FAILURES OF FLEXIBLE PAVEMANT

PRESENTED BY

RANDHIR KUMAR

14-CE-84

CIVIL ENGINEERING

HALDIA INSTITUTE OF TECHNOLOGY

FUNDAMENTAL DEFINITION

Types of highway pavement:(a) flexible pavement(b) rigid pavement(c) others

FLEXIBLE PAVEMENT: Flexible pavement are those, which on the whole have low or negligible flexural strength and are

rather flexible in their structural action under the loads.

RIGID PAVEMENT: Rigid pavement are those which possess noteworthy flexural strength or flexural rigidity. The rigid pavements are generally made of Portland Cement Concrete(cc) and are therefore called ‘CC pavement’.

Others Type of pavements include (a) ‘Semi-rigid pavements’ or ‘composite pavements’ (b) Interlocking Cement Concrete Block pavements

DIFFERENT LAYERS OF FLEXIBLE PAVEMENT

DIFFERENT TYPES OF FAILURES IN FLEXIBLE PAVEMENT

1. Alligator cracking or Map cracking (Fatigue)

2. Consolidation of pavement layers (Rutting)

3. Shear failure cracking

4. Longitudinal cracking

5. Frost heaving

6. Lack of binding to the lower course

7. Reflection cracking

8. Formation of waves and corrugation

9. Bleeding

10. Pumping

CAUSES OF FAILURES1. ALLIGATOR OR MAP CRACKING

Relative movement of pavement layer material

Repeated application of heavy wheel loads

Swelling and shrinkage of subgrade or others layers due to moisture variations

Primary causes of this type of failure are:

2.CONSOLIDATION OF PAVEMENT LAYERS 3. SHEAR FAILURE CRACKING

Repeated application of load along same wheel path resulting longitudinal ruts

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

Excessive wheel loading

Low shearing resistance of pavement materials

4. LONGITUDINAL CRACKING 5.FROST HEAVING

Differential volume change in subgrade soil Settlement of fill material Sliding of side slope

It depends upon:

ground water table conditions Climatic conditions

Primary causes of this type of failure are:

6.LACK OF BINDING WITH LOWER LAYER 7.REFLECTION CRACKING

Lack of prime coat or tack coat in between two layers is the primary reason behind this type of failure.

Differential movement across the underlying crack or joint

Potholes

8.FORMATION OF WAVES AND CORRUGATION

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

9.BLEEDING 10.PUMPING

Excess bituminous binder occurring on the pavement surface causes bleeding. Bleeding causes a shiny, glass-like, reflection surface that may be tacky to the touch.

Seeping or ejection of water and fines from beneath the pavement through cracks.