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Shotcrete Corner and for bringing it to required line and grade in a workmanlike slump of the mixture. The pump operator may change the manner. The nozzleman’s duties include coordinating the delivery rate of the transit and concrete trucks, including staging application with the foreman, finisher or rodman, and pump/ the trucks at the pump. The pump operator is also responsible gun operator. Before the shotcrete is installed, the nozzleman for the safety of the pump and delivery line. should ensure all areas to receive shotcrete are clean, sound, Mixerman’s Duties—The mixerman’s duties include, and free of loose material, and that anchors, reinforcement, and where applicable, the proportioning and mixing of the shotcrete ground wires are properly placed and spaced. mixture materials, and maintaining and cleaning the mixing In the dry process, the nozzleman controls the water content equipment. For field mixing, the mixerman is responsible for for hydration and ensures that the operating air pressure is storage, care, and accessibility of the materials. The mixerman uniform and will provide high velocity at impact for good sees that the mixture is free of contaminated materials and consolidation. In the wet process, the nozzleman controls the debris and that the aggregates have the proper moisture content. air that increases or decreases the velocity to ensure proper The mixerman ensures a constant flow of shotcrete materials placement, including proper encasement of the reinforcement. but is also careful not to mix more material than can be used The nozzleman provides leadership and direction for the within the specified time limits. The mixerman supervises the shotcrete crew, which aids in the task of shooting high-quality laborers who are supplying and loading the mixer. shotcrete. The nozzleman is usually an accomplished finisher Hose Tender’s Duties—The hose tender’s duties include or rodman and gunman/pump operator. moving tools, equipment, hoses, scaffolding, and materials. Wireman’s Duties—The wireman sets elevations and thick- Hose tenders clean work areas, remove rebound and overspray, nesses for the shotcrete placement, which may include the top and provide support for the shotcrete application. and face of the wall. Grades set by the wiremen are the lines Project Engineer, Project Manager, or Superintendent— the nozzleman and finishers will follow. The wireman may use On large or complicated projects, a project engineer, project many devices for setting grades, such as piano wire, fiberglass- manager, or superintendent may be advisable. A shotcrete metal rods, and plastic pipe. contractor usually employs engineers, project managers, or Finisher/Rodman’s Duties—The finisher rods or cuts the superintendents, but they may not be assigned full-time to a freshly placed shotcrete surface, bringing it to line and grade single project. The project engineer, project manager, or before final finishing. The finisher also locates and removes superintendent is responsible for the material selection, mix- sand pockets, sags, and sloughs, and guides the nozzleman to ture proportioning, preconstruction testing, qualifications of low spots that require filling with additional shotcrete. Before the crew, equipment selection, project planning, scheduling, the shotcrete takes final set, the finisher brooms and prepares logistics, materials handling, quality control, sampling and the surface for final application. testing coordinating, and troubleshooting technical problems Assistant Nozzleman’s Duties (blowpipe/air lance con- during construction. trol)—The assistant nozzleman helps the nozzleman by drag- ging the hose and performing other duties as directed by the Crew Qualifications nozzleman. The assistant nozzleman relays signals between General—The quality of a completed shotcrete application the nozzleman and the gunman/pump operator, and may also results from the combined skills and knowledge of the shotcrete relieve the nozzleman for short rest periods. The assistant crew. The foreman and crew should have performed satisfactory nozzleman may operate the air lance, if one is required, to work in similar capacities for a specified period. The entire keep the areas in advance of the shotcrete free of rebound and crew is responsible for the safety of each member and other’s overspray. The assistant nozzleman may be a nozzleman on any particular project. trainee and place shotcrete under the direct supervision of a Shotcrete Foreman—The foreman commonly has profi- certified nozzleman. ciency in all crew positions and is in charge of the crew and Gunman’s Duties (dry-mix)—The gunman provides a their safety procedures. The foreman typically has at least constant flow of properly mixed dry-mix material to the noz- 2 years of experience in the placement of shotcrete. zleman. The gunman operates and maintains a clean gun and Nozzleman—The nozzleman should be ACI certified (refer assists in ensuring quality control. The gunman should be to ACI CP-60) and have completed at least one similar applica- particularly attentive to the needs of the nozzleman and ensure tion as a nozzleman on a similar project for the shotcrete that the mixture is properly prepared. The gunman generally contractor. On congested reinforced projects, the nozzleman oversees, controls, and coordinates the material mixing and should also be able to demonstrate, by preconstruction testing, delivery operation. an ability to satisfactorily perform the required duties and to Pump Operator’s Duties (wet-mix)—The pump operator apply shotcrete as required by specifications. regulates the pump to uniformly deliver the wet-mix shotcrete Assistant Nozzleman/Nozzleman Trainee—The assistant at the required rate. The pump operator is responsible for nozzleman/nozzleman trainee should have 6 months of experi- cleaning and maintaining the material hose and pump. The ence in a variety of shotcrete field operations that may include pump operator coordinates the delivery of shotcrete mixture finishing, gun or pump operation, blowpipe/air lance control, and monitors the water content by observing or testing the and hose tending, and should be able to demonstrate knowledge Shotcrete • Winter 2014 53


2014WinShotcreteEMag
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