Road Pavement

Pavement: The Road Pavement or, Pavement is the portion of the road located directly above the sub-grade and beneath any wearing surface. In urban areas it is often bordered by kerb and channel and in rural areas by road shoulders. It is typically constructed from compacted from imported material such as crushed rock.

In other words,

That portion of a Road designed for the support of, and to form the running surface for, vehicular traffic is called Road Pavement. Or,

The portion of the road, excluding shoulders, placed above the design sub-grade level for the support of, and to form a running surface for vehicular traffic is known to us as Road Pavement.

Figure-01 indicates a cross section of Road Pavement,

 

Figure-01: Typical Cross Section of a Road Pavement

There are Two (02) main types of Road Pavement, These are,

            a)      Flexible Pavement,

            b)      Rigid Pavement.

       a) Flexible Pavement: A Flexible Pavement is that type of pavement with a structure that deflects, or flexes, under loading. A Flexible Pavement Structure is typically composed of several layers of material. Each layer receives the loads from the above layer, spreads them out, then passes on these loads to the next layer below.

Figure-02 indicates a cross section of Flexible Pavement,

 

Figure-02: Typical Cross Section of a Flexible Pavement

      

       b) Rigid Pavement: Rigid Pavement is another type of Road Pavement Structure which deflects very little under loading due to the high Modulus of Elasticity of their surface course. A Rigid Pavement is typically composed of a P.C.C surface course built on top of either the sub-grade or an underlying base course, because of its relative rigidity, the pavement structure distributes loads over a wide area with only one, or at most two structural layers.

Figure-03 indicates a cross section of Rigid Pavement,

 

Figure-03: Typical Cross Section of a Rigid Pavement

Difference between Flexible Pavement and Rigid Pavement:

Topics	Flexible Pavement	Rigid Pavement
Life Time	20 Years	40 Years
Initial Cost	Less	High
Effect on Environment	Most hazardous effect	Less hazardous effect
Maintenance Cost	High	Low
Reinforcement	No	Yes
Cracking	Does not crack by over-loading	Crack because of over-loading
Labor	Skilled labor not essential	Skilled labor essential
Material	Not available	Avaiable

Advantages & Disadvantages:

Advantages & Disadvantages of Flexible Pavement:

Advantages:

---Design is Empirical,

---Life time is 10 to 20 years,

---Initial cost is low.

Disadvantages:

---Hazardous effect on environment,

---Maintenance cost is high,

---Expensive than Rigid Pavement,

---Manufacturing materials are not available.

Advantages & Disadvantages of Rigid Pavement:

Advantages:

---Long life time about 40 years,

---Less hazardous effect on environment,

---Low maintenance cost,

---Economical than Flexible Pavement,

---Materials are available.

Disadvantages:

---High initial cost,

---Does not fit into stage construction.