Control joints are dependent on the amount of steel you put in the slab. If you want the bare minimum steel, like thin WWF, then you want relatively closely placed control joints because it will crack. Concrete does not handle tension well, so when the slab expands then the conrete will crack. Steel handles tension very well, thus its need to be in the slab for temperature and shrinkage. This is independent of Contractor induced cracking from bad practices. With enough steel in the slab and depending on its dimensions (size, any interior corners?, square or rectangular), control joints can be eliminated on smaller 2 car garages. The larger the slab gets the more steel is required and does not become economically feasible to eliminate control joints unless you have deep pockets
Buening, I'm sure I'm going to ruffle a lot of feathers with this but what the hell, let's keep the conversation lively.
The reality is that reinforcing steel does very little to control
shrinkage cracks. There I said it!
It is true that reinforcing steel increases a concrete's tensile strength but it does not prevent shrinkage cracks. It doesn't matter whether you use wire mesh or a double mat of #8 bars.
Reinforcing obviously plays an important role, primarilly keeping a crack engaged but it won't do much to prevent them.
If you want to avoid shrinkage cracks, pay attention to concrete mix design (bigger aggregate), slump(less water), waether(cooler) and curing (do it).
I realize this is contrary to a lot of long held beliefs but a careful reading of ACI and the studies on the subject will back me up.
