What's that black rubber in Artificial Turf Fields

It's ground up tires.

The tires go through steps to remove metal, grind and clean the rubber. It is transported in 4 foot square sacks on pallets and racked into the artificial turf.

This black rubber can get a little hot in the sun, but it is a safer surface than sand filled fields in general and don't get much harder over time.

If you have more insight onto Artificial Turf fields, lay it on me.