Proper shotcrete / Concrete applications are challenging and can be potentially dangerous. The shotcrete nozzle blast is dangerous.
A shotcrete operation requires several high pressure hoses (air, material, water, hydraulic).
Typically, hose ruptures occur at the connections and areas subject to abrasion. Special attention must be given to safety clamping all material hoses and air lines. All pressure lines-air, water and material-should be checked periodically for abrasions. Because of the various high-pressure hazards on shotcrete jobs, all personnel should wear eye protection and suitable clothing.
Never place hands into the piston or Hopper of a concrete pump. The valves that swing from one piston to the other can quickly and easily cut off a hand or arm. The hopper screen of all concrete pumps must be in place whenever the units are operating to avoid accidents with the rotating agitator or swinging valves.
The unattended nozzle is dangerous. Treat it like a loaded gun. It should not be casually put down until all pressure is off line. Pressure can build up in hose due to a plug in the line and temporarily stop the flow of material out of the nozzle. When the pump stops, the pressure in the line is not necessarily relieved.
Shotcrete operations usually require scaffolding so that the nozzleman can properly and safely place the shotcrete. Scaffolding to provide a safe working platform must be secure and large enough to allow personnel movement. Scaffolding should provide a back brace for the nozzleman to counteract the nozzle thrust.
Concrete Overspray / Dust Hazard:
Exposure to cement dust can irritate eyes, nose, throat and upper respiratory system. Skin contact may result in moderate irritation to thickening/cracking of skin to severe skin damage from chemical burns. Silica exposure can lead to lung injuries always wear protection
The project contractor is responsible for identifying and mitigating hazards and must always follow OSHA requirements. All Shotcrete projects are unique and each project has its own unique hazards which must be addressed. A Hazard analysis and procedures to mitigate the hazards must be developed for each job/project. In addition to an overall hazard analysis plan, daily hazard analysis and review must be performed before undertaking daily work. The Shotcrete crew should daily review the job site conditions which may include, pressured lines, equipment set-up ,hazards from debris and the environment. Always check to ensure that personnel have the proper Personnel Protection Equipment PPE). Always wear safety glasses or goggles, use safety shoes or boots and hearing protection.
A typical Shotcrete operation has multiple hazards. Shotcrete personnel should become familiar with all equipment and strictly follow the manufacturer’s safety precautions and all guards and screens should be in place whenever any equipment is operating. Before staring a project conduct a walk through so all personnel are familiar with the potential hazards, layout of the equipment and what actions are to be taken in the event of an accident.
Wet-Mix Process Shotcrete operations
Concrete pumps produce pump concrete at high pressures through a material line. The pressurized air line is also connected to the Shotcrete nozzle to propel concrete out of the nozzle. When a plugs occurs hoses and reducers can become potential hazardous due to the explosive potential of high pressure lines. All pressurized lines should be equipped with safety checks. The Shotcrete spray from the nozzle is also a potential hazard.
The work area must be well lit and ventilated to assure that the Nozzleman has a clear view of his surroundings, placement area and there is sufficient ventilation.Shotcrete placement, may create dust and overspray. Barriers may be needed to control, dust and overspray from the environment as well as prepared surfaces. Use local exhaust or general dilution ventilation to maintain exposure below applicable limits.
In cold weather (average temperature less than 40º F) tenting and heating should be considered to protect the Shotcrete placement area. Tenting can and should also be used to protect the Shotcrete placement area from rain and wind. Heat enclosed areas with vented heaters. Personnel should wear warm clothing. In hot weather above (100 F) tenting can help to lower the site temperature. In hot weather provide shaded break area and insure craftsmen hydrate by keeping plenty of cool water available.
Each work site is unique and will require an appropriate setup of equipment and placement of the supporting features. Care needs to be taken for general housekeeping; Rebar, Forms and materials from other trades should provide clear access for the Shotcrete operation. The environment of the job site condition is also important, other trades may be working near the Shotcrete operation and there may be a need for extra safe guards from overspray, dust, noise and traffic control.
Review Material Safety Data Sheets (MSDS) for all materials in use. Prevention is essential to avoiding potentially severe skin injury. Avoid contact with unhardened (wet) Portland cement products. If contact occurs, promptly wash affected area with soap and water. Where prolonged exposure to unhardened Portland cement products might occur, wear impervious clothing and gloves and boots to eliminate skin contact.
Exposure to Concrete can result in skin irritation or even first, second-or third-degree chemical burns.
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