Diversified Concrete Cutting, Sparks, Nevada, found itself facing dust problems when it attempted to clean sawed joints along I-395, just north of Reno, using conventional abrasive blasting methods. Contract specifications originally called for sandblast cleaning of expansion joints before sealing. But workers soon found that it blew so much sand and dust into the air that it created a visibility hazard for motorists. So the contractor decided to try wet blasting. This method doesn't create dust because it uses a mixture of abrasive and water, which is then removed from the area by vacuum equipment. On this project, however, it was impossible to remove all water from the pavement surfaces and joint cuts without interfering with traffic. After water evaporated, cutting fines, abrasive, and dust that were suspended in the water remained in the cuts.
In search of a suitable cleaning process, the contractor decided to try vacuum blasting. Fortunately, this method was successful. In this process, abrasive is loaded into a pressure vessel, mixed with compressed air supplied by a portable air compressor, then propelled at the work surface through a Venturi-style nozzle. The blast nozzle is mounted inside the blast head, which connects to a hose leading back to the vacuum. A circular nylon brush on the end of the head controls the escape of abrasive and allows air to be pulled into the head, creating a vacuum at the work surface. All abrasive and dust is contained within the blast head and pulled through the vacuum hose into a cyclone/hopper.