How can I lay cobblestone type paving over a pre-existing concrete slab??
We have this ugly patio slab mid yard and thought to dress it and its ajoining pathways up with cobblestone style paving such as we saw in Spain. I'd use river rock or round stones from the home DIY stores but do I lay cement and set the stones in or some sort of outdoor thinset and grout? How should I prepare the slab surface (its plain old cement/concrete and too big to smash and remove)? Please advise.