how to make sure that driveway does not crack

Salt (more properly, chloride ion from whatever source, i.e. sodium chloride or calcium chloride) used for deicing is the primary factor causing the failure of concrete structures on highways. Also, you'll find contractors who'll want to add calcium chloride to the mix to accelerate strength gain so that they can get the finishing over with and move on to the next job. Except in emergency repair situations, DOT's generally won't allow the use of calcium chloride in concrete. There are accelerators that don't cause corrosion, but they're more expensive than calcium chloride.

In a normal concrete mix, reinforcing steel will quickly form a passive coating and no rusting will occur for many, many years. If you apply chloride deicers, the chloride ions will gradually work their way down to the reinforcing steel. When the concentration of chloride ion gets high enough at the surface of the steel, the passive coating breaks down and rusting ensues. Since the rust takes up considerably more space than the steel it was produced from, the pressures can become high enough to rupture the concrete overlaying the steel (much like a tree root opening a crack in a rock). Concrete bridge decks fail at the highest rate since they have so much steel and more deicer is applied to them because ice forms there first but the rest of the bridge suffers also from splash and seepage.

Concrete slabs will crack eventually and it will happen more quickly if you haven't added sufficient expansion joints. Since you can't totally prevent the cracks, your best bet is to use reinforcing steel so that the cracks won't go anywhere once they form. If you put really heavy loads on the driveway, you'll have to include load transfer steel at each expansion joint.

If you absolutely must use large amounts of chloride deicers, then consider reinforcing with epoxy coated rebar. If you use epoxy coated rebar, you'll have to be on your toes to ensure that the epoxy coating isn't damaged during placement of the steel and you'll have to inspect the epoxy coating before placement to be sure it wasn't damaged (chipped, cracked) during shipping/handling. Damaged epoxy coating can sometimes cause more problems than not having epoxy coating at all.

Harry