The ‘non-filled’ synthetic turf debate is increasingly becoming cluttered, making it more difficult for both the informed as well as unsuspecting investors and emphatic followers of these developments to separate the wheat from the chaff. Sportsfields.info closely monitors all developments and consolidates all knowledge it has collected over the past year.
The non-filled synthetic turf developments stem from the expectation that the European Commission (EC) will eventually ban the sale of polymeric infills such as SBR, TPE or EPDM. Earlier this week, it became clear that this will likely become reality in July this year.
The development of non-filled synthetic turf is also a response to the demand by the market for synthetic turf football surfaces that require as little maintenance as possible. Irrespective of the natural or polymeric infill used in long-pile synthetic turf, the regular revitalisation of this performance infill seems to place an undesirable burden on the financial budget or staff contingent of most municipalities.
However, this so-called push and pull effect has some side effects. The most important of these is the question of which standard must be met and how this should be tested. In 2021, we published our first article on these developments, which you can find here. This first of at least two articles looks at developments in terms of the system. The developments in terms of research and testing will be discussed in a separate article.
The first non-filled synthetic turf surfaces were developed in Switzerland, where a company in the early 2000s already recognised the possible dangers polymeric infill would pose to the pristine environment of the Swiss Alps. Once microplastic pollution from polymeric infill became a hot topic, neighbouring Austria ruled that non-filled turf would become the norm.
FIFA viewed this as a bit premature, as the football governing body concluded that the products that were being offered at the time did not really match the deliverables of third-generation synthetic turf. It established a Non-filled Advisory Group, where representatives of synthetic turf yarn and carpet producers, test institutes as well as various FAs have been working on a route forward. Vivaturf from China was selected for an innovation program that aims to justify the embracing of non-filled systems and to develop a special test protocol for this type of surface. The non-filled carpet with curled fibre on a highly elastic shock pad that Vivaturf subsequently proposed does not yet appeal to FIFA. You can read the ins and outs about this here, but to cut a long story short: the rotational resistance, friction and wear all deserve improvement.
The problems FIFA has identified with the Vivaturf system are not unique. In fact, all non-filled turf systems that are currently being tested or offered experience the same problem. That is why many installing companies have decided to still add a mineral infill to the carpet. Strictly speaking, this no longer makes it a non-filled synthetic turf system, hence these companies are now referring to their product as being ‘4G,’ ‘sand-dressed synthetic turf for football’ or ‘non-filled with mineral infill.’ Buyers or tender specifiers of synthetic turf should keep this in mind, as an incorrect description of what it is they desire can result in excluding certain products or companies. This article describes the terminology FIFA uses to identify products. As it appears, the football governing body has no intention to widen the definition of non-filled turf. “Non-filled synthetic turf is synthetic turf without any infill,” a FIFA official told Sportsfields.info when asked whether it was considering widening its definition, with the synthetic turf industry experiencing challenges (in creating an approved system that has no infill) in producing such a solution.
Variations in pile weight
At the moment, virtually all suppliers of ‘non-filled systems’ are of the opinion that only a relatively open carpet with mineral infill offers the correct playing performance and comfort to the player. The sand is said to provide stability, grip, resilience and durability. It’s a concept that is already very popular in Germany. Systems currently being offered have a pile height that varies from 30 to 45mm, for which a mixture of different fibres, in various shapes as well as combinations, have been used. In case you desire the details or numbers, you’ll have a job browsing through the various Dtex, Lisport-XL cycles and ‘number of stitches.’ My apologies for spoiling your fun, but 13,200/6 Dtex and 8,000/4 Dtex seem to be ‘the norm.’ Having said that, the usual mantra is that all that “should count is the performance they offer and the number of years that the providers dare to guarantee this performance.” The reality is that all systems don’t comply with any (temporary) quality standard and that the claimed 10-year guarantee has yet to be experienced in real time.
Difference in construction
A relatively open carpet holds up to 40% less synthetic turf fibres compared to a non-filled carpet that fully complies with the definition. Carpets with mineral infill contain 1.5 to 2.5 kg/m2 of synthetic turf fibres, while the backing (with coating) weighs another 1.5 to 2.5 kg/m2. Up to 10 to 15 kg of sand is added per square metre. There is even a carpet being offered that has 3 or 4.5 kg/m2 synthetic turf yarn and that is finished with 13 or 24 kg/m2 sand respectively.
