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discusses the surface aestheticsof precast concrete panels, which require decisionsby the architect on considerations such as color, formand texture, and weathering. Because of the versatilityof the material, the architectural focus can vary greatlyfrom project to project, changing the relative importanceof each of these facets to the design.Proper selections of color, form, and texture for abuildings precast concrete exterior is critical to creatinga successful aesthetic appearance. The decisionsdepend not only on cost, delivery schedule, and clientsatisfaction but on the local and regional context aswell. The desired colors and textures can be achievedby varying aggregate selection, matrix color, finishingprocesses, and depth of exposure of the aggregate.The proper use of samples and mockups can ensurethe projects success.Precast concrete allows architects to be innovativeand create designs that cannot be accomplished withother materials. It provides the freedom and flexibilityof shaping concrete into structure and architecture.The Architectural Precast ConcreteColor and TextureSelection Guide, published by PCI, helps architects defineand achieve their aspirations. The guides photographs

serve as a visual reference for initial selectionof color, texture, and finish and should be followed byproducing samples at a precasters plant to aid in thefinal selection of color and texture.However, because of different material sources andmanufacturing techniques, the guides photographicsamples and the final product may not be an exactmatch. Samples must be made to ensure that the desiredcolors and textures are satisfactorily matched.Samples for architectural precast concrete are customproduced to translate the architects specific designconcept into a standard for realistic and economic productionrequirements.

In the schematic design stage, a schedule for creatingsamples and recognizing uniformity requirements shouldbe considered, and the designer should focus on selectingshapes, sizes, colors, textures, and finishes for thesamples well in advance of finalizing the bid documents.The buildings appearance results from the architectsuse of light, shadow, texture, and color. Color and,consequently, color tone represent relative values. Theyare affected by light and shadow, intensity, time ofday, and nearby colors. Thus, color selection should bemade in lighting that replicates the light and shadowsof the sites natural daylight.The architect should give sufficient details or descriptions

on the contract drawings to indicate clearly theextent of all exposed surfaces of the units and theirrespective finishes. This is particularly important forreturns and interior finishes. The location and dimensionsof reveals should also be shown. All of theseitems should then be shown on the shop drawings.3.2 UNIFORMITY AND DEVELOPMENTOF SAMPLESBecause acceptable color uniformity and shading intensityare evaluated visually, they are generally a matter

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of an individuals subjective judgment and interpretation.Acceptable variations in color, texture, anduniformity should be determined at the time the sample,mockup, or initial production units are approved.Accordingly, it is beyond the scope of this Manual toestablish precise or definitive rules for product acceptabilityon the basis of appearance. However, a suitablecriteria for acceptability requires that the finishedconcrete surface should have a pleasing appearancewith minimal color and texture variations from the approvedsamples. The finished face surface should showno obvious imperfections other than minimal color andtexture variations from the approved samples or evidenceof repairs when viewed in typical lighting withthe unaided eye at a 20 ft (6.1 m) viewing distance.Appearance of the surface also should not be evaluatedwhen light is illuminating the surface from an extremeangle, as this tends to accentuate minor surfaceirregularities (see Section 3.5.17).The major factors affecting uniformity of architectural