Which classification corresponds to well-graded, silty sands?

The classification that corresponds to well-graded, silty sands is "SM," which stands for silty sand according to the Unified Soil Classification System (USCS). This classification indicates that the soil has a significant quantity of fine material (silt) present alongside sand particles, and it is well-graded, meaning there is a range of particle sizes within the sand, providing good density and stability properties.

In the context of soil classification, well-graded materials exhibit enhanced engineering characteristics, such as better compaction and increased shear strength. This aspect makes the "SM" classification particularly relevant in various civil engineering applications, such as foundation design and earthwork projects.

Other classifications, such as "GW" (well-graded gravel) and "GP" (poorly graded gravel), refer to gravel-sized particles rather than sand or silt. "SC" refers to clayey sand, which implies a predominance of clay-sized particles and does not associate with the silty characteristics indicative of the "SM" classification. Therefore, "SM" is the appropriate choice for well-graded, silty sands.