How many impacts per foot are recommended for vibratory rollers?

The recommended range of 10 to 12 impacts per foot for vibratory rollers is based on the need to effectively compact asphalt materials. This level of impact is designed to ensure adequate density and stability during the paving process, ultimately contributing to the overall quality and longevity of the pavement.

Vibratory rollers exert a combination of weight and vibration on the asphalt, which helps to eliminate air voids and achieve proper compaction. The specified range of impacts strikes a balance between achieving sufficient compaction without causing excessive material displacement or damage to the asphalt layer.

Maintaining this impact frequency ensures that the density requirements outlined by engineering specifications and guidelines are met, leading to better performance characteristics in the finished pavement structure. This is essential not only for load-bearing performance but also for resistance to surface distresses such as rutting and cracking.

In contrast, the other options either fall outside the recommended frequency or do not align with best practices for vibratory roller operation. Low impact frequency might not achieve the necessary density, while excessively high impact rates could lead to harmful compaction effects and potentially compromise the quality of the asphalt surface.