For landscaping and road construction today, asphalt concrete is widely used, which allows you to get a durable and high-quality coating. This material is a mixture of bitumen and natural materials.
Natural ingredients provide strength, while bitumen is needed to bind them into a single structure. Asphalt concrete is laid according to the same technology in different countries, but the quality of the coating depends on the components that are added or not added to the mixture, this sometimes determines the laying method.
Material density
The density of asphalt concrete is one of the main characteristics of this material. Asphalt concrete, this is what it is also called, has the appearance of a building artificial conglomerate, which is formed as a result of achieving the necessary density of the mixture laid in the structure. The composition is prepared by mixing in special installations under the influence of temperature. At the same time, oil road bitumen is used, as well as mineral materials of different fractions, they are selected in certain ratios. Sometimes polymers, rubber, surfactants, sulfur, etc. are added.
The density of asphalt concrete depends on the variety. For example, a dense mixture has a density in the range of 2340 kg / m 3 , as for the porous mixture, its density is slightly lower - 2300 kg / m 3 . Fine-grained asphalt mixture of type A, B and C has the following density indicators: 2385, 2370 and 2343 kg / m 3, respectively. There is also sandy asphalt concrete in the “mix type D” variety, in which case the parameter of interest is 2280 kg / m 3 .
Density determination
Determination of the density of asphalt concrete is carried out according to laboratory tests of those samples that were removed from the coatings. This parameter is calculated by the ratio of the average density of the material that was taken from the coating to the average density of the reformed sample.
Each type of mixture has its own compaction coefficient. For example, for mixtures A and B, the coefficient is 0.99, for a mixture of B, D and D, the main and lower layers, the coefficient is 0.98. If among the ingredients contains crushed stone from artificial stones, then the coefficient should be equal to 0.97.
Asphalt Consumption
It is important not only the density of fine-grained asphalt concrete and its other varieties, but also the consumption. Usually this parameter is determined per 100 m 2 , but the thickness of the layer may vary. For a dense and porous mixture with a layer thickness of 55 mm, the consumption per 100 m 2 will be 12.87 and 12.65 tons, respectively. With an increase in the layer to 80 mm, the flow rate of the dense and porous mixture will be 18.7 and 18.4 tons, respectively.
Fine-grained asphalt mixture of type A has a lower consumption if the layer is reduced to 35 mm. At the same time, 8.35 tons will be spent on 100 m 2. And if we are talking about a sandy asphalt mixture of type D, then with a layer thickness of 45 mm, the consumption will be 10.26 tons for every 100 m 2 .
Density meter
Asphalt density meter can be purchased at specialized stores. It determines the density of the coatings and the foundations of the roadway. The purpose of the device is the operational control of density, during which you can find out the degree of heterogeneity and compaction of the bases and pavements.
The device can identify uncompressed areas, as well as control critical areas, this should include edges and joints. Using it, the average density of asphalt concrete can be determined, which is 2.35 g / cm 3 . The equipment evaluates how well the coating is before applying the top coat. The device can measure the temperature of asphalt, determine the compaction coefficient, and carry out thermal compensation of the density readings.
Asphalt Composition and State Standards
The density of asphalt concrete, GOST which determines the quality of the material and is indicated by the following numbers: 9128-2009, - was mentioned above. However, specialists should also know about the composition. The coating has gravel or crushed stone among the ingredients that are crushed and are crumbs. There are sand in the composition.
As mentioned above, bitumen acts as a resin-like product that holds components together. However, for this, the material must be brought to a heated state. This also determines the technology of laying asphalt concrete. But today there is a technology that allows you to get bitumen with a viscosity of up to +5 ° C. Oil is refined by modern methods, which makes it possible to obtain liquid bitumen that does not solidify to critically low temperature levels. Usually this value is -30 ° C.
The density of asphalt concrete (t / m3) is 2.35. But this value is not the only one that professionals should know about. For example, the content of minerals is divided into three values:
- Group A: from 50 to 60% (gravel or gravel);
- Group B: from 40 to 50% (minerals);
- Group B: from 30 to 40% (gravel or gravel).
Crushed stone fractionality is regulated by technical conditions. In accordance with them, the material is made using crushed stone, the granularity of which can vary from 10 to 20 mm. Such a composition is used to form the top layer of the web. The technology is traditional and is used everywhere today, but polymers can be added to the mixture.
Change in asphalt concrete under the influence of modern technologies
According to state standards, the density of asphalt concrete should remain the same, but the quality of the material is constantly improving. This is due to the constantly increasing loads on the pavement, which led to the search for modern materials to improve quality. As a result, it was possible to create cast asphalt concrete, which was discussed above.
It is used not only for construction, but also for road repair. This technology is regulated by state standards R 54401-2011 and involves the installation of the mixture without sealing. The conglomerate temperature in this case starts from 190 ° C, an increase in this level increases plasticity. The composition is characterized by such features due to polymer additives.
Cast asphalt contains more bitumen, but the volume of minerals decreases. The content of crushed stone fractions up to 5 mm is from ½ part of the total mass to 0%. The mixture is not so granular, so it is viscous and does not require compaction.
Additional ingredients
Bitumen binder improves physical properties, so the material gives the coating high strength, wear resistance, integrity and a long service life without cracks. The density of the asphalt concrete remains the same, but for this it is important to observe the technology, as well as the proportions. This is the vulnerability of the material, which distinguishes cast asphalt. If at the production stage a deviation from the norms occurs, then the strength characteristics will suffer.
Conclusion
The advantage of asphalt concrete is that it can be decorated. This greatly expanded the scope of its use, because with the help of the material you can draw beautiful paths, sidewalks and alleys. On the roadway with the use of such technology, colored asphalt concrete appeared, which indicates pedestrian crossings, markings and dividing strips.
The technology involves adding 5-mm gravel, pigments and sand from granite, clinker, marble and limestone to the composition. To obtain bright asphalt concrete, synthetic clarified bitumen is used. The technology increases the cost of coating, so it is rarely used.
But today I managed to find distribution in a different way. It involves rubbing colored chips, while its addition was refused during manufacture. At the stage of laying the road, an addition to the top layer of the coating takes place.