ABSTRACT
Soil can be defined as unconsolidated earth material composed of discrete particles with gas or liquids between, a relatively loose agglomeration of mineral and organic materials and sediments found above bedrock, or any earth material except embedded shale and rock. The dominant factors for the coarse-grained soils are mass or gravitational forces between particles, and water has very little or no influence; whereas for fine-grained soils, electrical and chemical forces dominate particle interaction, and the amount and nature of pore fluid affect the particle interaction significantly. Classification of the subgrade soil type and approximate judgment regarding the usability of the material can be made according to the American Association of Highway and Transportation Officials (AASHTO) and the American Society of Testing and Materials (ASTM). Subgrade soils that are used for pavements can be primarily of two types—coarse grained and fine grained.
