Asphalt pavement; Common diseases; measure
This paper systematically expounds the causes of common diseases of asphalt pavement, and puts forward corresponding engineering prevention measures according to specific diseases, so as to effectively strengthen the quality problems of highway pavement construction. At the same time, it also provides a reasonable reference for highway maintenance management.
First, the current situation analysis
Asphalt pavement has good mechanical properties, good durability and driving comfort, and has solid, durable, smooth, anti-sliding, anti-seepage, anti-fatigue and anti-high temperature cracking temperature stability, which is suitable for all kinds of vehicles. However, with the continuous extension of highway service time, due to various reasons, such as asphalt pavement under the repeated action of vehicle load and natural factors (such as rain, snow, temperature changes and differences in subgrade soil and hydrological conditions, etc.). ), plastic deformation will accumulate, and rutting, cracks, looseness, pits, peeling and other damage diseases will inevitably occur, thus affecting the safety performance of roads. On the other hand, expressway, where asphalt pavement is widely used in China, is facing serious diseases, so it is of great significance to the current expressway restoration work, especially to the asphalt pavement restoration and disease prevention, and to ensure the current transportation capacity and efficiency of expressway.
1. Cracks in asphalt pavement After the asphalt pavement is completed, various forms of cracks will appear. There are two main reasons for pavement damage: one is the temperature crack caused by the temperature change of asphalt pavement; The second is the structural damage cracks caused by traffic load.
2. The main causes of rutting on asphalt pavement are: (1) the asphalt mixture has too large asphalt-aggregate ratio; (2) excessive surface wear: (3) rainwater invades the asphalt concrete; (4) Because the base contains unstable interlayer, the pavement is pushed sideways, forming wavy ruts. Therefore, it can be seen from the above that the factors affecting the rutting depth of asphalt pavement are the result of the combined action of internal and external factors.
3. Loose asphalt pavement is a kind of pavement disease that directly affects driving safety, and the whole pavement surface may be loose. It may also occur in some areas, but it is generally more serious in the wheel track area because of the driving action. The main reasons are: (1) uneven settlement of local subgrade and base causes pavement damage; (2) Gravel contains weathered particles, which causes asphalt peeling after water enters; (3) With the increase of service time, the bonding performance of asphalt binder itself decreases, which promotes the asphalt wear in the contact part between the surface layer and the tire, resulting in the decrease of asphalt content and the loss of fine aggregate.
4. Damage of water to asphalt pavement Under wet conditions, asphalt pavement is repeatedly affected by traffic load and temperature rise and fall. On the one hand, water gradually invades the interface between asphalt and aggregate, and at the same time, due to the action of hydrodynamic force. The asphalt film gradually peeled off from the surface of aggregate, resulting in the loss of adhesion between aggregates and pavement damage.
5. Frost heaving and frost boiling of asphalt pavement mainly occurs in the freezing and thawing period. Due to the invasion of water, the water stability of subgrade soil is poor, and the water on the upper layer of subgrade freezes, which leads to the cracking of pavement bulge. Road frost boiling is the comprehensive result of five main factors: water, soil quality, temperature, pavement and traffic load. Among them, water, soil and temperature constitute three natural factors of boiling, and it is impossible to form boiling without any one factor.
6. The settlement of asphalt pavement is the most common pavement deformation, which has the characteristics of large area and deep structural layer, mainly appearing at the intersection of excavation section and filling and excavation. The main reasons are: (1) poor drainage of soil cutting, uneven settlement caused by over-wet genes under subgrade, and local settlement of pavement; (2) The pavement strength can't adapt to the increasing traffic volume, and it is easy to produce fatigue damage.
Third, preventive measures.
This paper analyzes some common diseases of asphalt pavement, and now mainly controls them from building materials, construction design or post-construction maintenance, traffic and other aspects, and puts forward corresponding preventive measures.
