Cement Block
Contents
Background
A concrete block is primarily used as a building material in the construction of walls. It is sometimes called a concrete masonry unit (CMU). A concrete block is a precast concrete product used in building construction. Most concrete blocks have one or more hollow cavities, and their sides may be cast smooth or with a design. In use, concrete blocks are stacked one at a time and held together with fresh concrete mortar to form the desired length and height of the wall.
Concrete mortar was used by the Romans as early as 200 B.C. to bind shaped stones together in the construction of buildings. During the reign of the Roman emperor Caligula, in 37-41 A.D., small blocks of precast concrete were used as a construction material in the region around present-day Naples, Italy. Much of the concrete technology developed by the Romans was lost after the fall of the Roman Empire in the fifth century. It was not until 1824 that the English stonemason Joseph Aspdin developed portland cement, which became one of the key components of modern concrete.
The first hollow concrete block was designed in 1890 by Harmon S. Palmer in the United States. After 10 years of experimenting, Palmer patented the design in 1900. Palmer's blocks were 8 in (20.3 cm) by 10 in (25.4 cm) by 30 in (76.2 cm), and they were so heavy they had to be lifted into place with a small crane. By 1905, an estimated 1,500 companies were manufacturing concrete blocks in the United States.
These early blocks were usually cast by hand, and the average output was about 10 blocks per person per hour. Today, concrete block manufacturing is a highly automated process that can produce up to 2,000 blocks per hour.
Raw Materials
The concrete commonly used to make concrete blocks is a mixture of powdered portland cement, water, sand, and gravel. This produces a light gray block with a fine surface texture and a high compressive strength. A typical concrete block weighs 38-43 lb (17.2-19.5 kg).
If granulated coal or volcanic cinders are used instead of sand and gravel, the resulting block is commonly called a cinder block. This produces a dark gray block with a medium-to-coarse surface texture, good strength, good sound-deadening properties, and a higher thermal insulating value than a concrete block.
Design
The shapes and sizes of most common concrete blocks have been standardized to ensure uniform building construction. The most common block size in the United States is referred to as an 8-by-8-by-16 block, with the nominal measurements of 8 in (20.3 cm) high by 8 in (20.3 cm) deep by 16 in (40.6 cm) wide. This nominal measurement includes room for a bead of mortar, and the block itself actually measures 7.63 in (19.4 cm) high by 7.63 in (19.4 cm) deep by 15.63 in (38.8 cm) wide.
Another block design, called a split-faced block, includes a rough, stone-like texture on one face of the block instead of a smooth face. This gives the block the architectural appearance of a cut and dressed stone.
A Foursquare-style house design, appearing in the Radford Architectural Company's 1908 catalog Cement Houses and How to Build Them. It was one of hundreds of concrete block house designs offered by the Radford company. They estimated that this design could be built for about $2,250.00, much less than traditional stone masonry houses of the time. (see: collections of Henry Ford Museum & Greenfield Village.)
Concrete blocks were first used in the United States as a substitute for stone or wood in the building of homes. The earliest known example of a house built in this country entirely of concrete block was in 1837 on Staten Island, New York. The homes built of concrete blocks showed a creative use of common inexpensive materials made to look like the more expensive and traditional wood-framed stone masonry building. This new type of construction became a popular form of house building in the early 1900s through the 1920s. House styles, often referred to as "modern" at the time, ranged from Tudor to Foursquare, Colonial Revival to Bungalow. Hundreds of thousands of these houses were built especially in the midwestern states, probably because the raw materials needed to make concrete blocks were in abundant supply throughout this region. The concrete blocks were made with face designs to simulate stone textures: rock-faced, granite-faced, or rusticated. At first considered an experimental material, houses built of concrete blocks were advertised in many portland cement manufacturers' catalogs as "fireproof, vermin proof, and weatherproof" and as an inexpensive replacement for wood. Many other types of buildings such as garages, silos, and post offices were built and continue to be built today using this construction method because of these qualities. —Cynthia Read-Miller. http://www.madehow.com/Volume-3/Concrete-Block.html
The Manufacturing Process
The production of concrete blocks consists of four basic processes: mixing, molding, curing, and cubing. Some manufacturing plants produce only concrete blocks, while others may produce a wide variety of precast concrete products including blocks, flat paver stones, and decorative landscaping pieces such as lawn edging. Some plants are capable of producing 2,000 or more blocks per hour.
