Applications VW embedment  strain gauges are used to measure strain in reinforced concrete and mass  concrete. The standard VW embedment strain gauge has a modulus similar to that  of typical construction concrete and is suitable for most applications. The low  modulus gauge has a modulus approximately 1/6th that of the standard gauge and  is particularly effective in mass concrete for measuring strains as the concrete  cures. Operation The body of the VW embedment strain gauge is a steel tube with flanges at  either end. Inside the body is a steel strip and a magnetic coil. The strip is  held in tension between the flanges, and the coil magnetically plucks the steel  strip, which then vibrates at its natural frequency. Strain in the concrete is  transferred through the flanges to the body and the steel strip, causing a  change in the tension of the strip. When the strip is plucked and set into  vibration in the proximity of the magnetic coil, it induces a frequency signal  that is transmitted to the readout. The readout processes the signal and  displays a reading. Installation VW embedment  strain gauges have preset measurement ranges for better unit to unit  repeatability and trouble free installation. In reinforced or pre-stressed  concrete applications, the embedment strain gauge is usually tied to the  reinforcing cage. In mass concrete applications, the gauge may be installed  either before or immediately after placement of the concrete. Gauges may be  configured in a rosette either by direct placement in the soft concrete or by  attachment to a rosette adapter. Advantages Superior Conformance: The embedment strain  gauge features a unique internal coil that minimizes inclusion effects, since it  does not key into the concrete between the reaction flanges. Also, the signal  cable exits the strain gauge axially and is guided away from the zone of  influence through a stainless steel cable protector. Superior Stability:To minimize zero  drift, the ends of the steel strip are fixed by precision welds. This eliminates  the high local stress levels and the potential for creep induced by mechanical  swages. Built-in Temperature Sensor: RTD or thermistor  temperature sensors are included for temperature corrections. Reliable Signal Transmissions: The VW sensor  provides a strong signal which can be transmitted reliably over long distances  with properly shielded cable. Specifications Description: VW Embedment Strain Gauge for reinforced  or mass concrete. Includes a built-in RTD temperature sensor or a thermistor  temperature sensor. Available in standard or low-modulus versions and 6 or 10  inch gauge length. Range: Two preset ranges are available. Compressive  strain setting accommodates 2600 microstrain of compression and 100 microstrain  of tension. Compressive and tensile strain setting accommodates 1350 microstrain  of compression and 1350 microstrain of tension. Resolution: Better than 0.5 microstrain with DataMate  MP. RTD Temperature Sensor Range: -45 to 100 degrees C  (-49 to 212 degrees F) with DataMate MP. Temperature Coefficient: 11 x 10-6 per degree C.