Stresses are the response of loading on the pavement. Material containing subgrade and environment condition are also responsible for stresses in the pavement. There are various types of stresses yields in flexible and rigid pavements under the applied live load.
The top most paved surface of such type of pavement is flexible, that is extremely dependent on the underlying layers. Due to flexible, pavement is free to move. In such type of pavements following stresses are the most common and are extremely effective.
- Vertical stresses
- Shear stress
- Radial stress
Vertical stress effects the pavement by compressing the pavement material. When pavement compresses, then material in a pavement gets crushed and as a result rutting become visible on the top horizontal pavement.
Rutting is the depression in the surface of wheel path. Along the sides of the rutting, pavement may uplift (due to shear). These ruts are very clear in the pavement after rain when ruts filled up with water.
Shear stress occurs in the pavement when load is more than the capacity of the pavement. When load approaches the critical point, then as a result movement occurs in the base layer and that movement is responsible for the shear stress in the top pavement.
When tension occurs at the bottom of layers due to seepage, removal of material from particular layer or by any other mean. As a result fatigue cracking occurs in the pavement due to wear and tear of loads. That cracking leads to radial stresses in the pavement.