First compaction:The larger
pores collapse, and the soil is compacted.
Relaxation:After the
wheel has passed, the elastic component of the soil (roots, pores with
compressed gas etc.) will push it back towards its original volume. But the
former level is seldom reached.
Subsequent
compaction (following passes):When the load is the same as with the former
traffic, the compaction and relaxation are as high as before.