Cracks must be free of all dirt, dust and debris before they can be sealed. Cleaning the crack so it is free of dirt, dust and debris starts with routing.
Surface preparation can be accomplished with compressed air being forced into a crack. This technique works well when the dirt is dry and not packed hard.
If the cracks are filled with wet dirt, the dirt needs to be removed and the crack must be completely dried. An air compressor or a hot air lance generates temperatures in excess of 2,000°F and can dry the clay and dirt, burn the vegetation and simultaneously blow out the crack.
Once a rout of the crack is complete, contractors should use compressed air (hot or cold) to remove the dust created by the router. Engine-powered steel wire brushes also can be used to clean cracks
