Crack meters are made of two plastic plates partially overlapped that have to be fasten on the two sides of a fracture. The upper-plate is equipped with a Cartesian grid, and the lower-plate is graduated in millimeters – both horizontally and vertically.
The displacement is measured by comparing the position of the two plates.
Various models are available:
• standard gauges for coplanar-surface movement
• gauges TT4 or TT3 for measuring floor settlements or consolidation
• TT2 for biaxial shifts near structure corners