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Mechanical Concrete Stripping Explained

by Kyle Carpenter

When a concrete sealer has reached the end of its serviceable life, it must be thoroughly removed in order for a new sealer to be applied. Otherwise, the bond between the sealer and the surface of the pavement simply may not be strong enough. There are two common ways of removing an aging sealer: chemical stripping and mechanical stripping. While both are effective, more and more people are leaning toward mechanical stripping, since it does not involve the use of toxic chemicals. If you would like to learn more about how mechanical stripping is accomplished, here are the four principal methods.

Shotblasting

Shotblasting is without a doubt the most severe way of removing a concrete sealer. Thus its use is often reserved for especially thick or hard sealers. Also known as bead blasting, this technique involves shooting a stream of high velocity steel balls at the concrete. These balls mechanically break the sealer up into tiny particles. If not accomplished with due caution, this method can easily damage the underlying concrete, gouging out shallow furrows that will then have to be repaired with an overlay or other restorative technique.

Sandblasting

The easiest way to think of sandblasting is as shotblasting's kid brother. The technique is more or less the same, the only difference being the size and make up of the material being propelled against the surface of the concrete. Here that material is--you guessed it--sand. This technique is not only gentler than shotblasting, but it is also especially well suited for outdoor applications, as any lingering sand can simply be swept away.

Grinding

Grinding represents a departure into a completely different mode of stripping--one that is a good deal safer for your concrete. The tool used here is known, appropriately enough, as a grinding machine. The bottom of this machine is equipped with special grit-covered grinding pads. These move back and forth as the machine is wheeled across the surface of the concrete, thus using friction to break up the hard sealer. Generally a first pass is made using a coarse grit, before smoothing the surface with a series of finer pads.

Scarifying

Scarifying is more closely related to grinding than to blasting methods. That said, the machine used is actually somewhat different. Rather than special grinding pads, a scarifying machine utilizes heavy-duty cutting wheels made from the metal known as tungsten carbide. These cutting wheels not only rotate, but they also oscillate up and down. This ensures especially speedy and effective results. 

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