Contractors or homeowners should begin with excavating by removing all organic materials such as sludge, tree roots, leaves, wood, etc. Concrete should be placed on a graded granular fill and compacted (if necessary). This eliminates settlement and variations in thickness, and allows drainage under the slab. Shortly before placing the concrete, wet the forms and the subgrade. Do not make the sub-grade so wet that puddles form. Do not place the concrete in muddy, standing water or on frozen subgrade. Before concrete is placed, install expansion joint material wherever the concrete is placed against buildings, steps, walls, columns, existing slabs, etc. These joints allow movement of the slab and help reduce cracking caused when such movements are restrained. Additional water may be added to the concrete, when the truck first arrives, to a maximum 6” slump. However, excessive water is detrimental to achieving the design strength of the concrete. The concrete should be placed in a manner that keeps wheelbarrow or buggy movement to a minimum. Spread the concrete with a come along. Do not use any tool that will cause segregation. Use a wood or metal straight edge to strike off and to level the concrete.