Concrete is the only long term sustainable solution for outdoor skateparks.
The advantages of concrete are:
- Fast, smooth performance
- Lowest noise emissions
- Vandal resistant
- Very low maintenance
- Rust free (no re painting etc)
However, concrete does require experience and knowledge to produce a professional finish and a long lasting product.
As for the others
Wood : Decays and burns
Steel : Unscrews, is noisy and gets stolen
Tarmac: Sinks next to ramps, goes soft and sticky in the heat
Basically Concrete: Is quiet, it lasts and it is great to ride.