Concrete Block at Midcentury
If you missed our first blog post "Behold the Lowly Concrete Block," read more about the early beginnings of this popular building material.
Following its period of popularity in the early 1900s, architectural concrete block next came into vogue in the mid-twentieth century. The ANSI modular standard block - commonly known as a concrete masonry unit or CMU - was introduced in 1946, and standard unit blocks with architecturally-designed faces followed shortly after. Pioneering modern architects - such as Frank Lloyd Wright, with his Textile Houses of the 1920s, and Paul Rudolph, with the Colgate University Creative Arts Center - began integrating concrete block into their designs. Contemporary architectural journals soon picked up on the trend, praising the unique patterns, textures, and shapes that can be cast into and built out of concrete block. Concrete block was seen as simultaneously utilitarian and glamorous – a modern architectural ideal. The same journal articles quoted structural engineers who praised the improvements that manufacturers had made in producing concrete blocks of consistent compressive strength, and in developing additives that lightened the overall weight of individual blocks. One engineer went so far as to suggest that concrete block would be a common structural material in the skyscrapers of the future – a partner and structural engineer from Skidmore, Owings & Merrill is quoted in a Progressive Architecture article noting that “a 50-story building with load-bearing walls made of reinforced concrete block is entirely feasible.” 
It seems fitting then, that the block would appear in a progressive design in Minneapolis for a printing company, where the modern architectural design sought to encourage a more efficient production process for printed materials. The Hoffman-Callan Company Building is a unique two-story round structure that was constructed in 1963 to house local entrepreneur Elliott Hoffman’s two businesses, the Hoffman-Callan Printing Company and Motor Travel Services. The Hoffman-Callan Printing Company provided commercial printing services, while Motor Travel Services is notable as the publisher of C.A.R., a travel guide published in the 1950s and 1960s listing what advertisements for the publication described as “a nationwide network of independently owned on-the-highway restaurants.” The building was designed by architect James Dresser of Madison, Wisconsin. Dresser is notable as a Prairie School architect and former Taliesin Fellow, who studied with Frank Lloyd Wright in the 1940s. Dresser conceived of the building’s round design as a way to optimize the efficiency of the printing process.
The building’s most significant feature is the custom exposed concrete blocks that make up its exterior walls. The unit construction allowed for by the blocks enables the building’s round shape, while also providing an intriguing texture to the walls. Each individual block is rectangular, with a pair of blocks taking the form of a recessed pyramid with a truncated top. The pairs of blocks are arranged in vertical columns that extend the full height of the building. The blocks are also visible at the interior of the building, providing an element of architectural interest to the interior spaces.
Concrete Block in the 21st Century
The tallest “printed” building was recently assembled in China. The large-scale 3D printer used a mixture of glass fiber, cement, steel, and recycled construction waste to print large modular building components which were then assembled on site. While the scale is much bigger, the process is not dissimilar from the historic precast block machines of Sears. In a short time, we may be able to print our own concrete block specifically designed for a project right on site and in any shape or form – “on rainy days or whenever.” Architects and structural engineers will determine the next transformation of this seemingly humble building material with a glamorous past.
 H. Lefer, “Technics: Concrete Masonry: What’s New on the Old Block,” Progressive Architecture, 57, No. 12 (1979), 88.