What type of soil classification is represented by well-graded, clean gravels or gravel-sand mixes?

The classification represented by well-graded, clean gravels or gravel-sand mixes is indeed referred to as GW, which stands for Well-Graded Gravel. This classification is utilized in the Unified Soil Classification System (USCS) and signifies that the soil has a wide range of particle sizes, allowing for good compaction and drainage characteristics.

Well-graded gravels contain a variety of grain sizes, leading to less void space and a more stable structure, which is desirable in construction and engineering applications. This enables the soil to effectively support loads and manage water flow, making it suitable for various civil engineering projects.

In contrast, other classifications such as GP (Poorly Graded Gravel), GM (Silty Gravel), or GC (Clayey Gravel) indicate variations in gradation or the presence of fines, which alter the soil's behavior and properties under load and environmental conditions. Thus, the specific term GW accurately captures the essence of well-graded, clean gravels or gravel-sand mixes.