A granular soil deposit is classified as medium dense if it has a standard penetration test blow count of:

The classification of granular soil density based on the standard penetration test (SPT) is vital in geotechnical engineering, as it provides information regarding the soil's behavior under load. A medium dense granular soil deposit is characterized by a blow count usually ranging from 10 to 30 on the SPT. This range indicates that the soil has enough density to bear certain loads without excessive settlement, while still being workable for construction purposes.

Soils within this blow count range exhibit moderate resistance, indicating neither very loose conditions, which would fall below a blow count of 10, nor dense conditions, which would exceed a blow count of 30. Understanding these classifications helps engineers assess the suitability of the soil for various constructions, such as foundations or retaining structures, and determine appropriate design and construction techniques.