One of the most common recycled materials obtained by processing is asphalt crumbs, also known as asphalt granulate and used in a wide range of construction and renovation applications.
It turns out this material by cold milling the old asphalt surface removed during the replacement or repair of the roadway. Thus, asphalt chips consist of particles of bitumen and small crushed stone from three to five millimeters in diameter, and may also contain traces of sand or other elements.
Using asphalt chips
Due to inexpensive prices, ease of operation, as well as the fact that crumbs, as a processed product, cause relatively less harm to the environment, the range of its application is extremely wide and includes almost all spheres of human economic activity:
Due to the widespread use of this material, as well as the presence of many other options on the market, consumers, trying to find the most suitable option for themselves, often ask the question of how much a cube of asphalt chips costs. Below, in abstract form, are the main reference characteristics of this material, including answers to questions such as how much 1 cube of asphalt chips weighs and how many cubes fit in a KAMAZ or dump truck.
- The average price of asphalt chips in Moscow is $12-14, in the regions it starts from $10;
- 1 cube of asphalt crumbs can weigh from 1500 to 1900 kilograms, depending on its composition;
- Accordingly, about 12 cubic meters will fit into the body of an average KAMAZ;
The crumb consumption per m2 with a layer thickness of 20 centimeters is approximately 400-600 kilograms.
Laying technology
- First of all, prepare the base for the asphalt chips. The area is leveled, large debris is removed: cobblestones and scrap metal. It is quite possible to skip this point if the terrain conditions are acceptable for this purpose.
- Variably, the surface is primed using a bitumen emulsion of asphalt chips for better adhesion in the future. Its consumption is about one liter per sq.m.;
- Laying crumbs on the surface, compacting the laid layer. This can be done either with specialized equipment or independently. It is worth remembering that the compaction coefficient of asphalt crumbs, depending on the composition, reaches a value of 2 units, which means that when rolling, the thickness can be reduced by up to two times and be sure to include this factor in the calculations!
- Impregnation of bitumen emulsion of asphalt crumbs. This will further strengthen it and increase its service life. Consumption is about 0.5 liters per m2.
Laying asphalt chips with my own hands not too different from the technology described above. The only difference is that you will have to lay it out yourself using shovels, and roll it away with cars. Difficulties may arise with how to melt asphalt crumbs: without the use of technology, this is not only labor-intensive, but also flammable. You can melt the crumbs on open fire V metal container of sufficient size. Be sure to have a fire extinguisher with you to put out a possible fire!
Pros and cons of using asphalt chips
First, let's mention the environmental aspect of using asphalt chips. Many people, from among those who will ennoble country cottage area Having children and animals in the family, I am wondering whether asphalt crumbs are harmful. Despite the fact that it contains bitumen - a product of oil refining, which accordingly causes more harm to the environment than good, the use of crumbs on the farm is more environmentally friendly than in the case of asphalt of the same volumes.
According to the documentation, asphalt crumbs have a hazard class of 4, along with household waste, such as old clothes and shoes.
- Wide range of applications covering most areas economic activity person;
- Affordable price, which makes asphalt crumbs stand out against the background of crushed stone or gravel and, due to similar properties, has recommended the crumbs as a suitable replacement for them;
- Long service life when used in suitable conditions: secondary roads and short paths and sports complexes;
- Easy to install. To do this, it is not necessary to prepare the surface in advance, and rolling asphalt chips does not necessarily require the participation of special equipment; in order to save money, it can be done with the help of passing cars;
- High resistance to adverse weather conditions.
Disadvantages of asphalt chips, like any other material, exist:
- More harmful effects on environment in comparison with crushed stone or sand;
- The need for periodic renewal of the canvas.
However, all the shortcomings are completely offset by its numerous positive qualities.
Alternative options
In addition, consumers often ask the question: which is better, asphalt chips or crushed stone? There is no definite answer to this, since these materials, including sand and broken brick and concrete, as a rule, perform the same functions. But the price of crumbs is lower, and crushed stone has less harmful effects due to the absence of bitumen in the composition. So you need to make a choice based on circumstances and personal preferences.
