Even the highest quality pavement will deteriorate over time, with cracks, potholes, and breaks in its surface.
However, all pavements require timely and systematic maintenance activities to maintain the required serviceability, as well as a number of repairs when necessary.
Causes of cracks and fractures
Among the many factors that have a devastating effect on the roadway, we can distinguish the following:
- Errors in design
- Freezing of water inside the pavement
- Errors in laying the subgrade
- Process failures
- Incorrect asphalt mix composition
- Increased load
The main causes of cracks in asphalt
Errors in design
Incorrect evaluation of various parameters, do not take into account the high growth capacity of the road, inaccuracies during the design and construction of drainage systems, as well as many other shortcomings can lead not only to the appearance of numerous cracks and fractures but also to more serious damage to the roadway.
Freezing water inside the pavement
Freezing water in the inner layers of the pavement. Hot mix asphalt is mostly used for the construction of highways. Such material is characterized by a porous structure, so water during heavy rains or snow melting, bursts pipes, is absorbed into the pores, and remains inside. When it freezes, it expands, which leads to cracks.
Subgrade mistakes
Poor compaction or rasping, improper selection of materials and other mistakes made during the laying of the base will cause shrinkage and destruction of the web. Improperly shaped routes, too little or too much slope, and poorly designed drainage systems will result in regular surface flooding.
Process irregularities
The most common mistakes made when paving asphalt mixtures include insufficient preparation of the substrate, overcooling of the composition, working in rainy weather, and at temperatures lower than recommended.
Incorrect asphalt mix composition
Incorrect composition of the asphalt-concrete mixture. If during the production of the mixture, its composition is violated, the finished material will not have the necessary margin of safety.
Increased load
Because of the large traffic flow, the daily capacity of the road is exceeded, laid down during the design. The service life of the road decreases, the roadbed quickly wears out and defects appear on its surface.
Exactly the presence of one of these factors or their complex impact causes the appearance of cracks, potholes, fractures and other defects on the surface and in the inner layers of the roadway.
Repair of asphalt concrete pavement
In case of problems with the destruction and damage of asphalt concrete pavement, it is necessary to use a complex of measures.
Of course, timely filling a small crack with a special composition for a while will suspend the process of the break, which will later turn into a pothole, but the problem that caused the appearance of these and other defects will remain.
Among the effective practical solutions by which the normal operating condition of the highway is maintained, it is possible to allocate the following:
- Application of modern technologies and quality materials during laying of asphalt concrete layer and during the arrangement of the base. Today the modified ABS, having lower elasticity and thermal sensitivity of the binder, are quite popular. Due to these properties the roadbed made of such materials has a higher thermal resistance in summer and successfully resists the appearance of temperature cracks at low temperatures and the so-called fatigue cracks that appear during prolonged use of the road.
- When carrying out road works, it is necessary to strictly adhere to all applicable standards and regulations.
- Systematic maintenance and timely repairs. Untimely performance of repair works causes deterioration of the general condition of the road bed, therefore additional expenses will be required to restore normal operating condition of the road. Delayed repair and rehabilitation work to sufficiently harden the roadway will require the laying of larger layers, and the necessary costs will double.
These are the main recommendations that, if followed, can significantly extend the life of an asphalt road.
Pothole Repair
This type of repair can be accomplished in a variety of ways:
Hot Mix Asphalt
When using hot-mapped asphalt mix, the part of the pavement where the defect occurred is removed. A water-bitumen emulsion is used for surface treatment of the base and the pavement itself in order to improve their adhesion to the patch. A heated asphalt-concrete mixture is poured into the prepared pit, and it is compacted with the help of vibratory plates or special equipment.
Jet-injection method
The damaged area is blown with air under high pressure, removing impurities and water. Then the damaged area is treated with water-bitumen emulsion (WBE) and black crushed stone is laid. After laying the material is leveled, compacted and well-impregnated with WBE. This technique is not particularly expensive, but the restored area can only withstand low loads.
Casting technique
It is performed with the cutting of the cards. Preparation of the damaged area is carried out according to the same scheme as in the case of using hot ABS. The prepared card is filled with cast ABS, which does not need to be sealed. In some cases, the patch is additionally reinforced with black rubble. This technology is of higher quality, but at the same time, the cost of such repairs is higher.
Filling with polymers
Dust and water are blown out of cracks and fractures by means of compressed air, treated with special emulsions, and poured with a highly effective polymer. This technology provides absolute sealing of the defective area, but the materials for it are not cheap. It is used for sealing when attention to the integrity of the pavement is particularly high: on runways, etc.
The choice of the best method is carried out depending on the technical equipment and financial capabilities of the organization involved in the work.
Wear layer installation
This layer is laid by casting technique and helps to seal the pavement. The finished layer has good repairability, low maintenance costs, and sufficient durability. When laying the wear layer, the repair and construction organization must have cohesives available. In the case of damage to the base or in the case of defects in the ground, it is obligatory to carry out a major repair.
Necessary equipment
Depending on the repair technology, different equipment is used for the work, but the most affordable and easy to use are joint fillers and tar pours.
Bitumen joint fillers
Bitumen joint fillers are used for melting bitumen and keeping it in a liquid condition. With this equipment, you can pour in joints, and small potholes and perform other work.
Pouring machines
Vacuum sprayers are indispensable during patching, which is carried out by jet injection technology. They are also used in road repair works to apply water-bitumen emulsions.
