Hot lance or heat lance are used in the crack cleaning and drying Hot lance or Heat lance or blowers are generally used to clean pavement surfaces prior to sealcoating. However, they have
been used to clean cracks. These blowers deliver high volumes of air at low pressures. As a result, blast velocity is generally limited to between 75 and 110 m/s. Although blowers require only one laborer and provide better mobility, the high-pressure (>690 kPa) capabilities of compressed-air units make them more desirable than blowers for crack cleaning.
High-pressure air blasting is fairly effective at removing dust, debris, and some loosened AC fragments. However, it is not nearly as effective in removing laitance or in drying the crack channel. Compressed-air units should have a minimum blast pressure of 690 kPa and a blast flow of 0.07 m3/s. In addition, compressed-air units equipped with oil- and moisture-filtering systems are highly recommended, as the introduction of oil or moisture to the crack channel can seriously inhibit bonding of the sealant to the sidewall.
