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ACI 310.1-20
ACI 310.1-20, Specification for Polished Concrete Slab Finishes, establishes requirements for a polished floor when incorporated into the project’s Contract Documents. The specifier still needs to select the finish, assign testing responsibilities and decide which optional provisions apply. Construction of the concrete slab requires a separate specification.
This guide covers the 2020 edition. For the broader process, see our polished concrete guide for builders.
Incorporate ACI 310.1-20 and establish precedence
The Notes to Specifiers direct use of the specification in its entirety by reference or incorporation, rather than copying isolated clauses into the project specification.
Three distinctions matter:
- Project-specific Contract Documents govern a conflict with ACI 310.1-20 (§1.1.3).
- ACI 310.1-20 governs a conflict with the materials and testing standards it references (§1.1.5).
- Cast-in-place slab construction is outside its scope (§1.1.4(a)).
If another adopted ACI specification overlaps, the Notes to Specifiers direct the specifier to identify the conflicts and state which requirements govern. The project specification also needs to assign responsibilities to participants other than the Contractor.
The Notes to Specifiers and the Mandatory and Optional Requirements Checklists are guidance, not part of the specification. Use them to identify project requirements and select alternatives or additions for the Contract Documents.
Separate defaults from optional requirements
ACI uses two phrases with different effects:
| Wording | Meaning for the project |
|---|---|
| Unless otherwise specified | A default applies unless the Contract Documents replace it. |
| If specified | The provision applies only when the Contract Documents include it; there is no default requirement. |
For example, the preconstruction conference applies if specified (§1.8.2), and the quality-control-plan submittal applies if required (§1.5.3). Surface treatments also require a project selection (§2.1.4.1).
Specify the finish for each area
| Finish property | Project decision and ACI requirement |
|---|---|
| Aggregate exposure | Select the class for each area. It must meet Table 3.2.3.1 and conform to the approved mockup. |
| Distinctness of image (DOI) | Select the appearance level for each area. It must meet Table 3.2.4.1 and conform to the approved mockup. |
| Specular gloss | State the required gloss where applicable. Measure it before protectant application and compare it with the approved mockup. |
| Haze | The default is an index below 12 and conformance with the approved mockup, unless otherwise specified. |
When the slab finish is unspecified, §3.2.7 defaults to no color, Class B aggregate exposure and Level 3 DOI appearance. The haze requirement remains below 12 unless replaced in the project documents.
DOI, specular gloss and haze are separate measurements. Our guide to specifying polished concrete appearance covers the criteria and reference editions.
Set approvals and the mockup before production
Work relating to a submittal cannot proceed until the Architect/Engineer approves it in writing (§1.5.1). Proposed alternatives also require written approval from the Architect/Engineer, Owner’s Representative, or both (§1.1.6).
If a preconstruction conference is specified, distribute its decisions and agreements to attendees within seven days and before placement of the slabs to be polished (§1.8.2.2). The coordination and approvals guide covers these preparations.
Before polishing, provide a field mockup to verify selections and demonstrate the finish. Unless otherwise specified, use the production procedures, equipment and materials. Protect the mockup and retain it until final acceptance (§1.8.3).
Mockup approval does not authorize departures from the Contract Documents without the Architect/Engineer’s specific written approval. Production grinding and polishing must follow the method used to achieve the approved mockup.
Assign testing responsibility explicitly
Unless otherwise specified, §1.6.1.1 assigns the listed quality-assurance services to the Owner’s Testing Agency when polished work exceeds 5,000 square feet. For work under 5,000 square feet, the Notes to Specifiers call for identifying who performs testing; otherwise, testing services will not be performed.
Those two provisions leave exactly 5,000 square feet unaddressed. Assign testing responsibility explicitly in the project documents rather than treating the boundary as an exemption.
When testing is required by the Owner or Architect/Engineer, §1.6.1.2(a) identifies:
| Measurement | Test method |
|---|---|
| Specular gloss | ASTM D523 |
| Distinctness of image | ASTM D5767 |
| Haze | ASTM D4039 |
Where the specified testing frequency applies, specular gloss is measured at three locations for areas up to 1,000 square feet, with one additional test for each additional 1,000 square feet or fraction. Locations are selected randomly within test areas distributed across the floor (§1.6.1.3(a)). This sampling rule does not set the acceptance values.
