What is the second basic type of compaction force?

The second basic type of compaction force is vibratory action. This method utilizes mechanical devices that generate vibrations to help compact soil, asphalt, or other materials. The vibrations create dynamic forces within the particles of the material, allowing them to rearrange and settle more closely together, thereby increasing density. Vibratory compactors are particularly effective for granular soils and are often used in construction and road building where high compaction is desired.

Direct pressure, while a form of compaction, is generally considered the first basic method. Water flooding and stone overlay are not standard types of compaction forces; instead, they might refer to techniques for soil stabilization or improving material properties rather than actual compaction methods.