It is far better to specify concrete performance requirements than to specify mixture proportions. Let the concrete supplier determine the mixture proportions to meet the needs of the project. Don't mix prescriptive and performance elements in the same specification.

Make the contractor aware that a test placement is required. Specify that the same equipment and finishers to be used on the actual placement are required for the test placement.

Specify the type of finish that will be required. The exact degree of finish can be established during the test placement.

Specify that the contractor must be prepared to protect the concrete against plastic shrinkage cracking. Protection should roll directly over into curing. Require submittal of a protection and curing plan.