A depth gauge with a pointed tip is set on the texture, and the height of the peaks above the sheet core is read at many points to give an average and a minimum. It is the quick factory and field check that texture is present and even. Low asperity on a roll can mean lower interface friction on the slope, so it is part of conformance testing for textured sheet.
Asperity height is 12 mils on half that roll, under spec, so keep it off the slopes and use it on the floor.
Also heard as
- texture height
- asperity
Related terms
Textured geomembrane
Geomembrane with a roughened surface that raises friction against soil and other geosynthetics on slopes.
Interface friction
Shear resistance between a geosynthetic and soil, or between two geosynthetics, that keeps lined slopes from sliding.
Conformance testing
Testing samples from rolls delivered to a site to confirm the material matches the specification.