Compaction is the mechanical pounding of soil and weathered rock into a dense mass with sufficient bearing strength or impermeability to withstand a load. It is primarily used in construction to provide ground suitable for bearing the weight of any given structure. With the advent of huge earth-moving equipment we are now able to literally move mountains. However, such disturbances loosen and expand the soil. Thus soil must be compacted to provide an adequate breathing surface after it has been disturbed. Inadequate compaction during construction results in design failure or reduced service life of a structure. Compaction, however, is detrimental to crop production because it makes root growth and movement difficult, and deprives the soil of access to life-sustaining oxygen.

With proper compaction we can build enduring roadways, airports, dams, building foundation pads, or clay liners for secure landfills. Because enormous volumes of ground material are involved, it...