There are many reasons for the rutting of asphalt pavement, which can be divided into three categories: internal factors, external factors and other factors. The internal factors are mainly reflected in the quality of the material itself, while the external factors mainly include climatic conditions and traffic conditions. Other factors refer to the influence of pavement and pavement structure and its construction quality on road rutting. When the internal factors, external factors and other factors together when the formation of asphalt pavement will have a comprehensive impact.
1 Rut the internal cause of the rut
The internal cause of the rut is mainly the strength of the asphalt concrete, and the strength of the asphalt concrete depends on the adhesion of the asphalt mixture and the internal friction angle. The cohesive force of asphalt concrete depends on the nature and consistency of the asphalt used, the ratio of bituminous ore to powder and the interaction between bitumen and slag. The greater the viscosity of the asphalt, the greater the strength of the asphalt concrete. When the amount of asphalt exceeds the optimum value, the adhesive force decreases rapidly. In recent years, it has been proved that the incorporation of high molecular weight polymer into asphalt improves the performance of asphalt, and the satisfactory effect of improving the anti-rutting resistance of asphalt mixture can be obtained. In addition, the gradation composition of the aggregate, the strength of the ore material, the shape of the particles and the surface properties all affect the internal friction angle of the asphalt concrete. The particle size increases, the internal friction angle increases; the needle-like particles increase, the internal friction angle decreases. Therefore, the nature of the materials used, the specifications and the ratio of reasonable or not is the internal factors that affect the rut.
1.1 Asphalt type
Asphalt mixture shear capacity depends mainly on the asphalt mixture of adhesive force and internal friction, the impact of asphalt mixture bonding factors are mainly asphalt viscosity, asphalt dosage, asphalt and mineral interaction characteristics, asphalt The higher the viscosity, the greater the adhesion of the asphalt mixture, and thus has a higher shear strength. Asphalt type should be based on the environment and climate, traffic conditions and other rational use, especially the high temperature, channeled traffic should be used in the road more viscous heavy traffic asphalt technical requirements of high-quality asphalt and modified Sui asphalt. From the asphalt quality and road performance, imported asphalt slightly better than domestic asphalt.
1.2 Asphalt dosage
The cohesive force of the mixture is related to the amount of asphalt. The larger the amount is, the more free asphalt is between the ore particles. The thicker the asphalt film around the mineral material, the lower the binder is. on the contrary. Asphalt can not completely cover the mineral particles interface also affect the adhesion of asphalt mixture, while the lack of mixing the amount of work should be difficult to compaction, and prone to loose, segregation phenomenon. In order to improve the adhesion of asphalt mixture, in addition to the use of high quality asphalt. Strict control of the rational use of asphalt is very critical. Asphalt dosage must be strictly according to Marshall test indicators, and taking into account the climatic conditions, traffic type, highway grade and other factors. At the same time, the residual stability and dynamic stability of the mixture were tested, and the proposed mixing ratio was tested by the vehicle to determine the optimum amount of asphalt.
1.3 Aggregate gradation, particle shape and surface characteristics
Asphalt mixture of the embedded force and internal friction depends mainly on the mineralization gradation, particle shape and surface characteristics, asphalt dosage. In order to increase the internal friction of the asphalt mixture to meet the ability to resist permanent deformation, in addition to using the best asphalt with the outside. The use of clean, with good particle shape, rough surface, crushing value is small, and the asphalt has a good adhesion of the mineral is very critical. The experimental study shows that the amount of mineral powder has a great influence on the high temperature stability of the asphalt mixture, and it has great influence on the anti-rutting ability of the asphalt. The specific impact is: (1) the greater the amount of ore powder. The smaller the Marshall modulus of the asphalt mixture, the worse the high temperature stability, the weaker the rutting resistance of the asphalt pavement. (2) the amount of mineral powder appropriate, asphalt mixture Marshall modulus larger, high temperature stability is better. Asphalt pavement with strong resistance to rutting.
2 Rutts produce external causes
The influence of traffic conditions on asphalt pavement can be attributed to load, tire pressure, traffic speed, traffic flow and so on. Under normal circumstances the heavier the load, the greater the tire pressure, the slower the speed, the higher the degree of channeling traffic, will greatly accelerate the formation of asphalt pavement rut. Such as Shitai Expressway, due to the large tonnage, large flow, slow driving the composition of coal vehicles is characterized by one of the important reasons for the formation of road rut. It should be noted that the degree of impact of the overloaded vehicle on the rut formation will be multiplied by the extent of the impact of the normal load vehicle.
2. 2 climatic conditions
The climatic conditions mainly include temperature, sunshine, radiation, wind, rain, ground temperature, etc., but comes down mainly in the temperature factor, the temperature above 25 ℃, road surface temperature above 40 ℃, asphalt pavement is an important external condition. Test data show that: road surface temperature between 40 ℃ -60 ℃, the asphalt mixture temperature increased by 5 ℃ each time the deformation increased by 2 times.
3 other factors
Mainly refers to the grass-roots level and construction quality.
3. 1 pavement base
When the strength and stability of the pavement is sufficient, the asphalt pavement rupture depends mainly on the nature of the asphalt layer and the base itself. Therefore, the strength and stability of the surface layer and the base layer are the basic conditions to prevent the rutting of the asphalt surface The
The impact of construction quality on rutting
Due to the construction is not fully compaction or material temperature is not enough and other reasons for the construction of the asphalt surface compaction caused by insufficient, resulting in the opening of the first high temperature season asphalt mixture under the action of driving, continue to compact the formation of the rut. This kind of rut in China has become a more prominent problem. With an asphalt surface of 15 cm, the discrepancy is increased by 1. 5 mm when the compaction is 1% difference. The rutting range proposed by rutting deformation varies from 10 mm to 20 mm. According to regulations, hot compaction asphalt mixture pavement compaction degree of 96%. So that even if the compaction requirements of the asphalt surface layer, under the action of driving to continue to compact 100%, still produce about 6 mm rut deformation, and for the construction of the degree of compaction is not satisfied
The required road surface rutting may be greater. So asphalt pavement construction will be the impact of rutting formation is one of the important factors.
Measures to Prevent Rutting of Asphalt Pavement
Asphalt pavement rutting is caused by a variety of reasons, often by a combination of a variety of factors arising. Therefore, in the prevention and control of rutting countermeasures, it is not a measure to solve the problem, only to take comprehensive measures to receive good results. This can be from the grass-roots strength and stiffness, asphalt mixture design, asphalt pavement construction and road traffic management and other aspects to take appropriate measures.