Where sports, innovation and public infrastructure come together
Where sports, innovation and public infrastructure come together
The synthetic turf systems with polymeric infills that are commonly used for football, rugby and American Football have really had their day. In the interest of the environment, the sale of polymeric infills will no longer be allowed in Europe from October 2031. This is to prevent microplastic pollution from polymeric infills migrating out of the surface. Synthetic turf systems with organic infills as well as mineral-filled synthetic turf pitches are now becoming the norm.
This year marks the eighth anniversary of the oldest mineral-filled synthetic turf football pitch in the Netherlands. Therefore, it will be subjected to the mandatory inspection according to the standards of the Dutch FA before the upcoming summer break. “That result will tell us for certain whether our decision to focus primarily on mineral-filled synthetic turf rather than non-filled was the right one,” says the Product Manager for Belgium and the Netherlands at Tarkett Sports, Rob Heusinkveld. Not that he has any doubts. “As the complaints about non-filled synthetic turf pitches that had been installed in the Netherlands, and that were filed in 2018, centred on player safety rather than the technical performance of the product, we made a conscious decision at the time to adopt a different approach. Players complained bitterly at the time, that they found non-filled synthetic turf, including our own product, too slippery. Together with the Dutch FA and test institute Kiwa ISA Sport, we started investigating this. Based on various studies, we concluded that a layer of sand is essential for players to maintain sufficient grip at all times. Polyethylene, a type of plastic that is commonly used for synthetic turf yarns, is always slippery when wet, even if there is only a little dew. Other types of fibres don’t offer a resolution. The player still needs something in which he can place the studs to still experience stability. That conclusion defined our development focus of a mineral-filled synthetic turf system.” In addition to supporting the players, the sand also provides substance for maintenance equipment. “Every pitch will at some point become contaminated with organic material that falls onto the pitch or is blown onto it from outside. In order for the maintenance machine to be able to do its job you’ll need some substance at the bottom of the carpet.” Last but not least, the weight of the sand is also required as its total weight keeps the carpet down.
The type of sand particle and total volume required, is a matter of science. “Historically, Germany has already been using mineral-filled synthetic turf systems for a long time. However, these carpets typically have a pile height of up to 40mm. They resemble sand-dressed synthetic turf carpets too much, which are not really popular in the Netherlands. That is why we have opted for a yarn density of around 200,000 filaments per square metre with a pile height of 35 mm. This high number of yarns provides stability for the sand and also partially covers it. These are the carpet characteristics that players demand.” Standard M4a infill sand is not suitable for that purpose. “It tends to compact, as a result of frequent foot traffic. Players perceive this hardness as slipperiness. That is why we investigated a variety of sands before we decided on a specific grade of relatively coarse sand with a grain size up to 1.6 mm. According to our research data, this type of sand provides the mechanical grip that players desire, drains well and is less prone to clogging the pitch.” Despite the informed decision, the decision was frowned upon initially. “It is a fact that coarser sand feels less pleasant underfoot.
We try to minimize that experience by working with a free pile height of approximately 17–18 mm. Just as synthetic turf fibers are allowed a production tolerance of 2 mm, an installation tolerance of 2 mm is also applied when installing the synthetic turf carpet. If the extremes of these two come together – meaning, a section of carpet where the fibres are 2 mm shorter than average while the layer thickness is 2 mm higher than desired – then the sand will be more obvious. A synthetic turf field can therefore be installed in accordance with the declaration yet still be experienced as sandy in the initial phase. This will of course change through use and maintenance, but it remains an important development topic.”
Tarkett Sports installed its first mineral-filled synthetic turf pitch in 2018 at OJC in Rosmalen, the Netherlands. The feedback Tarkett Sports has received since has helped in developing another two mineral-filled synthetic turf systems that have now also been approved for installation in the Netherlands. The innovation is now also used for korfball as well as baseball and softball. A third system will start the mandatory trial stage later this year. “That synthetic turf system contains 25% more fibres, but the fibre length is slightly shorter. It features a new, softer main fibre and less sand, meaning the sand is barely visible, whilst the natural appearance remains uniform.” Heusinkveld positions this new development as “better than what exists already”. “In our view, the 1,600 to 1,700 grams of yarn per square metre in mineral-filled systems with a fibre length of 32–35 mm is the minimum threshold we must adhere to in the Netherlands in terms of pile weight. Less yarn means a more open carpet, which will offer less stability, and in which sand is more visible and noticeable. In my view, this is undesirable.” Minimum specs do exist for synthetic turf for hockey in the Netherlands, yet this is not the case for synthetic turf for football. “If you base your decision purely on numbers rather than on the experiences of players and administrators, you could end up in a real pickle once players start complaining, or if the system proves unable to cope with the high level of usage.” Excessive use of yarns Heusinkveld also finds undesirable. “We are very well aware that this involves polyethylene made from fossil fuels. Yarns are necessary, but it is not our aim to produce as much of it as possible. That would burden the planet with an even greater heap of plastic, which would then have to be recycled.” He sees the future as one that focuses more on the reuse of existing plastic. “We already produce fibres that consist largely of recycled polyethylene, and with our new Origin Technology, we are able to provide a synthetic turf system that is fully circular.
"Yarns are necessary, but it is not our aim to produce as much of it as possible. That would burden the planet with an even greater heap of plastic, which would then have to be recycled.”
Furthermore, some of our production waste is now being used in the manufacture of a shock pad. We use this Trocellen shock pad, just as we use Schmitz Foams’ ProPlay – which is made from residual foam – underneath our mineral-filled pitches.”
In parallel with developments in systems, the synthetic turf sector has also been working on testing methodologies since 2018. “As player safety was at stake at the time, we looked into whether we should increase the number of tests, adapt the tests, or find a different way to assess the sporting and playing quality of non-infill and mineral-infill pitches.” However, by 2026, not much has changed in this regard. “Shock absorption is now determined using a single-drop test, whereby the weight is dropped onto the pitch just once, rather than three times. I regard that adjustment as a step forward, although not much experience has yet been gained with it.” In addition, the testing institutes have developed methods to determine the grip of synthetic turf systems. “There are now several methods available to determine this, but little is yet known about how the various grip testing methods align with the players’ experience on the latest generation of non-infill and mineral-infill synthetic turf pitches.”
In addition to gaining a better understanding of the synthetic turf system itself, more knowledge has been gained about the maintenance of these types of surfaces. “What has become really clear is that it’s all about a tailored approach. Keeping the turf clean and the fibres upright is very important. However, the frequency of carrying out this activity for pitches in built-up areas can be much less than pitches in areas surrounded by vegetation. In such cases, we recommend reducing the frequency during the season and giving the turf a thorough clean at the end of the season. Pitches that are close to treelines require the leaves and organic material to be removed more frequently to keep the surface comfortable and playable. But that actually applies to all synthetic turf surfaces and is not unique to mineral-infilled synthetic turf pitches.” The likelihood of the sand becoming compacted also varies by location and time of year.
The Netherlands now has more than 150 mineral-filled synthetic turf pitches. The oldest is at OJC Rosmalen, and this year has been in place for eight years. “The club is the largest football club in the province and has ten pitches to serve its over 2,300 members. Four of these are synthetic turf pitches, two of which are mineral-filled systems. The players are enthusiastic about the field from either the club or the municipality of ’s-Hertogenbosch, nor from players at the PSV Academy, who also come and train on these surfaces. For us, that is far more important than pushing out all the fancy talk and pretty pictures. The results speak for themselves and have proven their worth in practice for eight years already.”
