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Nozzleman Knowledge ledge and on-job experience to use the nozzle, and the many individual equipment components in a manner that will produce acceptable in-place material. Although nozzle skill is necessary for a quality shotcrete job, proper equipment function is a fundamental requirement. Quality in-place shotcrete is not possible without it. Nozzleman Equipment Maintenance Checklist • Select a wet-mix pump configured specifically Fig. 7: Air supply line diameter is critical to for wet-mix shotcrete use. maintaining adequate nozzle velocity • Adjust the pump to produce an even flow larger air supply lines when longer air supply lines of material, without excessive nozzle thrust. are needed (Fig. 7). • Perform necessary pump maintenance before worn sealing surfaces and wear Sufficient Lighting is Necessary components affect placement quality. Quality shotcrete is not possible without • Perform required maintenance on the acceptable lighting. Lamps should be used in nozzle. Inspection, disassembly, and areas where shadows can obstruct vision such as cleaning of all air metering ports, and under large overhangs, dark corners, or in under- replacing worn components, must be per- ground applications. formed daily by the nozzleman. The nozzleman and blow pipe operator must • Provide enough air volume to generate be able to clearly see the receiving surface. satisfactory impact velocity. Both the com- Nozzleman must have a clear view of the re - pressor and air delivery system must be ceiving surface when applying shotcrete to ensure sized to generate sufficient nozzle velocity. that the material is being applied at the correct • Use appropriate lighting to assure that both angle, at the correct distance from the receiving the nozzleman and blow pipe operator can surface, at a proper consistency, and at the speci- clearly see the receiving surface at all times. fied thickness. • Be aware that YOU are in control of a com- plex system which requires many individual Putting It All Together equipment functions. An understanding of Wet-mix equipment selection and maintenance the proper function of all required equip- procedures affect shotcrete in-place properties. A ment is critical to proper shotcrete place- capable nozzleman must possess sufficient know- ment. If any part of the system is not functioning properly, STOP, investigate, and correct the problem before continuing. Annual Nozzleman Compilation ACI Certified NozzlemanOscar Duckworth is an ASA and ASA 2013 American Concrete Institute (ACI) member with over 15,000 This 36-page black and white soft-cover Nozzleman Compilation book is an annual publication introduced hours of nozzle time. He hasAnnual in 2013. This document is a compilation worked as a nozzleman on over ASA 2013 of 10 previously published articles from 2000 projects. Duckworth is ASA’s Shotcrete magazine, Volume 15. currently an ACI Examiner for Order Code: ANC13 the wet- and dry-mix processes. He currently ASA Members: $9.00 serves as ASA Executive Committee Secretary Nonmembers: $14.00 and newly appointed Chair of ASA’s Education Visit www.shotcrete.org/BookstoreNet/default.aspx Committee. He continues to work as a shotcrete or call (248) 848-3780. consultant and certified nozzleman. 52 Shotcrete • Fall 2014


2014FallShotcreteEMag
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