Let's sum it up
Thus, asphalt crumbs will become ideal option, if you value simplicity and ease of installation and prefer to spend extra money on yourself and your loved ones rather than on building materials. For parking or driveway, sports ground or garage floor - this material will satisfy any of your needs!
The reliability of an asphalt pavement depends on the use of high-quality components in the mixture, their uniform mixing, and maintaining temperature regime during production and storage. In addition, the planned location for laying the asphalt pavement should be as close as possible to the place of its production, so that the time for transporting the material is as minimal as possible.
Advantages and disadvantages of the material
The main advantages of laying asphalt are:
- affordable cost, especially in the case of small-scale applications;
- possibilities instant cooking in factory conditions;
- durability of the coating, subject to compliance with the manufacturing and installation technology;
- the relative simplicity of laying asphalt in the presence of special equipment.
The disadvantages of asphalt and concrete are:
- a sharp decline technical characteristics when heated by sunlight;
- evaporation of bitumen when heated and the release of harmful fumes;
- the need to maintain the required temperature until the asphalt pavement is laid.
At the same time, despite the presence of serious shortcomings, a price alternative to asphalt concrete has not yet been found. Path from paving slabs it will be noticeably more expensive.
Work to improve the quality and versatility of the material is being carried out as part of the selection of more effective mixtures. Good performance gives the addition of polymer mixtures and a decrease in the volume fraction of bitumen.
Purpose of the constituent components
Asphalt concrete with and without mineral powder.The first asphalt was made from natural bitumen. Then they began to use bitumen, obtained as a result of oil distillation, when heating liquid hydrocarbons. Today it is the most common binder for the production of asphalt concrete mixtures.
Sand, gravel or crushed stone in asphalt play the role of the main working fillers. Sand is necessary to more evenly distribute pressure within the asphalt layer and fill voids between individual stones. Together with bitumen, it binds larger fractions of stone, holds them and does not allow them to go up beyond the layer.
Fractions of gravel and crushed stone determine the group of asphalt concrete and its area of application. All asphalt pavements are conventionally divided into three groups according to density, depending on the size of the stones used:
- dense, with a gravel fraction of 5-10 mm, for paving courtyards, sidewalks, paths and other surfaces with low load;
- porous, with a stone size of 10-20 mm, for laying lower layers in multi-layer coatings;
- highly porous, with a crushed stone fraction of 20-40 mm, for use on critical sections of highways.
This porosity distribution determines the ability of asphalt to transmit moisture and drain it into the drainage layer for further discharge into the ground. Therefore, highly porous material is more difficult to install, but it operational period much bigger.
Finely ground chalk, limestone or sandstone are added as mineral fillers. They fill the last remaining voids and make the asphalt path more uniform. Moreover, the best mineral filler is made from sandstone, as a chemically neutral substance.
By adding crumbled rubber, crushed to sizes of 1.0-1.5 mm, ductility and hydraulic stability increase. Therefore, asphalt with it is often used to cover the roof of workshops industrial enterprises. Asphalt concrete with rubber crumbs is less likely to crack and has spring properties.
Reinforcement polymer mesh. Polymer additives in the form of reinforcing plastic fibers significantly increase the strength of the material. This cooking technology is used only for the most critical areas. The strength of an asphalt path can also be increased by adding cement to it, but in this case you cannot use limestone as a fine filler.
Do-it-yourself asphalt production
Self-made asphalt does not allow it to be used for laying highways and city streets. However, such material can be effectively used for arranging garden paths or areas with low weight load during operation. To make your own asphalt you will need:
- ordinary, even unwashed sand;
- fine gravel or crushed stone;
- solid bitumen resin with a melting point of no more than 120°C;
- wide bucket or concrete mixer;
- metal barrel and a bucket;
- shovel;
- wide sieve or metal grid for sifting sand.
Prepare a dry mixture of sand and gravel in a bucket or concrete mixer in a ratio of 1:2 by volume. Place the barrel on the stand and light a fire under it. Pour a bucket of water inside.
