there are basically two ways to build a road. Concrete one (as seen here) and asphalt one. No mixing of them. What you might have seen was that sometimes they use a thin concrete base for the layered structured asphalt road.

no. two types of road surface: concrete or asphalt. The concrete is reinforced with metal (as seen here) the asphalt one has a layered structure. So no mixing of the two types. Or maybe what you has seen, was sometimes they use a very thin base layer of concrete is in the making of the layered structured asphalt road.