The base or otherwise elastic-layer (e-leyer) is most crucial, however invisible element of sport surfaces, football grounds and children playgrounds. It is responsible for shock absorption and top layer stability. Basic elements of the structure, which includes the base, are:
- Colorful top layer
- Base - elastic layer composed of mixed SBR and/or EPDM granules, usually from recycling, having fractions 1.0-4.0 mm or 2.0-6.0 mm with polyurethane adhesive. Thickness of sport surface covers depends on their use - the thicker base, the higher the elasticity of entire structure and kindness to joints and the spine, as well as returning energy to the athlete. Essential factor that influences base thickness in children playgrounds is the height of possible child's fall. It is determined by the HIC factor (Head Injury Criterion) – described in standard PN-EN 1177. For good base performance, it is required that the substrate is carefully prepared.
- Stable substrate - most common materials used to build substrate are: stone, gravel or debris.
Below, example of base made using SBR granules.