Transverse Screed Marks

Description

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.

Figure 1: Screed mark likely caused by the beginning of a day.

Figure 2: Screed mark and subsequent rough surface texture at a day.

Problem

Generally, transverse screed marks will not affect a pavement’s structure but they will affect roughness.

Possible Causes

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

Solutions differ depending upon the cause:

  • Paver related. Repair and set up the screed correctly and ensure proper haul truck-paver interaction.
  • Mix related. Eliminate the causes for tender mixes. Eliminate the need to stop the paver by using windrow paving and/or a MTV.