Density of asphalt concrete: consumption and composition of material

For the improvement of territories and construction of roads today, asphalt concrete is used universally, which allows obtaining 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 together in a single structure. Asphalt concrete is laid on 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 method of laying.

Density of material

The density of asphalt concrete is one of the main characteristics of this material. Asphalt concrete, just so it is 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 added polymers, rubber, surfactants, sulfur and so on.

The density of asphalt concrete depends on the variety. For example, a dense mixture has a density of 2340 kg / m ³ , as for the porous mixture, its density is somewhat lower - 2300 kg / m ³ . Fine-grained asphalt-concrete mixture of types A, B and C has the following density indices: 2385, 2370 and 2343 kg / m ^3, respectively. There is also sandy asphalt concrete in the variety "mixture of type D", in this case the parameter of interest is equal to 2280 kg / m ³ .

Determination of density

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 method of the ratio of the average density of the material that was taken from the coating to the average density of the reformed sample.

For each variety of the mixture, its compaction factor is applied. For example, for mixtures A and B the coefficient is 0.99, for the mixture B, G and D, the base and lower layers are 0.98. If the ingredients contain rubble from artificial stones, then the coefficient should be equal to 0.97.

Asphalt consumption

Not only is the density of fine-grained asphalt concrete and other varieties of it important, but also the expense. Typically, this parameter is determined at 100 m ² , but the thickness of the layer can vary. In a dense and porous mixture with a layer thickness of 55 mm, the flow rate per 100 m ² is 12.87 and 12.65 tons, respectively. With an increase in the layer to 80 mm, the consumption of a dense and porous mixture will be 18.7 and 18.4 tons, respectively.

Fine-grained asphalt-concrete mixture of type A has a lower consumption if the layer decreases to 35 mm. In this case, 8.35 tons will be taken for 100 m ^2. And if it is a sandy asphalt mixture of type D, then at a layer thickness of 45 mm the flow rate will be 10.26 tons per 100 m ² .

Density Meter

An asphalt density meter can be purchased at specialized stores. It determines the density of the coatings and bases of the roadway. As the purpose of the device is the operational density control, during which you can find out the degree of heterogeneity and compaction of the bases and road surfaces.

The device can detect uncompacted areas, as well as control critical areas, here are the edges and joints. Using it, the average density of asphalt concrete, which is 2.35 g / cm ^3, can be determined. The equipment assesses how good the coating is, even before applying the top layer. The device can measure the temperature of the asphalt, determine the coefficient of compaction, perform temperature compensation of the density readings.

Asphalt composition and state standards

The density of asphalt concrete, GOST of which determines the quality of the material and is indicated by the following figures: 9128-2009, - was mentioned above. However, experts should also know about the composition. The coating has gravel or small gravel among the ingredients that are crushed and are crumbs. In the composition there is sand.

As mentioned above, bitumen acts as a resinous product, which bonds the components together. However, for this, the material must be brought to a preheated state. This determines the technology of asphalt paving. But today there is a technology that allows to obtain bitumen with a viscosity of up to +5 ° C. Oil is processed by modern methods, which makes it possible to obtain liquid bitumen that does not solidify to critically low temperature grades. Normally this value is -30 ° C.

The density of asphaltic concrete (t / m3) is 2.35. But this value is not the only thing that professionals should know about. For example, the content of mineral substances is divided into three values:

• Group A: from 50 to 60% (crushed stone or gravel);
• Group B: 40 to 50% (mineral substances);
• Group B: 30 to 40% (crushed stone or gravel).

Fractionality of crushed stone 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 upper layer of the web. Technology is traditional and is used today everywhere, but polymers can be added to the mixture.

Change in asphalt concrete under the influence of modern technologies

The density of asphalt concrete, according to state standards, should remain at the same level, but the quality of the material is constantly improving. This is due to the constantly increasing loads on road surfaces, which led to the search for modern materials to improve the 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 repairing roads. This technology is regulated by state standards Р 54401-2011 and assumes installation of the mixture without compaction. The temperature of the conglomerate thus starts from 190 ° C, an increase in this level increases plasticity. The composition is characterized by such features due to polymer additives.

Cast asphalt concrete contains more bitumen in the composition, but the volume of minerals decreases. The fraction of crushed stone to 5 mm is from ½ part of the total mass to 0%. The mixture is not so granular, so it turns out to be viscous and does not involve compaction.

Additional Ingredients

Bitumen binder improves physical properties, so the material gives the coating a high strength, durability, integrity and long life without cracks. The density of 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 concrete. If at the production stage there is a deviation from the norms, the strength characteristics will suffer.

Conclusion

Advantage of asphalt concrete is also in the fact that it can be decorated. This greatly expanded the scope of its use, because with the help of the material you can make beautiful paths, sidewalks and alleys. On the roadway, using this technology, colored asphalt concrete has appeared, which means pedestrian crossings, markings and dividing lines.

The technology involves adding to the composition of colored 5-mm rubble, pigments and sand from granite, clinker, marble and limestone. Synthetic clarified bitumen is used to produce bright asphalt concrete. Technology increases the cost of coating, so it is rarely used.

But today another method has spread. It involves the rubbing of colored crumbs, whereas from its addition in the manufacture they refused. At the stage of laying the road and there is an addition to the top layer of the coating.