The Baha'i Temple in Wilmette, Ill., is literally a glowing example of how precast and cast-in-place concrete construction can create both structural strength and unmatched beauty. The nine-sided neoclassical temple is capped by a 90-foot-diameter dome that embraces natural light during the day and illuminates from within at night, creating a “Temple of Light and Unity." This luminous appearance is due to the reflective quality of the structure’s vivid white concrete with exposed clear and white quartz aggregate.
What’s more, every surface of the structural steel and reinforced concrete superstructure is covered with intricate ornamental precast concrete panels depicting many of the world’s religious symbols. Various materials, including stone, terra cotta, ornamental plaster and marble, were considered for the temple's ornamentation. But concrete proved an economical way to create designs in both precast and cast-in-place applications.
The architect worked with the precast concrete contractor to create the whitest possible surface. The mix consisted of Portland cement and crushed quartz to yield an extremely white architectural concrete with the necessary plasticity to create the designs as well as achieve the required durability. The contractor placed galvanized reinforcing steel in custom plaster molds to follow the intricate patterns, and the molds were filled by hand with concrete. After curing, the panels’ detailing was enhanced by exposing the aggregate via wire brushes. Stainless steel was used to connect the panels to the dome’s steel superstructure to minimize future rust damage.
Ornamental plaster was first considered as a material for interior walls, but the precast contractor’s bid was 10-percent less than those for plaster. Precast and cast-in-place methods were used for the wall areas, including the 45-foot-tall pylons. Thin ornamental precast panels were set into forms that simultaneously grouted the panels into place and created the flat wall surface. The tracery panels covering the windows also were set into forms and anchored into position when the flat sections were cast in place.
These techniques created an impression of seamless construction. Whenever possible, cold joints were tucked into shadowed reveals or along changes in the surface planes. Even now, more than 60 years after completion, the joints are nearly invisible.
The temple continues to serve as a beacon to all who wish to visit and worship.
Awards and Certifications
- National Register of Historic Places