Hello! In this example there is nothing holding the stones in place. In my experience, if the pebbles are 2" or larger they are heavy enough to stay in place on their own. The only suggestion I have is to be sure that the stones are below the grade of the concrete and not mounded up.

I'm sorry, I don't know of any adhesives that would work in this application. Good Luck!

Do you do any work with drainage issues? My area is notorious for water issues it seems because there is nowhere for the water to go. MSD stays on call during heavy rains right on our street corner.