Why do EPDM granules come apart from the sandwich systems (Type D and E according to EN 14877:2013-12)?

The wearing surfaces of these systems are designed to not show spike-use for a long time. This is why the granules broadcast into the polyurethane layer are partly fully, others partly and others only on their very edges embedded in the polyurethane wear coat. Over the entire service life of the synthetic track, individual EPDM granules will gradually come away but still leave a granular surface which is irregular enough to not show spike-wear for a long time. This has nothing to do with the production of the track but is a consequence of the system structure itself and does not constitute any deterioration in quality.