Concrete slab specification: Section 03 30 00 guide spec

This is a CSI 3-part guide specification for interior concrete slabs-on-grade that will receive a finished floor. It covers the four decisions made before and during the pour that determine what the finish can achieve: subgrade, mix design, flatness, and curing. Architects, engineers, and general contractors can copy it into a project manual or edit the bracketed values. It reflects the Pour-4-Polish discipline Bel Covo runs on every slab it places.

How do you use this guide specification?

Most projects run this section as supplementary requirements attached to the structural concrete section, not as a replacement for it. Three rules keep that arrangement clean:

1. Name the scheduled finish in Part 1. Every requirement here derives from what the floor becomes. A slab scheduled for mechanical polishing carries different mix, flatness, and curing requirements than one scheduled for a resinous coating.
2. Edit the bracketed values. Flatness numbers, vapor retarder class and thickness, cure duration, and lap dimensions are project decisions.
3. Keep the handoff article. Article 3.7 delivers the mix design, curing method, flatness survey, and placement dates to the finish installer. That single handoff closes out the most common source of disputes on a two-contract floor.

Section 03 30 00: cast-in-place concrete

Part 1: general requirements

1.1 Summary

Work of this section includes interior concrete slabs-on-grade scheduled to receive a finished floor: subgrade preparation and compaction, vapor retarder placement, mix design selected for the scheduled finish, placement and consolidation, flatness and levelness verification, finishing, and curing.

This section states the requirements the finish imposes on the slab. It does not replace structural design. Structural thickness, reinforcement design, load capacity, and joint layout remain the responsibility of the structural engineer of record. Where a requirement in this section conflicts with the structural documents, the structural documents govern and the conflict is reported before placement.

1.2 Related sections

• Section 03 35 43, Polished Concrete Finishing: mechanical polishing of slabs placed under this section.
• Section 09 67 23, Resinous Flooring: fluid-applied resinous systems over slabs placed under this section.
• Section 03 01 30, Maintenance of Cast-in-Place Concrete: resurfacing and repair of existing slabs.
• Section 07 26 00, Vapor Retarders: under-slab moisture protection where specified separately.

1.3 References

• ACI 302.1R, Guide to Concrete Floor and Slab Construction.
• ACI 302.2R, Guide to Concrete Floor and Slab Construction Containing a Vapor Retarder or Vapor Barrier.
• ACI 318, Building Code Requirements for Structural Concrete.
• ASTM E1155, Standard Test Method for Determining FF Floor Flatness and FL Floor Levelness Numbers.
• ASTM E1745, Standard Specification for Plastic Water Vapor Retarders Used in Contact with Soil or Granular Fill under Concrete Slabs.
• ASTM C31, C39, C143, and C231 for sampling, strength, slump, and air content.

1.4 Definitions

• FF / FL: floor flatness and floor levelness numbers measured per ASTM E1155. Higher numbers mean a flatter or more level floor.
• Finish-ready slab: a slab-on-grade placed, finished, and cured so the scheduled finish can be installed without corrective grinding beyond normal surface preparation.
• Dissipating cure: a curing compound that breaks down and releases the surface, as distinct from a membrane cure that must be mechanically removed before a finish will bond.
• Vapor retarder: the sheet membrane placed under the slab to limit water vapor transmission into the floor assembly.

1.5 Submittals

• Concrete mix design for each class of concrete, stating cement content, aggregate gradation, water-cement ratio, and admixtures, with the scheduled finish identified.
• Vapor retarder product data showing compliance with ASTM E1745 Class [A].
• Curing method and product data, with confirmation of compatibility with the scheduled finish.
• Subgrade compaction test reports.
• Flatness and levelness survey results per Article 3.5.
• Joint layout coordinated with the structural documents and with the finish scope.

1.6 Quality assurance

• Placing and finishing crew experienced with slabs placed to receive the scheduled finish.
• Field testing per ASTM C31: strength cylinders, slump, and air content at the frequency stated in the structural documents.
• Preinstallation conference attended by the concrete placer, the finish installer, and the general contractor before the first placement.

1.7 Project conditions

• Do not place concrete on frozen, saturated, or unprepared subgrade.
• Protect placed concrete from precipitation, freezing, and rapid drying for the duration of the curing period.
• Building enclosed or the slab otherwise protected where the schedule requires an interior finish.

Part 2: products

2.1 Basis of design

The basis of design is the Pour-4-Polish discipline by Bel Covo, which governs four decisions that determine whether a slab can accept its scheduled finish: Set (subgrade), Portland (mix design), Even (flatness), and Cure (curing protocol). Equivalent approaches that meet the requirements of this section may be submitted for approval.

2.2 Concrete materials

• Portland cement per ASTM C150, Type [I/II].
• Aggregate per ASTM C33. For slabs scheduled to receive mechanical polishing, coordinate coarse aggregate size, color, and hardness with the specified aggregate exposure class; the aggregate that appears in a polished floor is the aggregate placed in the slab.
• Water-reducing and air-entraining admixtures as required. Do not use calcium chloride accelerators in slabs scheduled to receive a finish.

