There should have been some form of vibration during that pour to eliminate the voids in the finished product. A 4-5 inch slump is too much. A 1-2 inch slump with proper vibration would be better. After finishing the concrete, a sealing agent should have been sprayed on the surface to reduce the rate of moisture loss during the curing process. The more moisture in the concrete during the curing process lends toward a stronger finished product and a reduction in cracking.