Soil compaction is important before construction on the surface is done for pathways, driveways, parking lots, tarmac roads and many other projects. Compaction of the surface before construction is done ensures that a solid stable ground is achieved for the project. If not achieved, there is a lot of compression and shifting that happens destroying the construction made. Compaction reduces the voids in the soil and increases its density so it can provide a solid ground for whatever will be constructed on it.
Take for instance a road that has been tarmacked without proper compaction of the sub-base being done. As vehicles continue using the road, the weight they exert on the road causes displacement and compression. Eventually the road starts to form depressions and ruts and then soon after the tarmac starts to shift comes off the surface. This happens because the soil was not compacted well enough before the tarmac was laid down.
The equipment used in soil compaction before such projects are rollers and plate compactors. Rollers use a circular wheel called a drum to crush and compact the soil. As the roller moves, the drum is rotated on the surface at a chosen speed to cause compaction. Rollers can either be; smooth or padfoot rollers or single or double rollers. Single rollers have one drum while double rollers have two. Smooth rollers have a smooth drum while the padfoot rollers have a drum with tapered pads that penetrate deep into the soil for compaction. There are big rollers used for huge construction projects and also small pedestrian rollers that can be used for smaller projects and in areas where the large rollers are unable to reach.
For a single drum compactor, the engine of the machine drives the back tires and also provides power to move the drum since it is quite heavy. For the double drum rollers, they do not have any tires but two drums with the drivers cab between them. The engine is used to power the front drum that crushes and compacts soil first while the other one uses the momentum created and gives the ground a second pass for more compaction.
The other type of machinery used for compaction are plate compactors. Plate compactors are usually small and driven by hand. The come in different sizes too and with differing capabilities. Plate compactors use oscillatory and vibrating movements to compact the ground. They have a heavy plate at the bottom that comes into contact with the soil during operation to compact it.
When the engine is running, it provides vibratory power that rocks the plate forward and backward while still allowing to oscillate to cause compaction. As the plate moves it forces the particles of the surface to get manipulated into position.
The kind of performance to expect from a plate compactor or drum roller is dependent on the engine capability. The more compaction power you need the stronger the engine should be.