At the same time, place a bucket filled one-third with water on another fire. When the water in the bucket begins to boil, put bitumen in it to heat and melt. Pour the crushed stone-sand mixture into the barrel. Boiling water in a bucket and barrel will ensure that the temperature is maintained at 100°C.
Pour the crushed stone-sand mixture into the barrel and wait until the water boils. Boil the bitumen in water until the bitumen melts and the water gradually boils away. Then pour the molten bitumen into a barrel with a crushed stone-sand mixture and begin to actively mix. It is recommended to stir metal pipe or others a durable object. At the time of pouring, there must be boiling water in the barrel; hot bitumen cannot be poured into cold water.
The ratio of the volume of bitumen to the volume of crushed stone-sand mixture is approximately 1:15. More accurately, the density of asphalt can only be determined visually.
In order to improve the plasticity of the asphalt mass, simplify mixing and facilitate subsequent laying, you can use special or liquid detergent. The plasticizer is added in accordance with the instructions, liquid detergent at the rate of 1 glass per 40-50 liters of asphalt.
As soon as the water has boiled away, the homemade asphalt is ready and can be laid on the path. If by this time you have not finished preparatory work, then add water to the barrel again. Please note that you can only add boiling water, cold water If it gets on a hot surface, it can instantly boil and cause burns.
Laying asphalt pavement
Do-it-yourself installation work begins with acceptance planning solutions and markings. At this stage of work it is necessary to clearly define:
- with the location of the track;
- its width and height above ground level;
- with the type of curb and its installation height;
- with places for laying drainage systems.
When determining the location of the path, you should take into account the presence of possible underground engineering communications, location garden trees and the direction of slopes for rainwater drainage. After making decisions, you need to drive pegs around the perimeter of the future asphalt pavement, defining its exact contours.
Along the marked contour, it is necessary to dig a so-called “trough” or trench, 15 cm deep. Lay a layer on its bottom, which will prevent the germination of weeds and allow moisture to freely drain into the lower layer of soil.
Install and secure the curb and fill the “trough” to the top with crushed stone. The surface must be thoroughly compacted. The durability of the asphalt pavement depends on the quality of the compaction.
Next, you should buy asphalt or prepare it yourself and lay it on top of crushed stone in a layer 4-5 cm thick at a time. Pre-leveling can be done with an inverted rake or a wooden mop.
During the leveling process, it is necessary to check for slopes using building level. Compacting the asphalt concrete layer on a garden path is best done.
It should be noted that the process of laying asphalt with your own hands depends on weather conditions. This work should not be carried out when negative temperatures and in wet rainy weather.
Technology for recycling asphalt pavements
Need for savings Money during the repair and construction of new asphalt roads led to the development of an effective recycling system ( recyclable materials). In this case, the asphalt removed from the road surface is processed, both in stationary factory conditions and in mobile equipment at the work site.
Using this technology, the asphalt concrete coating is removed using special mechanism with a mechanical cutter - remixer. Next, the removed material is crushed into a crushed stone fraction and can be used to prepare dry mixtures for the construction of road bases and fills for suburban highways and roads.
Asphalt base. According to the second technology, the collected and crushed material is placed in a furnace and heated without access to fire to 170°C with the addition of required quantity fresh bitumen and additives. This processing method is widely used when repairing city streets and courtyards, since the price, production and laying of asphalt in this case is much lower.
Recycling asphalt at home
The old road surface made from asphalt mixture allows home handyman arrange on personal plot comfortable and neat asphalt pedestrian paths, which can easily replace paving slabs. This DIY asphalt can also be used, for example, to cover the floor in a garage or in front of it.
Only the top bitumen layer needs to be removed. The removed material must be broken into pieces as small as possible. The maximum fraction should not exceed 40 mm.
Methodology for checking the quality of asphalt road surfaces
Each manufacturer of building materials is required to issue the buyer of asphalt a certificate of product quality conformity state standards. To do this, the plant must have a certified laboratory that can conduct necessary complex tests. In addition, in all major cities There are independent laboratories for checking the quality of construction and manufacturing of materials.
