Eric O'Donnell Answers the Top 10 Most Common Questions About Hybrid Turf

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As leading sports surfaces consultants, we get a lot of questions about turf. We've compiled a list of the most common questions and asked Eric O'Donnell, our Managing Director, to share his answers. Here are the top ten questions about turf.

1. How have the materials that hybrid turf now uses advanced over recent years?
Hybrid Turf has changed a great deal in the last 10 years. We have seen the development of many textile based tufted systems now widely available and the introduction to the market of a competitor to the Grassmaster system with SISGrass by SIS with injected systems we have seen the development of technology which speeds up installation and uses PE fibres in the yarn filaments. It is therefore still an evolving technology.

2. What are the challenges when deploying hybrids turf solutions?
The biggest challenges when deploying hybrid pitches is in educating the groundsmen who may have been successful in their maintenance practices pre hybrid but have to adapt and change to maintaining hybrid pitches. There is a myth that hybrid pitches are easier to maintain than traditional natural pitches, while in actual fact they can be more difficult.

Burying fibres in the soil matrix (which is the common problem we observe when a hybrid pitch fails to meet expectations) basically turns the Hybrid pitch into a natural pitch, as the reinforced fibres do not interact with a player, therefore players are more likely to lose traction. Regular renovations involving mid-season lifting of the fibres is an essential part of the maintenance practices of a reinforced pitch.

3. How do manufacturers choose their grass seeds in order to be compatible with the artificial portion?
The grass selection has no bearing on the Hybrid system, the grass selection is based on the environment the Hybrid pitch is installed into. i.e. Warm season grass species for the warmer regions, cool for the colder regions.

4. How do manufacturers decide on what materials to use? Can you outline fibre materials choice and how they are stitched?
The fibre selection is based on many factors; durability is a major one as Hybrid pitches will see many renovations in service and this can cause wear and tear on the fibres. The selection of the filaments is based on rigorous testing so that length, thickness and the quality of the polymers used are all factored into the equation. Of course the many years of experience that some companies have also feeds into fibre selection. With textile based systems most of the experience is based on the manufacture of artificial turf which is fed into the development of the Hybrid turf system.

5. How does the climate where the stadium is located influence the fibre choice and tolerances?
Same as above the climate does not influence the fibre choice, extensive laboratory research is made prior to the 1st ever production and based on the UV specs, tensile strengths of the fibres and various other assessments the fibres are selected and used for ALL venues across the globe.

6. Are there particular choices or differences in materials and manufacture depending on differing sports? (I.E. does football require different types of stitching or fibres to rugby or baseball?)
Football, Rugby and NFL would all use the same stitching method, aprox 20mm centres stitched across the pitch, the depths of the fibres stitched are up to 200mm, whilst carpets systems (lay and play) would normally have fibres up to 65mm deep. As Hybrids venture into cricket, baseball and other applications there has been the application of different stitch rates. This is equally true for textile base Hybrid turf where manufacturers have looked carefully at pile height, pile density and the type of backings used.

7. What are the challenges of maintaining a hybrid turf pitch?
As mentioned in question 2, the biggest challenges is educating people, buried fibres are very difficult to rectify mid season and can cause players to slip on the organic mater which has buried the fibres. The other challenges are coaches and trainers thinking the pitch is reinforced therefore they can train more on certain areas, reinforced pitches are only 5% fibres, the rest of the pitch is natural grass, therefore these areas can thin out the same a natural pitch if over used! With textile based systems compaction or perceived ‘stiffness’ of the playing surface can be the feedback from the playing community so regular decompaction becomes an important intervention with these systems.

8. What is your view on the injury debate when artificial surfaces are played upon?
The debate rages on and this is fuelled by players, coaches, managers and pundits. However scientific research by FIFA indicates that in major competitions where artificial turf has been used that there is no difference in injury rates? Rugby has a different take on the situation and the PFA have recently fuelled the debate by suggesting a ban on artificial turf in the league primarily due to injuries. In reference to Hybrid turf this is more difficult to mine. One big benefit on Hybrid technology is that the playing surface is firm to play on but forgiving against impacts. However there has been some suggestion via the English Premier League that Hybrid pitches do result in a higher incidence of injuries to elite players. We await further science on this before we can conclude anything significant.

9. What does the future of hybrid turf look like?
The future for Hybrid is a bright one, with more and more elite venues adopting Hybrid technologies. The challenge to the suppliers is maintaining quality and ensuring proper maintenance practices are in place so that Hybrid pitches perform as they should. The advice would be to only deal with reputable companies, do your research on systems and be aware of the care these pitches require. Seek professional advice and speak to Ground staff who are already operating Hybrid pitches. Major tournaments are leaning towards hybrid pitches, as hybrid pitches mitigate some risks. Again before installation, ensure you have the correct machinery to maintain the upkeep of the turf, select your hybrid, Stitched or carpeted based on the stadiums business plans.

Do you have a view on how your business can approach the issue of microplastics?
As a business we design, Consult and test all types of sports surfaces. Most have a plastic element to them so we are acutely aware that we must design features into sports facilities that reduce or mitigate the use of materials which add microplastics to the environment. Locally we work with our Clients to find solutions however in Europe we are actively involved with the ESTC in providing best practice advice to our Community and Clients and also with the STC in the USA. We are therefore taking a responsible approach to this issue.

