The Vibrating Wire Embedment Jointmeter is ideal for monitoring movement of joints in mass-concrete structures. Typical applications include:

• Abutments, slabs, foundations and retaining walls
• Tunnels or shaft linings, arch, gravity and buttress dams

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 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 When the concrete has hydrated the formwork is withdrawn leaving the exposed end of the installed socket ready to accept the main body of the jointmeter.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.