Tuesday, July 28, 2015

Concrete: Ancient and Modern Building Material

I have always been fascinated with processes—how things come to be—printing, photography (old school), manufacturing (anything), baking, cooking, winemaking. And now construction; and this week, concrete.
The concrete process mixes together, water, aggregate, cement, minerals, and chemicals to make a structural element. Unlike other construction materials (wood, pipe, insulation, roofing), concrete comes to the site in its raw form.
For the concrete foundation of our barn/workshop we originally planned to have an Alaskan or mono slab, an economical design that calls for pouring the footings and barn floor at the same time. That turned out to be impractical due to the slope of the land, revealed only on clearing, and extreme weather considerations. The design now incorporates 5-foot frost walls, a 6-inch crushed stone base over insulation board and vapor barrier with a 4-inch pour for the floor instead of a 6-inch one. It will be solid, which is what we want when the winds howl across the mountainside at 25 mph and the mercury drops to the minus double digits.
Looking from back corner of barn up driveway.
(All photos by author.) 
Precisely positioned rebar in poured wall.
Concrete construction entails precision craftsmanship. After the footings (with reinforced steel bars or rebar) were poured and allowed to cure, the concrete crew constructed the formwork, a double-walled structure of treated wood panels atop the footings. Bob placed the forms in position by crane. Other workers locked in place reinforcing whalers to create a structure strong enough to withstand the outward pressure of poured wet concrete. They snapped lots of blue chalk lines to guide the height of the pour. They placed more exactly spaced rebar. The formwork accommodates four doors—three garage and one pedestrian. Windows will be placed in the frame structure above the frost wall.

Left side, garage and pedestrian doors.






D tells me that the curing of concrete is not simply a drying of a wet mass but “hydration,” a chemical process that forms a microstructure to give concrete its compression strength. Suffice to say, many a PhD thesis has been written about the materials science of concrete.

Concrete has a long history. The Egyptians used a cementitious material in the Pyramids (3000 BCE). The Roman Pantheon’s concrete dome (300 BCE) remains the world’s largest. But the ancients’ building material was lost for more than a thousand years. Modern concrete dates to 1824 when Englishman Joseph Aspdin, building a lighthouse in southwestern England, discovered a mortar that hardened under water, inventing portland cement and naming it for its resemblance to limestone quarried on the Isle of Portland. (Grammar geeks take note: portland cement is not capitalized per the Portland Cement Association.)
Edison's garage at home in West Orange, NJ.

Thomas Edison revolutionized the production of portland cement when in 1909 he received a patent for the first rotary kiln, a process for making cement still in use today. Edison was so enamored with the material that he designed all-concrete houses (furniture, too), which did gain the popularity he had anticipated. Today a few houses built by Charles Ingersoll using Edison molds and concrete remain in Phillipsburg and Union, NJ. (The Thomas Edison National Historical Park in West Orange, NJ, and his nearby home are worth a visit. The garage and greenhouse at the home site are concrete construction and remain in superb condition.)
Concrete has figured prominently in the building of skyscrapers (first in 1903, Ingalls Building, Cincinnati, Ohio), New York City subways (1904), the Panama Canal (1909), and the Hoover Dam project (1936).

So, with our humble barn we pay tribute to ancient and modern engineering history. It doesn’t get more concrete than that. 


2 comments:

  1. I am enjoying the photography as much as the writing -- as I think you do, too.

    ReplyDelete