Seal between stucco exterior and asphalt

I am trying to find the correct product to use for a water barrier between exterior stucco and the asphalt pavement in the corners where they meet. I have tried using roof tar but it doesn't last very long was hoping someone had a more permanent solution.

 

I would use a polyurethane sealant that has been tested to comply with adhesion standards for stucco and masonry. (such as Vulkem 116)

In the link above, you will notice a list of comparable sealants that would also work. The Lowes in our area carry vulkum in several colors... limestone and/or grey are usually the best colors for such a joint. My favorite is Sonneborn NP1, but that might be hard to find.

Obviously the joint needs to be clean... if there is a wide gap to span, it should be filled with caulk-saver foam backer rod. The backer rod does more than just save on caulk, it allows the sealant to bond to only 2 sides of the joint... the 3rd side- that sticks to the foam- is flexible and can expand and contract. This results in longer life for your sealant joint, provided you're following the directions about how thick to apply the sealant.

Mask the cement with tape if needed to give you a straight clean line, and fill (but don't overfill) the joint. Running 2 thick beads is sometimes better than trying to pump the joint full all at one time. To smooth the bead of sealant, wet the surface lightly with paint thinner as you are tooling it. It will help achieve a nice smooth surface and will also help pack the sealant into the joint so that there are no voids and that will also give you better adhesion.