Compaction

The maximum height of fill beneath floor slabs and slab-on-the ground foundations measured at the lowest point should not exceed 400mm unless certified by the engineer.

Fill should be moistened prior to compaction so that a handful squeezed in the hand is firm but does not show signs of moisture. Fill should be placed in uncompacted layers not exceeding 100mm in respect of hand compaction or 150mm in respect of mechanical compaction.

Each uncompacted layer should be well compacted before additional fill material is added.

Compaction should be such that in excess of 3 blows of a dynamic cone penetometer are required to penetrate 100mm of the fill, provided that fills do not comprise more than 10% gravel size less than 10mm and contain no isolated boulders.