This is not laid on concrete, there is poly metric sand in between the stones to keep weeds at bay. The poly metric sand is great too because it is able to move with the stones (expanding and contracting).

Very nice!

I like that look so much more than when the bluestone is laid in concrete.

@aehaile you can buy polymer sand at your local hardware store to if you are planning to DIY. It's rather affordable as well and as you said before, looks a look better aesthetically than laying the stone on concrete, and it comes in a few color options too!

Thank you for the awesome input!!