1. Reasonable determination of asphalt pavement structure from the perspective of materials. The crack problem of asphalt pavement is mainly caused by the low temperature shrinkage crack of asphalt pavement itself. Therefore, in the selection of materials, the quality control measures of high-quality asphalt with low stiffness, large ductility, poor temperature sensitivity and low wax content at low temperature are mainly adopted. In the aspect of quality control, the main measure is to select the mineral aggregate, combine the mineral aggregate prepared by graded asphalt pavement with the reasonably configured mineral aggregate, and control the best mixture ratio, so as to configure the asphalt mixture with better performance. The most basic thing is to control the amount of asphalt and ensure the excellent quality of asphalt mixture.
2. In terms of design, the comprehensive material design of concrete and the comprehensive complexity of terrain are stipulated. Therefore, it is necessary to do a good job in geological exploration, and pay special attention to the control methods of strengthening the foundation to prevent uneven settlement of the foundation due to weak conditions. Therefore, it is very necessary to use qualified fillers and carry out effective construction in Xining area, so as to effectively control the fillers before filling the roadbed. It is necessary to ensure that the subgrade engineering has sufficient strength and stability control, and that the subgrade can have a stable foundation treatment process. Semi-rigid materials with good scouring performance, small shrinkage coefficient and high tensile strength are selected as the base, so asphalt materials are selected as the quality control work of asphalt surface layer. On the premise of stable asphalt quality, asphalt materials with high applicability should be selected as asphalt surface course.
3. Construction: In the process of construction, we should choose advanced construction technology and mechanical equipment to apply comprehensive control measures, formulate a perfect construction plan to guide the construction, ensure the comprehensive control measures of subgrade compactness, meet the compaction control and specification requirements of subgrade engineering, and effectively analyze and treat the soft foundation in strict accordance with the design requirements, so as to improve the construction quality control of soft foundation engineering as a whole. Strictly control the water content control in the rolling process of semi-rigid base, and the water content of mixture should also be controlled. Within the scope required by the construction specifications, due to the comprehensive control measures, the optimal water content control required for compaction cannot be effectively implemented, and finally it cannot meet the requirements of the specifications and standards. In this way, in the process of semi-rigid base rolling, not only the 2008 Olympic Games and maintenance work should be carried out in time, but also a series of cracks should be prevented according to comprehensive control measures. If the cracks have overall quality adjustment work on a certain basis, they will be reflected to the asphalt surface according to a certain water content of the mixture to ensure that the water content of concrete is out of control. After curing, base oil should be sprayed in time, and asphalt surface should be paved as soon as possible.
4. Maintenance: In the maintenance of asphalt pavement, we should not only strengthen strict maintenance work, but also strengthen the cleaning work of the pavement to ensure that the drainage performance of the pavement is effectively controlled, and scientifically control the cracks in time to avoid further development of the disease.
5. Strengthen traffic management, strengthen traffic management, and restrict the passage of large overloaded vehicles. During the operation of high-temperature vehicles, the operation management unit generally undertakes road maintenance work, and some heavy vehicles generally pass at night or in the early morning when the temperature is low. Overweight vehicles and tires with nails are prohibited from passing, and the damage behavior in the process of road use is severely cracked down.
Four. conclusion
To sum up, through the analysis of the causes of common diseases of asphalt pavement, engineers can fully realize that there are many places worthy of reflection in the current pavement structure setting. Combining the usage of asphalt pavement in expressway and other related problems, as well as the asphalt pavement damage caused by various reasons under heavy traffic conditions, is a difficult problem that must be overcome before highway construction and maintenance managers! Therefore, in practical work, scientific management and strict construction are needed. Mastering skilled technology to ensure highway construction quality.
refer to
[1] Miao, Zhao. On the causes and prevention measures of highway asphalt pavement diseases [J]. Heilongjiang Science and Technology Information.2009 (34)
[2] Yuan Yanqin. Discussion on Common Diseases of Asphalt Pavement and Preventive Measures [J]. Science and Technology Information.2011(22)
[3] Yu Zhenning. Cause analysis and prevention measures of asphalt concrete pavement diseases [J]. Heilongjiang Science and Technology Information.2010 (19)
[4] Yuan, Li Ge. Causes and prevention measures of asphalt concrete pavement diseases [J]. Science and Technology Information .2009 (05)