YOUR FORUM FOR PLAY, SPORTS UND LEISURE AREAS
The basic properties are indicated by the technical functions, whereby all parameters are summarised which serve to provide long-term maintenance of the sport and protection functions. These include, among others, ageing, wear behaviour, tensile strength of the synthetic grass fibres and the joint connection between the lengths of carpet as well as the pull-out resistance of the tufts
The sport functions of synthetic turf surfaces include ball bouncing and rolling behaviour as well as the levelness and water permeability of the whole system. These parameters have a direct influence on the playing of a kind of sport e.g. football.
The last group covers the protective functions. These serve to reduce stress and strain on the musculoskeletal system of athletes during their sporting activities, in particular, a reduction in injuries from falls. The decisive protective functions of a sport surface include energy absorption, resistance to torque (rotation) and vertical deformation, previously referred to as standard deformation, as per DIN 18032-2:2001-04.
According to DIN EN 14808, energy absorption is the physical measurement of absorption and resilience. It describes the capability of a sport surface to reduce the force created by a falling body. This measurement is achieved using a testing device called the "artificial athlete" which subjects the surface being tested to pulsed mass. The maximal force achieved is recorded and compared with the maximal force measured in the same way on a rigid (concrete) surface. The relative difference between the two maximum forces is defined as energy absorption in percent. According to DIN EN 15330-1, the energy absorption of an artificial turf pitch designed for main use as a football pitch, must lie between 55% and 70% under dry and wet conditions, whereby absorption and resilience increase with higher energy absorption.
Resistance to torque according to DIN EN 15301-1 descries the force which is required to start rotation of a test shoe sole. This sole may have studs or knobs, adjusted to suit the type of sport in question. The test involves a test foot weighing 46 kg falling from a height of 60 mm onto the surface to ensure that the studs or knobs actually penetrate it. Using a torque wrench, the test foot is moved evenly and without interruption until it has passed through an angle of at least 45°. The force required is measured in newton metres (Nm).
The requirements of resistant to rotation for surfaces designed mainly for use as a football pitch according to DIN EN 15330-1, lie for both wet and dry conditions, between 25 Nm and 50 Nm, whereby the strain on the joints increases with increasing resistance to rotation.
A further parameter which must be taken into consideration is vertical deformation measured according to DIN EN 14809. This describes the deformation of the whole surface under a determined load. The fall weight of the "artificial athlete" is allowed to fall onto a soft spring arranged on the sports surface and the maximum deformation caused recorded. The deformation is determined using a defined load of 1500 N. According to DIN EN 15330-1, vertical deformation for surfaces designed mainly for use as a football pitch, lie for both wet and dry conditions, between 4 mm and 9 mm.
In order to ensure the protective function of a new synthetic turf surface, the suitability of the material should be tested by the manufacturer and certified in a test report before it is installed. This should be carried out by an testing institute accredited according to DIN EN ISO/IEC 17025 like, for example, the ISP - Institute for Sport facility testing (Institut für Sportstättenprüfung, Dr. Uwe Schattke).
A conclusive evaluation of the installed synthetic turf system should be ensured with in-situ testing whereby at five defined measuring points, the protective and sport functions such as ball bouncing and roll behaviour, energy absorption, vertical deformation, resistance to rotation, water infiltration rate and levelness of the surface are determined and compared with the of the current DIN EN 15330-1. According to this standard, dependent on the frequency of use and local regulations, a control test should be carried out after installation and repeated every two to three years by a qualified testing institute. These periodic tests ensure that the installed synthetic turf surface continues to maintain its expected performance properties and in particular to fulfil its protective function.
