Among the early damage phenomena of asphalt concrete pavement, the most frequent pavement diseases are cracks, potholes, subsidence, oil spills, looseness, etc., which lead to poor road conditions, poor pavement flatness and poor skid resistance, seriously affecting the pavement performance.

1. Pavement cracks
Cracks can be divided into transverse cracks, longitudinal cracks and network cracks according to the pavement distribution. The width and density of cracks determine the degree of damage to the pavement and directly affect the service life of the pavement. Due to cracks, water on the pavement seeps into the base layer. Under the repeated action of driving, mud pumping occurs, resulting in structural damage to the pavement base layer, thus destroying the pavement and forming various diseases. One of the main causes of pavement cracks is the influence of the material of asphalt itself, such as high wax content in asphalt, which is easy to age; uneven settlement of the roadbed and insufficient strength of the pavement base layer can also lead to pavement cracks. For example, pavements built on soft soil foundations often have cracks and subsidence.
2. Pavement oil spills, subsidence and poor flatness
(1) Pavement oil spills are mainly due to the influence of the asphalt (oil) stone ratio. The design of the oil-stone ratio only focuses on the indoor Marshall stability control experiment, such as satisfying the three major indicators of flow value, stability, and void ratio to determine the oil-stone ratio, but lacks dynamic stability index experiments to determine the oil-stone ratio and aggregate mix ratio. In order to ensure good adhesion between the pavement interlayers, the construction method of tack coat oil is usually used on the pavement base, but the impact of these tack coat oils on the future oil-stone ratio is often ignored. It is easy to cause the oil-stone ratio to be too large and oil overflow. In addition, since the pavement base is not very flat and there are potholes, and the asphalt layer oil is a flowing liquid, the tack coat oil is often excessively concentrated in low-lying areas, resulting in serious oil overflow on local pavements.
Fast speed and poor flatness are mainly manifested in the influence of density. On the one hand, the subgrade density is not enough, resulting in uneven subsidence of the subgrade, causing local subsidence of the pavement: on the other hand, the pavement base is uneven, the pavement thickness of the mixture is inconsistent, and the compaction is insufficient. As the number of vehicle loads increases. It leads to local subsidence of the pavement. The influence of insufficient aggregate and temperature. Improper mix ratio of oilstone and gravel in the road mixture and insufficient specifications of crushed stone lead to poor road stability. As vehicles load on the road, potholes, oil spills, and bumps appear on the road. High summer temperatures (above 37°C) last for a long time, causing road deformation, are another reason for accelerating the decline in flatness.
(3) In the construction of asphalt concrete pavement, the pavement mixture is inherently insufficient in paving and rolling. The rolling equipment models are not matched and the tonnage is small. The rolling is not timely or in place. The paving temperature of the mixture is too low, which has a great impact on the flatness of the asphalt concrete pavement.
(4) In the construction of asphalt concrete pavement, the poor quality of asphalt, the mixing temperature of the asphalt concrete mixture is too high or too low, the acid-base combination is not good, and the interlayer is seriously polluted, etc., may all lead to loose pavement, potholes, peeling and other diseases.