Can I add concrete cement over polymer around my flat stone patio

  1 answer
  • Hillela G. Hillela G. on May 12, 2017
    Flagstone, bluestone, and other 'slate' type stones are frequently installed on concrete slabs in many applications. Typically there's a mortar bed on top of the concrete into which the stones are set. Sometimes an asphalt base is installed on top of the concrete, and the mortar bed is installed on top of that. The difference between what you have and a new installation is the concrete base. A new concrete base has no cracks. Cracks in an exterior slab usually indicate movement of the slab in some manner. And on can never be certain that the cracked slab won't move in some way yet again. A new slab constructed for the specific purpose of being the base for a stone surface is usually reinforced, yours is probably not. Going to all the work of covering the cracked slab with mortar and stones, only to see it all crack if the slab moves again, which it may, would not make you happy. Although your slab is large, in the long run, it may make more sense to remove the slab and then install the stones on a new base and bed that would not necessarily have to be concrete.