Asphalt pavement: technology and instructions

The road made on the basis of asphalt - concrete mixture is considered one of the most profitable coatings. It is practical, inexpensive and generally allows you to provide the performance characteristics necessary for operation. Of course, not without drawbacks, but they are usually manifested in cases of non-compliance with the technology of laying. On the other hand, a high-quality asphalt-concrete coating provides a sufficiently high load-carrying capacity and elasticity. In this case, there are different approaches to the creation of such roads and sites, the differences in which are determined by the composition of the mixture and the technology of laying.

Asphalt mix composition

The traditional technology of the asphalt device provides for the presence in the basic composition of mineral fillers and a binder component. The first group of materials includes sand and gravel. At the same rubble can be replaced with gravel, and sand is used in whole or crushed form.

Also, depending on the requirements for the coating and the conditions of its operation, a finely divided mineral powder can be used . The organic component for the base compound is usually bitumen. Characteristics that result in asphalt concrete coating are determined by the approach to the formation of the base mixture. Differences in the methods for manufacturing the solution are due to the parameters of the components used. For example, gravel or crushed stone can be selected with a fraction of 10 to 40 mm. So, bitumen can have different values of viscosity and density. These and other factors ultimately determine the characteristics of the coating.

Instruction on the delivery of mixtures to the object

First of all, the type, quantity and carrying capacity of vehicles that will deliver will be determined. This choice depends on the scale of the work, the volume of the mixture and the pace of future laying. The transportation process includes several stages, among which weighing, material loading, direct transportation and discharge to the receiving point. For maintenance of crushed stone, cold and hot mixtures use a dump truck with a clean body, which is covered with a protective tent or watertight canopies. Cast mixtures, from which the asphalt-concrete coating is formed, are transported in so-called cochairs. These are cars with thermos-mixers, which ensure the mixing and heating of the composition during transportation. As for the time of transportation, in the case of hot and mastic mixtures it depends on the characteristics of the mixture, and for cold solutions there are no restrictions on the duration of transportation.

Preparatory work

The main step in the process of preparing for the final laying of the mixture is a test coating device. The length of such a strip is not less than 200 m, and the width is taken in accordance with the parameters of the asphalt paver pass. On the basis of the results of the trial laying, the technologists determine the most suitable recipe for the mixture, and also, if necessary, make adjustments to the method of laying it and the sealing technology.

The test asphalt-concrete coating is checked for such characteristics as temperature, compaction quality, the state of the substrate, etc. Special control technologies are used for this. In particular, non-destructive express methods and taking core samples, which are further investigated in the laboratory. Based on the received conclusion, the technologists give recommendations for the manufacturer's factory. If necessary, the composition of the mixture is adjusted to the specific conditions of operation of the coating.

Mixture distribution technique

Before the distribution of the finished mass, the asphalt paver plate is installed on the edge of the previously laid bar, the height of which will correspond to the thickness of the layer to be arranged. To prevent the mixture from spreading, sliding type formwork is used - it must move behind the asphalt paver. If there is no such device, then before the beginning of the distribution in the longitudinal direction, it is necessary to fix metal strips with a length of about 20 m. At the same time, the thickness of this barrier must not be less than the height of the formed coating. By the way, the thickness of asphalt-concrete coatings varies on average from 5 to 10 cm. As the stacking and compacting of the mass are carried out, the metal bars are removed. As for the width, the distribution of the mixture is most often covered with coverage of the entire carriageway.

If after the distribution of the substrate on the surface defects are detected, they must be handled manually. Practice is the use of tampers, which allow point correction of loose seams, tubercles and other flaws. Usually, defects are formed in the areas of abutment of the strips to the stop elements - the same metal bars. Separately, and crushed stone and gravel. These layers of asphalt-concrete coating are formed evenly in bulk immediately after the distribution of the mixture. Further, the granular material is heated into the base of the coating by a light roller.

Compaction technology

The compaction process must go in parallel with the operation of the auto-trowel, which distributes the mixture. Tramping is carried out continuously by the link of the rollers. Also in the work can be used glovkovaltsovaya, pneumatic wheel and combined special equipment. The force and load of the cold and hot asphalt compaction in the structural layers are calculated by several indicators. In particular, technologists take into account the density characteristics and the temperature of the mass.

The asphalt-concrete coating is made from a dense hot mixture with a seal factor of 0.99. Cold mixtures, however, assume a load with a coefficient of 0.96. The transverse matings of the laid lines are arranged perpendicular to the road axis in one strip without leaving the ledges. To fulfill this condition, the end of the previously arranged strip is cut with a special tool with a diamond disc.

The instruction on repair of asphalt-concrete coverings

Before performing any repair operations, a survey of the coating is carried out. To do this, the surface is cleaned using road brushes, after which geodetic tools are used to check the smoothness of the coating. Depending on the nature of the defects identified, appropriate repair measures are applied. To further ensure the smoothness of the layers with the help of the slats, the place of the stump is marked. The bar with the level is overlapped on the overlap. The place under the bar, in which the reduction in thickness is noted, is considered as the line of future transverse pruning. Also, repair of asphalt-concrete cover may include operations to build up layers. Usually, such measures are used for the device of a covering framing wells. Special inserts and reinforced concrete segments can be used for this.

Safety instructions

Even before the start of the work, the target area should be protected with the use of appropriate road signs. Workers on the site should be in uniforms, established by standards. At night, the site should also be provided with lighting and signal lights. Separate safety measures are provided for the handling of solutions. So, when unloading the carrier, the mixture is forbidden to find people between the car and the material bunker. During laying and sealing, the asphalt-concrete covering of roads must be free from foreign objects and workers. After the completion of the events, all inventory, equipment and supplies must be removed from the cover and delivered to the appropriate storage locations.

Coating Quality Control

The quality of the coating is assessed using special tools. In particular, calibrated automated measuring instruments are used, as well as special equipment, which allows to derive a complex output on the basis of the data obtained. Among the most common characteristics on the basis of which the "work" of asphalt-concrete coatings is assessed, the design parameters for thickness and width, the smoothness of the layers, slopes, temperature and quality of the joints between the strips are noted.

Conclusion

Works on the construction of asphalt are a complex of technical measures. At the same time, from the point of view of forming a high-quality road surface, design calculations are of considerable importance. Even under the condition of conscientious packing and sealing, the coating will not be able to perform its functions if an unsuitable mixture has been selected. Although the basic technology of asphalt-concrete coatings involves the use of a standard set of components for the preparation of mortar for laying, their parameters may differ. Therefore, the practice of laying trial mixtures, which in the future give an idea of the most beneficial characteristics of the coating for a particular area. And in the future, the responsibility for the quality of the road passes directly to the working team, which distributes and compacts the asphalt concrete mass.