install sign post in concrete or asphalt

Either a small jack hammer or a large SDS type of core drill. They can go up to 6" diameter.

 

Rent a core drill from Home Depot, bring water hose and some quick set concrete or epoxy to fill.

 

I've banged several of these directly through asphalt with our post drivers....we have oversized custom made post drivers to drive them through our rocky hard ground and usually the asphalt is the easy part to get through HA. Concrete I would say you are out of luck without cutting the concrete.

 

for concrete, I would do a surface mount
https://www.safetysign.com/products/11170/u-channel-surface-mount-post-base

asphalt, a good & heavy post driver will work.
then you can beat the asphalt back into place or heat it and let the tar settle

 

Core drill a hole with a 4 inch bit, install the post then put concrete in the hole.

 

I use an SDS drill and fill it back with concrete.

 

If its only a few to be installed in concrete, look into the bold down bases, way less expensive then renting a core drill or hiring a company.

For asphalt if you have a sleeve pounder it should go through it relatively easily. But if you have a bunch, do yourself a favour and rent a gas powered post pounder!

 

If you're in a cold area with the asphalt you can heat it up with blow torch first and then pound through. Save some time and it looks cleaner. For concrete I agree with canuck, the bases are a good way to go. For concrete it's always smart to know if there is anything structural going on with where you are installing and if it is pre-stressed or not. If it's just a pad do whatever but be careful in parking garages, etc., about drilling too deep.