The SME Model crack meter can measure the change in width of a surface crack with a resolution of 0.5 mm. It consists of a graduated scale with a resolution of 0.5 mm and a transparent acrylic plate with a hairline cursor mark. The graduated scale and the transparent acrylic plate are assembled across the crack with expandable anchors in 5 mm diameter holes drilled to a depth of 30 mm as shown in the figure.
As the crack opens or closes, the graduated scale and the cursor move relative to each other representing the amount of movement occurring. The reading of the marking is initially noted and is taken as a base.
