What is the typical range of field water contents during compaction?

The typical range of field water contents during compaction is indeed found within a few percentage points below the optimum to a few percentage points above the optimum. This range is critical because achieving proper moisture content during soil compaction is essential for maximizing density and stability.

When soil is compacted, the optimum moisture content is the level at which the soil particles can be arranged most closely together, yielding the highest density. Being a few percentage points below or above this optimum allows for some variability in field conditions, such as weather changes and natural moisture content levels. Staying within this range ensures the soil can still achieve good compaction without resulting in excessive voids or stress, which might occur if the moisture content strays too far from the ideal.

The other options do not align with the established understanding of soil compaction. Specifically, exact optimum to ten percentage points above would likely lead to over-saturation, which adversely affects compaction efficacy. Below standard to optimum would not provide a clear indication of the necessary moisture range. Similarly, dry to saturated encompasses too wide a spectrum, hindering effective compaction if the soil is either too dry (leading to poor particle interaction) or too saturated (resulting in a loss of effective stress). Thus, the chosen answer