Concrete is everywhere. Foundations, buildings, bridges, sidewalks, roads, sculptures, tunnels, retaining walls, and even skateboard parks are made with concrete. We are surrounded by this gray, cold, often impersonal, and ubiquitous material. Yet, I know very little about concrete, except that it is a construction material composed primarily of aggregate (sand and crushed rock), cement, and water, and that it is often reinforced with steel. On the rare occasions when I think about concrete, I immediately picture the Hoover Dam, a construction and engineering marvel built with more concrete than I can fathom. According to the Bureau of Land Reclamation, Lower Colorado Region, the Hoover Dam “contains enough concrete to pave a strip 16 feet wide and 8 inches thick from San Francisco to New York.” However, prior to the Hoover Dam’s construction in 1931, others were mixing it up with concrete.
In the early-twentieth century, for example, Robert Augustus Cummings (1866-1962), a civil engineer who worked primarily in Pittsburgh, Pennsylvania, made significant contributions to the field of reinforced-concrete construction and foundation work. Cummings clearly stated his confidence in his material of choice in a 1904 presentation to the Member Engineers’ Society of Western Pennsylvania (and “member” refers to construction components, not engineers with a secret handshake):
Reinforced concrete makes an excellent paint for preserving iron or steel, adhering to the metal very firmly and protecting it thoroughly against corrosion. It can easily be made water tight, and its durability is beyond question. . . . Correctly designed re-enforced concrete structures are not liable to sudden failures, as is the case with ordinary concrete, but gives warning by the falling off of the surface concrete long before the point of failure is reached.
Cummings knew his concrete and built his reputation and livelihood around it. Founded in 1900 and incorporated in 1911, Cummings Structural Concrete Company specialized in reinforced concrete for the construction of all types of structures, from bridges, barges, warehouses, filtration systems, private residences, machine shops, dry docks, and piers, to retaining walls, abutments, factories, dams, and locks. If it involved concrete, Cummings was doing it.
Cummings is best known for inventing the “Cummings System of Reinforced Concrete,” in which iron or steel bars are embedded within a mixture of Portland cement (a finely ground powder made of limestone mixed with clay or shale) water, sand, and gravel or broken stone. The Cummings system utilized steel rods of any size or grade that were welded together to form a variety of shapes. Cummings held over 25 patents related to reinforced concrete and metal structures (see U.S. Patent 761,288 for one example). Spaces between the metal structure were filled with concrete to form arches, walls, floors, walls, and roofs.
Some of Cummings more noteworthy projects included the Davis Island Dam on the Ohio River; a water tank for the Pittsburgh & Lake Erie Railroad; the Ninth Street Bridge in Pittsburgh; the Harbison-Walker Refractories in Birmingham, Alabama; a concrete floor for the machine shop, National Tube Company in Mckeesport, Pennsylvania; a mill building and boiler house for the National Casket Company in Ashville, North Carolina; pilings, abutments, and retaining walls for the New York Central and Hudson River Railroad Company; and a clear water basin (a drainage area to collect runoff) for the H. J. Heinz Company in Pittsburgh.
In 1915, the Scott Paper Company (also known as the Chester Paper Company) of Chester, Pennsylvania, manufacturers of Scott tissues, toilet paper, and paper towels, contracted with Cummings to work on their beater rooms (housing machines that beat, rolled, and processed paper fibers) and machine rooms. Cummings work at the Scott Paper Company is well documented through sketches, blueprints, design notebooks, specifications, correspondence, progress reports, payroll records, and photographs. For example, in a July 21, 1916 letter, Cummings sent a quote for the work to Mr. Leibeck at the company:
[O]ur bid, entire job, $132,250.00. Substitutes reinforced concrete for structural steel in floors. Also flat slabs for docks. Sheet piling omitted. Reinforced concrete piles $1.40 per [linear?] foot in place. Can start work immediately. Alternate bid, actual cost, labor, materials, and miscellaneous expenses, plus ten percent.
The negotiations with Scott Paper Company were carefully and thoroughly recorded, primarily through correspondence. Details of the work, especially the timeframe for completing the job would become an issue for Cummings. Among papers related to “contract planning” is a letter dated May 7, 1917, from President Edward Irvin Scott of Chester Paper Company to Cummings.
Now Mr. Cummings, we have got some plain talk to give you. We cannot stand for the delay on the buildings at Chester; our beater rooms are nowhere near completion; you only have a small amount of people, and we have absolutely got to have that work finished, and we cannot submit to further unnecessary delay.
Cummings finally finished the project a month later; clearly, Cumming wasn’t working with quick-set.
The National Cyclopaedia of American Biography, Volume 50, Ann Arbor: University Microfilm, 1971.
United States Department of the Interior, Bureau of Land Reclamation, Lower Colorado Region, http://www.usbr.gov/lc/hooverdam/History/essays/concrete.html (last accessed October 17, 2012)
All images are from the Cummings Structural Concrete Company Records, Archives Center, National Museum of American History.