Asphalt concrete pavements are used when constructing and repairing high-quality roads. Such kind of pavements may be layed in one or two layers on a macadam or a boulder base. If two layers are required, then the lower one is made of a coarse-graded asphalt concrete and the upper one of a fine-graded asphalt concrete. The latter may be also called sand asphalt. The thickness of asphalt concrete layers range from 2.5 to 8 mm and depends on the road class and traffic load.
In general, there is the main requirement for the preparation of the asphalt mixture: the binder in a ready mix should fully cover all outer surfaces of the stone material and along with a filler.
The production of asphalt concrete pavement may be divided into three stages:
(1) preparation of asphalt concrete mixture;
(2) its transportation and laying; and
(3) compaction of the poured asphalt concrete.
Each of the listed stages is complicated since the asphalt concrete mixture is applied only at a set temperature. It is absolutely prohibited to lay and compact material at the temperature that is lower than the set value. If mismanaged, the pavement will not meet the necessary requirements.
The process of asphalt concrete production consists of two separate stages that include (1) bitumen preparation, and (2) mixture production.
In recent years, more and more often paving companies use polymer modified bitumen for asphalt concrete pavement. It is prepared in special plants in the GlobeCore UVB-2 line, where a highly efficient colloid mill is the main part operating part of the system. Additionally, such bitumen possesses better characteristics and increases the quality of the asphalt concrete mixture which in turn produces a better and more durable road surface.
For the most part, bitumen is delivered to the construction sites by train in gondolas or tanks. This material requires warming up before being discharged from a tank. Only then bitumen may be supplied to a bitumen storage tank.
In today’s modern environment, there are temporary bitumen storage tanks. They normally feature a pit, dug into the ground to a depth of betwenn 0.3 to 1 meter. To take bitumen from a storage pit, it needs to be warmed up, then pumped and supplied to the operational unit. It is necessary to remove water from bitumen before applying it which is done by evaporation in bitumen boilers. At this point in the process, bitumen is warmed up to betwe