What is critical for achieving proper soil compaction?

Achieving proper soil compaction is fundamentally linked to the amount of moisture present in the soil. When soil is compacted, moisture plays a crucial role in how well the soil particles bond together. The right level of moisture helps to lubricate the soil particles, allowing them to shift closer together under compression, which leads to denser packing.

If the soil is too dry, the particles may not stick together effectively, leading to insufficient compaction. Conversely, if the soil is overly wet, it can become saturated, which prevents proper bonding and can even lead to soil instability. Therefore, controlling the moisture level and ensuring it falls within an optimal range is essential for achieving the desired compaction density.

This focus on moisture illustrates why some of the other options might not be as critical. For example, compaction during sunny weather might not be beneficial if it leads to rapid evaporation and a change in moisture levels. Heavy machinery can aid in the compaction process but is not effective without the right moisture content. Likewise, while manual techniques can be useful, they typically cannot achieve the same level of compaction as well-managed moisture conditions in larger applications. Thus, the correct balance of moisture is fundamental to successful soil compaction.