Cold asphalt / cold tar
If you are going to be installing a fence on asphalt or a tarred surface (depending on where you're reading this!) you're going to first need to cut through the asphalt or tarmac layer before you can dig the hole for your fence posts.
One way to repair the surface when you have installed your fence posts is to fill the concrete up to the surface, but that doesn't always look as neat as it could.
Cold asphalt, or cold tar as it's known in countries that use UK English, is a premixed, bagged product with the same kind of stone or gravel you find in regular asphalt, mixed with a special type of bitumen that stays soft and workable in the bag.
To use this product, you would simply finish your concrete footing an inch or so below the top surface of the asphalt, and then once the concrete is set, add a layer of cold asphalt and compact it. This is not as strong as ordinary road asphalt, but since you won't have vehicles driving right next to your fence, it's good enough to give a neat finish to fences installed on asphalt or tarmac surfaces.