A must on everyone's list of places to experience in the nation's capital, the blade-sharp triangular structure of the East Building of the National Gallery of Art has become world famous since its dedication in the spring of 1978.
DESIGN CONCEPT AND PLAN
The two main structures which make up the East Building were built on an awkwardly shaped trapezoidal site. The smaller of the two buildings, a right triangle, houses the Center for Advanced Study in the Visual Arts. The larger isosceles triangle is the exhibition area. A third triangle, a faceted glass roof, ties these primary elements together. Major steel trusses and long span post-tensioned concrete members are an important part of the total scheme, which consists of five level beginning at an underground concourse. Concrete and brick core walls 12 inches thick serve as backup for marble which faces much of the wall area, while architectural concrete is concentrated in deeply coffered ceilings and the spectacular long-span beams. The concrete is highly visible, yet many viewers fail to identify it as concrete, so exceptional are the soft pink color and the subtle texture.
Harmonizing the color of the concrete with various tones of white, pink, and darker shades found in the marble presented a problem. The solution involved adding marble dust to the white sand and coarse pink aggregate used in the white-cement concrete. In addition, the marble facing was lightly sandblasted to modify grain and color variations, thus enhancing its compatibility with the exposed concrete.
The concrete supplier developed a mix that satisfied all specifications for color, 4000-psi compressive strength, workability, and the need for a delayed initial set. The 3- to 4-inch slump gave sufficient workability to overcome the difficult placement caused by dense concentrations of reinforcing steel and the sharp angle and blade-like sections of the forms. Over 12,000 cubic yards of this concrete was placed without honeycomb.