For about 150 years, concrete has been a popular construction material in the United States, but became especially popular for buildings and structures in the first part of the 20th century. Modern concrete is a mixture of many different materials and is used for many purposes, but the word generally describes the building material created by mixing water, cement, sand, and gravel.

Although many use the terms "cement" and "concrete" interchangeably, cement is actually the calcium-based binder that gives concrete its hardness and bonds the sand and gravels in concrete together.

Ancient History

Cement has a long history that goes back to the Romans and Egyptians, both of whom used a variety of binding mortars in masonry construction and for stucco facing. The use of cement as a binding agent in concrete, however, began in the late 18th and early 19th centuries. Cements are one category of mortar binders, and can be classified broadly as either natural or artificial.

Natural cements are derived from burning argillaceous, or clay/silt containing, limestone rocks and pulverizing the result into a fine powder. Argillaceous limestone is comprised of varying amounts of lime, silica and aluminum oxide.

Natural cement has been used in the United States since the early 19th century. The material played an important part in engineering during the first part of the 19th century as East Coast cities established artificial canal systems for shipping -- including the Erie Canal in New York. Because of its resistance to water, cement was an ideal material for early waterways.

Demand for cement lead to the discovery of large natural cement deposits in many areas of the eastern and mid western United States, and by the mid-1800s the natural cement industry was well established.

Portland cement is the most common type of artificial cement and is created by burning a mixture of measured amounts of certain minerals, including silica, aluminum oxide, ferric oxide, lime and other compounds such as gypsum, which allows the mixture to remain liquid during transport. These minerals are found naturally in calcareous rocks, including limestone, marl, or chalk, and argillaceous rocks, such as shale, slate or clays.

Although many individuals experimented with artificial cement mixtures in the early 1800s, the invention of Portland cement is credited to an English bricklayer named Joseph Aspdin who filed his patent in 1824. Aspdin called his invention "Portland cement," after the building stone quarried in the Isle of Portland. Its use spread rapidly in Europe, and several European companies began importing Portland cement to the United States by the 1880s.

European cement was used largely for paving, including sidewalks in major cities, and established such a reputation as a superior building material that early domestic manufacturers had a hard time competing with established foreign brands. Competition between railroad monopolies resulted in complex shipping agreements. Because Portland cement made effective ballast, importers could often get their cargo shipped across the Atlantic Ocean for little or no cost.

Domestic Production

Nonetheless, the remoteness of the western United States gave domestic operations a slight pricing advantage for those rapidly growing markets, and by the last decades of the 19th century regional domestic operations began to out compete European imports.

Established in the early 1870s, the Lehigh District in Pennsylvania is acknowledged as the historic center of the Portland cement industry in the United States, and continued to dominate through the 1920s. In 1884, another early Portland cement works in the United States was established in Oregon City. By the first decades of the 20th century, Oregon had at least four major cement operations.

In Washington, the first cement plant incorporated was likely the Washington Portland Cement Company, founded by Washington Pioneer Amasa Everett in 1905. Everett was a prospector looking for gold and coal seams, and staked a claim on the Baker River. Instead, the claim contained valuable limestone and clay deposits conveniently close to one another, and resulted in the company town of Concrete, WA.

In 1906, the Superior Portland Cement Company of Seattle established a mill across the river from the Washington Portland Cement Company and in 1910, the two companies merged. That same year, the Olympic Portland Cement Company incorporated in Seattle and opened a mill on clay deposits in Bellingham, and the International Portland Cement Company established itself in Spokane.

In 1899, the Polk City directory for Seattle listed four companies specializing in cement or concrete, but a decade later this number had grown to 54, reflecting the importance of concrete in modern construction.

A Versatile Material

Builders historically used cementitious materials to bind or reinforce masonry, but by the turn of the 20th century concrete had become common for many uses. Originally used in the United States for canals, and then as a paving material, concrete became increasingly popular as a foundation material, as a structural material, and as an ornamental faux stone for elements such as quoining and lintels.

Reinforced steel construction became popular for large buildings in the first decades of the 20th century as a way to create a structure that was both strong and fireproof. While concrete was extremely fire resistant and could withstand strong compressive forces, it was relatively weak against pulling forces. Conversely, steel was highly resistant to pulling but not compressive forces, and also could be structurally weakened by heat.

Another principal advantage of concrete is that it can be set in wet weather, which extends the building season. Rain was a significant concern for 19th century and early 20th century brick builders; sometimes the onset of fall would halt a major project until spring.

Perhaps the most notable early use of concrete and steel construction is Seattle's Smith Tower, which, as a state-of-the-art skyscraper, incorporated many modern engineering achievements into its design.

Concrete is also a cheap material and is extraordinarily flexible - concrete allows buildings to take on solid sculptural qualities unlike any other material. Early concrete buildings often employed traditional building materials as cladding, such as brick and terra cotta. Eventually, many designers and the general public came to appreciate the straightforward use of the material without traditional frills. Seattle's Saint Joseph's Church is an excellent example of this move from hidden to overt concrete use.

As a design element, concrete is used in ways that accentuate or highlight structure and engineering. With the rise of modernist design, concrete in itself became a design feature of non-industrial buildings as well. As internal structure and technological achievement became increasingly important elements of design, exposed concrete became more common.

The Washington Talking Book and Braille Library in the Cascade-Denny Triangle neighborhood, a former car dealership built in the streamline moderne style, is an excellent example of the design possibilities afforded by concrete. At the time it was built in 1948, the foundation pour was the longest continuous concrete pour in the history of Washington State.

Because of its strength and flexibility, concrete also became a principal material for warehouses and industrial buildings beginning in the first decades of the 1910s. Examples of such buildings can be found in Seattle's historic industrial areas, including Interbay, the Denny Triangle, and south of Pioneer Square. Generally, ornamentation for concrete industrial construction from the same time period consists of patterns cast into the concrete itself, rather than the addition of other materials.

Concrete construction techniques include both poured in place and prefabricated slab construction. Seattle has many examples of poured concrete construction in commercial architecture dating from the late 1920s through the present-in styles ranging generally from the Art Deco periods, through Modernist and International, to contemporary.

Prefabricated concrete, in which individual elements are cast at the factory and transported to the build site, are also commonly used. Notable examples in Seattle include the Lacey V. Murrow Bridge across Lake Washington, which utilized hollow concrete construction to create several floating sections. The 1962 Seattle Monorail, designed and built by Alweg International of Germany, also used hollow concrete guideways to reduce the weight on the pylons. Each section of the track has a unique shape that had to be precisely cast in order for the cars to ride smoothly.

Sources

Leslie, Robert W. History of the Portland Cement Industry in the United States. Chicago: International Trade Press, Inc, 1924.

Slaton, Amy E. Reinforced concrete and the modernization of American building, 1900-1930. Baltimore, MD: Johns Hopkins University Press, 2001.

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