2.3 Mix design by scheduled finish

Specify the mix for the finish, not for the structural minimum alone. A slab batched to pass inspection and nothing more transfers cost to the finish scope.

2.4 Vapor retarder

Sheet vapor retarder per ASTM E1745, Class [A], minimum [15] mil. Place the membrane in direct contact with the underside of the slab per ACI 302.2R. Do not place a granular blotter layer between the vapor retarder and the concrete: a layer above the membrane holds water indefinitely and drives vapor transmission failures in the finish months after closeout.

2.5 Curing materials

Dissipating curing compound, wet cure, or curing blanket compatible with the scheduled finish. Standard membrane-forming curing compounds are not acceptable on slabs scheduled to receive polishing, staining, or resinous coatings unless the finish scope has priced their mechanical removal.

Part 3: execution

Each step below states its objectives, its hazards, and the key best practices and methods that matter to the finished floor.

3.1 Subgrade preparation

Objectives:

• Uniform bearing at the density stated in the structural documents, verified by test before the vapor retarder is placed.

Hazards:

• Do not bridge soft spots or differential bearing conditions with additional concrete.

Key best practices and methods:

• Correct soft spots before the membrane goes down, and keep the compaction test reports with the slab records.

3.2 Vapor retarder installation

Objectives:

• A continuous membrane under the full slab, with laps and penetrations sealed.

Hazards:

• Punctures left unrepaired before placement defeat the membrane.

Key best practices and methods:

• Lap seams [6] inches minimum, seal laps and penetrations per the manufacturer instructions, and repair punctures before placement.

3.3 Placement and consolidation

Objectives:

• Concrete placed and consolidated at the designed water-cement ratio.

Hazards:

• Water added at the truck to improve workability raises the water-cement ratio, weakens the paste, and shows in a polished surface as a soft, dusting field.

Key best practices and methods:

• Adjust workability through the mix design and admixtures, not site water.

3.4 Finishing

Objectives:

• The surface the scheduled finish requires.

Hazards:

• Burnish marks and blisters on a slab scheduled for polishing survive into the finished floor.
• Trowel imprints and boot prints left in the surface become deviations from grade for the finish scope; Section 03 35 43 defines the remediation decision the Owner then has to make.

Key best practices and methods:

• A slab scheduled for polishing receives a hard trowel finish free of burnish marks and blisters. A slab scheduled for a resinous coating does not require a burnished surface, because the coating scope grinds to profile regardless.

3.5 Flatness and levelness

Objectives:

• [FF 35 / FL 25] minimum for slabs scheduled to receive mechanical polishing, exceeding the structural minimum that governs an unfinished slab.

Hazards:

• Flatness and smoothness are different properties. A slab can be smooth and still be out of tolerance for flatness, and it is flatness that decides how much grinding the finish scope has to buy back.
• Low spots that exceed a 4 percent slope between two adjacent grade points are not accessible with standard polishing tooling. Each one becomes a remediation decision under Section 03 35 43.

Key best practices and methods:

• Measure per ASTM E1155 within [72] hours of placement and before the placing crew leaves the project. Report values below the specified numbers before the finish scope mobilizes.

3.6 Curing

Objectives:

• Cure by the approved method for [7] days minimum, with a method compatible with the scheduled finish.

Hazards:

• A membrane-forming compound that does not dissipate must be mechanically removed before any finish will bond.
• On wet-cured slabs, the curing medium itself can stain the surface.

Key best practices and methods:

• Where a curing compound is used, confirm in writing that it dissipates or is otherwise compatible with the scheduled finish. Where wet cure is used, protect the slab from staining by the curing medium.

3.7 Protection and handoff

Objectives:

• The slab protected until the finish scope mobilizes, with its records delivered.

Hazards:

• Traffic, staining, adhesives, and coring debris between placement and finish mobilization.

Key best practices and methods:

• Deliver to the finish installer: the approved mix design, the curing method used, the flatness survey, and the placement dates.

What does the finish require from the pour?

Each finish imposes a different set of demands on the slab beneath it. Specifying all three the same way is how projects end up grinding a floor they already paid to place.

The polished column is the demanding one, because in a polished floor the paste and the aggregate placed on pour day are the finished wear surface. Nothing gets added later to cover a decision made at the truck.

Where does this section stop and the engineer’s begin?

This section governs what the finish needs. The structural engineer of record governs what the building needs: slab thickness, reinforcement design, load capacity, and joint layout. The two rarely conflict, and where they do, the structural documents win and the conflict gets reported before placement rather than discovered after.

That boundary is worth stating in writing on any project where the concrete sub and the flooring sub are the same company. Bel Covo places slabs and finishes them, and we are not the engineer of record on either scope. Our general contractor page covers how the combined subcontract works.

From the field

Concrete slabs we placed

Related documents

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