LAWN EDGING STRIP

To cut down on having to trim my lawns to neaten the edges, I have a project in mind to do a concrete slab edging strip. My plan is to dig out some soil, use sharp sand as a base and then lay the concrete slabs on top of the sand, brushing it in between the joints once the level has settled. Would this plan work? Would I need to use membrane to deter weeds before putting the sharp sand in place? Any advice would be appreciated.