GB1381921A - Apparatus for determination of the density of inplace materials by measurement of their dielectric strength - Google Patents

Abstract

1381921 Detecting material properties electrically SOIL TEST Inc 3 March 1972 10128/72 Heading G1N The dielectric properties of a material are measured, to determine the density of the material, utilizing two electrode assemblies, one consisting of members 20, 21, 22 and 23 which rest against the material to be tested, and the other consisting of members 30, 31 and 32 which are vertically spaced from and offset with respect to the members of the first assembly. The capacitor formed by the electrode assemblies are connected to a resonance circuit 72 which is connected to an oscillator, Fig.4. Any change in capacitance from normal detunes the circuit 72, and the resultant voltage is amplified and applied to a meter and/or recording circuit 96, 84. This circuit is also provided with a reference from a reference resonance circuit 72'. The upper electrode assembly may be vertically adjustable in order to adjust the penetration depth of the electric field, Fig.8 (not shown), and spacers may be provided between members 30-32 and the material under test, Fig.9 (not shown). As shown, Fig.2, the members 20-23 are in the form of runners enabling the assemblies to be pulled along the surface of the test material, e.g. concrete, asphalt. A platform can be arranged above the electrode assemblies, Fig.1 (not shown), which platform mounts the electric circuitry and recorder.