ASPHALT PREPARATION METHOD Russian patent published in 2008 - IPC E01C19/10 

FIELD: construction industry; road pavements.

SUBSTANCE: asphalt concrete components are supplied to drying drums, where they are dried. After that material is supplied to screens to be divided into fractions which, in appropriate sequence, are fed to hot material hopper, weigh box, and to the mixing device connected with bitumen measuring hopper. At that evaporable gases mixed with bulk of asphalt concrete components enter dust-collecting system. The following is prepared: broken stone with particle size of 5-10, 20-30 and 20-40 mm, natural shelf sand, mineral fines, screenings obtained after crushing, and bitumen. Besides mineral fines are measured and dried. At that mineral materials are classified and measured once more, and at the same time, bonding materials are mixed and measured, after which intermediate storage of the obtained material is performed, and then preliminary amount of asphalt concrete components is determined, and material is supplied to drying drum. Asphalt concrete mixture is checked at least once within the 8-hour period in strict order of priority of components on the basis of per one batch. Material is dried in drying drum in the mode of current opposed to burnt natural gas stream section, and dried material temperature is controlled by weight of supplied material within the range of 160-170°C. At that exit gases from drying drum together with dust particles are taken by ID-fan and are supplied to cyclones, besides separated dust is supplied to hot elevator and then together with mineral materials to the screen. At the same time materials are supplied from drying drum via hot elevator to screen, where they are divided into three fraction groups depending on grain size: 0-20, 20-30 and 30-40 mm, and each of intermediate material fractions is fed to individual compartments of hot hopper. At that mineral fines are pneumatically fed without being pre-heated to hot hopper compartment and/or mixer with LP supply chamber pumps with capacity of 3-5 m³. For extracting asphalt concrete mixture components, there is weigh box with electric pneumatic gate located under hot hopper compartments, and then asphalt concrete mixture materials are batched according to particle sizes with progressive total, and materials from weigh box are supplied to weigh mixer where mixtures components are mixed with bonding material which coats inorganic materials as much as possible. At that discrete portions of hot bitumen are fed to be mixed with asphalt concrete mixture within 4-45 sec. At the same time asphalt concrete is supplied form mixer to skip pocket and then to storage hopper with capacity of 90 t, and after that ready asphalt concrete mixture is discharged from storage hopper to trucks by means of hydraulic gate.

EFFECT: ensuring high process characteristics when obtaining asphalt concrete.