too late for control joints?

[matemike]

And would they even be needed by this point?

I had my 40x40 slab poured a year ago with 3500psi concrete. It's a 4" slab that has a 12"X24" beam around the perimeter and 12"x18" beams running N-S and E-W across the middle. The contractor did not install control joints, expansion joints, nothing.
In my area I have never seen any joints cut or troweled into the house slabs that I've seen poured. And for another example, even our 15 year-old house slab with an attached 26x36 garage has no joints in it. So when I asked about having joints made in the shop slab and the contractor said it wasn't necessary, I took it as sound advice.

Anyways, the new lab sat uncovered last year for 6 weeks and we had torrential rains over that entire time span. I can only imagine that helped the concrete to cure as well as possible. The building has been up for almost 10 months now and still no surface cracks. There are some very tiny surface hair lines, but nothing too concerning at this time.

Questions are:

Should I consider cutting some 1" deep joints every 10x10 feet?
Is it too late for control joints at this point?
Would I degrade the slab if I cut them this late in the game?
Since I haven't seen any surface cracks yet, a year later, is my slab in the clear?

Please consider my location, SE Texas, very muddy clay on flat flat land. There is very little if any at all ground shifting around here.

 

[J king]

My guess would be that if it has any structure weak points they are there and you won't control it now.You cut it and then the stress or shrink crack may be a foot away and it won't control the crack.I would let it go now unless you have a crystal ball.be happy it's done so well. Must have a good pour.��

 

[astroracer]

If it's going to crack, it's going to crack. If it hasn't why worry about it?
The floor in my shop is cracked and that doesn't prevent it from being a floor... AND it's covered with oil stains and spray paint and welding burns. It still works as a floor though so I am happy with it.
Mark

 

[DanEC]

It's too late for saw cut contraction joints to do any good. In concrete paving we found that if joints were not cut by the following morning after placement, then we could generally not control cracking with them. If it's going to eventually crack, the micro-fracturing in the concrete matrix has already started to form. If you do cut any joints try to work around areas you plan to tile or hide under wall plates.

 

[larry_g]

I wouldn't bother at this late in the game. Like said above the control cuts are mainly to help in the curing stage and your past that now.

lg
no neat sig line