Which soils are identified as nonplastic?

The classification of soils as nonplastic primarily refers to their ability to change shape or deform without cracking or breaking under mechanical pressure. Sandy soils are characterized by their granular structure, which allows them to drain water quickly and resist compaction. This results in low cohesion and minimal plasticity. The particles in sandy soils are larger and are not able to retain moisture in the same way that finer particles, such as those found in clay, can.

In contrast, clay soils are highly plastic and can be molded into shapes, which is due to their fine particles and high moisture retention. Mixed soils may contain varying proportions of different soil types, which can include plastic materials. Peaty soils are also known for their organic content, leading to some plastic behavior.

Focusing on sandy soils as nonplastic helps clarify their importance in engineering applications, especially in foundation work where drainage and stability are essential. Understanding material properties, such as plasticity, allows engineers to make informed decisions regarding soil treatment and building techniques.