The rolling zone for the static steel-wheel finish roller is the position where marks from other rollers can be removed from the surface of the layer without adding new marks by the finish roller itself. Finish rolling normally takes place within a temperature range of 185 F down to 160 F. Finish rolling for a stable mix is accomplished at higher temperatures than finish rolling for a tender mix.
Rollers operate whenever the paver operates. Interestingly enough, when the paver stops, often the breakdown and intermediate rollers also stop. When the paver restarts, the rollers follow suit. While the paver and rollers are stopped, the mix that has not been completely compacted is cooling. Depending on the length of the shutdown, it may be difficult to obtain the desired level of density if the mix has cooled too much. It is very important that rollers continue their pattern, regardless of what the paver does, until the required number of roller passes are applied to the pavement surface and the compaction process is finished.
For each roller used on the project, the width of the paved lane should be divided by the width of the compaction rolls on each roller to determine the number of passes needed to cover each transverse point of the surface. A tandem static steel-wheel roller, 41¦2 ft wide, for example, would need to make at least four passes across the width of a 12-ft-wide lane. This allows for a minimum overlap of 6 in. over each longitudinal edge of the lane and a minimum 6-in. overlap between each roller pass.
However, a 7-ft.-wide double-drum vibratory roller could cover the full 12-ft-wide lane in only two passes across the width, still allowing for a minimum overlap of 6 in. over each longitudinal edge and between each roller pass. Thus, in terms of a roller pattern, the 7-ft-wide roller is twice as efficient as the 41¦2-ft-wide roller. A roller that is 51¦2-ft-wide would need to make three passes up and down the 12-ft-wide lane to obtain complete transverse coverage of the surface, allowing for the minimum overlap between passes.
In the longitudinal direction, the rollers should not stop at the same transverse end point with each pass of the roller. The reversal points should be staggered to prevent shoving of the mix. When paving is suspended for a period due to a lack of haul trucks, for example, the roller should not sit on the hot layer. The rollers should be parked either on an adjacent lane, on the shoulder or at the back of the cold, fully compacted layer.
