Design of Flexible Pavement

In this present electronic age, the development of the country is going at a very fast pace. So, with the development of the country, heavy load vehicles are also rapidly increasing. Road transport is the only transport by which you can travel door to door.

A road surface is layers of surfaces which are laid down on an area that can sustain vehicular or foot traffic loads (which also called pavement). This road surface is marked by different marking for the smooth flow of traffic. A pavement consists of superimposed layers consisting of different materials above the natural hard soil (usually called a subgrade) and the function of pavement is to distribute the loads from the surface of the pavement to subgrade. The pavement structure should be able to provide a surface of acceptable riding quality, adequate skid resistance, and favourable light-reflecting characteristics. The ultimate purpose of laying different layers between the surface coarse and subgrade is to minimize the stresses due to vehicular loads sufficiently so that when it reaches the subgrade it will not be more than bearing capacity of the subgrade. Generally, pavements are divided into two types Flexible and Rigid. Flexible pavements are surface coarse is laid by bitumen or asphalt material. The rigid pavement surface is also a concrete surface.

In India, most of the highways are flexible pavements. For designing of flexible pavements, there are different methods. The California Bearing Ratio (CBR) test is an empirical method of designing flexible pavement. California department of transportation has developed this before World war - II.

California Bearing Ratio (CBR) test is performed to know the required thickness that is to be provided for the pavement. This test is carried out as per IS 2720 – 16. Generally, it is the ratio of force per unit area required to penetrate into a soil mass with a circular plunger of 50mm diameter at the rate of 1.25mm/min.

The CBR test is performed in two methods:

Soaked sample
Unsoaked or dry sample

Testing of the sample in soaked condition will help us to know the stresses in the subgrade in worst conditions that can occur in the field. To get the specimen to this condition it is submerged in the water for 96 hours before testing.

Testing the sample in the unsoaked or dry condition is done to know the stresses in the subgrade in normal conditions that occur on the field. For this, the optimum moisture content of the specimen is evaluated and maximum dry density of the specimen is achieved before testing. This is the condition of soil subgrade after the construction of pavement.

Requirements:

Knowledge of Geotechnical Engineering (for Optimum Moisture Content, Maximum Dry Density, etc…)

Knowledge of performing the CBR test.

Knowledge of Traffic Engineering.

Knowledge of using catalogs in IRC 31 – 2001.

Project Implementation:

Calculate the optimum moisture content and maximum dry density of the sub-grade soil sample.
Perform the CBR test for the soaked and unsoaked conditions for the same sample.
Obtain all the values that are needed like VDF, Traffic growth and convert the heterogeneous traffic to standard wheel load.
Find the total thickness pavement and thickness of all layers from the IRC 31- 2001.

Advantages:

The easiest method for designing flexible pavement.
The thickness is dependent on CBR value, so it is considered as efficient.

Software Requirements:

Design can also be done on software like MXRoads, ESurveying CADD, etc…

Conclusion:

From this project, you will get to know how to design the flexible pavement and also you will recall the basics of Geotechnical Engineering.

Kit required to develop Design of Flexible Pavement:

Technologies you will learn by working on Design of Flexible Pavement:

Design of Flexible Pavement

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