What type of rock particles are low in plasticity and commonly used for building foundations?

Gravel is composed of coarse rock particles that provide excellent drainage and stability, making it a preferred material for building foundations. Its low plasticity is important because it minimizes the risk of deformation when subjected to loads or moisture changes, ensuring that the foundation remains stable over time. The angularity and size of gravel particles contribute to a high degree of interlocking, which enhances the load-bearing capacity of the foundation. In contrast, materials like clay and silt exhibit higher plasticity, which can lead to expansion and contraction with moisture changes, while sand, though more stable than these options, does not provide the same level of support and drainage as gravel does when used in foundational applications.