What symbol denotes high plasticity silt?

High plasticity silt is designated by the symbol MH in the Unified Soil Classification System (USCS). This system categorizes soil types based on their physical properties and behavior. The "M" in MH signifies that the soil is a silt, while the "H" denotes that it possesses high plasticity, which indicates that it can undergo significant deformation without cracking or breaking.

High plasticity means that the soil can hold more moisture and has a greater ability to change shape under stress than soils with lower plasticity. This characteristic is important in construction and geotechnical engineering, as high plasticity silts can impact the stability and drainage of structures built on or within them.

In contrast, other symbols represent different soil classifications. For instance, CL denotes low plasticity clay, CH indicates high plasticity clay, and ML refers to low plasticity silt. Each classification is vital for engineers and soil scientists to determine the appropriate handling, testing, and construction methods for soil in various projects.