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SECTION 03400

INTEGRALLY COLORED PRECAST CONCRETE

Davis Colors add color to the design of concrete buildings and structures. Integral colors are economical to use because they are mixed right into the concrete at the plant. In addition, integral colors are permanent and do not require periodic refinishing as can coatings and applied finishes. Davis Colors are made with pure, concentrated pigments especially treated for mixing into concrete. They are lightfast, alkali-resistant.weather resistant, and formulated to give long-lasting appeal to concrete.

In general, integrally colored precast concrete is produced the same way as high-quality uncolored precast concrete. This document suggests specification provisions which pertain to colored precast concrete. INCORPORATE INFORMATION FROM THIS GUIDE SPECIFICATION INTO A COMPLETE MASTER SPECIFICATION FOR PRECAST CONCRETE. Then edit to meet project requirements. Prepare specification in accordance with PCI recommendations and other applicable industry guidelines. Show locations of colored precast concrete on Drawings or in Schedules.

This document is available in word processing format from Davis Colors via the Internet or diskette. For product literature or technical assistance about pigments, contact Davis Colors at:

East: 800-638-4444 (301-210-3400 Maryland)
West: 800-356-4848 (213-269-7311 California)

 

PART 1 GENERAL

 

1.01 SUMMARY

    A. Section Includes: Integrally colored [structural] [and] [architectural] precast concrete.

Davis Colors can also be specified in other specification sections. Include the paragraph below if you wish to coordinate precast concrete colors with colors specified in other sections. Note, however, that an exact color match of precast concrete and work specified in other sections may not be practical because of the differences in the various manufacturing and construction processes; make final color selections on the basis of product samples or mock-ups.

Guide specifications for other types of colored concrete work are also available from Davis Colors.

    B. Related Sections:

    1. Section [02750 - Portland Cement Concrete paving]: Coordination of sample submittal [and color selection].
    2. Section [02780 - Concrete Unit pavers]: Coordination of sample submittal [and color selection].
    3. Section [03300 - Integrally Colored Cast-In-Place Concrete]: Coordination of sample submittal [and color selection].
    4. Section [04200 - Integrally Colored Masonry Units]: Coordination of sample submittal [and color selection] for [concrete masonry units] [and] [colored mortar].
    5. Section [07320 - Concrete Roofing tiles]: Color coordination.
    6. Section [07900 - Joint Sealers]: Colored sealants for joints.

 

 

1.02 REFERENCES

Edit references to include standards used in Project specifications. For a copy of ASTM C979, contact Davis Colors.

Other useful publications about colored precast concrete include:

PCA PA124.H - Finishing Concrete Slabs with Color and Texture.
PCA SP021A - Color and Texture in Architectural Concrete.

    A. American Concrete Institute:

    1. ACI 301 - Structural Concrete for Buildings.
    2. ACI 304 - Guide for Measuring, Mixing, Transporting and Placing Concrete.
    3. ACI 306R - Cold Weather Concreting.
    4. ACI 318 - Building Code Requirements for Reinforced Concrete.

    B. American Society for Testing and Materials:

    1. ASTM C309 - Liquid Membrane-Forming Compounds for Curing Concrete.
    2. ASTM C979 - Pigments for Integrally Colored Concrete.

    C. Precast/Prestressed Concrete Institute;

    1. PCI MNL-116 - Manual for Quality Control for Plants and Production of Precast and Prestressed Concrete Products.
    2. PCI MNL-120 - PCI Design Handbook Precast and Prestressed Concrete.
    3. PCI MNL-122 - PCI Architectural Precast Concrete.

 

1.03 SUBMITTALS

    A. Submit product data and manufacturer's instructions for:

    1. Pigments.
    2. Curing compounds.
    3. Form facing materials.
    4. Form release agents.
    5. Surface retarders.
    6. [________________________.]

    B. Samples:

    1. Submit pigment manufacturer's [color chart] [sample chip set] for color selection; indicate pigment number and required dosage rate. Submittals are for general color selection and may vary somewhat from concrete manufactured according to Specifications.

If color selection has not been made at time specification is issued, include above. If color selection is specified, include below.

    1. Submit sample chip[s] of specified color[s] indicating pigment number[s] and required dosage rate[s]. Submittals are for general verification of color and may vary somewhat from concrete manufactured according to Specifications.
    2. Submit samples of [select aggregate,] [and] [_________].
    3. Submit [three] [________] samples [2 foot by 2 foot (610 x 610 mm)] [________] indicating concrete color range, texture and uniformity.

