Replace Asphalt Blacktop with Concrete Gravel Over Asphalt
Karen Cesar, who lives in sunny and warm Tuscon, AZ, is getting ready to tackle a paving project at her home.
"We are replacing part of an old asphalt drive way with concrete. The rest of the old driveway - which is presently too large - will be covered with crushed rock. Is it necessary to remove the asphalt? If so, why must the asphalt be removed?"
Here's my answer to Karen:
Karen, you can place crushed stone on top of the old asphalt. Just be sure it's at least 4 to 6-inches thick and it contains lots of sharp angular pieces of stone ranging in size from walnuts down to pieces of sand.
If you put a thin coating of stone on the old asphalt, aggressive drivers can spin the tires of cars and trucks and the asphalt will be exposed. The new stone will not interlock with the old asphalt.
You should really read my column about how to build a great gravel drive to understand what's going on and why the shape of the stones is so important.