Concrete over Asphalt

#1
I have searched, but can't find anything clear. o_O

Is it possible to place concrete Aprons over Asphalt Aprons? A lot of airports have asphalt either side of concrete taxiways. So I'm trying to place asphalt Apron pads and then lay concrete taxiways over the top, but the concrete always disappears. Any help would be muchly appreciated.
 
Top