At a construction site, testing occurs by drilling a core of a given diameter from the road surface and then restoring the road surface. Externally, the quality of the delivered asphalt can be determined by its temperature and the presence of a black, greasy film on the surface.
16 /04/2016
To make asphalt yourself you need to know a few details that will help you avoid injuries during work. The main materials for asphalt are crushed stone, resin and sand. In addition, polymeric materials are needed to lay the surface. At first glance, making asphalt yourself is not at all difficult, but before you start, you need to prepare for this process. First you need to find a container in which all the ingredients will be mixed. You also need a small fire, which should burn for at least 8 hours. In order to cool the suspension, you need to prepare about 100 liters of water. In order for all materials to stick together, you need to use a paste in the form of resin or bitumen.
Cold asphalt
Today there is another type of asphalt - cold, that is, polymer. The main advantage is that it can be installed at any temperature. Through testing, it was found that the viscosity of this asphalt is maintained even at -15. It is this fact that gives huge benefits this type of asphalt, since it allows roads to be repaired at any time and in any weather. For such installation, special equipment is used, and you can also use a service such as renting a soil compactor.
Hot asphalt
1. Preparing the container.
First of all, you need to make some object that would do the job of a concrete mixer. For this you can use iron barrel. You need to cover it with a lid on top, and at the bottom in the very center you need to drill a hole with a drill. Then you need to thread a thin pipe or rod and weld it so that the barrel does not leak. You need to weld an L-shaped rod to one of the edges of the pipe and you will get a skewer.
2. B homemade concrete mixer add crushed stone and sand according to the 2:1 principle and mix everything well. You should not pour wet mixtures, as they dry out very quickly and are difficult to pick out.
3. Bitumen must be heated in another container. For this would be better suited bucket. Once heated to boiling, polymers must be added. To make the bitumen elastic you need to add a little shampoo. As a result of boiling, it will burn out, and stirring the mixture will become much easier.
4. Hot bitumen must be added to the barrel, where the sand and crushed stone have already warmed up. Under no circumstances should you pour bitumen into a cold barrel, as it will harden quickly.
5. Before pouring asphalt, the holes must be thoroughly cleaned. In addition, using a compressor you can blow out all unnecessary debris. After pouring the hot mixture into the pits, you need to compact the material using a roller. To prevent the tool from sticking to the bitumen, it must be moistened with water.
Historians claim that the first mention of something similar to asphalt concrete appeared in the 6th century BC in Babylon. But the technologies of those times were unreliable, plus unnecessarily expensive, as a result, such roads were forgotten until the twentieth century. Construction asphalt concrete pavements in Russia began in 1928 and to this day it is predominant.
What it is
This composition is used everywhere, from laying federal highways to arranging city squares and garden paths in private construction.
According to GOST and SNiP, the design of asphalt concrete pavement can be different.
But general composition mixtures, has remained unchanged for more than 100 years:
- First of all, bitumen is included as a binder..
- Sand and large mineral fillers must be present to one degree or another..
- The list is completed by various mineral or synthetic additives.
At the time when the composition was developed, natural bitumen was used, but since there is little of it in nature, an artificial analogue was synthesized based on petroleum products, which is still successfully used by road workers around the world.
Quarry sand is taken, as for coarse filler, along with various types of sand, crushed rocks and some crystallized slags are widely used.
Natural mineral or synthetic additives are used to increase certain useful properties coverings. In particular, frost resistance, road adhesion level, viscosity coefficient and much more increase.
What formulations are produced
The range of presented types is quite wide, depending on the percentage of components, as well as what additives were used, experts divide asphalt into the following varieties.
- For arranging sidewalks, garden paths or internal space city courtyards, sand compounds are used.
- Fine-grained compounds cover city streets with medium and high traffic intensity.
- Coarse-grained asphalt is used as a base layer in multi-layer laying technology.
- Polymer-bitumen coatings are used for the installation of bridges, large parking lots or road junctions. They have increased strength and durability.
- Crushed stone-mastic types of asphalt are considered the strongest; they are used to lay federal highways and expressways with increased traffic load.
