Estimating Practice Exam

When using backfill, how does compaction affect the material?

1. It decreases the volume needed

2. It increases the volume needed

3. It has no effect on volume

4. It requires less material to be effective

The correct answer is: It decreases the volume needed

Compaction during backfill operations is vital since it reduces the air voids within the soil or material being placed. This densification process inherently decreases the total volume of the backfill material needed to achieve the desired fill elevation. When soil is compacted, particles are pressed together more tightly, which leads to a reduction in the overall space that the soil occupies. This is particularly important in construction and civil engineering, as having a lower volume of material can lead to cost savings and more efficient project execution. Therefore, the correct choice reflects how effective compaction minimizes the amount of backfill material required, as densely packed material takes up less space than loose material.