Bricks, Masonry, Asphalt and Concrete - Bad concrete Job?

I had a cement contractor poor a 16x26 garage slab and a 16x20' approach. By the end of the day they poured, the approach started cracking in about 5 places. Cracks about 5 feet long in random areas. It appears these are not surface cracks. The slab is 4 inches thick with rebar. The garage slab is perfect. Did they pour the approach too wet? Bad mix? Is this common? What should I do. I have not paid for this yet and am reluctant too until I hear from the contractor. I notified him of the cracking the next day and he said he would be by to look at it.

Did they tool crack control joints in the slab when they poured it? They should have, to make the concrete crack there instead of randomly. Even so, for concrete that fresh to crack in so many places, I would bet that it was poured awfully wet and that the base they poured on was bone dry.
I've seen a basement floor exhibit widespread cracking while the finishers were still in the process of finishing it. They had poured it really wet, and it was a hot, sunny day. Immediate cracking is almost always from shrinkage from pouring too wet.

You have confirmed what I thought. They did saw joints in the pad the next morning. Will this continue to get worse or is what I have going to be the worst? I do not want to pay for this work or at the least the contractor should offer to redo the pad. If the concrete was poured too wet that is the falt of the contractor. Am I being unreasonable here?

First, see what the contractor is willing to do. He may be perfectly willing to tear out and re-do. If he is uncooperative, call the ready mix plant that supplied the concrete and ask for a copy of the batch ticket. It will tell you at what slump the concrete was delivered, and if you are lucky the driver will have written down how much water was added on site. Some drivers don't write in the added water but many do. The driver's name will also be on the ticket so you could ask him personally about adding water or the conditions on site that day. If 15 or 20 gallons were added, you'd have some ammo to confront the contractor with. An on-site meeting with a representative of the ready mix plant would help too. Take a lot of photos in case it needs to go to court.
If there is rebar in the slab, it may not get any worse, but who knows? Good luck.

Pecos

OK, Talked with the contractor and he offered to take $300 off the job if I would accept it as is. He claimed the cracking was due to weather conditions. I still believe it was poured too wet. I can live with it the way it is if it does not get worse. Any advise on what to do?