Silty gravels and poorly graded mixes of gravel are known as what type?

The classification of silty gravels and poorly graded mixes of gravel falls under the "GM" category in the Unified Soil Classification System (USCS). This designation represents "Gravel-Silty" soils, which are characterized by a high gravel content along with significant silt content.

The presence of silt is crucial in identifying this group, as it influences the engineering properties of the material, such as its drainage capacity, compaction behavior, and overall stability. Silty gravels typically exhibit both cohesive and non-cohesive properties, making them behave differently under various loading conditions compared to clean gravels or heavily clayey materials.

Understanding the classification of soils like GM is essential for geotechnical engineering, as it aids in predicting how these materials will perform in construction and environmental applications. This classification also assists engineers in developing appropriate design standards and construction methods tailored to the specific characteristics of the soil.