Introduction
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Introduction
The Resonant Frequency Tester may be used in the laboratory for
research purposes or in the field to assess quality control and
concrete stiffness evolution or the damage induced by freezing and
thawing of concrete. It is a non-destructive method to determine
the longitudinal, torsional, and flexural or transverse resonant
frequencies of a variety of materials. The specification complies
with ASTM C-215, ASTM C- 666, BS 1991, and JISA 1127
standard for testing concrete specimens by the resonant frequency
method. It also meets standards to measure modulus of Elasticity
of rocks and other materials.
The instrument consists of the Resonant Frequency Tester, a test
bench for longitudinal, flexural and torsional resonance
measurements to take
specimens up to 28” x 6” x 6”, a miniature
accelerometer is used as a receiver and a set of 6 hardened steel
balls are used to generate the vibrations on the sample by a
mechanical impact. In order to obtain the resonance frequency of
the sample, the received signal is analyzed in the time domain and
the frequency spectrum is displayed on the instrument’s screen.
The Emodumeter system comes with 6 different (steel) ball sizes:
6mm, 8mm, 10mm, 12mm, 14mm and 16mm. The maximum
frequency that can be generated by each size can be found in the
chart below.
Steel ball diameter = Maximum Resonant Frequency possible
6mm = 48.5 kHz max freq.
8mm = 36.4 kHz max freq.
10mm = 29.1 kHz max freq.
12mm = 24.3 kHz max freq.
14mm = 20.8 kHz max freq.
16mm = 18.2 kHz max freq.
(
Note
: All impactors sold and manufactured at James Instruments,
Inc. are made of steel.)
