0 Third generation artificial football surfaces – maintenance understandings revealed!

Field turf artificial deep pile. modified jpg.jpgAlternative surfaces used for football have been around for at least forty years. The first surfaces were little more than a carpet consisting of a plastic based pile and backing layer. From these crude designs, a slightly more successful line of products followed with better quality materials and an infill layer of sand, known as the second generation.

Most of us can remember certain professional football clubs using the second type, or generation, surface during the late eighties, unsuccessfully. There were many problems with the playability of these sand filled pitch types mostly related to surface hardness, grazing, traction/grip and erratic ball bounce behaviour. Subsequently, the clubs that chose to use the artificial surfaces at professional level quickly removed them and returned to natural turf.

Since then, natural turf has dominated the game and little has been heard of artificial football surfaces in a professional light until now. Recently, a new design of artificial surface emerged (third generation) with an altogether new construction specifically designed at replicating the playing performance qualities of natural turf. The design consists of more durable polymer materials, longer pile fibres, a soft absorbent infill material and shock pads. Suppliers have made promises of low to non-existent maintenance needs and subsequent major maintenance cost savings. Rubber fill pic modified .jpg

The new design is certainly much closer to natural turf in terms of its appearance and to a certain degree its performance. The longer pile lengths and polymer-based infill has improved ball-to-surface interactions, increased traction/grip and helped to enhance cushioning. It will still have a long way to go before a true comparison can be made, if at all, between that of itself and natural turf. Maintenance managers are beginning to realise that the true cost to maintain these third generation surfaces, if the best playability and longevity is to be gained from them, is actually comparable to that of basic natural pitches
(£7-10,000/annum).

This article has been written to address issues related to the maintenance of the third generation long-pile surfaces. In doing so it is hoped that users, owners and those responsible for their maintenance will be able to develop a greater understanding of their requirements. However ,before we look at maintenance issues we need to examine structural differences between natural and artificial pitches.

It would be fair to say that the expectation on artificial surfaces is one of high wear tolerance. To a certain degree this statement is true. Because a high-grade polymer based plastic is used to form the basis for the fibre element, structurally it is much stronger than the soft organic tissue within a grass leaf. There is a key difference here though - grass has the ability to recuperate but plastic polymer has not. In the short-term, this key difference is negligible, in the long-term however it becomes significant.

Natural turf, given the necessary time and conditions to do so, will repair play and maintenance damage. Artificial turf cannot. So, resistance to wear, on the side of the artificial surface, is on a sliding scale from construction, whereas that of natural turf is ongoing given favourable conditions. Unfortunately, we cannot apply any preservative products to the artificial surface that will help to extend its working life e.g. polymer wear resistant coatings or Uva Uvb protectants. Until such products are available, the goal is to tailor efforts to extend the useful life of the artificial types as far into the future as possible through basic maintenance and usage control.

One major similarity between the two types of surface is the need to have a high construction quality from the start. Artificial surfaces rely on the quality of materials and the installation process to maximise their useful life. Polymer type, amount of contaminates absorbed during manufacture, backing materials, method of securement, infill selection, presence of shock pad, amount and type of maintenance together with usage environment all collectively contribute to the actual working life of an artificial surface.

Independent feasibility analysis, using reputable suppliers/contractors, site supervision and materials testing will help to minimise any problems whilst maximising the potential for the artificial surface. It is then up to the initial and ongoing maintenance routines to further reinforce the progress.

Once the pitch is constructed and installed, the maintenance approach is split into five main areas:

· Fibre management
· Infill management
· Pitch surrounds management
· Wear management
· Performance testing
· Resource management

Fibre management

In order to produce the desired ball-surface and player-surface interactions, the fibre pile must be regularly treated. All those performance quality aspects i.e. ball; roll, bounce, slip, player; traction, grip are directly proportionate to fibre position and support. Flattened fibres do not maintain the ball and will affect both pace, roll direction and bounce behaviour adversely (not to mention exposing a greater fibre surface area to Uva/Uvb damage). This is normally addressed by brushing with a drag brush in several directions; raising fibre uniformity levels to the intended position.

Conversely, too much brushing, and in particular, too high brush filament strength, will cause the fibres to wear prematurely. Fibre "memory" is partly responsible for the return to its original position after load is exerted upon the polymer filament. Excessive brushing reduces this memory and causes the pile fibres to return to the flattened state much sooner. It can also cause seam failure. Brushing and/or decompacting across the seam lines may lead toward seam stress and eventual splitting/separation. Following the direction of seam lines when brushing will help to preserve their integrity. A good way to assess a brush for suitability is by feel. If you rate it based upon firmness from one to five and consider a brush made for laminate flooring as a one, and a brush made for yard areas a five, the desired level is somewhere in between. It is much more logical to replace the brush more frequently than the surface.


IMG_0485.modified jpg.jpgInfill management

The infill layer provides: support for the fibre layer, resilience for ball bounce, fall cushioning and together with fibre condition forms the basis for traction and grip potentials. The depth of infill material as well as its orientation or distribution is the most important point of concern.

The choice seems to be between using either pure rubber crumb (EPDM, or re-cycled tyres) or a rubber crumb/sand mix. Both options have relative merits and drawbacks but both primarily depend on even depth and distribution for optimum performance. It is important to recognise that this infill material will need to be completely replaced at least twice over the working life (assuming a ten year life period is achieved). The resilience produced by the rubber crumb particles diminishes over time requiring replacement material to be added. If left, the polymer-based fill will eventually break down leading to compaction and infiltration problems. There is also evidence to support that the infill itself reacts, at diffident levels, with the fibre filaments leading to amplified wearing rates.