- For stadiums, running or bike paths, as well as other sports facilities, there is a rubber-bitumen coating.
Making asphalt at home
The production of road surfaces is considered to be difficult and inaccessible. But, nevertheless, there are enthusiasts who are ready to experiment. Of course, such compounds are not designed for federal highways, but at the dacha it is quite possible to prepare such asphalt with your own hands.
Advice: from experience, we can say that a mixture prepared in a homemade way is, of course, suitable for arranging, but more often it is used for repairing potholes on an already finished surface.
Classic recipe
To prepare, we need regular river or quarry sand, bitumen resin or bitumen and fine crushed stone. Equipment you will need is a metal barrel and a bucket.
It is better to cook asphalt over a fire, since using gas is unsafe and expensive.
- Initially, add crushed stone and sand in a 2:1 ratio and mix well. All this should be filled with water and hung over the fire.
- At the same time we prepare the bitumen base. To do this, take a metal bucket and heat the bitumen in it until it boils. You can add synthetic polymers as a plasticizer, but it’s cheaper to use shampoo or any detergent.
- When the resin has warmed up and the water in the barrel with crushed stone has also boiled, they need to be combined. Water is needed to ensure that the crushed stone and sand do not heat up above 100ºС. Next, this broth must be stirred, maintaining a boil until all the water has boiled away. While the solution is hot, it can be poured.
Important: be careful, bitumen melts at 80 ºС, and boils at 100 - 120 ºС.
But already at 170 ºС bitumen can ignite.
Actually, to prevent such a fire, we use water.
Using old road surfaces
Dismantling asphalt concrete pavements and bases can become good material to prepare new asphalt.
The technology is partly similar to the previous version, but with some amendments.
- The dismantling of the asphalt concrete pavement itself is carried out old-fashioned method, using a sledgehammer and other percussion instruments. Only used upper layer asphalt bound with bitumen, the road cushion can be left untouched.
- The old road surface is broken into pieces with a fraction of no more than 40 mm. For 100 kg of old asphalt, take 10 kg of bitumen.
- After this, the crushed substance must be poured with water and boiled in a barrel until melted. The technology then repeats the option described above. The heated bitumen combines with the molten asphalt and the water evaporates.
Cold asphalt
The two methods described above are well suited for economical repair of damaged asphalt in the yard or near the yard. If you need to cover a large area, we recommend using cold asphalt.
On the market of our country this coating appeared about 5 years ago. The principle of operation here is similar to the well-known cold welding. Modified bitumen is used for the binder, so it can be laid even when sub-zero temperatures. Instructions are included on the packaging.
The only disadvantage of this material is its significant price. But, as you know, asphalt is shipped hot from the factory and must also be laid hot. Therefore, for remote locations, cold polymer asphalt is the only alternative.
Important: when repairing road surfaces, the problem is the quality of the joint in the asphalt concrete pavement.
Cold polymer-based asphalt completely solves this problem, since it reliably adheres to any bitumen-based composition.
Rules for laying coatings
The construction of asphalt concrete pavements is a responsible matter and it is not so important whether you lay it yourself or hire professionals. Laying and acceptance of asphalt concrete pavement is carried out in accordance with SNiP 2.07.01-89, as well as a number of GOSTs.
Only a specialist can understand these documents, so we have outlined the main provisions of these norms and rules in a more understandable language.
Preparatory stage
Any work begins with markings. You need to clearly decide where the asphalt will be laid. Where will the curb be installed and what will it be like? It is also very important to ensure that the drainage and drainage system is fully installed and drainage systems are installed in advance.
All work on the installation of underground communications must be completely completed by this time. If you are arranging a parking lot or access roads to an office, then it is better to find out in advance where city communications are located, since, if necessary, municipal services They will rip off your coverage and may also impose a fine.
It was mentioned above about the varieties and purpose existing species asphalt. So, at the preparation stage, you need to choose what kind of material you are going to lay.
Important: the estimate for installing an asphalt concrete pavement should contain not only data on the cost of the material and the amount of work.
It will be useful to include transportation costs in it, as well as leave a column for unforeseen expenses, such as permission to carry out work from the relevant official or service.
