Polished concrete guide for builders

ACI SPEC-310.1-20 applies when incorporated into the project Contract Documents. It sets requirements for the polished slab finish, while project-specific documents govern a conflict. It excludes construction of the cast-in-place slab, so the concrete and polishing requirements need to be coordinated. Its Notes to Specifiers are guidance, not part of the specification.

The Concrete Polishing Council (CPC) guide specification also applies through adoption into the project documents. CPC position statements provide trade-association guidance. Manufacturer instructions and individual project specifications retain their own scope.

Our guide to using ACI 310.1-20 in a polished concrete specification covers its project choices, defaults and approval requirements.

CPC recommends coordinating the concrete and polishing subcontracts together so the teams can discuss and price changes in flatness, floor protection and the work needed to achieve the intended appearance.

The CPC guide specification calls for a preinstallation conference before concrete placement. Its review covers:

• The contract requirements, approved submittals, mockup and representative work areas.
• The concrete mix, curing procedures and projected strength tests.
• Substrate preparation and work performed by other trades.
• Grinding, honing and polishing stages, equipment, liquid treatments and slurry or dust disposal.
• Project phasing and protection after polishing.

Decisions and agreements are recorded and shared with everyone attending. The preinstallation coordination guide covers the meeting, submittals and scheduling in detail.

The CPC guide specification requires a mockup using the project’s concrete mix before polishing work starts. The Architect approves the submittal selections, aggregate exposure, appearance level and color when specified. CPC also recommends making samples on the actual slab to be polished.

The approved mockup remains protected and undisturbed as the reference for judging the completed work. Its approval does not approve departures from the contract unless the Architect specifically accepts those departures in writing.

Planning and approving a polished-concrete mockup explains what the sample must establish before production work proceeds.

ACI SPEC-310.1-20 treats aggregate exposure, DOI appearance, specular gloss and haze as separate properties. Each is specified for its area and judged against the approved mockup.

Traction needs its own evaluation. A DCOF result under ANSI A326.3 compares surfaces under controlled conditions; it does not by itself make a floor suitable for a project or predict whether someone will slip. Our slip-resistance guide explains how traction is tested and evaluated.

Testing and accepting the installed finish explains how to organize appearance criteria, traction evidence and project acceptance.

Slab placement and finishing affect the later polished appearance. Changes in flatness over time, including curling in slabs-on-ground, also belong in the early coordination discussion.

The guide to new concrete slabs intended for polishing covers the slab-design and placement decisions that need to align with the specified finish.

An existing slab needs a condition survey before repair quantities and costs can be established, according to CPC. ACI requires examination for curling, stains, cracks, trowel marks and other defects that would prevent the specified finish.

Before polishing, ACI SPEC-310.1-20 requires confirmation of curing and surface hardness, with unsatisfactory conditions corrected or covered by an approved remediation plan. A hardness reading alone does not establish readiness; the surface hardness guide covers the threshold.

Assessing an existing slab before polishing brings together the condition survey, preparation checks and consequences of removing previous coverings.

Plan surface repairs, crack treatment and joint filling before polishing.

CPC describes semirigid polyurea or epoxy joint filler as protection against wheel-impact damage at contraction and construction joint edges. These fillers are relatively stiff and have limited ability to accommodate widening joints.

The guide to cracks, surface repairs and joints covers how these treatments fit into polished-floor installation.

ACI requires grinding and polishing to follow the method used for the approved mockup, with thorough cleaning between grit levels.

Use the following guides to plan the individual installation steps:

• Densifier application and surface preparation
• Stain guards and burnishing
• Jobsite preparation for concrete polishing
• Dye application and residue checks
• Return to traffic, water and full cure
• Task-specific silica controls
• Slurry containment and waste routing
• Edges and transitions

The floor protection plan needs to cover both the period after slab placement and the period after polishing. Under ACI, the completed finish is protected until Substantial Completion.

Construction protection and trade access covers protection responsibilities, equipment, coverings and work by other trades.

The CPC guide specification calls for maintenance instructions covering methods, frequency and cleaning products or practices that could damage the finish. Define the repair and treatment records to be included in the closeout documentation.

The closeout and maintenance guide covers the records and instructions to deliver with the accepted floor.