Synthetic grass can be installed on top of sound concrete. If it is broken up or cracked you will have to remove it and install as per a standard installation. If it is in good condition it will save you from having to install aggregates and prepare the surface.
Fill any minor flaws in the concrete with a self-leveling compound. If there is a slight slope to ensure good drainage that is ideal. If not then drill holes for drainage and fill them with shingle.
If there are any minor irregularities in the concrete you should lay the synthetic grass on to a foam underlay fixed with special glue. Fix the synthetic grass using the adhesive around the edges. Complete the installation as per a standard installation.
