shorty wrote:
I have a small area of turf that I need to raise up by 20mm to make it
slightly above the concrete edging stones that surround it, as the
wife keeps hitting the stones with the lawn mower.


Don't raise it that high. You want the soil level just below the paving
height - that will allow th3 mower to ride over the edge without hitting it.

Soil above edge encourages the soil/grass to encroach over the paving

pk