Embedment Jointmeter

The vibrating wire displacement transducer used for jointmeters consists of a vibrating wire sensing element anchored at one end and connected to a spring loaded push rod at the other end. As the push rod is moved out from the transducer body the spring is elongated causing an increase in the vibrating wire tension. This tension is directly proportional to the spring extension and therefore the joint opening or closing. The VW Jointmeters can also be connected to a CR10X datalogger.

The jointmeter is installed in two parts, a socket and the main body. During the first lift of concrete the socket is fixed to the framework with an installation plug and bolt. When the concrete has hydrated the formwork is withdrawn leaving the exposed end of the installed socket ready to accept the main body of the jointmeter. Before the second lift of concrete is cast the jointmeter is screwed into the installed socket, extended sufficiently to allow for expected joint movement and then tied securely onto rebar supports.

When both lifts of concrete are complete the jointmeter now firmly anchored into each lift will measure opening or closure of the joint. The sensing transducer is smaller than the protective body of the Jointmeter, therefore a degree of shearing motion is accommodated by universal joint connections within the unit.

Triaxial Jointmeter

The vibrating wire triaxial jointmeter consists of two elements each having a hot zinc coated arm attached to a reinforcing bar anchor stem. One arm incorporates three orthogonal (X,Y and Z) vibrating wire displacement transducers located in stainless steel bushes and spring loaded on stainless steel anvils mounted on the other arm.

The vibrating wire displacement transducer consists of a vibrating wire sensing element anchored at one end and connected to a spring loaded push rod at the other end. As the push rod is moved out from the transducer body the spring is elongated causing an increase in the vibrating wire tension. This tension is directly proportional to the spring extension and therefore the joint or crack opening or closing.

Accurate, robust and very good long term stability.
Accuracy unaffected by cable length.
Suitable for remote reading and data-logging.
Over-voltage surge arrestor fitted to protect against electrical damage.
Connecting cable is strong, screened and flexible and can be used in lengths in excess of 1000m.
Waterproof and sealed to 7 bar pressure (High pressure version available to 25 bar pressure for Triaxial Jointmeter).

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