Transverse indentations in the mat surface across the width of the mat. These indentations occur when the paver stops between truckloads of HMA and the screed rests on the hot mat.
Generally, transverse screed marks will not affect a pavement’s structure but they will affect roughness.
Causes can be related to either the paver or the HMA mixture:
- Paver related. If the screed is set up incorrectly and rides more on its back end, this back end can cause a transverse mark when the paver is stopped because the weight of the screed is being supported by a smaller area than if the screed were set up properly. Haul trucks bumping the paver can also cause transverse screed marks.
- Mix related. If a HMA mix is particularly tender, a heavy screed (e.g., one with hydraulic or rigid extensions) may leave a mark when left stationary on the mat.
Solutions differ depending upon the cause: