The most popular method of covering roads and sidewalks that meet modern concepts of quality coverage and the price of which, moreover, is relatively low, can be called asphalting. But besides the mixture itself, the reliability and efficiency of laying approximately 50% depends on the preparatory work, that is, on the cushion, which serves as a rough basis for the face layer.
Below we will talk about the technology of this production, and also pay attention to the demonstration of the thematic video in this article relating to our topic.
Note. The name comes from the Greek ???????? which means mountain tar, where 60% -75% bitumen is mixed with minerals. In the artificial version, bitumen is limited to from 13% to 60%, and the filler serves as gravel / rubble, sand and mineral powder.
- First of all, the technology of laying the asphalt concrete mix, however, like other construction and installation work, depends on the layout, therefore, before the start of production, a technical design and financial estimate should be drawn up. Then follows the markings with reference to the features of the terrain of the area, to ensure the possibility of removal of sewage and passing near underground and surface communications. In addition, the presence of large trees with a developed root system is of great importance - if necessary, they are cut down so that no further problems arise.
- At the end of the preparatory work, the top wet soil layer is removed using an excavator or bulldozer, where the depth will primarily depend on the operational purpose of this section.. For example, for asphalting a sidewalk or garden paths, 10–25 cm depth is enough, but for the roadway this is certainly not enough - the larger the planned load, the deeper the foundation will have to be laid.
- In addition, the technology of laying asphalt concrete implies the mandatory construction of a drainage system - water should not accumulate on the floor or under it. In this regard, it is very important to remove all the soil that was removed during the preparation of the base, so that during the rainy season it would not be washed away and it would not block the drainage system.
- After the end of the excavation work, asphalt can be laid on a concrete base (hard pillow) or on crushed stone (gravel) with sand (non-rigid pillow) and this again depends on the future degree of load when operating the site according to SNiP 06.03-85. For example, for walking paths, the height of a sand and crushed stone pillow may be only 5-10 cm, but if this is a roadway with low traffic (entrance to a house or gate), then here the height will be from 10 cm or more. Moreover, under the condition that during operation large loads are foreseen, the cushion is placed in layers - first gravel (fraction 40-60 mm), then rubble (fraction 20-40 mm), and on top of them - large river sand.
Note. In order to accelerate the shrinkage of the pillow before laying asphalt, it is poured abundantly with water. When the bedding shrinks, it also gains additional strength. Ramming is done with vibrating plates, rollers, and at home it can even be done with your own hands with the help of some bits.
- In those cases when a very heavy traffic and, consequently, a large mechanical load is provided for on the roadway, then concreting or laying of reinforced concrete slabs is used for the foundation, as shown in the top photo. Due to the high cost of this type of coating in our country, they are made extremely rarely and for the most part such structures are limited to use for runways or test sites.
- The most beneficial use of construction debris as bedding is broken brick, stone, old broken slabs, blocks and floors, cement and sand plaster, and so on.. It is noteworthy that with sufficient tamping of such materials, they are in no way inferior to the same rubble or gravel, while the cost price of the pillow decreases dramatically - because garbage, instead of its disposal, is used as a building material. But here, of course, the laboriousness of the process significantly increases - after all, such waste, as a rule, has a very large fraction and because of this, it is more difficult to compact it (it is necessary to break it).
Note. Laying the base (concrete or sand-crushed stone pillow) implies the presence of flanging, which is made of stones or special reinforced concrete curbs - this allows you to shape the future coating. In addition, asphalt is also required for molding, therefore, the height of the curb must be designed for a face coating.
Currently, asphalt is laid in the Russian Federation in accordance with GOST 9128-2009 on asphalt road and airfield mixtures, and the instruction given in this document is also applicable to laying such coatings in private (on country and country sites). Usually, asphalt concrete is ordered at the nearest point of its manufacture - this is preferable to handicraft production.
There are quite a lot of asphalt plants, including small ones, so buying ready-made mixtures will be much cheaper than producing them independently; moreover, it is easier to follow the proportions of state standards in continuous production than in one-time production.
It is important to take into account that the air temperature outside should be not lower than 5? C, and the production process should be carried out in dry weather - installation during the rain is strictly prohibited! In case of violation of these conditions, the next year after laying, cracking and erosion of the coating will be observed, and the asphalt wear resistance will significantly decrease.
To calculate the amount of consumable material on a particular object, you will need to calculate the area of the site and determine its thickness - for an asphalt layer 10 cm high and 10m square2 need one ton of solution.
