Which subbase is better for a synthetic track: asphalt or concrete?

In most cases asphalt is used as a subbase for a Regupol® synthetic athletic track. But concrete is also possible. The water permeable synthetic track Regupol PD IS needs a water permeable asphalt layer. Concrete subbases are possible with all other Regupol® synthetic tracks. This depends on local conditions and often depends on the costs in other parts of the world. In Germany, asphalt is used almost exclusively as a subbase.