Story and photos by Kristen Cart
In the summer of 1954, Mayer-Osborn Construction built an elevator with a stepped headhouse in the northwestern Iowa town of Blencoe. As my dad, Jerry Osborn, explained, after the crew poured the first ten feet of concrete in the slip-form process, the concrete sides below the forms showed signs of crumbling. An investigation revealed that the concrete mixture had not been set correctly. It took as many hours to remove the concrete and start over as it did to pour it. Dad worked on the project and saw the fallout first hand.
Builders were required to do a destructive test on the concrete mix at various stages of curing, to ensure the proper strength for each part of the elevator structure. Engineers tested various mix ratios to decide upon the best one. Naturally, this process was used at Blencoe, but when the mix was finally set and the pour began, it was done incorrectly. I can imagine the blue language wafting from the site as the concrete was taken down. Someone on the site had his ears pinned back pretty fiercely. But the construction continued, and a handsome elevator still stands there today, nearly 60 years later.
Not until this year, when Tim Tillotson located the Tillotson company records and photographs, did we discover that Tillotson Construction of Omaha faced a similar problem as they built their elevator nearby about a year later. This time, the error was not caught as early, and the consequences became immediately apparent.
Tim Tillotson said he thought the blowout happened in about 1955. Whether Tillotson Construction did the repairs and completed the project, or whether another contractor was brought in, is not known to me, but I hope to revisit the site later this year and learn more. The image below is a rare one. It is amazing that photographic evidence survived, serving as a cautionary note, lest any builder were to become overconfident.
Errors were a constant threat in this business. In the best cases, they manifested themselves in embarrassing delays, in the worst, they incurred expensive lawsuits or physical harm.
Tillotson Construction and Mayer-Osborn both recovered from their respective forays into bad concrete and lived to build again, leaving handsome and serviceable elevators at Blencoe and elsewhere. The lessons they learned were priceless.
- J. H. Tillotson, Contractor, built their elevator scale houses with distinctive flair (ourgrandfathersgrainelevators.com)
- Full specifications of Tillotson Construction’s elevator in Moscow, Kansas (ourgrandfathersgrainelevators.com)
Great photos! I notice in the photo, that the unplanned hole, is in the curved wall directly above the driveway opening. This appears to be a wall that is started after the slipform has risen above the driveway. When slipforming, a common practice is to start (or stop) walls “on the fly”. In otherwords, the wall does not go full height from foundation to roof. Starting a wall part way up can be difficult. A header is installed in the form to place new concrete on and it must be substantial enough to take the full weight of several feet of wet (plastic) concrete. Sometimes, when picking up a wall on the fly, either the header fails or the new wall is not cured sufficiently to stay in place after the form advances. When this happens, a fall out occurs. The wet concrete sloughs out from under the form and a hole develops. It is possible that the photo shows the aftermath of a fall out. The vertical side on the right is a bit unusual but the crew may have successfully installed a bulkhead to stop the fall out from spreading. The sloping edge on the left side of the hole is a classic example of a fall out.
This is one AWESOME blog you have here! Congratulations.
I happened upon a complex of concrete rice dryers and fortunately had my camera with me. I would love to know more about them and would welcome your comments: http://ancestralyuba.com/category/on-the-road/
[…] Concrete problems plagued consecutive elevator projects at Blencoe, Iowa (ourgrandfathersgrainelevators.com) […]
Holy Toledo… I had NO idea a structure such as a grain elevator can “blow” like that. Is it more of a structural collapse under pressure rather than gasses forming inside the elevator? And as for sub-standard concrete, Hitler’s infamous Atlantic Wall was sabotaged in a way by the use of sub-standard concrete components.
In the case of the Mayer-Osborn project, the mix ratio of concrete was set incorrectly, and the error was caught. But the problem at the Tillotson project was apparently structural. Both issues happened before any grain was loaded, so no explosive grain dust was involved.
How interesting that the concrete the Nazis used could be sabotaged, especially on such a major project. I never knew about it. Fascinating!
[…] an earlier post, we showed that the elevator built by the Tillostson Construction Company in the northwest Iowa […]
[…] only story I can verify is the tear-down and restart of the Mayer-Osborn elevator in Blencoe, Iowa. The concrete mix was wrong there, and it cost a few days and quite a lot of money to correct. […]
[…] with his partner, Gene Mayer, in McCook, Nebraska, in 1949. This example of the type went up in Blencoe, Iowa–and not without incident, as we have related in this […]
[…] there’s the problem of blowouts. We have written before on Our Grandfathers’ Grain Elevators about […]