Carborundum is the trade name for silicon carbide, an artificial crystal invented in 1890. Although the result of a failed experiment that sought to create diamond by putting carbon under pressure, it was quickly discovered that carborundum was a useful abrasive. Carborundum is still widely used today as a material in grinding stones and abrasive cutting blades. Although not as hard as diamond blades, carborundum blades are be used to cut new or "green" concrete.
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Fit a carborundum blade to your circular saw, concrete saw or hacksaw. To fit a circular or concrete saw blade, loosen the nut on the blade hub and pull out the pin, then insert the new saw blade into the blade housing and pass the pin through the center of it. Tighten the nut again to secure the blade. To fit a hacksaw blade, loosen the blade tension nut until the blade is sitting loosely on the pins passed through each end. Pull the blade off and replace it with a carborundum blade, then retighten the nut.
Put on safety goggles, boots and gloves, and move to your work area. A carborundum blade can be used to cut "green" concrete that is less than 30 hours old and has been mixed with soft aggregates such as dolomite, slag or limestone. Carborundum blades are also used to cut natural stone and masonry.
Mark the line for your cut using a chalk line or a chisel and secure the piece in place with a weight if you are cutting a small stone or piece of masonry.
Start the saw engine (if gas-powered) or turn the saw on. Squeeze the trigger to get the blade up to speed before making contact with the stone or concrete.
Press the blade down slowly and firmly into the material being cut. It will have a natural tendency to move forward as it is pulled by the rotation of the blade.
Pull the blade free of the cut material before letting go of the trigger; this will prevent it from sticking.