    C. Certificates: Submit PCI Plant Certification.

 

1.04 QUALITY ASSURANCE

    A. Perform work in accordance with ACI 301, ACI 304, ACI 318, PCI MNL 116, [PCI MNL 120,] [PCI MNL 122,] [and] [________].

    B. Obtain each material from same source throughout Project and maintain high degree of consistency in workmanship throughout Project.

    C. Fabricator: Company with PCI Plant Certification specializing in performing similar precast concrete work and having minimum 5 years experience including organized quality control and testing procedures.

Specify a mock-up to demonstrate that proposed materials and workmanship produce acceptable concrete appearance.

    D. Colored Concrete Mock-Up:

    1. Provide full-scale mock-up under provisions of Section [01400] [________]. Construct at least one month before fabricating other precast concrete to allow concrete to cure before observation [unless accelerated curing techniques are used].
    2. Provide initial mock-up at fabricator's plant. After approval by Architect, transport mock-up to job-site and erect where directed by [Architect] [________]. Mock-Up shall include joint conditions, sealant, anchorages, and supports used in Project.
    3. When approved by [Architect] [________], the mock-up will demonstrate the minimum standard for the Work.
    4. [Approved mock-up shall not be demolished or removed from site until the Work has been completed and approved.] [Mock-Up may remain as part of Work.]

 

1.05 DELIVERY, STORAGE AND HANDLING

    A. Pigments: Comply with manufacturer's instructions. Deliver pigments in original, unopened packaging. Store in dry conditions.

 

PART 2 PRODUCTS

In general, integrally colored concrete can be specified with the same cements, aggregates, reinforcing, forms, and admixtures used in high-quality uncolored concrete.

 

2.01 CONCRETE MATERIALS

    A. Pigments:

    1. Manufacturer:
      1. Davis Colors manufactured by Davis Colors; phone 213-269-7311.
      2. Substitutions: Comply with [Instructions to Bidders] [Section 01600] [________________] for substitution request procedures.
    2. Materials: Pigments shall contain pure, concentrated mineral pigments especially processed for mixing into concrete and complying with ASTM C979.

Select one of following methods to specify colors. Typical dosage rates range from 1 to 5 percent and shall not exceed 10 percent.

    1. Color[s]:
      1. [Provide color[s] to be selected by [Architect] [________] from manufacturer's [standard] [premium] color line. [Allow for up to [two] [________] colors on Project.]
      2. [Concrete mix shall contain [________] percent dosage rate of Davis Colors pigment No. [________]. Dosage rate shall be based on weight of portland cement, fly ash, silica fume, lime and other cementitious materials but not aggregate or sand.]
      3. [Pigment as necessary to match [existing building.] [sample in [Architect's] [________] office.] [Plate Number [________] in PCI MNL-122.]]

Color of cement, sand, and aggregates affect final appearance of colored concrete.

    B. Cement: Color shall be [gray] [white].

    C. Sand: Color shall [be locally available natural sand.] [match sample in [Architect's] [________] office.] [be color required to match approved concrete sample.]

    D. Select Aggregate: [________________________________.]

    E. Admixtures: Do not use calcium chloride admixtures.

 

2.02 FORMS

    A. Form Facing Material:

      1. [Provide smooth, non-porous surface such as steel, plastic, or high-density overlaid plywood.]

Decorative form liners provide textured or patterned relief on the concrete surface and increase the design possibilities with colored concrete.

    3. [Decorative Form Liners: Fiberglass, plastic, or other non-absorptive form liner. [________________.]]

Specify a form release agent that is non-staining and minimizes formation of "bug-holes" in surface of concrete.

    B. Joint Sealants: [Tape,] [foam rubber gaskets,] [or] [sealant].

    C. Form Release: [_______________________________________.]

 

2.03 ACCESSORIES

Use only curing compounds specifically recommended for use with colored concrete. W-1000 Clear Cure & Seal allows the natural appearance of concrete to show. Color Seal II wh covers concrete with a thin colored coating, creating a more uniform appearance. Do not use Color Seal II on exposed aggregate finishes.

    A. Curing Compound for Colored Concrete: Curing compound shall comply with ASTM C309 and be approved by pigment manufacturer for use with colored concrete. Provide [W-1000 Clear Cure & Seal] [Color Seal II tinted to match colored concrete and] manufactured by Davis Colors.

Surface retarder can be used with exposed-aggregate finishes.

