I’m not satisfied with my subtrades blowout procedures for the shotcrete lines. I’m not an expert in this; however, the way they are doing it does not look safe. I’ve tried to Google and reach out to other shotcrete companies but have not had any luck. They use a hopper that concrete is pumped into and is disbursed through lines that are moved manually; this step is normal. But when they have a blockage or cleaning the line when done, they have two workers sit on the end. They use compressed air. There must be a better way to clean and clear a blockage than having human bodies as weights. Please give me some guidance.

ASA’s “Safety Guidelines for Shotcrete” specifically addresses hose blockages. Use of compressed air to clear blockages or for cleaning the lines is not recommended. The Guidelines state:

“With the variety of shotcrete material delivery systems available, and their placement on individual job sites, the Contractor should establish site-specific safety procedures applicable to the specific delivery systems and site conditions for blockage removal. Any field procedures for clearing blockages should not use compressed air as means to remove or dislodge blockages.”

Using water to clear blockages or the delivery lines when finishing shooting is the recommended procedure. However, if compressed air is used, the hose end must be securely fastened with a substantial fastening system that can routinely and safely handle the forces created if the concrete is discharged explosively. Shotcrete contractors have developed cleanout bins that clamp the hose end into a heavy steel tank and collect the waste concrete from the line for disposal. Others have created clamps that firmly hold the end of the hose to a loader bucket or other heavy piece of equipment, thus depending on the weight of the equipment to hold the hose end. Simply having two people sitting on the hose end is not safe and can result in injury to crew members. Even when holding the hose end with a clamping system on heavy equipment, clearing the line can cause an explosive discharge of concrete with material flying in a wide path from the hose. Unless planned for and contained, the material stream can hit adjacent workers, facilities, equipment, and vehicles.