Opinions on Cold Weather and Joints

[Anonymous]

I have a 20'x30'x4" pad in front of my garage that was poured yesterday, 12/2. I have it covered in plastic to cure and told the guys this morning to not worry about sawing joints in it. Temperture here is flucuating between high 40's and low 30's and is forecast to do so for the next 7-10 days. Did I screw up on the joint decision and do I need to worry about the weather?

[Rich]

The 3rd day is typically the day you will need to worry about freezing. With the plastic over it it will help hold the heat in for a time but not long enough. Your best bet would be to cover it with concrete blankets from a local equipment rental center. Worth the expense of them in my opinion.
As far as the joints - it's a judgement call. Too soon and it will tend to fracture the edges but too late and it's very hard on the saw blades. The best time to saw cut is as soon as you're able to get the saw on the slab without marring the surface. So it may have been a mistake to hold them off - but not detrimental. I would have them come back as soon as possible to do the control joints though. Is what happens during the cure process (more than any other time) is the concrete expands and contracts from the heat of the curing process. When you add in the weather you are asking for early cracking - and with no control joints it'll crack wherever it wants to.
Hope that helps.

[grumpydasmurf]

I'd rather replace saw blades then concrete slabs any day.

I've no real opinion since I am not a concrete specialist.