- Develop and Approve a Project Mockup
A representative mockup should be completed and approved before the primary placement. The mockup establishes realistic expectations for color, texture, finishing, curing, jointing, and overall appearance.
The mockup should use the same:
- Concrete mixture proportions
- Cementitious materials and sources
- Pigment type and dosage
- Aggregates
- Chemical admixtures
- Target slump
- Placement method
- Finishing tools and techniques
- Curing materials
- Sealer, when applicable
A full-scale mockup is more representative than a small laboratory sample because it captures the effects of actual batching, placement, finishing, weather, and curing conditions.
The approved mockup should be used as the visual reference for the project. Some variation should still be expected because concrete is manufactured from natural materials and its appearance is influenced by environmental and construction conditions.
- Use Pigments Intended for Integrally Colored Concrete
Pigments should comply with ASTM C979/C979M, Standard Specification for Pigments for Integrally Colored Concrete.
Pigment quantities should be based on the approved concrete mixture and calculated according to the pigment manufacturer’s recommended dosage method. Depending on the color system, pigment dosage may be based on the amount of Portland cement or the total cementitious material content.
Any change in cementitious content, cement source, supplementary cementitious material percentage, or pigment dosage should be reviewed because it may alter the final color.
- Add Integral Color at the Ready-Mix Plant
Integral color should preferably be added at the ready-mix production facility rather than manually added at the project site.
Plant-controlled addition provides improved control over:
- Pigment quantity
- Addition sequence
- Mixing time
- Batch-to-batch consistency
- Documentation
- Quality assurance
- Employee exposure to powdered pigment
The pigment should be added using a consistent sequence that promotes complete dispersion. Adequate mixing time should be provided before the concrete is discharged.
When color must be added at the job site, a written procedure should be established that addresses:
- Pigment quantity
- Existing water in the truck
- Addition sequence
- Required mixer revolutions
- Minimum mixing time
- Slump verification
- Documentation of the addition
Color should not be added inconsistently from truck to truck or without oversight from the concrete producer.
- Maintain Consistent Concrete Materials
The appearance of integrally colored concrete is affected by all materials in the mixture, not only the pigment.
For the best color consistency, the project should use the same:
- Cement type and source
- Supplementary cementitious material source
- Aggregate sources
- Pigment product and dosage
- Chemical admixture products
- Mixture proportions
- Water-to-cementitious-materials ratio
Changing cement sources during a project may alter the background shade of the concrete. Aggregate color can also influence the final appearance, especially when the surface is broomed, exposed, polished, or otherwise textured.
Material substitutions should not be made during the colored portion of the project without evaluating their effect on appearance and performance.
- Cementitious Content and Paste Volume
There is no universal ASTM or ACI minimum cement content established specifically for pigment dispersion. However, the concrete mixture should contain adequate cementitious paste to provide uniform pigment distribution, acceptable workability, proper consolidation, and a consistent finish.
As a practical starting point, a minimum cementitious content of approximately five sacks per cubic yard—about 470 pounds per cubic yard—is recommended for conventional integrally colored flatwork.
This should be treated as a mixture-design recommendation rather than a prescriptive industry standard. The appropriate cementitious content may vary based on:
- Aggregate grading
- Maximum aggregate size
- Desired finish
- Pigment dosage
- Placement conditions
- Strength requirements
- Durability requirements
- Use of supplementary cementitious materials
Increasing cementitious content beyond what is needed does not automatically improve color consistency and may increase shrinkage, heat generation, curling, and cracking potential.
The final mixture should provide sufficient paste for finishing without relying on excessive water.
- Use of Supplementary Cementitious Materials
Supplementary cementitious materials such as fly ash, slag cement, and natural pozzolans can be used successfully in integrally colored concrete.
A straight-cement mixture is not automatically required and is not necessarily superior. The primary concern is maintaining consistent material sources and replacement percentages throughout the project.
SCMs may influence:
- Base concrete color
- Pigment response
- Setting time
- Bleeding
- Finishing characteristics
- Early-age color development
- Long-term appearance
Fly ash can affect the shade depending on its source, carbon content, and natural color. Slag cement often produces a lighter base color, which may change the appearance of the selected pigment.
The proposed cementitious system should be evaluated in the project mockup. Once approved, the SCM type, source, and replacement percentage should remain consistent.
A target slump of approximately 4 inches is generally recommended for conventional integrally colored flatwork, with a maximum target of approximately 5 inches unless the placement requires a different engineered workability.
The most important requirement is consistency from load to load.
A higher slump should be achieved using an approved water-reducing or high-range water-reducing admixture rather than uncontrolled water additions.
Excessively high or inconsistent slump can contribute to:
- Color variation
- Segregation
- Bleeding
- Surface laitance
- Uneven finishing
- Increased shrinkage
- Reduced surface durability
- Lower compressive strength
Specialized placements, congested reinforcement, pumping conditions, or architectural applications may require a different slump. In those situations, the selected slump and admixture system should be demonstrated during the mockup.