There are certainly carpets that adhere to the strict non-filled definition. These carpets have between 2.5 and 4.2 kg yarn/m2 and use 3.5 to 4.5 kg sand/m2. In the absence of weight to hold the carpet in place, they have to be clamped on the edges of the field to prevent them from shifting, bulging under the influence of the sun or from folding as a result of sliding.
Irrespective of the carpet composition, the various systems currently being tested have all been installed on top of an at least 20mm thick shockpad with high elasticity.
Reduced need for maintenance
All suppliers of ‘non-filled systems’ point out that irrigating the surface is desired. Please don’t forget to include that in your budget! In addition, the following is being said about maintenance: fields with mineral infill require periodic maintenance to keep the sand loose and airy and to spread it evenly. Any contamination such as leaves, glass, cigarette butts or other waste must also be removed from the surface. This is to prevent the formation of algae or moss which can compact the carpet or impede its drainage capacity. This means monthly attention. In addition, the field requires a thorough inspection every three years. Where necessary, the mineral infill must be supplemented.
The use of a drag mat is strongly discouraged. Given the absence of performance infill, this is actually superfluous. Furthermore, this could result in unnecessary fibre wear, which will turn the non-filled surface from “a solution to the microplastic pollution problem” (due to the absence of the polymeric infill) into “a contributor to the problem.” The European Commission has microplastic pollution from fibre wear in its sights anyway. In anticipation of that, one of the international test institutes subjected several synthetic turf systems to 6,000 cycles on the Lisport XL last year. That is comparable to a year and a half of real-time use. The test was performed on a variety of systems, including carpets finished with performance and mineral infill, carpets with only mineral infill and carpets without any infill. One of their conclusions was that “modern fibres show considerably less wear than old fibres.” For the sample with the worst result, a loss of 2.3% was reported. Of this, 1% was fibre and 1.3% so-called fluff. The system design was, unfortunately, not reported.
What does a non-filled field cost?
The big question is of course: “What does a non-filled synthetic turf surface cost?” During the past 12 months, our Dutch sister publication Sportvelden.info attended several conferences, seminars and introductions in the Netherlands. Despite being a small country, the Netherlands appears to have become the battleground for all major turf producers. One of the big installing companies, which is currently promoting a non-filled system in accordance with the definition, claims that such a solution will cost EUR 36.50/m2 compared to EUR 27/m2 for a carpet with a combination of mineral and cork infill or EUR 26/m2 for a carpet with only mineral infill. This seems to be in line with claims made by their competitors, who are all stating that a ‘non-filled’ surface with mineral infill is between EUR 40 and 100,000 cheaper. Prices mentioned only include the carpet, and, where applicable, infill. The shockpad that appears to be preferred by most installing companies vying for a slice of the cake is charged at EUR 6 and 7 per square metre. In case you go for a completely non-filled carpet, you’ll have to add costs for the clamping solution too.
However, the maintenance costs for both solutions differ enormously. For example, the maintenance of an absolutely non-filled mat would cost only EUR 0.25/m2, while the maintenance of a mineral-filled surface is quoted at EUR 1.15/m2. For comparison: the maintenance costs for a carpet with mineral and cork infill are estimated to be EUR 1.60/m2. Based on this data, the TCO for a carpet with cork infill would be EUR 22.29/m2, for a mineral-filled carpet this would be at EUR 19.17/m2, and in the case of a non-filled carpet, the TCO is set at EUR 18.66/m2 in the Netherlands.
Depending on the way you look at things, you can either claim that the developments of non-filled systems are disappointing or very exciting at the moment: ‘disappointing’ because no company has managed to produce a solution that meets all expectations, ‘exciting’ because there are so many (different) things happening. It has been a long time since the industry has been this dynamic. More importantly, it has been a long time since companies have had such radically different views and opinions. The good thing is that there is ample opportunity to continue reporting on non-filled systems.