The responsibility for delivering the right concrete mix and for its meeting all of the requirements of the specification and the contractor's needs is shared by the contractor, ready mix producer and the owner or specifying engineer who is the owner's representative. Each has to be thoroughly familiar with the contents of the specification and all three must be in agreement on its interpretation.
CHECKING THE SPECIFICATION
There are several factors in the specification that must be checked: strength; cement content; water-cement ratio; cement type; maximum aggregate size; fly ash; air entrainment; slump; admixtures; delivery time; concrete temperature; and curing.
PREPARATION AT THE SITE
It is impossible to overstress the importance of doing everything that can be done in advance, and of preparing for every predictable eventuality before the concrete is ordered.