The Future
The simple concrete block will continue to evolve as architects and block manufacturers develop new shapes and sizes. These new blocks promise to make building construction faster and less expensive, as well as result in structures that are more durable and energy efficient. Some of the possible block designs for the future include the biaxial block, which has cavities running horizontally as well as vertically to allow access for plumbing and electrical conduits; the stacked siding block, which consists of three sections that form both interior and exterior walls; and the heatsoak block, which stores heat to cool the interior rooms in summer and heat them in winter. These designs have been incorporated into a prototype house, called Lifestyle 2000, which is the result of a cooperative effort between the National Association of Home Builders and the National Concrete Masonry Association.
Progressive Market National Historic Register Desription
Municipality: Hartford, VT. Location: South Main Street, White River Junction UTMs: (Zone 18) E: 716220. N: 4834880. Site: V11-19
The Progressive Market stands in a mixed-use neighborhood of houses and businesses approximately one block south of White River Junction's central business district. Both business (1st floor) and private residence (2nd floor), the Progressive Market reached its present appearance through four, and perhaps five, separate building campaigns. Constructed c. 1922, the 2-story structure at the front of the composition and its slightly later l-story integral rear ell are constructed of unpainted rockface hollow concrete block. The hollow concrete building is joined at its back wall to a truncated frame building that antedates the c. 1922 structure. A shed addition runs across the back of the frame structure. A "connecting" room stands between the shed addition and the house; it was not possible to determine if this small link is associated with the construction of the original house or the shed, or is independent of both building efforts. Neither the concrete block nor frame portions of the building display stylistic references. While the frame building retains much of its original exterior fabric, its interior has been modified. The concrete block structure retains most of its original exterior and interior architectural fabric and details, which strengthens the integrity of setting and association. The nominated acreage of approximately 0.1 acre encompasses only the market building and its associated lawn.
Exterior
Unobtrusively sited between two early 20th-century frame dwellings, the Progressive Market faces White River Junction's South Main Street. The building is set back from the street and shares the same front lot line as the flanking houses. Four - perhaps five - building campaigns brought the market to its present configuration. The original building is a frame, two-story house that probably was similar in form and detail to the frame, 2-story, gable-end houses that surround it. Around c. 1922 the front of this house was removed for the addition of a two-story rockface concrete block structure. The two separate buildings were joined to create a single large structure that functioned as both a business and residence. At an unknown date, but likely within a few years of the c. 1922 addition, a l-story rockface hollow concrete block ell was added at the north elevation.
Architecture In 1900 Harmon S. Palmer transformed the American building industry when he patented a machine for making hollow concrete blocks. While the technology for more crudely manufactured concrete blocks existed in the 17th century, regular improvements in both the material and production during the 19th century lead to the material's increased popularity. The introduction of Palmer's machine and the availability of high quality Portland cement promoted mass production of the building material. In the first three decades of the twentieth century, houses and commercial structures in every state were built with the cheap, readily available and easily assembled concrete blocks. (Simpson, "Cheap, Quick and Easy": 108-109).
A number of concrete block structures from the early 20th century still stand in the Upper Valley region, on both sides of the Connecticut River. At least one concrete block manufacturing operation, the Hartford Pressed Stone Company, operated locally in the first quarter of the 20th century. It is likely that these various local structures, including the Progressive Market and the Agway store that stands across the street from the market, are built of blocks purchased from the Hartford Pressed Stone Company.
From the perspective of the Progressive Market builder (presumably Giachino Romano) who wished to enlarge an existing building with a substantial addition at the South Main Street elevation, concrete block had much to recommend its use. Most obviously, the material could be purchased locally, and its low price relative to lumber, brick or stone made it attractive to a builder of limited means. The blocks' uniform shape and size meant a building could be laid up quickly, without the expense and labor of carpentry. Concrete blocks were fireproof, rarely needed repair and did not require paint for a finished appearance. Moreover, concrete block was a "modern" building material, and its use identified the builder as a "modern" or "progressive" businessman. And the rockface finish gave the material, at first glance, the appearance of a fine and expensive stone (Simpson, "Cheap, Quick and Easy": 110-118).
Such transformations of a house-into-business using a distinctive building were common in an era of combined retail/housing infrastructures.
