Cutting the Hazards of Cutting Concrete
Jordan Hollingsworth, ASP, CHST, CHSP
Since ancient times, concrete has been valued as a building material largely because of its durability and permanence. However, those very properties create challenges when there’s a need to change something that has been constructed from concrete. During renovation and expansion projects, there is frequently a need to cut into concrete, whether to eliminate an existing area or to create a space for pipes or wiring.
Fortunately, technology has provided specialized saws and core drills that make cutting into concrete a relatively simple and routine task. But as any safety professional will tell you, anything that becomes routine can easily become very dangerous, if workers become complacent about the proper safety procedures.
The most obvious potential for injuries is having part of a worker’s body come into contact with a moving saw blade or core drill. But there are other significant hazards that workers don’t always think about.
One of the biggest is the presence of electrical lines or other utilities inside the concrete. Even when as-built drawings exist, they may not be completely accurate when it comes to pinpointing the location of hidden conduits, electrical lines, and junction boxes. That’s a particular hazard when you are core drilling, because you typically wet-cut to limit the exposure to silica dust. If your drill comes into contact with a live electrical line or equipment like a switch, there’s a hazard for electrocution and fire. At the very least, you can inadvertently knock out power to a large portion of a building.
Having accurate drawings is one way to avoid interfering with electricity (or other utility lines), but we all know that reality isn’t always that cooperative. That’s why it’s a good idea to shut off all electricity and other utilities in the area where you’re drilling.
Another potential danger involves proper use of equipment. I recently encountered a situation involving a core drill that had multiple clutch settings. The worker is supposed to choose the setting based on the torque needed for the material and type of drilling. In this case, the worker was wet-core drilling through a masonry wall, which normally required a torque setting of 2. The workers failed to verify the setting, and the saw was actually set at a torque of 1.
As he drilled into the wall, the saw snagged a piece of rebar. Because the clutch was set incorrectly, instead of stopping, it became caught in the rebar, twisting the drill in his hand, and creating a spiral fracture that took him off the job for a couple months.
The other type of hazard involves cutting concrete with a demo saw. If the saw hits a piece of rebar or some other material, it can kick back and flip the saw up. That’s frightening when it happens, but it usually isn’t deadly — unless the worker isn’t wearing the proper PPE. For example, if he isn’t wearing a face shield, the saw can catch his neck or face, with catastrophic results. Another thing workers may forget when using a demo saw is a respirator, because of the amount of dust that can be generated.
Finally, if the concrete is being dry-cut and the material is brittle, there is always the possibly that pieces of the aggregate could break loose and fly out. Once again, the proper PPE is the best protection for that type of situation.
As with most construction tasks, cutting concrete is inherently hazardous. But ensuring that workers have the right training for the equipment they are using, performing a hazard assessment before each task, and verifying that they are wearing the correct PPE will go a long way toward minimizing the danger and potential for damage.