15 March 2001
the router is forced along the crack. The bits must yield the proper shape for the sealant reservoir
and not cause spalling or ravelling along the crack path.
9.4. Sandblasting Equipment. The necessary sandblasting equipment includes an air compressor,
air hose, and a 1/4-inch- (6-millimeter-) diameter venturi-type nozzle. The compressor must be
capable of delivering 150-cubic feet/minute (4.25-cubic meters/minute) at 90 pounds/square inch
(620 kPa) and be equipped with operating in-line traps to keep the air hoses and the sandblasted
surface free of oil and water. This device must be capable of removing all sawed slurry, dirt, and
old sealant that may be present in cracks that are being resealed. Ceramic and tungsten carbide
nozzles are available for sandblasting, but the tungsten nozzles last longer. A guide that keeps
the nozzle a constant height from the pavement surface promotes consistency to the
sandblasting technique and reduces operator fatigue. The nozzle should have an adjustable
guide that will hold the nozzle aligned with the joint approximately 1 inch (2.5 centimeters) above
the pavement surface.
Safety must always be a primary concern. Sandblasting operators are required to follow OSHA
guidelines. A helmet with a separate air source and air purification equipment reduces the
possibility of inhalation of silica dust. Protective clothing may also be required.
9.5. Compressed Air Equipment. Compressed air can be employed for the final cleaning
phase of the project. The air source must produce sufficient pressure and contain no oil that may
foul the surface prior to sealing. Some compressors have in-line sources for the constant
lubrication of air tools. These devices must be removed along with the oil-coated pressure hoses,
and in-line oil and water traps must be installed to provide a clean air source for the airblasting
9.6. Hot-Air Lance. A hot-air lance is sometimes employed to dry the surface of the pavement
immediately prior to sealing (Figure 9.3.). Strict safety precautions that must be employed to