Concrete block was indeed quick, cheap, and easy. A machine could cost as little as $60, and its manufacturers promised that experience was "really unnecessary," that "anyone can do this work." A 1917 Sears and Roebuck catalogue asserted that the device would be "profitable whether you manufacture for your own use or for sale. If for your own use, you can make them during your spare time, or on rainy days." There is plenty of evidence that some individuals did indeed cast their own block, but for the most part it was made by people already in the construction business who were captivated by advertisements that ran in builders' journals, the inescapable Sears catalogues, house pattern books, manufacturers' promotion publications, and trade catalogues.
All it took was a single machine to get the industry going in a community. In Lexington, Virginia, contractor H. A. Donald introduced rock-face concrete block in 1915 when he erected a building for his friend Frank Brown. The town's blacksmith and liveryman, Brown had decided to expand his business beyond stabling horses to accommodate gasoline-powered carriages and desired a larger structure. To make the concrete block, Donald set up on site a portable machine that might very well have been a Palmer. He went on to create some twenty other rock-face concrete structures in the Lexington area in the 1920s, including the Bank of Fairfield, finished in 1926 for $2,400. It may well be the only concrete block building immortalized in poetry. Local versifier Ernest Sale wrote a humorous dedicatory poem for the opening that included this stanza:
Now for the building, shall it be frame or brick? We want something we can build right quick; Don't mind the expense, we can sell more stock, Then they decided to build it of concrete block!
Sale's line, "Don't mind the expense," refers to the fact that although concrete block was much cheaper than stone, it cost more than wood. Still, a block could be produced for about 13 cents and was less expensive than brick to lay. Moreover, it was promoted to "last practically forever," since it required little maintenance and was fireproof (a characteristic that made it especially appealing for garages as well as banks).
Yet, with all these advantages, concrete also unquestionably attracted customers because of its ornamental potential. Any number of wreaths, scrolls, or cobblestone faces could be reproduced. Most in demand was rock-face, the imitation of quarried stone which became the standard unit on all Sears machines. Manufacturers and builders commonly referred to this pattern as "artificial stone," underscoring the fact that though it was cheap and easy, it looked like something considerably more expensive.
Ideas is published twice a year. Editor: Jean Anne Leuchtenburg. Copyright © 1997 by the National Humanities Center. Comments to: lmorgan@ga.unc.edu Last modified: October 1997 nationalhumanitiescenter.org
References
- Hornbostel, Caleb. Construction Materials, 2nd Edition. John Wiley and Sons, Inc., 1991.
- Koski, John A. "How Concrete Block Are Made." Masonry Construction, October 1992, pp.374-377.
- Schierhom, Carolyn. "Producing Structural Lightweight Concrete Block." Concrete Journal, February 1996, pp. 92-94, 96, 98, 100-101.
- Wardell, C. "Operation Foundation." Popular Science, December 1995, p. 31.
- Yeaple, Judith Anne. "Building Blocks Grow Up." Popular Science, June 1991, pp. 80-82. 108.
- Chris Cavette Longstreth, Richard. The Buildings of Main Street: A Guide to American Commercial Architecture. Washington, DC: The Preservation Press, 1987.
- _____. "Compositional Types in American Commercial Architecture." In Perspectives in Vernacular Architecture, 11, ed. Camille Wells. Columbia, MO: University of Missouri Press, 1986.
- Rising, Mary. From Italy to White River Junction, Vermont: Some Oral Histories. Privately published, 1986.
- St. Croix, John W. Historical Highlights of the Town of Hartford, Vermont. Privately published, 1974.
- Simpson, Pamela H. "Cheap, Quick, and Easy: The Early History of Rockfaced Concrete Block Building." In Perspectives in Vernacular Architecture. III, eds. Thomas Carter and Bernard L. Herman. Columbia, MO: University of Missouri Press, 1989.
- Tomasi, Mari. "The Italian Story in Vermont," Vermont History 28 January 1960): 73-87.
- Vermont Division for Historic Preservation. The Historic Architecture of Addison County. Montpelier, VT: Vermont Division for Historic Preservation, 1992.
- _____. The Historic Architecture of Rutland County, Montpelier, VT; Vermont Division for Historic Preservation, 1988.
- _____. "Industry and Commerce: Property Types." Montpelier, VT: Vermont Division for Historic Preservation, n.d.
- _____. "Industry and Commerce Theme." Montpelier, VT: Vermont Division for Historic Preservation, 1989.
- http://www.crjc.org/heritage/V11-19.htm FORM PREPARED BY: Marlene Elizabeth Heck, 8 Blueberry Meadow Road, Lebanon, NH 03766-2017. Tel: 603-448-9791. Date: February 1995. Date: July 10, 1995. (Source 127)
