Foot traffic at 24 to 48 hours, a passenger car at seven days, and a loaded truck or RV at 28 days when the mix has reached its design strength. In hot weather, keep it wet or covered for the first seven days or you lose strength at the surface no matter what the ticket says.

If anything heavier than a pickup will ever sit on it, yes. Going from four inches to six with #4 rebar adds roughly $3 to $5 per square foot but multiplies the load the slab can carry, and it is far cheaper than replacing a cracked four inch slab in year three.

Usually because it is a four inch pour with no rebar, no base rock, no demo, and no apron. Ask each bidder for the same section on paper and the numbers usually converge within about fifteen percent.

No. Steel does not prevent cracks, it holds them tight and keeps the pieces working together. A slab with #4 bar at 18 inches on center will still crack at the control joints, but you get hairline joints instead of an open half-inch step you can catch a tire on.

The active moisture zone is usually the top four to eight feet, though it can run deeper next to a mature tree in a long drought. That is why deepened edges and turned-down beams help a driveway more than simply adding thickness across the middle.

Thickness alone is the expensive way to solve half the problem. A six inch slab on untreated, uncompacted clay will crack too, just in bigger pieces. Base preparation and drainage do more per dollar than the last two inches of concrete.