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CONCRETE DESIGNS INC. - SPECIFICATIONS

SECTION 03450 - ARCHITECTURAL PRECAST CONCRETE - PLANT CAST

PART 1 - GENERAL

SUMMARY

This Section refers to architectural precast concrete units.

Architectural precast concrete includes the following:

Precast concrete units as defined in the architectural plans. Potentially includes wall caps, columns, balustrade, quoins, pavers, finials, moldings or any other decorative element designed to be cast out of concrete.

These are non-structural, self supporting units.

SUBMITTALS

Product data and instructions for manufactured materials and products.

Shop drawings prepared by CDI showing complete information concerning the precast concrete units. Indicate member dimensions and cross-section. Unless otherwise noted, anchors will be embedded in a standard configuration.

Samples - Submit samples of color options and texture options for selection process.

QUALITY ASSURANCE

Fabricator Qualifications: CDI has over 40 years of successful experience in fabrication of architectural precast concrete units. Fabricator has sufficient production capacity to produce, transport and deliver required units without causing delay in the work.

Design modifications will be made only as necessary to meet field conditions and to ensure proper fitting of the work and only as acceptable to Architect. Maintain general design concept shown without increasing or decreasing sizes of members or altering profiles and alignment shown without architects approval. Modifications may need to be considered in view of budget constraints.

DELIVERY, STORAGE AND HANDLING

Deliver precast concrete units to project site in such quantities and at such times to assure continuity of installation. Products to be packaged to protect the finish during transport. Precast may be a long lead time item and should be ordered accordingly.

PART 2 - PRODUCTS

REINFORCING MATERIALS

Epoxy coated rebar used in some product designs to insure safe handling.

Corrugated Wall Ties - Included in moldings as the mechanical fastener. 22 gauge mill galvanized steel - 7/8" x 7".

Threaded Inserts - Plastic inserts are included in very large castings such as large moldings, columns and stackable column components. These are for mechanical ties and not for lifting purposes.

Adhesives - Latex - modified mortar used on a stable substrate in conjunction with the mechanical fastener should be used. White cement can be used to adjust the greenish color created by using the latex mortar.

Premium grade construction adhesives which come in tubes should be used for bonding columns and on flat surfaces where latex mortar cannot be used.

CONCRETE MATERIALS

Portland Cement: Type 1 Portland Cement Gray or Lehigh White

Use only one brand, type and source of supply of cement throughout the project, unless otherwise acceptable to Architect.

Coarse/Fine Aggregate - Sand and Gravel: Hard, durable, selected and graded; free of material that causes staining or reacting with cement.

Pigments: Nonfading, resistant to lime and other alkalies.

Water: Drinkable, free from foreign materials in amounts harmful to concrete and embedded steel.

Air-Entraining Admixture: Utilize standard mix designs incorporating admixtures which facilitate the workability, curing and strength of the mix.

Compressive Strength: 5000 psi minimum at 28 days.

FABRICATION

General: Fabricate precast concrete units complying with manufacturing and testing procedures, quality control recommendations, and following dimensional tolerances, unless otherwise indicated.

Molds: Accurately construct molds mortar-tight and of sufficient strength to withstand pressures due to concrete placing operations and temperature changes. Maintain mold work to provide completed precast concrete units of shapes, lines and dimensions indicated, within specified fabrication tolerances.

Dimensional Tolerances of Finished Units: Ornamental architectural precast concrete, being tapered by design, is measured for length, width and thickness at the surface from which the mold is loaded maintaining plus or minus 1/16 of an inch tolerance. Overall height and width measured at face adjacent to mold at time of casting:

Surface Finish: Fabricate precast units and provide exposed surface finished as follows:

Traditional - Randomly spaced/sized voids inherent in the texture.

Modern - Less voids than traditional but not typically void free.

Seasoned - Light abrasive blast applied to the cast finish.

Tapestry - Medium abrasive blast applied to the cast finish.

Rustic - Heavy abrasive blast applied to the cast finish.

Antique - High irregular, rusticated finish.

Color: Select from CDI color chart to minimize variations in color.

PART 3 - RECOMMENDED EXECUTION OF THE INSTALLATION - The successful installation requires experienced, knowledgeable installers in order to achieve a quality installation. Considerations for installation include:

Install precast concrete members plumb, level and in alignment. Provide temporary supports and bracing as required to maintain position, stability and alignment as members are being permanently connected.

Maintain horizontal and vertical joint alignment and uniform joint width as erection progresses.

Accessories: Install clips, hangers and other accessories required for erection of precast units to supporting members and backup materials.

Anchor units in final position by bolting, welding, grouting, or as otherwise indicated. Remove temporary shims, wedges and spacers as soon as possible after anchoring and grouting are completed.

Cleaning: Clean exposed facings to remove dirt and stains on units after erection and completion of joint treatments. Protect other work from damage due to cleaning operations. Do not use cleaning materials or processes that could change the character of exposed concrete finishes.

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