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Wet-Mix Pumps Fig. 14: Schwing 750 trailer pump setup for easy maneuvering in and around the jobsite can be reduced down to a 2 in. (50 mm) hose for shotcrete work or up to 5 in. (125 mm) for Fig. 12: An Allentown Powercreter 20 is shown concrete pumping with a hydraulic mixer attachment. The attach - ment is being used as a remixer for concrete supplied by a mobile, or a volumetric mixer for site batching to achieve a consistent mixture for pumping operations. A vibrating screen was installed to reduce the risk of plugging the 1.5 in. (38 mm) hose due to randomly occurring large aggregate particles. The electronic control technology produced a continuous flow of concrete material that allowed the nozzleman to apply a uniform shotcrete layer to the walls with very little line surge. The unit can pump concrete containing up to 1 in. (25 mm) stone mixes through a 4 in. (100 mm) hose Fig. 15: Allentown Powercreter Model 40 pump with hydraulic outriggers can be reduced down to a 2 in. (50 mm) hose for shotcrete work or up to 5 in. (125 mm) for concrete pumping. The electronic swing tube control allows for faster shifts between cylinders, thus reducing the line surge to the nozzleman that has a vibrator (a vibrator on the hopper face only compacts the concrete, allowing all the water to rise to the top). These are just a few issues with the wet pumps. One needs to keep in mind that Fig. 13: Reed C50HP concrete pump can be only about 18 yd3/h (14 m3/h) can be pumped reduced down to a 2 in. (50 mm) hose for through a 2 in. (50 mm) hose unless you are shotcrete work or up to a 5 in. (125 mm) hose pumping cement grouts. An average manually for concrete pumping applied shotcrete application produces between 6 and 15 yd3/h (5 and 11 m3/h) of pneumatically pumping distance; hose size; type of application; applied concrete. Hose sizes of 2, 2.5, and 3 in. quantity of material to be pumped; production rate (50, 65, and 75 mm) are typically used for robotic desired; and use for the multiple applications other applications. The outputs for robotic applications than shotcrete, such as grouting or concrete placing. range from 20 to 30 yd3/h (15 to 23 m3/h). All three trailer-mounted concrete pumps (Fig. 13 through 15) are for medium- to large- Shotcrete Application Breakdown volume output projects. Remember, all concrete pumps were designed to pump large aggregate between Both Processes mixtures. There are pumps on the market that were The breakdown comparison between processes designed to pump harsh stiff mixtures and small in Table 1 may help with your decision making. aggregate mixtures, which also can pump large The dry-mix process requires more volume of air aggregate mixtures. You have to look at the line than the wet-mix process, but is easier to stop, start, surge between strokes, how well the mixture can and move than the wet-mix process. All areas other be drawn into the cylinders for discharge, whether than the equipment and maintenance costs of dry- the hopper has an agitator remixer, and a grate mix are about the same. Admixture technology has Shotcrete • Fall 2015 15


2015FallShotcreteEMag
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