Brushing will help to regulate the fibre uniformity but will not remove finer particles or contaminates from the infill/fibre profile. An appropriate vacuum sweeper should be used regularly so that infill is agitated (decreasing problems with moss, weed grass germination etc) and all types of debris removed. Finer particle build-ups will result in reduced drainage rates, problems with ball and player-surface interactions and may invalidate manufacturer guarantees. Decompaction of the infill is needed on a regular basis although there is a range of methods used to do so. A rake like attachment commonly found on dedicated machine-drawn brushes can be used. Care must be taken to avoid damage to the fibre pile with this technique.

The correct selection of maintenance materials is an essential part of pitch management. Choosing the wrong infill materials, maintenance machinery and/or implements together with any chemical products for cleaning or weed removal will reduce the surface working life. Acidic selective and non-selective herbicides for example can react with the polymers and cause premature aging of all pitch constituents.
weed invasion.modified jpg.jpg
It is imperative that a full maintenance guide be asked for when reviewing pitch specifications. It is the responsibility of the manufacturer and supplier to inform their clients exactly how their products should be managed. Any materials not recommended for use should be avoided so that warranty coverage will remain intact.

Pitch surrounds management

It is vital that surrounding areas be thought of with regard to maintenance issues. Fine particle contamination, general litter, vandalism and excess traffic will all help to degrade the working life of these surfaces quickly. An accurate section within the feasibility study should point out all potential threats in detail and make recommendations as to their control. Options such as security fencing, litter bins and surround area cleaning will minimise associated problems. An entry area with footwear cleaning facilities should be used to intercept debris before users come into contact with the surface. In addition, grass banking, car park areas and open soils should also be controlled; preventing dust and seed migration as much as possible.

Wear management

The ability to spread wear over the surface area should be regarded a high priority. Where possible, alternate playing directions should be enforced to prevent wear damage concentrations occurring in goalmouth and centre lines (especially important to non-multisport facilities). Vehicular traffic, either from maintenance or exceptional uses, must be regulated evenly. Alternating the direction of travel together with using multiple entrances will help reduce damage. In exceptional use situations i.e. temporary car parks, protection in the form of boarding must be used to protect construction integrity.

Performance testing and monitoring

Normally, a newly installed artificial surface is performance tested after one month in place. The goal is to measure the performance characteristics so that they are benchmarked as close to design specifications as possible. After that insufficient consideration may be given to ongoing performance testing. One must assume that together with a natural reduction in physical structure over time, the playing performance will also diminish. Setting initial benchmarks and conducting progressive tests throughout the pitch lifetime define maintenance needs. Provision should also be made for a monitoring programme so that many factors can be assessed related to pitch performance and care. The STRI can provide site-monitoring visits where pitch condition, playing performance and the effectiveness of maintenance operations are measured. A full maintenance plan can be produced and further visits agreed. This service is especially important for facility providers who wish to be protected against litigation if an accident occurs.

Resource management

Artificial surfaces are not maintenance free! Perhaps a little obvious now, but many of these surfaces have been sold based on this untrue statement. A lifetime maintenance cost must be drawn at the project planning stage so that the integrity and playability of the surface is maintained well into the future. The cost/benefit ratio of surface ownership is dependent upon longevity, quality and cost of service in these cases. Ideally, the pitch owner should provide for a full maintenance programme and the eventual carpet replacement by paying into a sinking fund from the outset. Typically, the life expectancy of an artificial surface is quoted to be between ten and fifteen years; although there are no examples of third generation ones getting close to this age as yet. It is essential that maintenance practitioners follow the exact maintenance guidelines supplied with their specific artificial surface (if such recommendations exist). It also important to keep in regular communication with suppliers as their recommendations have been known to change, frequently. In doing so, the warranty of the surface in question remains valid.

Conclusions

The maintenance of third generation artificial football pitches is a key factor related to their surface playability characteristics and effective working lifetimes. They are not maintenance free and although they are capable of taking high amounts of play, their resistance to its negative effects are on a diminishing sliding scale. Without the ability to physically recover from surface wear, it is important to understand that the aim of maintenance then focuses solely on preservation rather than recuperation; as opposed to natural turf.

Table showing a suggested maintenance programme for a third generation surface

Operation

Frequency

daily

weekly

monthly

annually

Inspections-pitch & surrounding areas

x

in-house

^(X)

professional

pitch debris clearance

x

(X)

Cleaning entrance ways

(X)

X

rolling

x

during setteling in period

(X)

with decompacting & topdressing

(X)

with decompacting & topdressing

(X)

with decompacting & topdressing

brushing

*X

drag brush

x

rotary brush

de-compacting

X

High wear areas

X

entire pitch

topdressing & divoting

(X)

to 80% fibre height

X

to 80% fibre height

Performance testing

(X)

professional

Emptying refuse bins

X

drainage clearance

X

(X)

alternating wear pattern

(X)

X

(X)

(X)

documenting maintenance-usage & climatic data

X

X

X

X

contacting manufacturers

as needed

as needed

as needed

X

vegetation removal

(X)

(X)

(X)

(X)

line painting

as needed

as needed

as needed

as needed


X = Recommended application time (X) = Acceptable application time

^ Rejuvenation will be decided by results of professional inspection along with infill replacement

As a general rule brushing should be performed with the direction of the seams, not against, to reduce the stresses imparted on them (with a manufacturer approved unit if possible).
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