Q: Where can we get some pure white and pure black pebbles for a special concrete mix? Our exposed aggregate renovation job calls for matching some existing concrete, and it looks like black and white were both used.

A.: In June 1988 (page 571) Concrete Construction published a list of 22 companies supplying a virtual rainbow of colors in crushed stone, gravel, and volcanic rock from numerous sources. Since then, we've heard from several other suppliers of decorative aggregate, so we're publishing an addition to the list here in Problem Clinic. We're also showing one of the photos sent in by Robert M. Lentz of Genstar Stone Products Company to demonstrate the versatility of architectural precast concrete surfaced with exposed aggregate. Recently one supplier of special aggregates and sand, Fister/Warren, compiled and published a list of aggregates that have been or are being used for various types of architectural concrete--exposed aggregate precast, cast-in-place, terrazzo, and tilt-up. It includes such exotic names as Devil's Head Quartz, SanSaba Yellow Verona Marble, Bull Mountain Red Granite, and Royal Salmon Feldspar. To make it an easy reference guide, they arranged the list alphabetically three ways: by name, generically, and by color. Fister/Warren also offers help in identifying duplicate names. For example, the same pink quartzite is named (by different suppliers) Tifton, Rosebud, Kinso, and Coral. If the specifier asks for an aggregate that is no longer available, they also offer to suggest the best substitute at a convenient location. To contact Fister/Warren, write to 200 East Howard Street, Des Plaines, Illinois 60018; telephone 708-296-4450.

Editor's update:

For information about sources of decorative and special-purpose aggregates, see the July 1997 issue of The Concrete Producer.