What do the shims used in straightedge calibration typically consist of?

Shims used in straightedge calibration are designed to ensure that the straightedge aligns perfectly with the surface being measured. The reason various thicknesses of shims are utilized is to allow for precise and customizable adjustments during the calibration process. Different surfaces or conditions might require specific adjustments in height, which can be efficiently addressed by using shims of various thicknesses. This flexibility is essential as it enables the calibration to account for minor imperfections and variances in the surface profile without relying on a single thickness, which may not adequately accommodate different situations. Using only one standard thickness would limit the calibration's accuracy and effectiveness, making it less adaptable to the diverse conditions encountered in asphalt paving.