What term is used to describe soil composed primarily of small particles passing through the No. 200 sieve?

The correct term to describe soil composed primarily of small particles that pass through the No. 200 sieve is fine-grained soil. This classification is critical in geotechnical engineering and soil mechanics, as the particle size influences the soil's behavior, including its compaction, permeability, and strength characteristics.

Fine-grained soils, which include silts and clays, have a particle size smaller than 0.075 millimeters. The No. 200 sieve is typically used to establish the boundary between fine and coarse materials. Understanding these differences is essential for determining suitability for construction projects, drainage capabilities, and potential for erosion and settling.

In this context, although silty soil may also be considered fine-grained, the term "fine-grained soil" encompasses all soil types with small particles, including silts and clays, making it the broader and more accurate term in this scenario. Therefore, recognizing the distinction in classification can aid in effectively analyzing soil for various engineering applications.