Reusing & Value Engineering Shock Pads

by Niall MacPhee, International Business Development Manager

In many countries now, the number of pitch refurbishments is significantly higher than new pitch installations.

This dynamic supports the fact that for the private owner, council facility operators, sports club or a contractor, a feasibility study to assess the reuse of a shock pad is key to realising the budget and increases the probability that refurbishment plans can move forward. Only a laboratory with accreditation and the appropriate testing facilities can provide an independent, non-commercial statistical analysis to assess refurbishment project costs with accuracy. Commonly these results are requested by governing bodies and should be appended to the new field reports. Without this step, many contractors are apt to price without any knowledge as to what lies beneath the surface, thus creating a risk of sudden increases to the budget during installation and cost over-runs. Without this, it would be wise to carry a significant contingency fund to be able to cater for what lies beneath.

The main problem during the feasibility stage is that the existing facility may still be in use, perhaps leased out as a revenue generator, and most commonly artificial grass will be covering the shock pad. There is a solution to this problem, and it’s exercised frequently - it’s a requirement as per governing body specifications. It is part of the FIFA Quality Programme and the Handbook of Test Methods for Football Turf.

Below are some photos of examples of in-situ sampling of shock pads which demonstrate the type of testing carried out.

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Here we will look at the type of shock pads that are commonly sampled as well as mandated testing via FIFA, forensic testing, the costs associated with undertaking inspection, and the time required to complete everything.

Type of Shock pad: In-situ or Prefabricated?
Every shock pad is a candidate for reuse and a feasibility study. The two common types of shock pads are in-situ and prefabricated. In-situ (or e-layers) comprise of a mixture of PU binder and granulated rubber crumb and are laid on-site, occasionally the PU/Rubber can be mixed with clean stone to change the properties of the shock pad. For In-situ, a shock pad's long term performance is dependent on many factors such as binder content, SBR shape, size, chemical composition, and contaminant, to name a few. In-situ/elayer type shock pads naturally degrade over time due to oxidation of the thin binder film which sticks the rubber granulate together. Even under normal stress, they lose their tensile strength and elongation properties. Sometimes the life expectancy of in-situ pads are not reached, and the binder contents are not always to contract. As a rudimental assessment, if loose rubber is visible on top of the pad, there may be underlying issues, and the pad could be failing. It's also a concern if the shock pad is brittle. In several recent projects, we have seen carpet bound with glue to the shock pad, and this diminishes the chances of its reuse as it is challenging to remove the existing carpet without extensive damage to the In-situ.

Prefabricated shock pads are made with a variety of different material types, density, thickness, shape, and design. They are typically manufactured in a plant and transferred to the site where they are laid loosely and jointed in several ways — butted together with jointing tape, a key link design, or tongue and groove design to name a few. Most pads are constructed from bi-product PE, PU or expanded PPE, but due to heat expansion properties, they may require slits or grooves to prevent disruptive expansion and contraction from temperature changes. Many large producers have evolved to optimize their designs to the European, ASTM, Italian, and Dutch standards. There are now ESTC guidelines which are very descriptive.

Prefabricated shock pads generally have a longer life expectancy, with some manufacturers offering warranties beyond 20 years. Always be sure to check the warranty on these shock pads when considering budgeting for a refurbishment.

Testing Table
FIFA Manual Extract

"Despite practical implications when a turf has not yet been replaced, it is not acceptable to determine the suitability based on the values obtained from testing the corner areas only. Tests shall be made no sooner than 12 months before the initial field test after resurfacing. The results of the shock pad tests shall be appended to the FIFA Field Test Report and issued to FIFA following the initial field test. Compliance with the above requirements does not override the need for the field to fully satisfy the field test requirements of the FIFA Quality Programme.’’

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Costs
A feasibility study on the shock pad will vary dependant on the scope of works, but the work can generally be carried out on site in under one day. Samples are then taken back to the laboratory for further examination of tensile strength and elongation properties. It is half a day’s work for a competent test technician in a laboratory to complete these tests. Often the turf system will need to be cut open to allow access to the underlying shock pad. This is a specialist activity, especially if the pitch is still in use. Here an installer would be called upon to open and close the turf so that proper joints are made in the playing surface. In comparison to buying a new shock pad and perhaps repairing the asphalt, the costs of a site assessment are a fraction of these, which makes it a cost-effective approach to de-risking your refurbishment contract. Exclusive of international travel, an in-situ inspection is typically less than 1% of the cost of a new shock pad, making it a very cost-effective approach to assessing the reusability of a shock pad system.

Test Locations
FIFA requires 6 test locations, as seen below in Figure 2. This is compulsory for FIFA Quality Pro or Quality certification. Many projects proceed without this, unknowingly stepping outside the rules and quite regularly experiencing problems after refurbishment during certification testing.

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Reinstatement of the Surface After Testing
A competent maintenance contractor, or commonly an interested contractor for the refurbishment can reinstate the 1m2 areas on the field straight after the test. Glue and new seaming tape are needed with the original carpet being re-used. Again approximately half a day’s work for a competent site installation contractor. Time is required for the glues to set so this may put your pitch out of action overnight. The key is knowledge of how and where to make the clean carpet cut, so the repair is much easier after testing is complete.

Feasibility is Value Engineering
Whenever it’s possible, it is always good to re-use suitable components because it reduces the carbon footprint and ultimately cost. There’s a wealth of knowledge available on this subject and protocols you can follow to benefit your project.