If a pedestrian path or platform with occasional passage of passenger cars is being laid, then the crushed stone-gravel cushion can be made up to 15 cm thick. The thickness of the asphalt concrete pavement will be in the range of 4 - 5 cm.
If you are equipping a gas station or any access roads along which, with a high degree of probability, heavy-duty equipment will periodically pass, then in this case the thickness of the gravel cushion will be about 25 - 35 cm. Plus the asphalt itself is laid in at least 2 layers.
After marking, the construction of the so-called trough or foundation pit for the road begins. In urban areas or in private construction, as a rule, roads and sites are built at approximately the same level, so the soil must be selected to cover the entire thickness of the “road pie”. Federal highways are being developed using a slightly different technology, but we will not dwell on it.
When the soil has been selected, the entire site must be well compacted, this is done with a roller or vibrating plate. Pay attention to the presence of trees nearby; the roots can tear up the asphalt over time, so, if possible, it is better to remove them immediately. Although the price of the work will be slightly increased, we recommend covering the soil with geotextiles so that vegetation does not break through the covering.
Important: at this stage, curbs are installed; they act as a kind of formwork for the “road cake”.
If when laying paving slabs the curb is made below the road level, then here it is the other way around.
In this regard, it is necessary to immediately plan drains for water drainage.
Now you can start filling the crushed stone cushion. For pedestrian paths with a cushion thickness of 10–15 cm, 1 layer of crushed stone with a fraction of 30–40 mm is sufficient. More powerful bases are laid in several layers.
The bottom layer serves for drainage in case of lifting groundwater, it is filled with large crushed stone with a fraction of 40 - 70 mm. The next layer with a fraction of 20 - 40 mm will be responsible for uniform distribution of the load on the base of the road.
The final layer of filling is made of fine gravel with a fraction of 5 - 20 mm. It will also be responsible for distributing the load, but in addition it will turn the pillow into a dense, monolithic structure.
All laid layers must be compacted tightly. For serious surfaces, road rollers weighing from 2 to 10 tons are used. Each ball of filling is compacted separately, the roller must go over it at least 5 times, plus modern road rollers have a vibrating press function, which increases efficiency several times. During the compaction process, the surface should be regularly watered.
Advice: during the compaction process, you must immediately take into account the angle of inclination of the road; on average, it is about 1º per 1 linear meter.
To do this, you should periodically check the markings or data of the level.
Laying asphalt
After completing the compaction of the cushion, you can proceed directly to laying the asphalt. As mentioned earlier for sidewalks and adjacent areas It is enough to lay the fine-grained composition in a layer of up to 50 mm. Heavy road rollers are also not required; you can get by with a light roller or vibrating plate.
Note!
According to SNiP, this type of coating is not recommended for laying in recreation areas.
More serious objects are paved in 2 layers. In this case, the bottom layer is laid with coarse-grained asphalt at a level of 40 - 50 mm. A fine-grained composition is almost immediately applied to it, which in most cases is the finishing compound.
Currently, technologies have been developed according to which a reinforcing mesh of polymer materials. As a result, the durability and strength of such a road increases significantly. This technology is used when laying federal highways and roads with increased load.
Important: restoration of asphalt concrete pavement is most often done only with hot bitumen.
Although according to GOST, thermal profiling of asphalt concrete pavements must be carried out.
This procedure involves preheating the road surface to a depth of 2–5 cm.
The mixture must be delivered to the site hot; as a rule, it is delivered by dump trucks with a carrying capacity of 7 - 20 tons. After which the asphalt is manually or by machine distributed evenly along the road plane, observing the slope. On average, 1 ton of asphalt is consumed per 10 m² of road surface with a thickness of 40 mm.
The construction of asphalt concrete pavements is a weather-dependent process. In the cold season, that is, at temperatures below +5 ºС, it is generally not recommended to carry out work. Plus, during rain or wet weather, the quality of installation is significantly reduced, as the composition becomes moisturized and cools faster.
