The term 'subgrade' identifies what aspect of site preparation?

The term 'subgrade' specifically refers to the prepared surface elevation of the ground that exists before any surface materials, such as asphalt or concrete, are applied. It serves as the foundational layer for constructing roads, pavements, and other structures, providing the necessary support and stability needed for the weight and traffic expected in those areas.

Understanding the role of subgrade in site preparation is crucial for ensuring proper drainage, load distribution, and overall longevity of the built structure. It directly impacts the quality of the work that follows, as an improperly prepared subgrade can lead to settlement, cracking, and other issues in the finished surfaces. Thus, recognizing that the subgrade is the surface elevation before the addition of any additional materials is key to proper construction practices.