Making perfect cuts in concrete is a challenging task unforgiving of mistakes. Use these tips to achieve superb results.
Whether you’re cutting concrete blocks, slabs, walls or floors, using the right equipment and techniques will make the job easier, safer and more precise.
Of course, wear protective gear when cutting concrete — a heavy long-sleeved shirt, pants, steel-toed boots, gloves, face shield, hearing protection and a dust mask. Knee pads and shin protectors will further protect your legs.
1. Time it right.
Wet concrete is very difficult to cut, and fully cured concrete can fracture as it’s being cut. So if possible, cut the concrete when it’s hard but only half cured. The cut will come out smoother with less dust.
2. Use the best saw for the job.
There are several types of hand-held saws (wet or dry) that are good for most concrete cutting applications. For a large job on the floor, consider using a walk-behind saw. These heavy saws make the straightest and deepest cuts, eliminating the need for repeated shallow cuts. Walk-behind saws are wet saws. Water keeps the dust down and also keeps those big blades cool. With hand-held saws, wet vs. dry is partly a matter of personal preference. Wet saw creates a messy slurry, but they do keep the dust down.
3. Select the right blade.
In most cases, a diamond saw blade is the way to go. The exposed synthetic diamond crystals on the surface of the blade do the cutting. As the diamonds become dull, they fall away, and new ones are exposed. You can use a dry-cutting diamond blade with or without water. A wet blade must be used with water.
4. Deal appropriately with the dust.
This especially critical for professionals due to the new OSHA respirable crystalline silica standards. If you’re using a dry saw, make sure it has the appropriate dust extractor. (With a wet saw the dust is washed away before it becomes airborne.)
5. Use a GFCI extension cord.
If you’re using an electric saw (as opposed to a gas-powered saw), use a GFCI-protected extension cord to protect against power surges, shocks and overloads.
6. Mark your cuts.
Clearly mark the places you want to cut using a chalk line. Consider using bright orange chalk powder. If you’re using a wet saw and the chalk is washing off, use a crayon so the line will stay.
7. Tape the saw to prevent scratches.
Put a strip of duct tape along the bottom of the saw body where it runs against the concrete. This will keep the saw from scratching the concrete surface as you cut.
8. Use a guide board.
Secure a straight, smooth board along the outside of the chalk line. Maintain a constant, firm, two-handed grip on the saw and slowly move the saw forward tightly against the guide board.
9. Make a series of shallow cuts.
When using a handheld saw, make several shallow passes instead of one deep cut. After each pass, shut off the saw, then increase the blade depth by ½-inch increments. With handheld saws, making multiple shallow cuts is safer because it provides more control of the saw. It also allows the blade to stay cooler.
10. Don’t force the blade.
Let the saw and gravity do the work. All you need to do is guide it in the direction of the cut. Forcing the blade could cause it to overheat. Using the saw’s low RPM setting will also help keep the blade from overheating.
Concrete is definitely hard. But cutting it doesn’t have to be if you know how.