What happens to the void ratio of soil during the compaction process?

During the compaction process, the void ratio of soil decreases. Compaction involves reducing the volume of voids within the soil by applying mechanical energy, which pushes soil particles closer together. As the soil is compacted, the air and water that occupy the voids between the particles are expelled, resulting in a higher density of the soil mass. This leads to a reduction in the amount of empty space (voids) between the particles, which directly decreases the void ratio.

The void ratio is defined as the ratio of the volume of voids to the volume of solids in a soil sample. Since compaction decreases the volume of voids without changing the volume of solids significantly, the overall void ratio must decrease. This is an essential aspect of soil behavior in engineering, as it influences the strength, stability, and compressibility of the soil, impacting the overall performance of the geotechnical structure being designed or constructed.

In the context of the other choices, an increase in void ratio would suggest that the soil has become less dense or more porous, which contradicts the purpose of compaction. Remaining unchanged would imply that the process has no effect on soil density, which is not the case, as compaction fundamentally alters the soil structure. Fluct