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2013FallShotcreteEMag

Nozzleman Knowledge facturers also recommend coating the water ring with oil to prolong its usefulness. Replace the water ring when it cannot be cleaned or when it has become misshapen. Do not drill out the holes in the water ring because they are specifically sized to provide proper distribution of water into the dry-mix mate- rial flowing through the water ring. Dismantle the nozzle assembly after each day of use and thoroughly clean the inside and outside to ensure performance on the next job. (Fig. 7) You may also be able to clean the nozzle without disassembly by one of two methods: 1) you can use the valves on the gunite machine to send air to the nozzle from the gunite machine without Fig. 8: Dry-mix nozzle liner with interior steps/ribs sending material. Combine this with water flow to the nozzle and you may be able to thoroughly the quality of the concrete being placed on the clean the nozzle parts, including the water ring; construction surface is compromised. It may lead or 2) you may achieve success without the use of to uneven distribution of sand and cement, which compressed air by simply pointing the nozzle can result in an unreliable or even unsafe struc- down and allowing water to flow through the ture. Polyurethane tip designs may last longer nozzle’s water connection. than a liner. Their overall longevity may vary Nozzles may either have a steel tip with a depending on the thickness of the material used rubber liner or a polyurethane tip. If using a nozzle or overall design and shape. with a liner, be sure to inspect it regularly and replace the nozzle liner when worn through. The amount of wear is dependent on the type of mate- rials being used; however, liners should provide approximately 80 yd3 (61 m3) of service. The nozzle liner should include “steps” or ridges that are built in to help mix material in the nozzle. (Fig. 8) These steps can be seen close-up or can be felt by touching inside the end of the nozzle liner. When steps have worn away from material flow, it is time to replace the nozzle liner. Nozzle tips should not be cut or shortened, as this can prevent material from mixing adequately in the nozzle. Without proper mixing within the nozzle, Fig. 9: Nozzleman using anti-static dry-mix hose Shotcrete • Fall 2013 41


2013FallShotcreteEMag
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