Schmidt Rebound Hammer

Instrument Details

Make

Proceq SA, Switzerland

Model

Silver Schmidt

Specification

Impact energy Type N	2.207 Nm (1.63 ft lbf)
Concrete compressive strength range Types N/L	10 – 100 MPa (1450 – 14500 psi)
Dimensions of housing	55 x 55 x 255mm (2.16” x 2.16” x 9.84”)
Weight	570 g (1.3 lb)
Max. impacts per series	99
Memory capacity	ca. 400 series of 10 impacts
(PC version only)	ca. 200 series of 20 impacts
Useful memory capacity ST version	Last 20 series may be reviewed in the data list
Display	17 x 71 pixel, graphic
Battery life	>5000 impacts between charges
Charger connection	USB type B (5V, 100 mA)
Operating temperature	0 to 50°C (32 to 122°F)
Storage temperature	-10 to 70°C (14 to 158°F)
IP classification	IP54

Working Principles

Schmidt Rebound Hammer

A Schmidt hammer, also known as a Swiss hammer or a rebound hammer, is a device to measure the elastic properties or strength of concrete or rock, mainly surface hardness and penetration resistance. It was invented by Ernst Schmidt, a Swiss engineer. The hammer measures the rebound of a spring-loaded mass impacting against the surface of the sample. The test hammer will hit the concrete at a defined energy. Its rebound is dependent on the hardness of the concrete and is measured by the test equipment. By reference to the conversion chart, the rebound value can be used to determine the compressive strength. When conducting the test the hammer should be held at right angles to the surface which in turn should be flat and smooth. The rebound reading will be affected by the orientation of the hammer, when used in a vertical position (on the underside of a suspended slab for example) gravity will increase the rebound distance of the mass and vice versa for a test conducted on a floor slab. The Schmidt hammer is an arbitrary scale ranging from 10 to 100. Schmidt hammers are available from their original manufacturers in several different energy ranges. These include: (i) Type L-0.735 Nm impact energy, (ii) Type N-2.207 Nm impact energy; and (iii) Type M-29.43 Nm impact energy.

Applications

The Schmidt concrete test hammers can be applied on all concrete structures such as bridges, buildings, retaining walls, barrages and many more. But they are also the perfect instruments to test in tunnels (e.g. the formwork stripping strength which is the concrete compressive strength fc to be achieved before removal of the formwork).

User Instructions

TILT – Tilting the device means that you raise the left side (plunger side) of the device to scroll to the icons to the left of the “centered” icon or you raise the right side of the device (SELECTOR button side) to scroll to the icons to the right of the “centered” icon.
ROLL – Rolling the device means that the device remains in the horizontal position, but the display is rolled away from you or towards you. ○ SELECT - Press the SELECT button. ○
TIP – Depress the plunger a short distance, but not enough to trigger it. ○
IMPACT – Depress the plunger until it triggers.

Contact Details

CSIR-Central Road Research Institute,
Delhi-Mathura Road, New Delhi-110025
Phone: 011-26832173, 26832325
Website: http://www.crridom.gov.in
Email: director [dot] crri [at] nic [dot] in