scope:

ACI 211.1 provides methods for selecting proportions for concrete mixtures. Concrete may require adjustments to the mixture proportions throughout the course of the project due to the normal variation of the materials used in production, and the various conditions under which it will be delivered, placed, consolidated, and finished. The concrete properties required in the hardened state may also require adjustments to the mixture proportions. It is important to note that no document can replace experience with the materials at hand when deciding what adjustments need to be made for a concrete mixture.