It is very common that artificial grass field for football is infilled by rubber granules, do you know why the grass field need that rubber granule, the following information will tell you the reason,
1) Artificial grass are made of grass yarn which comes from polymer, these artificial grass yarn is easily moved or damaged without infillings, with the support of infillings of rubber granule or silica sand, the grass yarn can be stably held and the grass turf can be well stabilized. Usually, the bottom layer is silica sand, the upper layer is covered by rubber granules.
2) Artificial grass turf do not have soil as real grass growing in the earth, so people who play in the field can be easily hurted by the harden basement when fall down, while with the infillings of rubber granuels, the artificial grass turf becomes softer and elastic to supply protectional cushion to avoid hurts.
3) The grass yarn surface is much slipperier than real grass that is growing in the earth, so people may easily fall down when walking at artifical grass field especially in rainy day, with the infillings of rubber granules which can increase friction force of artificial turf fields, functional performance of artificial turf is well improved.