The causes and repair process of potholes on asphalt pavements on highways is a technical system for analyzing and repairing potholes on asphalt pavements, covering the cause mechanism and repair methods. This process is applied to the field of highway pavement maintenance to ensure road safety and durability.
The main causes of damage include excessive porosity in the permeable asphalt layer leading to water seepage, segregation of the base mixture leading to insufficient strength, and the formation of an isolation layer due to the failure to clean the base slurry, which causes mud gushing. The repair methods are divided into three categories: cold material cold repair, hot material hot repair, and hot material cold repair: the cold repair process is easy to operate and suitable for emergency repairs but has poor durability; the hot repair process achieves deep repair by heating recycled asphalt and has a longer service life; the hot material cold repair adopts a layered filling strategy, with temporary repairs first and secondary hot repairs in the rainy season.
In the early days, cold repair technology was the main method, and hot repair technology was gradually promoted with the upgrading of mechanical technology. Hot repair uses radiation heating regeneration technology to improve the repair effect, and in some scenarios it can reach permanent repair standards. Hot material cold patching is an adaptive improvement solution, combined with emergency repair and long-term maintenance needs, to form a composite model for seasonal disease treatment.

Cause Analysis
Water permeability of asphalt pavement concrete layer: Some construction units did not fill the asphalt pavement concrete layer with coarse materials in order to save costs according to the design and construction requirements, resulting in more coarse materials and less fine materials, and the void ratio is far greater than the national requirements. After being put into use, especially in rainy seasons, water permeability will occur, which is one of the causes of potholes on the road surface.
Insufficient base strength: During the construction of asphalt pavement, due to mechanical failure or improper operation of workers, the base mixture will be segregated, and the local base strength will not meet the requirements of design and construction. If the gravel base will be segregated on a general road section, it will cause the local coarse aggregate to be too concentrated and the water tightness is too poor.
Interference layer appears locally between the asphalt concrete layer and the base layer: Due to the poor cleaning of the local floating soil and floating slurry of the base layer, an isolation layer is generated locally during the construction process. If the asphalt concrete layer at the corresponding position leaks, a mud bag will be formed, resulting in the shear resistance and compressive strength of the road surface not meeting the design requirements. Under the repeated action of vehicle pressure, mud will gush out.
Repair method
Asphalt pavement pothole repair technology can be roughly divided into three types, cold material cold patching technology, hot material hot patching technology and hot material cold patching technology. Each method has its own characteristics and is suitable for different situations. Construction personnel should choose the appropriate method according to the actual situation.
The cold material cold patching technology of the road surface is mainly suitable for emergency repairs. First, the dirt and mud in the potholes should be cleaned up, and the prepared cold patch material should be poured into the potholes and spread evenly. It is necessary to ensure that the cold patch material in the potholes is sufficient, but not overflowing. Then use a road roller to compact the road surface. The deeper potholes should be sealed with cold patch material and compacted in layers. If the compaction degree of the repair does not meet the requirements, the road surface will sink after it is put into use. At this time, the cold patch material must be further filled and compacted. Therefore, in order to avoid sinking during the actual operation, the potholes filled with cold patch material are usually 5 to 10 mm higher than the surrounding road surface. The cold patching process has a short operation time and can be put into use after 10 minutes of repair. It also has the advantage of being easy to construct, but the adhesion between the repaired material and the original road surface is poor. Under the influence of rain erosion and vehicle load, the life of the repaired road surface usually needs to be repaired again after 2 months [1]. This is only a temporary repair measure that can promptly solve the road damage that affects safety.
With the development of the mechanical level of maintenance equipment, the region has gradually begun to adopt hot repair technology. Hot repair technology can better meet the quality requirements than cold repair technology. The principle of hot repair technology is to use radiation heating to heat the potholes of the asphalt road surface, so that the asphalt material returns to a molten state, regenerates the asphalt, and then fills in new materials. The road surface is compacted by a roller, which can achieve a better repair effect than cold repair. However, the construction time is longer than the cold repair cycle, and the cost is relatively high. Hot repair technology usually requires expensive repair equipment and a large initial investment, but the raw materials for each repair are cheap. Usually, the repaired pothole road surface can be used again for more than one year, and in some places it can even reach the level of permanent repair. This repair technology is suitable for highway maintenance units with independent maintenance functions and can play a long-term advantage.
The hot material cold patching process is suitable for repairing damaged roads in the rainy season. If the asphalt road surface encounters the rainy season after it is put into use, a large number of potholes will appear. If it is not repaired in time, the potholes will deteriorate and seriously affect the use of the road surface. The principle of the hot material cold patching process is to temporarily use cold patching materials to fill the potholes along the highway, compact it with a roller, so that the road surface temporarily meets the traffic requirements, and then use the hot patching technology equipment-radiation heating to apply the hot patching technology principle to the potholes to repair the potholes of the asphalt road surface after the rain stops. This process combines the advantages of the two repair technologies, so that the road surface repair is not limited by time and temperature.
Conclusion

The repair of potholes on asphalt pavement is closely related to the selected repair process and the selected repair materials. The relevant construction units should choose the appropriate repair methods according to the actual situation of the expressway to extend the service life of the asphalt pavement of the expressway. The expressway is a very important part of the development of the national economy. The damage to the expressway pavement should be taken seriously by the relevant departments. The three repair methods proposed in this article have been tested in practice and are practical repair technologies.