Estimating Practice Exam

What happens to the density of the soil after it is excavated?

1. The soil becomes denser than before

2. The soil remains unchanged in density

3. The soil becomes less dense than before

4. The soil becomes more compact

The correct answer is: The soil becomes less dense than before

When soil is excavated, the density typically decreases due to the change in structure and arrangement of the soil particles. Excavated soil is often disturbed, which means that air can fill the spaces between the particles more easily, resulting in a looser structure compared to its original state when it was undisturbed in the ground. As a consequence, the void spaces that were previously filled with other particles or water become more pronounced, leading to a reduction in overall density. A significant factor impacting soil density is compaction, which generally occurs when soil is subjected to mechanical pressure after excavation, but in its raw excavated state, the soil tends to have lower density than before it was disturbed. Thus, after excavation, the tendency is for the soil to become less dense due to this disturbance and reorganization of the particle arrangement.