Why are high clay and silty soils more challenging to compact?

The statement that improper water content can prevent effective compaction is correct because the moisture content plays a crucial role in the compaction of soils, particularly for clay and silty types. These soils have fine particles that behave differently compared to granular materials. When moisture content is too low, the particles do not have enough lubrication to slide past each other effectively, leading to inadequate densification during compaction. Conversely, if the moisture content is too high, it can result in a saturated condition that prevents the soil particles from being compacted tightly together, as excess water creates pore pressure that counteracts the compaction efforts. The right balance of moisture is vital to achieve optimal compaction, making the control of water content a key factor in the effectiveness of compaction for these soil types.

High clay and silty soils can expand when wet and contract when dry, which is important to consider, but this characteristic alone does not directly explain the challenges faced during the compaction process. Similarly, while these soils may be less dense than granular materials, their density is not the primary factor affecting compaction. High weights for compaction can be helpful, but the effectiveness still largely depends on managing the water content appropriately. Thus, the most significant challenge arises from the moisture content