Stacking procedure and compaction
Laying technology асфальта на бетонное основание или на песочно-щебневую подушку подразумевает выполнение работ без малейшего промедления после того, как самосвал с раствором прибыл на строительный участок - это одна из важнейших граней требований ГОСТов и СНиПов.
For a large amount, for example, of a highway, special car-laying machines and large self-propelled rollers are used for the installation work, but when arranging the same sidewalks one has to use shovels and mops. In addition, small areas can not always be tamped with even a small self-propelled roller, therefore, in such cases, vibrating plates are used.
If you are doing similar work on the plot, it is unlikely that you will begin to invite a designer there, but, nevertheless, you will have to adhere to certain parameters of the coating thickness. Therefore, for garden paths you can withstand a layer 3-4 cm high, while for access roads (if there is no parking for heavy vehicles there) a thickness of 5-7 cm is required.
The quality of laying asphalt concrete and its operating life largely depend on the correct and timely made sealing of the coating. Such a process can be carried out in three ways, it is vibration, rolling and tamping. To do this, you can use an automatic or manual roller, a vibratory roller and a vibrating plate.
According to GOST 9128-2009, the laying temperature of the asphalt concrete mix should be maintained not lower than 105? C - this is one of the prerequisites for good compaction of the laid layer - the colder the asphalt concrete, the harder it is to tamp (the more passes the roller). To avoid sticking of the solution to the roller or vibrating plate, they can be moistened with water.
In order for the entire surface to be the same, you will have to keep track of the number of passes of the rink - it must be the same, besides, you should avoid reverse movements in order not to disturb the integrity of the monolith.
Note. If you have to make laying asphalt on a slope, then the movement of the roller during compaction should be carried out only from the bottom up and nothing else. To level (eliminate) the seams formed in such cases, the movement of the roller is almost perpendicular - with the same advantage of movement from the bottom up.
It is strictly forbidden to allow heavy tracked vehicles to enter such coatings - it is quite soft and the tracks will surely leave dents, which, in turn, will contribute to the destruction. In addition, during the hot season, the arrival of heavy wheel equipment is contraindicated, since at such temperatures the asphalt softens and again will be destroyed.
If necessary, all potholes and cracks should be repaired in time so that they do not cause further destruction of the structure.
Types of asphalt concrete
All asphalt mixes can be divided into three main groups, by the type of mineral filler - crushed stone, gravel and sand. In addition, the solutions can be hot and cold in accordance with the viscosity of the used and laying temperatures.
So, hot are made using road viscous and liquid bitumen and creep at a temperature of at least 120? C, while cold, using the same bitumen - at a temperature of at least 5? C.
Asphalt can be coarse-grained when the filler fraction reaches 40 mm, fine-grained, with a fraction of up to 20 mm and sand, with a fraction of filler up to 5 mm. At the same time, cold mixtures are only fine-grained or sandy (large river sand).
In accordance with the value of the residual porosity, the hot asphalt mixture can be: a) high density - residual porosity of 1-2.5%; dense - 2.5-5%; porous - 5-10%; highly porous - 10-18%. For cold asphalt, the residual porosity is allowed from 6% to 10%.
Depending on the content of rubble and gravel in the hot mixture, they can be classified according to the types:
- A - contains from 50% to 60% of crushed stone;
- B - 40% to 50%;
- B - from 30% to 40%.
In addition, cold fine-grained asphalt concrete, depending on the gravel content, are classified into types Bx and Bx. Hot and cold solutions can be of type G and Gh, that is, it is sand from crushing screenings or a mixture with natural sand, if the latter is at least 30%. Types D and Dx are based on natural sand or if it is mixed with screening crushing, but at the same time, its content is not less than 70%.
|Mixtures and asphalt concrete||Brand|
|Hot high density||I|
|Hot dense type a||I, II|
|Hot dense type B, G||I, II, III|
|Hot dense type B, D||II, III|
|Porous and highly porous||I, II|
|Cold type Bh, Bh||I, II|
|Cold gh type||II|
|Cold type dx||II, III|
Table marking of mixes and asphalt concrete
Note. The processing of frozen asphalt is almost identical to such actions as cutting reinforced concrete with diamond circles and diamond drilling holes in concrete. But in this case it is better to focus on cool weather, as in the heat the bitumen will stick to the circles, drills and core cutters, which will create certain inconveniences in the work.
If the asphalt mix is being laid in your home, on or near the plot, then most likely you will not need high-density first-grade asphalt. However, as we have already mentioned above, in order to maximize the operational resource, it is important to pay special attention to the rolling and tamping of the non-frozen solution.