Mother Nature's palette comes alive in architectural concrete through the exposure of aggregates...quartz, granite, obsidian, basalt, limestone, and many more. In addition to finding the right color of aggregate, users must also be sure its durability is appropriate for the planned exposure. Aggregate suppliers should be able to give helpful advice on this point.
AGGREGATE EXPOSURE METHODS
Aggregate exposure is a valuable technique for architectural precast concrete, for cast-in-place formed surfaces, and for flatwork where decorative walks, drives, or plazas are desired. Varied methods of exposing aggregate include: brushing and washing; chemical surface retardation; abrasive blasting; high-pressure water jetting; acid washing or etching; mechanical tooling and grinding.
MIX DESIGN FOR AGGREGATE EXPOSURE
For best results with exposed aggregate, special attention must be given to mix proportions as well as to materials. White or colored cements, colored sands, and added pigments may be needed to complement the special aggregate chosen.