Conclusion
We have outlined the general basic principles high-quality asphalt laying, but science does not stand still and technologies are supplemented and improved. In the video in this article you can look at the process of laying asphalt in more detail.
It is a multicomponent mixture based on sand, stone and bitumen binder. The “correct” name of the material is asphalt concrete, which does not prevent the term “asphalt” from being used even in specialized publications.
Asphalt consists of bitumen, sand, types of crushed stone or gravel, as well as mineral additives and fillers. The only constant component is bitumen, and the remaining components can be added in various proportions.
Functions of fine components of asphalt mixture
Sand, contained in asphalt, plays the role of a filler and a fine base, helping to distribute pressure from the road to the ground. Without sand, the bitumen binder would leak out and crushed stone would be squeezed out onto the top.
In the case of special asphalts containing cement, sand participates in the cementation process and gives the coating additional hardness.
Mineral filler– is a rock (sandstone, limestone or chalk) crushed to a dusty state, intended to fill residual voids. Sandstone is the most universal, as it is inert to almost any chemical exposure. Calcium carbonates (limestone and chalk) are commonly used on roads general purpose, while sandstone can be used near chemical plants.
Rubber– added to asphalt in the form of rubber crumbs (1-1.5 mm), it gives the coating high water resistance and plasticity. Asphalts treated with rubber are much less likely to crack, which increases the period between repairs. The disadvantage of such roads is high price, therefore their use is limited to laying the most critical sections of highways.
Change in asphalt structure when adding mineral filler
Classification
One of the main parameters is the size of the crushed stone used, dividing asphalts into the following groups:
- dense– used for laying the top layer of coating and contains fine crushed stone. In the case of a crushed stone fraction of less than 5 mm, such asphalts are used for pavements with low loads (sidewalks and pedestrian crossings) and are called fine-grained. Larger fractions of crushed stone (5-15 mm) are suitable for creating the top layer of highways;
- porous– used in the lower part of a multilayer pavement and contain less bitumen than dense asphalts;
- highly porous– optimal quality bases for heavily loaded roads. In their production, the largest crushed stone of the 15-40 mm fraction is used. Such dimensions provide the necessary water permeability, creating drainage in lowlands and marshy areas. Larger grain size reduces the movement of the road base and indentation into the top layer of soil, reducing the risk of washout and subsidence of the pavement.
Manufacturing technology
The basis of any asphalt production is the preparation of the initial components, mixing high temperature and storage in special heated bunkers.
It is important that the plant is located close to the construction site, since the material must be transported for installation in a heated state. If the mixture cools down, it will be very difficult to compact and the resulting coating will not be strong enough. Let's look at the stages of asphalt production.
Preparation of components from which asphalt is made
This includes drying and sifting. Sand, crushed stone and rock usually arrive at the plant in a wet or air-dry state. The presence of residual moisture is fraught with a decrease in the strength of the coating and splashing of the hot bitumen mixture when water gets into it.
To eliminate possible consequences, the material is dried at a temperature of 150-160? C - this temperature allows you to get rid of moisture adsorbed in the pores of the material.
Screening of crushed stone is carried out using a screen. The mineral filler is pre-crushed in a crusher, after which it is also subjected to fractionation. Depending on the production technology, drying can be single or double, repeated after crushing or sifting.
Mixing components
Crushed stone and sand are fed onto a conveyor belt, which transports them to a common bunker. Mixing with filler and bitumen can occur simultaneously or be carried out after achieving a homogeneous crushed stone-sand mass.
After adding bitumen, the temperature is maintained at 160-170? C. After reaching the required consistency, the mixture (now asphalt) enters a storage bin, where it can remain heated for up to 4 days. During this period it must be shipped to the consumer to avoid loss of strength characteristics.
Asphalt modification with additives that impart useful performance properties is carried out simultaneously with asphalt mixing. When creating a rubber-asphalt mixture, crumb rubber is added to a heated, ready-to-use product.
Delivery
Transportation of asphalt concrete to the construction site is carried out by motor transport. Most often, conventional dump trucks with a body resistant to hot asphalt are used. For transportation over long distances, kochers - vehicles with special heat-saving containers - can be used. They are designed to preserve the properties of asphalt concrete for 2 days.
