strength of 1 MPa.



  • Pendulum type rebound system
  • Large, half circular scale with high resolution
  • Two different plunger types adopted to the different applications
  • Assessment of light weight concrete, gypsum boards and fresh concrete
  • Assessment of the mortar quality of joints in brickwork
Product Variations

Schmidt OS-120PT: Equipped with a larger plunger surface, it is especially designed to test on softer material such as light weight concrete, gypsum boards and on fresh concrete. It is often used to determine the right time to remove formwork.

Schmidt OS-120PM: Designed to test and to classify the mortar of joints in brickwork. It has a specially developed plunger whose shape ensures the impacts are applied to the surface of the mortar joint. Based on the rebound values the mortar quality can be classified.


The rebound number is determined on the basis of the following standards: EN12504-2 (Europe), ASTM C 805 (North America), JGJ/T 23-2011 (China). Applies to Schmidt OS-120PT only.
For the creation of user defined conversion curves, we recommend the procedures described in EN 13791 (Europe), ASTM C805, ACI 228.1R (North America), JGJ T23-2011 (China). Applies to Schmidt OS-120PT only.

Austrian Guideline for tunnel lining, published December 2012. Austrian Construction Association. (To determine the time for formwork removal during tunnel construction). Applies to Schmidt OS-120PT.
TNO Report BI -88-009/61.8.2060-VOE from IBBC Delft Netherlands (Mortar joint testing). Applies to Schmidt OS-120PM.

Technical Data
Schmidt OS-120PTSchmidt OS-120PM
Measuring range1 N/mm2 (145 psi) - 5 N/mm2 (725 psi)Classification of brickwall mortar from Poor - Excellent
Impact energy0.833 Nm (0.614 ft lbf)
Hammer mass720 g (1.59 lb)665 g (1.47 lb)
Hammer head diameter40 mm (1.57“)8.0 mm (0.315“)
Weight3.45 kg (7.60 lb)
Dimensions of housing230 x 60 x 200 mm (9.06“ x 2.36“ x 7.87“)
Operating temperature-10 - 50°C (14 to 122°F)
Storage temperature-10 - 70°C (14 to 158°F)


  • The standard warranty covers the mechanical portion of the instrument for 6 months
  • Optional extended warranty periods up to 3 additional years