    B. Surface Retarder: [________________________________.]

    C. Sealants: Joint sealers shall be [type specified in Section 07900.] [________________.] Provide in color matching colored concrete.

Use corrosion-resistant chairs and supports to prevent rust stain on face of concrete.

    D. Supports for Reinforcing Bars: Use corrosion-resistant types at locations in contact with exposed surfaces.

 

2.04 MIXES

When specifying concrete mix, 4" slump is recommended. If greater slump is required, use water-reducing or super-plasticizing admixture instead of adding water. Low water-cement ratio promotes richer, darker concrete colors.

    A. Pigments: Mix in accordance with manufacturer's instructions. Mix until pigments are uniformly dispersed throughout mixture.

    B. Provide a consistent water-cement ratio to achieve uniform color and texture.

    C. Monitor and record manufacturing equipment settings.

 

PART 3 EXECUTION

 

3.01 CASTING

Leakage around forms changes water-to-cement ratio in concrete surrounding joint, leading to discoloration. Similarly, removing forms when concrete is at various ages can result in color variations.

    A. Provide watertight joints, sealed to prevent leakage.

    B. Schedule work to minimize differences in time concrete remains in forms in order to minimize differences in curing conditions.

Instead of using colored concrete throughout entire thickness of panel, some fabricators prefer to pour panels in two layers. Retain below if this is acceptable.

    C. [[At Contractor's Option,] panels may be poured in two layers. Use colored concrete for face layer and uncolored concrete for backing. Construct so layers bond fully and uncolored concrete does not show on exposed face.]

 

3.02 FINISHES ON FORMED SURFACES

See ACI 301 and PCA Color and Texture in Architectural Concrete for more information about formed finishes.

    A. Finish to match approved mock-up panels and in accordance with ACI 301.

    B. Formed Surfaces:

    1. As-cast, rough form finish.
    2. As-cast, smooth form finish.

The finishes below will have the more uniform color than as-cast finishes.

    1. Textured form liner finish.
    2. Exposed aggregate, scrubbed finish.
    3. Exposed aggregate, sandblasted finish.
    4. Exposed aggregate, tooled finish.

The unformed surfaces of precast panels are generally given a utilitarian finish. For creative effects, however, they can also be given a patterned, exposed aggregate, or other decorative finish. Note that finishes must be coordinated with lifting inserts and other hardware.

    C. Unformed Surfaces: [Steel trowel finish.] [______________.]

 

3.03 PATCHING

    A. Fill holes and defects in concrete surface within 48 hours of form removal.

    B. Use the same patching materials and techniques that were approved on mock-up.

    C. Make patches with a stiff mortar made with materials from the same sources as the concrete. Adjust mortar mix proportions so dry patch matches dry adjacent concrete. Add white cement to mortar mix if necessary to lighten it. [With exposed aggregate finishes, add aggregate to mortar mix so patches will have the same texture and appearance as adjacent concrete.]

 

3.04 CURING

    A. Maintain concrete between 65 and 85 F (18 to 29 C) degrees during curing.

Curing with an approved curing compound is recommended whenever possible. Curing with steam or water can change the water-cement ratio of the concrete, causing a change in the concrete's color. Curing with plastic sheets or non-approved compounds can also discolor concrete. If these techniques are required due to precast manufacturing process, verify that appearance of resulting concrete is acceptable. Note that sand blasting or other exposed aggregate finishes are less affected by curing method.

    A. Colored Concrete: Apply curing compound in accordance with manufacturer's instructions. [If use of curing compounds is not practical with precast manufacturing operations, use curing techniques which have been show to adequately cure concrete and which produce acceptable color and appearance.

 

3.05 TOLERANCES

As with any natural material, some variation in appearance is a normal design feature of concrete, whether colored or not. Note that concrete lightens as it cures; allow up to 28 days for process to occur.

    A. Minor variations in appearance of colored concrete, which are similar to natural variations in color and appearance of unpigmented concrete, are acceptable.

 

3.07 SCHEDULE

If locations of colored concrete are not shown on Drawings, include schedule here. Examples are given below.

LOCATION

PIGMENT

DOSAGE

FINISH

Exterior Walls

160

1%

Sandblasted

Accent Wall

160

4%

Form liner

 

END OF SECTION

Color Seal II, Davis Colors, and W-1000 Clear Cure & Seal are trademarks of Davis Colors. Copyright 1996; qualified design and construction professionals may copy for preparation of construction specifications. Issued September 3, 1996.

We welcome questions or comments.
Or call:   West: 800-356-4848   East: 800-638-4444