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2013SumShotcreteEMag

Qualifications of the Shotcrete Construction Team By Charles Hanskat Svariety of concrete structures. Shotcrete has as a quality shotcrete contractor are then pre-to help establish field crew qualifications. Therequirements for designating a contracting firmhotcreting is an efficient method for placinghigh-quality, durable concrete in a wide been successfully used in substantial number of sented. A shotcrete team that meets or exceeds the projects for well over a century. As with cast-in- presented crew and contractor requirements will place concrete, the quality of the shotcrete place- be best qualified to provide a cost-effective, high- ment is dependent on the quality of the materials, quality, and durable shotcrete application. proper mixing and transport, substrate/subgrade preparation, the placing process, and protection Field team Duties until final strength is reached. However, a comparison of the shotcrete pro- and Qualifications cess to the traditional “form and cast” process (based on input from ACI 506 Subcommittee shows significant differences. Specifically, when developing updates to 506R, “Guide to Shotcrete”) using the shotcrete process: • Formwork is eliminated or substantially reduced. Composition and Crew Duties • It is necessary to identify the best shotcrete The basic shotcrete crew may consist of a process (wet- or dry-mix) for the job. foreman, a nozzleman, a finisher or rodman, an • Special gunning equipment is required, including assistant nozzleman, a wireman, a gun or pump pumps, guns, hoses, nozzles, and admixture/ operator, a mixer operator (if needed), and laborers. water pumps. Depending on the size and complexity of the • Knowledge is required to safely use and project, one person may perform more than one maintain the shotcrete equipment. operation. For example, the foreman could also • A trained field crew that performs work totally function as the nozzleman; one person could unlike casting concrete in forms is required. perform as the rodman and finisher; an assistant • Environmental conditions that are unsatisfac- can help the nozzleman by both pulling the hose tory for quality shotcreting must be identified. and operating the air-lance/blowpipe; and, if • The nozzleman must be well-versed in shooting necessary, the gun or pump operator and mixer techniques, including proper air, water, and functions could be combined and, with proper mix flow. equipment, performed by one person. Larger, • The crew must be prepared to properly finish, congested reinforced projects, on the other hand, protect, and cure freshly placed shotcrete. may require more than one nozzleman and air • Knowledge of quality control procedures lance operator and several finishers. Where sev- specific to shotcrete is required. eral crews are operating, a foreman, superinten- Based on these factors, it is apparent that a dent, and engineer may be required. contractor offering to place quality shotcrete can Shotcrete Foreman’s Duties—The foreman only truly be considered a qualified shotcrete plans, directs, organizes, and coordinates the contractor if every member of the shotcrete con- work of each member of the shotcrete crew to struction team—from company management obtain a safe and successful application. This through the field team—has specific knowledge, includes ensuring the safety of the work area and equipment, training, and hands-on experience in following quality control procedures. The the shotcrete process. foreman is responsible for the inspection and ACI 506R-05, “Guide to Shotcrete,” is a great maintenance of equipment, as well as ordering primer on shotcrete design and application. ACI and expediting the delivery of materials. The Committee 506, Shotcreting, is currently work- foreman sets the pace of the work, maintains crew ing on revisions to the “Guide to Shotcrete”; in morale, ensures good housekeeping, and acts as the latest drafts, the committee developed an liaison with the general supervisor or the owner’s expanded section covering shotcrete crew require- inspection team. The foreman is usually a vet- ments. The following provisions are summarized eran nozzleman, finisher/rodman, or pump/gun 28 Shotcrete • Summer 2013


2013SumShotcreteEMag
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