Coordinate access, notice and reporting
Unless otherwise specified, the Contractor provides the Owner’s Testing Agency with site access and at least 24 hours’ notice of operations requiring the testing services in clauses 1.6.1.2(a)–(b). The notice supports scheduling, review of project requirements and assignment of personnel.
When the Owner or Architect/Engineer requires the gloss, DOI and haze testing in clause 1.6.1.2(a), it takes place at least two weeks before the Owner’s possession. Where the services in clause 1.6.1.1 apply, the Owner’s Testing Agency reports test and inspection results to the Owner, Architect/Engineer, Contractor and other relevant parties within seven days after the tests and inspections.
These reporting duties are assigned to the Owner’s Testing Agency, not transferred to the Contractor. The agency cannot accept or reject portions of the Work or change the Contract Document requirements; its report records results rather than determining acceptance.
Before work begins, confirm the slab and site meet ACI’s substrate-acceptance requirements, including correction or written approval of a remediation plan for unsatisfactory conditions.
Resolve the surface-treatment wording
ACI requires a gloss-enhancing and stain-resistant treatment only if specified. One treatment category has different wording in two places:
| Location | Description of a stain-resistant, gloss-enhancing treatment |
|---|---|
| Definitions, §1.3 | Water-based and film-forming; penetrates polished and densified concrete. |
| Product provision, §2.1.4.1(b) | Water- or solvent-based and film-forming; penetrates or adheres to polished and densified concrete. |
Resolve the applicable product requirements in the project documents or seek clarification from the issuer. Do not exclude a solvent-based or adhering product solely by reading the definition in isolation.
Apply specified treatments according to the manufacturer’s published instructions. Burnishing follows the manufacturer’s instructions and the treatment’s proper dry time.
State the acceptance values clearly
ACI §1.9.2.1 requires comparability with the accepted mockup, as determined by the Architect/Engineer, and compliance of the average DOI, specular gloss and haze measurements with the specified values.
The printed references need attention: §1.9.2.1 points to §§3.4.4–3.4.6, which concern honing, polishing and surface treatment. The appearance requirements sit in §§3.2.4–3.2.6. State the intended acceptance values explicitly in the Contract Documents; this guide does not treat that discrepancy as an issued correction.
Submit and verify corrective work
ACI requires submission of proposed repair methods, materials and modifications needed to meet the Contract Documents (§1.9.1.3). Areas not accepted by the Architect/Engineer are repaired in accordance with §2.1.2; repair products and equipment follow the Contract Documents and manufacturer’s instructions to match the approved mockup (§§3.5.1.1–3.5.1.2).
Work repaired into compliance is accepted under §1.9.1.1. Work that cannot be brought into compliance is subject to rejection under §1.9.1.2; the wording does not make rejection automatic. The installed-finish acceptance guide covers the measurements and comparisons used in that review.
For surface-treatment over-application evidenced by streaking, §3.4.6.4 requires complete product removal from the affected areas and replacement with unused product. This is a condition-specific instruction, not a finding that every streak has the same cause.
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Frequently Asked Questions
No. ACI 310.1-20 covers polished slab finishes and excludes cast-in-place slab construction. Projects adopting it need separate, coordinated requirements for the slab itself.
In ACI 310.1-20, “if specified” applies only when the Contract Documents include the requirement. “Unless otherwise specified” establishes a default that applies unless the Contract Documents replace it.
No. The conference applies if specified. When required, its decisions and agreements must be distributed to attendees within seven days and before placement of the slabs to be polished.
ACI 310.1-20’s testing assignment provisions leave that boundary unaddressed: the Owner’s Testing Agency default concerns work exceeding 5,000 square feet, while the Notes to Specifiers address work below it. The project documents should explicitly assign testing responsibility.
No. Where specular gloss is required under ACI 310.1-20, it must be measured before protectant application and conform to the approved mockup. Later measurements do not replace that required check.
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