PAVEMENT( Road and Highway)

What is a Pavement?

It is a structure or a set of layers which serves as a medium for smooth passage of traffic ( light or heavy) by distributing the load to the ground .

Types of Pavement:

There are two types of pavements in general

1-      Flexible Pavements

2-      Rigid Pavement

Flexible Pavement:

·         It is the pavement which consists of certain layers e-g

·         Wearing course which is the top layer

·         Base course which is below the wearing course generally consists of aggregates.

·         Sub Base course which comes below the base course.. usually not needed

·         Subgrade which is the lowest part of the pavement is generally the natural ground compacted.

Types of flexible Pavements:

Flexible pavements are further of three types according to the aggregates used

1-      Densely graded

2-      Uniformly graded

3-      Gap graded

According to depth they are further of three types:

1-      Partial depth

2-      Full depth

3-      Other (CRAM)

Rigid Pavements:

In this type of pavement the load is transferred to ground by the beam action of a concrete slab PCC or RCC. It consists of following layers:

·         Wearing course which is the topmost layer consisting of bitumen and asphalt

·         Below the wearing course concrete slab is provided with is 6” to 12” according to traffic.

·         Base/Sub base course too is optional( usually of aggregate)

·         Sub grade which is compacted natural ground

Types of Rigid Pavements:

There are two main types of rigid pavements

1-      Continuously reinforced concrete pavements(CRCP)

2-      Jointed  plain concrete pavements(JPCP)

Continuously reinforced concrete pavement consists of a continuous reinforced bar passing throughout the slab.

Jointed plain concrete pavement consists of longitudinal and transverse joints which are held together by dowels and tie bars.

Flexible and Rigid Pavement comparison

Flexible pavements:

•          They have Deep foundations / multi layer construction

•          Energy is consumed  due to transportation of materials

•          Increasing cost of asphalt due to high oil prices

Rigid pavements

•          Generally have Single layer

•          Generally last for longer time

Failure types:

Following are the failures types in the rigid and flexible pavements

Flexible Pavement:

·         Fatigue cracking

·         Rutting

·         Thermal Cracking

Rigid Pavements:

·         Fatigue cracking

·         Pumping or erosion

·         Faulting

·         Spalling

·        Erosion

Safety is an important Consideration:

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