The JM utilizes a vibrating wire sensor attached to a spring tensioned between two anchors. Any variation of distance between these anchors will change the tension in the wire. The sensor is protected by a sliding stainless steel housing.
3 models are available:
The JM-S Crackmeter is attached to the surface of the structure using groutable or bolt-on anchors. Ball joints at each end of the sensor compensate for any anchor misalignment. The JM-S is also available in 3-D configuration for measurement in three orthogonal directions, or with special clamps for installation on a geogrid.
The JM-E Embedment Jointmeter is embedded in concrete structures such that its active length spans the construction joint to be monitored. This model consists of two sections: the socket and the sensor, which are installed and connected during two successive concrete lifts.
The JM-T is used in Borehole Extensometers.
A thermistor is integrated to the JM allowing temperature measurement.
|Range||25, 50, 100, 150, 2001, 2501, 3001 mm|
|Overrange||1.00 × range|
|Accuracy||± 0.25 % F.S. (± 0.1 % in option)|
|Resolution||0.02 % F.S. (min.)|
|Operating temperature||−20 °C to +80 °C|
|Cable||IRC-41A, IRC-41AP, IRC-3902, IRC-21A (JM-T)|
|Length ‘A’ of JM-S (mid-range)||289.5, 357, 500, 651, 797, 933, 1076 mm|
|Length ‘A’ of JM-T (mid-range)||230.5, 298, 442, 593, 738, 875, 1018 mm|
|Length of JM-E (at rest)||383, 432, 602, 772 mm|
|Diametre of JM-E (flanges)||47.6 mm|