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2015FallShotcreteEMag

Mobile Batching of Shotcrete By Mason Guarino and Tom Norman Sminutes ago and were wondering where the as part of the team rather than someone who justtruck to show up late or not at all. The truck driveris our employee, so he will work with our crewsite foreman to the local ready mix plantdispatcher: “Hi, we ordered concrete 30 truck is?” Local ready mix plant dispatcher to the wants to empty his truck as fast as possible and site foreman: “Oh, sorry about that, we are run- move on. On large projects of 150 yd3 (115 m3) ning behind. He is batching now and will be on or more, we are also able to park a portable cement site soon,” or maybe, “Oh, sorry, due to tomor- silo and an excavator next to the mobile batch row’s rain, one of our large customers moved up trucks and create an on-site batch plant to be even a big job and we will get to you in about 3 hours.” more efficient. We do not need to shut down for The variations are endless, but it usually means 15 minutes every 8 to 10 yd3 (6 to 8 m3) to swap the we’ll be waiting for concrete. At least for our concrete trucks. We can shut down and restart when company, these comments have been relatively needed—not at the whim of a concrete supplier. common in all of our experiences with ready mix SSG is a pool company that uses both the wet- concrete suppliers, not just with shotcrete. We and dry-mix processes. We prefer the dry-mix wanted to gain more control over our concrete process on the smaller projects under 50 to 60 yd3 deliveries and the simplest answer was to buy a (38 to 46 m3). We use Airplaco mobile batch plants batch plant and a truck. So we did, only it was a on our smaller projects (refer to Fig. 1). The Airplaco mobile batch plant mounted on a truck—a volu- mobile batch body is mounted to, in our case, a metric batch plant. Once we started running our triaxle heavy-duty truck that can legally drive own batch trucks, we were then able to get rid of around with a 77,000 lb (35,000 kg) total weight. the ready mix delivery headaches and have more These dry-batch trucks produce material quickly control over our concrete needs. At South Shore and efficiently to supply the Gunite Supply C-10 Gunite Pools & Spas, Inc. (SSG), we have been able gun we use on all of our dry-mix projects. These to successfully batch both wet- and dry-mix shot- trucks are easy to calibrate with the manufacturer- crete and use the trucks in a few different ways. provided calibration bin. One of the benefits to The driving factor behind using mobile the dry process is that when the truck is empty, batching trucks was to be more profitable. If our they can be cleaned up more quickly and throughly concrete costs less, our bids can be less and we than a wet-batch truck or a conventional concrete can win more jobs. However, once we started truck. When the job is done, it is also very easy working with the batch plants, we realized that to clean the area around the gun that has dry sand we could also be more efficient and, in turn, and cement, as opposed to a pile of wet material. become more profitable. Because we control the When working in residential backyards, being trucks, we always know where they are and do quick and clean is helpful. We have been running not have to wait for a promised ready mix concrete three dry Airplaco mobile batch trucks for close to 15 years now. The trucks fill up on a regular basis at one of our two cement silos. The sand is kept dry under a sand barn and when not in use the trucks are parked under a roof to keep the sand from getting too-wet, because too-wet sand will really clog up a gun. SSG uses the wet-mix process to do the work on the larger projects, as it is roughly twice as fast as the dry process. When walls start to get thick, it’s nice to have the higher productivity. SSG uses a Cementech mobile batch plant for all of the wet-mix batch work we do. Ninety-five percent of our wet-mix mobile batch work is on large jobs, where we set up a Cementech portable silo and Fig. 1: On-site dry-mix batching truck an excavator next to the truck (refer to Fig. 2). If 20 Shotcrete • Fall 2015


2015FallShotcreteEMag
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