In simple terms a heat lance uses hot, compressed air that blows cracks clean while drying them out. Results from the SHRP study showed there is almost a 40 percent greater chance of sealant success if cracks are routed prior to sealing. Cutting a reservoir above the crack allows adequate sealant expansion and contraction. The reservoir also ensures that the proper amount of sealant penetrates the crack. An operator passes the pavement cutter or router over the crack and cuts a reservoir into the crack.
Modern routers can follow even the most random pavement cracks.
Although tar pots are still used for applying mineral-filled materials, they will burn or destroy crack and joint sealants that utilize polymers or rubbers. Hot pour sealants are effectively applied through a delivery hose and wand. To prevent sealant cooling, set up and clog, the hose is placed under constant pressure and the sealant constantly circulates back into the main tank. Crew members therefore must be trained not only in proper safety procedures but also in proper operation of the melter. Recent innovations in melter designs have greatly improved melter safety.