When concrete flatwork has to be resurfaced, the first steps in the process are often the most critical. Several questions have to be answered before choosing the equipment for a job. What thickness of concrete or coating has to be removed? What is the condition of the concrete? Is there reinforcing steel close to the surface? What kind of new surface will be applied? Once these questions have been answered, you're in a better position to pick the best method or combination of methods.
Sandblasters are machines that use compressed air to eject a high-speed stream of sand or other abrasive from a nozzle. Dust and cleanup are problems that must be considered when sandblasting is used. A metallic abrasive (steel shot) is used in shotblasting machines to scour the concrete surface. Shotblasting is typically used for cleaning or scarification to depths up to 1/8 inch.
SCABBLERS AND SCARIFIERS
Scabblers use compressed air to hammer piston-mounted bits into the concrete surface. They tend to roughen the concrete surface more than either abrasive blasting or shotblasting. Unlike scabblers, in which bits move vertically to hammer the concrete surface, scarifying machines apply a rotating circular cutting wheel to the concrete surface.
Newly developed high-pressure waterblasters are now being used to prepare concrete surfaces for repair. Advantages of waterblasting include: no dust; minimal noise; and more efficient concrete removal than most conventional methods, such as jackhammers.