As advised we cut saw slots in our nice pristine concrete slab, this is to allow the concrete to crack in a predefined place if the ‘plastic shrinkage’ exceed the tensile strengthof the concrete. When laying standard concrete it is normal to leave breaks between sections to allow this shrinkage, but as our slab was poured in one piece other arrangements has to be made.
We cut two slots, the first from left to right under the dividing wall (2.5m from Mass wall) and the second from front center back to the first line.