What is new in ACI 301-20, Specifications for Concrete Construction

Photos courtesy American Institute of Concrete
Photos courtesy American Institute of Concrete

by Michelle L. Wilson, FACI

The American Concrete Institute (ACI) published ACI 301-20, Specifications for Concrete Construction, in October 2020. This standard specification establishes criteria for concrete construction that can be incorporated by reference into contract documents. ACI 301 is written to the contractor.

When an architect or engineer (A/E) cites ACI 301, the document is intended to be adopted in its entirety into the contract documents. Requirements set forth in ACI 301-20 meet the minimum requirements in ACI 318-19, Building Code Requirements for Structural Concrete. Approximately every five years, ACI 301 is updated to complement the ACI 318 code cycle.

A/E can apply the reference specifications of ACI 301 to many forms of concrete construction. A notable change was made in ACI 301-20 to the specification’s title (previously the document was titled ACI 301-16, Specifications for Structural Concrete). The new specification title recognizes the breadth of the document. For example, ACI 301 covers industrial floor slabs and architectural concrete.

ACI 301-20 is organized into two parts, distinguishing basic items that are always required for concrete construction from those that may be needed on a particular project. The first five sections cover the core requirements for most cast-in-place concrete. Sections 6 to 14 cover specialty applications that may be designated on a project.

ACI 301-20 contains the following sections:

  • Section 1—General Requirements;
  • Section 2—Formwork and Formwork Accessories;
  • Section 3—Reinforcement and Reinforcement Supports;
  • Section 4—Concrete Mixtures;
  • Section 5—Handling, Placing, and Constructing;
  • Section 6—Architectural Concrete;
  • Section 7—Lightweight Concrete;
  • Section 8—Mass Concrete;
  • Section 9—Post-tensioned Concrete;
  • Section 10—Shrinkage-Compensating Concrete for Interior Slabs;
  • Section 11—Industrial Floor Slabs;
  • Section 12—Tilt-up Construction;
  • Section 13—Precast Structural Concrete; and
  • Section 14—Precast Architectural Concrete.

ACI 301-20 is not a complete specification until the specifier reviews and completes the instructions to the A/E, listed at the end of the document titled “Notes to Specifier.” It includes two checklists for the A/E to use in incorporating ACI 301 into the concrete specification. The “Mandatory Requirements Checklist,” indicates specific qualities, procedures, and performance criteria the specifier must include in a project specification that are not defined in ACI 301-20. The “Optional Requirements Checklist,” identifies choices and alternatives the specifier can include as requirements in a specification. These checklists provide information allowing specifiers and owners to have options to change or customize their specifications where appropriate. The specifier should review each of the items in the checklists and make adjustments to the needs of a particular project by including those selected alternatives or additions as mandatory requirements in the project specification.

What is new in 2020

This revision expanded the scope of ACI 301 and revised many of the requirements that have been in previous versions. The scope of the document was expanded to include shotcrete, internal curing, mineral fillers, and recycled concrete aggregates. Evaluation requirements for concrete made with self-consolidating concrete and structures designed for modulus of elasticity were also included in the update.

Compliance details throughout ACI 301-20 have been updated to align with ACI 318-19. For example, ACI 318-19 saw a major reorganization of Chapter 26, “Construction Documents and Inspection.” Inspection requirements were unified in the chapter. It was also recognized many projects have roles for multiple design engineers; the updated Chapter 26 provided a framework for their coordination of work. Many of the changes in 301-20 were included to reflect the requirements in Chapter 26 on information the engineer must provide in the construction documents to achieve compliance with ACI 318-19.

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