Liquid asphalt cement, the "glue" used to hold the rock aggregate together in hot mix asphalt, is a petroleum by-product. At certain spots in the process, a haze of hydrocarbon droplets can escape. This haze is called "blue smoke." Astec provides complete systems to capture and dispose of blue smoke. Silo top and loadout area systems are available. Powerful fans route the hydrocarbons either to the drum burner for incineration or to mist collection units.