5 FORMS OF FAILURE IN RIGID PAVEMENT

Failure in a rigid pavement (or cement concrete pavement) can be identified by creating cracks on the surface of the pavement. There are two major factors responsible for hard pavement failure:

  1. use of substandard material
  2. Inadequate stability of the pavement structure

Poor quality of material includes the following items:


  • using soft aggregate
  • poor quality of sub-grade soil
  • Bad Joint Filler Sealer Material

Inadequate stability of the pavement structure may be due to the following reasons:

  • insufficient pavement thickness
  • Lack of sub-grade support
  • improper compaction of the sub-grade
  • improper spacing of joints

Types of failure in hard pavement

The following 5 types of failures are commonly found in hard pavement:

  1. scaling of cement concrete
  2. shrinkage cracks
  3. combined spelling
  4. deformed cracks
  5. pumping

1. scaling of cement concrete

scaling
scaling

Scaling of hard pavement simply means peeling or peeling of the top layer or skin of the concrete surface. This may be due to the following reasons


  • improper mix design
  • Excessive vibration during compaction of concrete
  • Concrete Latency
  • finishing work on surface bleed water

2. shrinkage cracks

shrinkage rupture
shrinkage rupture

The formation of hairline shallow cracks on a concrete slab is a sign of shrinkage cracks.

Shrinkage cracks develop on the concrete surface during setting and curing operations. These cracks can form in longitudinal as well as transverse direction.

3. combined spelling

Joint spalling is the breakdown of the slab near the edge of the joint. Normally this is within 0.5 m of the joints. Common causes of this defect are:

combined spelling
combined spelling
  • Faulty alignment of incompressible material under concrete slab
  • Insufficient strength of concrete slab near joints
  • freeze-thaw cycle
  • excessive stress on the joint due to wheel load

4. deformed cracks

In hot weather, the concrete slab expands. Therefore the joints must be designed in such a way as to accommodate this expansion. When the joints are not designed properly, it inhibits the expansion of the concrete slab and results in the development of excessive stress. This stress leads to the formation of deformable cracks of the concrete slab near the joint edge.

This type of cracking can be prevented by providing proper reinforcement at longitudinal and transverse joints. Hinge joints are commonly used to relieve stress caused by warping.


5. pumping

pumping
pumping

When the material under the road slab leaks out through the joints or cracks, it is called pumping. When the mud solution comes out, it is called mud pumping.

Common causes of this defect are:

  • Soil slurry is formed by the infiltration of water through pavement joints, cracks or edge. The movement of heavy vehicles on the pavement forces this mud slurry to drain out, thereby pumping the soil.
  • When there is free space between the underlying base of the slab and the sub-grade layer
  • Poor joint seal allowing water infiltration
  • Repeated wheel loading causes corrosion of the underlying material

Pumping can also cause cracks. this is because; Evacuation of sub-grade material below the slab leads to loss of sub-grade support. When there is traffic movement at these locations, it fails to resist wheel load and develops cracks due to lack of sub-grade support.

This type of defect can be identified when there is the presence of base or sub-grade material on the surface of the pavement near joints or cracks.

Er. Mukesh Kumar

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Er. Mukesh Kumar is Editor in Chief and Co-Funder at ProCivilEngineer.com Civil Engineering Website. Mukesh Kumar is a Bachelor in Civil Engineering From MIT. He has work experience in Highway Construction, Bridge Construction, Railway Steel Girder work, Under box culvert construction, Retaining wall construction. He was a lecturer in a Engineering college for more than 6 years.