The lifespan of the artificial turf systems used for athletic fields (football, five-a-side, or rugby) depends on various factors, including the site’s geographic location, how heavily the field is used, and how it’s maintained. But when it’s time to replace the surface, the removal of the old field can result in considerable technical, financial, and environmental advantages. The key is salvaging the performance infill rubber granules from the old system, especially because of the significant cost savings.
But salvaging the performance infill rubber granules from an old field to be used for a new one requires a technical feasibility study, so experts can analyze the condition of the system and the artificial turf, determine whether space is available for collecting the old material, and evaluate the sand and rubber granulate mixture for both quantitative (the amount of sand and rubber in the existing surface) and qualitative (the mechanical properties of the granulate meant to be recycled) properties.
The resulting data must then be cross-checked to confirm that the rubber granulate can be reused in the new synthetic surface. The results will determine how much new crumb rubber granulate must be added to guarantee the new surface’s technical and sports performance characteristics.
Studying the rubber granulate involves analyzing its mechanical properties. After the mixture is checked and sifted to separate the sand from the rubber, the rubber granulate undergoes a series of tests to assess its condition.
First, its real and apparent densities are examined in an immersion test using a pycnometer.
The rubber granulate is then sifted again to establish its granulation curve.
Next, the mechanical aging degree of the rubber granulate is examined to evaluate whether it can be recycled. (Its recovery behavior is based on its elastomeric properties, which are determined in two tests: one for volumetric compression and the other a creep-recovery test.)
This type of testing allows us to determine and compare the rigidity of various types of rubber, and how deformed it becomes after being subjected to long-term use by observing its gradual deformation due to its viscoelastic nature and the variation in its mechanical properties.
More specifically, the study produces a series of metrics that indicate whether the crumb rubber can be used, and if so, how much of it can be.
The test results are used to confirm the project’s technical feasibility, and to define—in a reliable manner—whether the existing granulate is suitable for reuse and the amount of additional rubber granulate needed for the installation of the new artificial turf.