The video will tell you how asphalt is made at a factory and whether it is possible to make it yourself:
How to check the parameters of the road surface and raw materials for its production
To avoid purchasing low-quality asphalt concrete, you should ask the seller for a certificate of product conformity. It is issued only after passing a set of tests corresponding to GOST or SNiP (depending on the scope of application).
In the quality control market, there are a number of regional laboratories that conduct sampling and testing of asphalt pavements. During the study, an average sample is selected from the total mass of the material. Analysis of the road surface is carried out by examining a core, which is an asphalt core obtained by drilling the road with a special hollow drill.
DIY cold asphalt
Let’s immediately make a reservation that cold asphalt is only laid independently, and its production is carried out only at the factory. The technology itself differs from traditional coating in lower operating temperatures (70-110 °C) and the addition of a complex of protective and polymer additives to its composition. The latter are necessary to impart greater strength and form a protective antioxidant film on the surface of the bitumen.
Despite the name, cold asphalt will still have to be heated in cold weather in order to convert the bitumen into a plastic state. At the same time, you need to use a burner to heat the place where the asphalt will be laid. Depending on the manufacturer, work with cold mixtures can be carried out even at subzero temperatures (down to -20...-10 °C).
The advantage of cold asphalt is long term storage Unlike classic asphalt concrete, it does not need to be used immediately after purchase. The disadvantages include lower strength, which is almost 2 times less than that of hot asphalt.
To compact the coating, use a vibrating plate or improvised means - thick wooden beam, car wheel. The final finishing of the surface occurs after repeated passage of vehicles. It is not recommended to make entire sections of the road from cold asphalt, since they are destroyed under the pressure of a vehicle weighing over 3.5 tons.
Modified cold asphalt:
Recycling old asphalt
The high cost of creating a road forces us to look for ways to save money. One of them is recycling - the processing of waste asphalt in order to reuse. Processing is carried out in stationary conditions or in mobile recyclers.
The process is carried out in several stages:
- Removing a layer of old asphalt is done with a remixer, which removes the road surface by milling;
- crushing the milled layer to the size of crushed stone. The resulting product is called granulate and can be used for laying roads and preparing crushed stone-sand building mixtures;
- heating in an oven without direct contact with fire (to avoid ignition);
- adding a fresh portion of bitumen and polymer additives, if necessary.
Recycling technology is of industrial importance and is usually used in the construction of urban and intercity highways. If the opportunity arises to buy recycled asphalt for private purposes, do not hesitate - there is no difference in performance properties, while the price will be significantly lower.
Mobile asphalt recycling plants
Installation No. 1 Installation No. 2
Modernization of asphalt concrete pavements
Despite being quite practical, road surfaces can be improved. One way is to use special mastics for asphalt. They contain bitumen or bitumen emulsions containing rubber polymer additives.
Regular bitumen mastics are used hot, and emulsions are used cold. The principle of operation of mastics is to seal cracks and pores on the surface of the canvas. This prevents water from getting inside the road and destroying it - water contributes to cracking of the coating during freezing and water hammer when vehicles pass.
Advantages and disadvantages of the material
It is worth noting the following:
- For light-duty applications, asphalts are not very expensive, unlike the multimillion-dollar cost of laying highways;
- With proper quality, asphalt is irreplaceable in any weather.
- Numerous defects that are clearly visible to pedestrians are rarely visible from a car window;
- The production of heated and viscous mixtures is not a simple task, despite the automation of the process;
- The difficulty of using heated mixtures is partly compensated by the appearance of cold asphalt;
- Asphalt paths in the garden are not made precisely for the reason unpleasant odor bitumen, although over time the mixture hardens and causes inconvenience only in hot weather.
Existing alternatives to asphalt are currently too expensive and not as practical. Unlike other building materials, asphalt is being improved not by developing new materials, but by upgrading old ones.
The widespread introduction of polymer modifiers makes it possible to fundamentally improve the properties road surfaces and expand the limits of their technological application, which is confirmed by numerous tests of the material.