ADA INSTRUMENTS Schmidt Hammer 225, Operating Manual

Page: 28 / 36

MEASUREMENT FOUNDATION
Schmidt Hammer 225
3. Rebound operation
Follow the operation abovp-mentioned and to continue pushing and press the Test Hammer until the rebound hammer
and hook was disengaged and under the stretched actoin of strike tension spring, strike hammer along the center guide
rod impact quickly, kinetic energy will decomposition of hammer and rod in the moment of collision : a part of the energy
to produce plastic deformation of concrete have been absorbed, the other part so that produces elastic deformation of
concrete transfer to sreike hammer to rebound.
Operation reading the rebound values
“ When the strike hammer and rod collision for the irst time rebound, will pointer slide into a certain position (through the
spring plate), then should continue to hold down the Test Hammer, and reading rebound values Ri from the slider scale
mark corresponding to the pointer ruler scale line ; if the inconvenience to reading, can press the button and lock the
machine, the movement to retain the slider pointer position, and then get the Test hammer to the place ease of reading
rebound values. The above is a rebound test operation process, which get the rebound value Ri of a measuring point,
Repeat the above operation will get the rebound value of measured points which needed.
Inspecting methods
Using Test Hammer inspect the compressive strength for structure or component of concrete which is base on measur-
ing area as basic unit to carry out. This is that the structure or components divided into several measuring area, each
test area distribution of 16 measuring points, one measured area inished then test another, in the structure or structures
to orderly rebound inspect. Speciic test method, see the appendix to this manual the industry standard “JGJ/T23-2001
<Technical Speciication for Inspecting concrete compressive strength by Rebound Method> The new revision standard
of rebound method has a greater change, Wish our customers seriously and carefully read the standard, it is a guide to
the work of non-destructive testing.
The new revision standard of rebound method,changes are as belows:
1. Measurement strength curve range iiJ£-60MPa?)
2. Increased the calculation method for intensity conversion value of pumping concrete.
2