On Oct 10, 1:14 pm, "** Frank **" wrote:
Contractors and DIY use groovers or saw cut control lines so that the
concrete will break at the joints. That's the plan but more lightly the
concrete slab will crack everywhere except at the joint lines. For the
concrete slabs I saw on patios, driveways and sidewalks, it seems pointless
to have control joints. Expansion joints excepted, off course.

So the question is, when concrete cracks then how do you make it break at
the control joints more often than elsewhere?


Depends the slab thickness but for a 5" slab......place cuts such that
you have 150 sq ft max panel size (try to keep the panels somewhat
squarish) & cut depth 1/4 to 1/3 of slab thickness, cut as soon as
concrete can be worked upon without damaging surface.

Too much water in the mix can cause shrinkage cracks that cuts will
not totally help avoid.

This should work out pretty well.

cheers
Bob