By Ronald Ahrens
Today I ask the reader’s forbearance as I interrupt our road-trip series. We have three more elevators to visit, including Tillotson Construction Co.’s first reinforced-concrete elevator, a little honey in Goltry, Okla. You can see the Goltry elevator complex in the photo above; Tillotson’s 1939 elevator is on the right.
More to come in the next post.
But today I share some thoughts with an important point about impermanence. This topic came up in bold relief when I got to Pond Creek, the second of the remaining three stops, where the issue arose of an elevator’s rated life.
I had already seen crumbling concrete at the Johnson-Sampson elevator in Orienta. I was discussing this just the other day with Uncle Chuck Tillotson. He reminded me the problem lay with the right recipe for the original mix: cement, sand, and water weren’t blended in the correct proportions. Some 65 or 70 years later, we see the results.
Uncle Chuck recalled his own struggles as a teenager, whose mind was on girls, while being in charge of mixing the concrete on grain elevator construction sites around 1950. Was that the fourth or fifth load he had scooped in the tractor’s bucket and brought over to the batch plant.
(And then the tractor’s clutch would give out as it always did.)
Uncle Chuck elaborated upon our lunchtime discussion in a subsequent email. “Most people don’t realize that a grain elevator, as is the case with any concrete structure, does not provide an indefinite lifetime,” he wrote. “It is subjected to all the elements of nature–wind, rain, freezing temps, terrific heat, and most of all the internal bearing pressure from the grain on the walls of the storage bins.”
Bearing pressure on the walls of the Goltry elevator was rated at 2.47 tons per square foot.
“Concrete is not a permanent material,” he continued. “Unlike stone it is a man-made material and subject to deterioration over the years and very dependent on the proper amounts of sand, gravel, and cement made into a cementitious mixture and poured into a form to encase steel reinforcing.”
Our conversation received amplification from a June 17 op-ed piece in the Los Angeles Times. The essay is adapted from Vince Beiser’s new book, “The World in a Grain: The Story of Sand and How It Transformed Civilization,” which comes out Aug. 7.
Concrete, Beiser writes, provides “an almost magically cheap way” to build things. But this “man-made stone” brings its own problems.
“Concrete fails and fractures in dozens of ways. Heat, cold, chemicals, salt and moisture all attack that seemingly solid artificial rock, working to weaken and shatter it from within.”
He forecasts 100 billion tons of concrete buildings, roads, and dams need to be replaced.
And that’s the question at every elevator I visited.
I was happy to discover most were still working and in good condition. But what happens in 20 years? There will probably be even more steel bins, although these have problems of their own.