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2015FallShotcreteEMag

A Team Approach to Any Project is the Best Approach By Darin Cielocha Iare exactly the same.” McGill Restoration over the years across the great plains of theThis is especially true when it comes to wet-shotcrete mixture designs that have been usedn the industry of restoration, one thing can besaid that continues to ring true: “No two jobs knows that all too well. The company’s history Midwest. Portland cement is one of our greatest and experience spans over the past three decades building material resources in Nebraska, and we and they have skilled craftsmen that range from have some of the country’s best-paved roads and trades such as laborers, carpenters, masons, painters, highways. Unfortunately, although many of the concrete finishers, and shotcrete nozzlemen. With ready mix producers are great at producing that kind of lineup, there’s not really a whole lot concrete for cast-in-place concrete applications, you can’t tackle in the world of restoration! many ready mix producers lack the knowledge of In the Midwest, it’s not uncommon for people the proper portions of portland cement to use in to respond to a call for some help from their a wet-shotcrete mixture design as well as the right neighbors. In this case, McGill Restoration was proportion and/or gradation of aggregates. So, asked to help out the company neighboring their with the help and willingness of Rod Leber warehouse in Lincoln, NE. It just so happens (General Testing Lab Manager for NEBCO Inc.) that this neighbor is one of the largest grain and Oscar Duckworth (Valley Concrete Services), receiving/storage facilities in the state. Interstate we were able to design a concrete mixture well- Commodities (ICI) is based out of Troy, NY, and suited for our application. We lowered our has several grain receiving/shipping terminals concrete mixture costs by crafting the right located across the East Coast and upper Midwest proportions of portland cement, fly ash, and regions of the United States. With a rising demand admixtures. The gradation of aggregate was for storage capacity, ICI contracted McGill probably the most challenging. Most of the Restoration to reline and strengthen a grain silo aggregates used in concrete mixtures in our part that had been determined to be structurally of the country tend to be heavy on the sand-gravel deficient for grain storage. side. To use a larger aggregate (1/2 in. 13 mm), Challenges: we had to consider using limestone. Limestone is • Getting assistance from local ready mix producer one of this region’s most available type of to help develop a suitable wet-shotcrete mixture aggregate sources, and provided the additional that could be pumped over eight stories— sieve size of aggregate we were needing to round straight up. out our mixture design. By adding the 1/2 in. • Working with a local structural engineering (13 mm) limestone aggregate, we were still able firm to develop a relining strategy and survey to produce a very pumpable and workable of the structure. mixture. By bringing together the ready mix • Providing enough illumination for crews to see producer and contractor along with a little help what they were looking to accomplish. from ASA, we made a winning team to overcome • Having restrictions to work with only air- this project challenge. driven tools and hoists while working on the inside of the silo. Current Condition of the • Using a suspended scaffolding system that would accommodate being close enough to the Structure wall to dowel and tie reinforcing bar, and far Many of the grain storage facilities that were built enough from the wall for a nozzleman to work. across the Midwest in the 1950s to 1960s were • Being safe at all times! built using slipform construction methods. This method of construction during this period of time Mixture Design did not vary the thickness of the wall from the One has to sometimes overcome the parity in the base of the structure to the roof. So, the condition construction industry of “what worked on the last of the grain silo we were looking at relining was job, will probably work again on the next job!” constructed of 8 in. (200 mm) walls from the 30 Shotcrete • Fall 2015


2015FallShotcreteEMag
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