What makes it different from conventional rolling
A conventional roller applies static weight or vibration through a round drum. An impact roller has a non-circular drum: as it turns, the drum rises and falls, striking the ground. The impact reaches deeper than a conventional roller, which allows thicker layers to be compacted and near-surface ground to be improved in place.
Where HEIC fits well
- Large, open areas where the roller can travel at operating speed in long runs.
- In-situ densification of loose sands and granular fills near the surface.
- Bulk earthworks, where fill can be placed and compacted in thicker lifts.
- Proof-rolling, to find soft or weak zones before construction.
- Collapsible soils near the surface, sometimes together with moisture conditioning.
Where another method is needed
- The required improvement depth is beyond the near-surface zone. Dynamic Compaction, Rapid Impact Compaction or Vibro Compaction may then be considered.
- The area is small or confined, so the roller cannot reach operating speed.
- Sensitive structures or services are close by.
- The soils are saturated and fine-grained.
HEIC also leaves the top of the layer loosened and uneven, so final trimming and conventional rolling are part of the method.
How suitability is proven
A trial pad on representative ground shows how the surface settles with increasing numbers of passes. When the settlement per pass levels off, further passes add little. Tests before and after (density tests, plate load tests or CPT) confirm what has been achieved and to what depth.
The number of passes, the pattern and the verification tests are then fixed for production. Where the equipment provides GPS coverage mapping, it gives a clear record that every part of the area received the agreed passes.