Everything about artificial turf structure, layers and testing
A synthetic turf sports field comprises not only the surface that gives it its name, but also several layers - the entire structure is designated a ‘system’. DIN 18035-7 specifies the basic structure and requirements for the individual layers, whereas DIN EN 15330-1 pertains to the synthetic turf system in its entirety. Following the most recent revision of the DIN 18035-7 standard, there are now only two basic methods for the construction of synthetic turf systems, as outlined in Table 1. The first method involves the installation of an infill or non-infill synthetic turf surface on a bound elastic base layer, which in turn is laid on a two-layer elastic base layer. The second method entails the installation of an infill or non-infill synthetic turf surface on an elastic layer, which is then laid on an asphalt base layer, which in turn is installed on a two-layer elastic base layer. Synthetic turf systems with infill material (usually sand and granules, but also just sand) are primarily used for football and rugby pitches. The non-infill version is primarily employed for hockey pitches, but also for multi-use fields. It is possible that existing sports fields may still feature systems that have been constructed in a different manner.
ISP GmbH – Institut für Sportstättenprüfung tests system components such as infill granules for synthetic turf surfaces, synthetic turf surfaces or elastic layers for compliance with the requirements of the relevant standards. These tests are carried out in our accredited testing laboratory. We are also able to conduct on-site inspections and assess the condition of individual components. This is particularly important in the run-up to a planned refurbishment of your sports field if individual components of the synthetic turf system, such as the lower layers, are to remain in place when the surface is replaced. What is the condition of the individual layers? Is proper drainage still ensured? Is the structure and condition of the system in line with the planned modernisation? An inspection of the existing sports field can provide answers to all these questions. However, even if no renovation is planned, the condition of your sports field can be professionally assessed by ISP GmbH – Institut für Sportstättenprüfung.
The layers of a synthetic turf sports field
The basic layers of a synthetic turf sports field are the subsoil and the subgrade. Of particular importance is the potential installation of a drainage system and the drainage capacity thereof. Depending on the nature of the natural soil, backfilling may be a viable option to improve its load-bearing capacity. Prior to the commencement of construction, it is advisable to undertake a thorough inspection of the subsoil. Further requirements for the subsoil and subgrade are specified in DIN 18035-7.
The elastic base layer is installed on top of this layer. Usually, crushed stone or gravel is used. Drainage capacity is also critical for this layer, as the water must be able to drain easily into the underlying layer. For infill systems, the base layer must be two-layered.
In synthetic turf systems, an asphalt layer serves to stabilise the elastic layer above it and must be designed to be water-permeable.
The (unbound) elastic layer consists of elastomer granules (rubber granules) and an elastic binder. This is widely available as a prefabricated product and is always installed on an asphalt layer.
A (bound) elastic layer is applied directly to the base layer without the use of a binder and also consists of elastomer granules and an elastic binder. The incorporation of mineral aggregates enhances the load-bearing capacity.
The synthetic turf surface, the so-called synthetic turf carpet, is then installed on top of the unbound or bound elastic layer. This carpet is usually installed in strips, which are adhered together at the back. The properties of the adhesive must also meet certain requirements. The surface must be laid out meticulously to avoid unevenness or overlapping.
The infill granules
Several variants are available for infill surfaces. In fact, for many years, it was standard practice to use quartz sand and synthetic infill granules. However, the recent legislative developments within the European Union pertaining to microplastics are set to culminate in prohibition of the placing on the market of plastic granules (for instance, those composed of EPDM, SBR, and TPE) within the coming years.
Although the basic use of synthetic infill granules will not be directly prohibited, it will no longer be possible to purchase them, which will result in these infills being discontinued. Consequently, numerous new alternatives have been developed recently, ranging from pure sand infill to many forms of natural-based infill granules (e.g. maize, olive stones, cork).
However, it is imperative that these granules also meet the requirements of the standard. Especially when changing the infill (infill granules) or before new variants are placed on the market, they must be tested for their usability. This is also necessary when new solutions need to be found within a short space of time.
ServicesHave your synthetic turf sports facility checked.
In recent years, there has been a shift in the way synthetic turf systems are composed of towards two basic construction variants with different layers. The requirements for these layers are set out in DIN 18035-7. There have been many new developments in recent years, particularly with regard to infill materials for synthetic turf surfaces.
ISP GmbH – Institut für Sportstättenprüfung will be pleased to test the components of the synthetic turf system on your sports field and provide you with a professional assessment of their condition and compliance with the relevant standards.
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We will be happy to advise you on the procedure and background to testing your synthetic turf sports facility.
Synthetic turf
| Sports | Test criteria |
|---|---|
| Football | Sports function |
| Hockey | Protective function |
| Rugby | Technical properties |
| Tennis | Environmental compatibility |
| American Football |