I Classification and causes of asphalt pavement diseases in wuhan
After the new highway is opened to traffic, under the action of driving load and natural factors, the pavement may suffer from cracks, ruts, potholes and other common diseases.
1. Cracks
Pavement cracks can be divided into (net cracks), longitudinal cracks and transverse cracks.
(1) It is also called net crack. The main reason for this kind of crack is that the overall strength of the pavement is not enough, and the humidity of the base layer is large and soft, and the stability of the subgrade is not good. Or the aging of asphalt pavement makes the pavement brittle, which will also lead to the appearance of network cracks.
(2) Longitudinal cracks generally occur at the junction of new and old widened pavements or the junction of subgrade. The main reason for the formation is that the pavement and subgrade are uneven, and the road surface has different capacity; Or it is caused by improper treatment of contact points at construction joints of asphalt pavement.
(3) The cause of transverse cracks is mainly the change of temperature and humidity, which directly leads to the contraction and expansion reaction of the pavement structure layer. No matter what the cause of the crack, under the interaction of driving or natural factors such as temperature, humidity, wind, frost, snow and rain, the pavement crack will have the trend of accelerating expansion.
2. Rut
Rutting is the accumulation of strip grooves on the road surface under the repeated action of driving load. Rutting is affected by both internal and external factors, including pavement structure and material composition, and external factors include design, construction, traffic conditions and meteorological conditions.
3. Pit
Pits and grooves are common diseases of asphalt concrete pavement, and the causes are as follows:
(1) In the construction process, due to the high temperature of mixing production, the asphalt is aging, the cohesive force is weakened, and the brittleness is increased. Under the driving load, it is easy to appear pits; The mixture temperature is too low, resulting in uneven paving, inadequate compaction, lack of compactness, and potholes.
(2) After the pavement has cracks, water will seep into the base course. Under the action of driving load, the base course is easy to loose and collapse, thus leading to the depth of the surface course. If the cycle continues like this, the asphalt surface will fall off and sink, causing pits
4. Subsidence
The subsidence of pavement can be divided into two types: local subsidence and large-area subsidence.
(1) Local subsidence is caused by uneven stress on the road surface, or cracks on the road surface caused by some vehicles. If water seeps in, it will lead to pavement subsidence.
(2) Large area subsidence is generally caused by uneven settlement or local slip of subgrade. Although the road surface diseases are theoretically classified as the above, in fact, many kinds of diseases coexist in a damaged road surface, such as cracks, ruts, pits and depressions.
