Types of failure in Bituminous Pavement

1. Alligator/Map cracking

  It is also called fatigue failure.

The causes are:

a. Relative movement of pavement materials.

b. Repeated application of heavy wheel loads.

c. Swelling or shrinkage of layers

 

2. Consolidation of pavement layers/rutting

Rut is depression or groove worn in road by the travel of vehicle

It is caused due to

a. Relative movement of pavement layer

b. Repeated application of load along the wheel moving side resulting longitudinal rutting

c. Wearing of the surface course along wheel path resulting shallow ruts

 

3. Shear failure/cracking

It is localized type failure. Failure occurs due to cracking and fracture.

Causes

a. Due to upheaval of pavement material.

b. Excessive wheel loading

c. Low shearing resistance of pavement mixture

 

4. Longitudinal Cracking

This type of cracking extends to full thickness of pavement. The reasons are:

a. Differential volume change in subgrade soil

b. Settlement of filling material

c. Rise of ground water table up to subgrade level

d. Sliding of the slide slopes

 

5. Frost Heaving

It causes up heave of localized portion of pavement. The level of frost depends upon ground water table and climatic condition.

The causes are:

a. G/W table

b. Lack of proper camber

c. Caused due to localized upheaval of local portion of pavement

 

6. Potholes and Slippage

It occurs due to lack of proper binding of surface layer with lower layer of pavement. Due to this some portion of surface course looses up materials creating patches and potholes. Slippage cracking is one form of this type of failure.

The reasons are:

a. Lack of binding with lower layer

b. Proper prime coat and tack not used

 

7. Reflection cracking

If bituminous layer is provided above cement concrete, cracks in cement concrete goes to bituminous pavement. 

 

8. Formation of waves and corrugation

Transverse undulation appear at regular interval due to unstable surface course caused by stop and go traffic.

 

9. Bleeding

Use of excessive binder causes bleeding. It causes shiny, glass type, reflective surface which is usually found in the wheel path.

 

10. Pumping

Seepage and ejection of fines and water beneath the pavement from crack is pumping.