What does Compression Mean?

Definition of Compression in Construction
Compression is a term that describes a force within a structural system that squeezes down , across or even up, on another structural member or immobile component . Concrete is an excellent structural member under a compressive force due to its physical characteristics, however concrete will yield under a tensile force, which is the opposite of a compressive force. To push together is compression, to pull apart is tension. This is why reinforcement steel is installed within a concrete component to provide stability and strength under tensile stresses as the concrete resists the compressive forces.

Compression is also used in construction to stabilize various substrates such as gravel, to provide a strong and compacted base material. To compress a material is also referred to as compaction and compaction testing is a common element of properly preparing earth and gravel to support flatwork, such as concrete, asphalt or other hard surfaces. A testing lab is used to determine the degree of compaction of a material which is measured in percentages. Normally the building code requires material under slabs, asphalt or other hard surfaces to have a minimum of a 95% compaction rating.

There are various types of construction equipment used to compact the soil, gravel or other material. Vibratory rollers, tampers, hammers, etc. are all pieces of equipment used to reach acceptable compaction ratings. To compact a material basically means to remove as many of the air voids as possible and improve the packing factor of the material.