Courtesy BTHL

This post is part of a monthly series that explores the historical applications of building materials and systems through resources from the Building Technology Heritage Library (BTHL), an online collection of AEC catalogs, brochures, trade publications, and more. The BTHL is a project of the Association for Preservation Technology, an international building preservation organization

Now known as concrete masonry units, concrete blocks exploded onto the building scene in the late 19th century with a flurry of different patents for block designs and production. After Harmon Palmer invented the first commercially successful concrete block machine in 1900, the industry expanded rapidly with multiple manufacturers producing the blocks with their stone-like surface created through either a mold or the use of special aggregates in the concrete mix. Although stonelike concrete blocks were popular for the first quarter of the 20th century, they fell out of fashion following World War II.

Manufacturers marketed concrete block as an economical building material that was also ideal for industrial, agricultural, and residential projects. As the block became associated with such utilitarian structures, it transitioned into a supporting role as a substrate for applied finishes, such as stucco. In a 1925 catalog for concrete block, artist Alfonso Lannelli was quoted as saying that “stucco becomes a sensitive medium through which the texture-and-tone qualities of each period can be expressed.“ One noteworthy exception, however, was the 1950s and 1960s "screen block," which allowed concrete block to assume a major design role. These ornamental screen block designs created free-standing walls that served as partitions while allowing the passage of air.

Catalogue of the Century Cement Machine Company: Manufacturers of the Hercules Cement Stone Machine, Century Cement Machine Co., Rochester, N.Y., 1907

The use of concrete to imitate stone started with its initial name—it was called Portland Cement due to its resemblance to the Portland stone found in England. “Cast stone” was also used to describe a variety of cementitious products that replicate stone; in the early 20th century, concrete blocks with a “rock face” became particularly popular. In most cases, the formwork was created to simulate the appearance of rock. Later versions were done with custom concrete mixes so that the block surface also had a “stone-like” appearance.

Concrete machinery: Triumph, Wizard and Knox Block Machines, Sears Roebuck & Co., Chicago, 1915

Sears, Roebuck & Co. sold the equipment to make decorative concrete blocks with a variety of designs.

Concrete Building Block and Brick, Portland Cement Association, Chicago, 1918

This publication includes examples of concrete block structures from across the U.S. as well as technical specifications for “concrete architectural stone building blocks.” It alleges a “greatly increased popularity of concrete as a building material" and "the many ways of giving concrete block and brick a very attractive finish.”

The Zagelmeyer System of Casting Plain and Granite Faced Concrete Building Blocks, Concrete Brick, Zagelmeyer Cast Stone Block Machinery Co., Bay City, Mich., 1923

“The Zagelmeyer system makes it possible to manufacture a perfect concrete block, but also that the process of applying a pure, sparkling granite facing is a crowning feature that distinguishes this project as the last work in concrete block.”

Straub Cinder Building Blocks: A Consideration of the Architectural and Structural Availability ... with working plans and instructions, National Cinder Concrete Products Association, U.S., 1925

One of the most comprehensive documents on concrete block for its era, this publication includes design details andtesting data on structural and fire ratings.. A special section covers the use of stucco over concrete block—a popular design choice for the era.

Waylite-Superock: the modern building material: plan book, Waylite Co., Chicago, 1939

Waylite Co. created Waylite-Superock through a process that gave concrete block a lighter weight and higher insulation value than other concrete block materials. This also improved its fire resistance. This publication features a dozen house plans and examples of commercial and agricultural buildings.

Recommended Practices for Laying Concrete Block, Portland Cement Association, Chicago, 1954

This publication for masons includes details on the mortars, coursing, tooling, and anchoring systems that represent the best concrete block practices.

Popular Mechanics' Famous Concrete Block House, Popular Mechanics Press, James R. Ward, Chicago, 1949

This book “describes step by step the construction of a five-room, concrete-block house from the first shovelful of soil for the foundation excavation to the last swipe of the paintbrush.”

Duro Concrete Masonry Units, Duro Block Co., Cincinnati, 1957

The Duro Block Co. offered four different aggregate mixes for heavy- and light-weight concrete block.

Welcome to the Pavilion: Fashion Gateway to the Wonderful New World of Block, National Concrete Masonry Association, Chicago, 1959

The concrete block “screen wall” appears in this publication, which recognizes the architects who designed the various specialty and decorative units.

Waylite, Waylite Co., Bethlehem, Pa., 1960

The Waylite Co patented a process that made its block lighter than other blocks with improved insulation and acoustic properties. This 1960 catalog also featured a wide range of bonding patterns for both interior and exterior applications.