Peeling back the layers.
There is far more to a synthetic field than meets the eye. Synthetic fields are divided into different layers. The substructure consists of the drainage, the base, a sport-technical layer and a geotextile membrane. The layers that do meet the eye are the turf carpet and infill. We'll give you a brief description of each component below; you can follow us through the layers with the diagram on the right.
Down the drain.
Most sports fields have a drainage system. These consist of underground pipes that drain off surplus water as soon as the groundwater level rises, preventing the surface from flooding.
Base of operations.
A stable and suitable base is extremely important for the overall quality of the field and its life expectancy. The sub-base and earthwork may vary between continents, countries and even regions. In most cases, it is a porous, drained sub-structure of crushed stone or asphalt (except in hot climates). But whatever it's construction, a well-planned base has sufficient load-bearing capacity to support the playing surface and maintenance machinery without deformation and will not have to be rebuilt each time the turf itself is replaced.
A layer called sport-technical
This layer, between the base and the turf carpet, determines the stability of the field to a large extent affecting the ball behavior and player movements. A good sport-technical layer prevents bumps in the field helping to prevent injuries. In some countries, it is a mixture of sand, lava rocks and/or rubber. Fields with a "hardbase" (base materials other than sand) are usually installed with an e-layer - elastic rubber 10-20 mm thick that serves the same function as a sport technical layer.
Geotextile: the stabilizer.
Short for "geosynthetic textile," materials used in places that need to be stabilized such as artificial dykes. The geotextile lies between the base and the sport-technical layer to protect the backing of the carpet while evenly spreading the load so that underlying layers do not deform during later installations and sports activities.
Turf carpet. Finally, something you can see.
This is the most conspicuous part of a synthetic field. Together with the infill, the carpet greatly determines the playing properties of the field such as ball roll and footing. Synthetic turf carpet is made of a backing and synthetic turf blades. The blades are punched (or tufted) through the backing by a tufting machine usually producing blades that are 50-70 mm long. The finished carpet is supplied in rolls, which are rolled out over the geotextile layer during installation. The rolls are then joined with glue, sewn or both, and spread with infill.
A combination of sand and rubber granules is used as infill for most synthetic soccer fields. As a rule, 15 to 25 mm of sand is spread first and then toped with 10 to 20 mm of rubber granules. The purposes of the infill are to weigh down the carpet to keep it in position and provide a surface for cleats to sink into. This helps prevent damage to the carpet and joint injuries to the players. The combination of turf carpet and infill is largely responsible for how comfortable the field is to play on. It affects grip, ball behavior and several other properties including shock absorbency and energy restitution.