Flexible pavement structures are constructed of a flexible pavement (typically asphalt) surface layer that is placed over a treated or untreated base layer and an untreated subbase layer . Flexible pavement types and procedures are found in Chapter 630 of the Highway Design. Manual (HDM).
What is pavement design?
Overview. A highway pavement is a structure consisting of superimposed layers of processed materials above the natural soil sub-grade , whose primary function is to distribute the applied vehicle loads to the sub-grade. ... Improper design of pavements leads to early failure of pavements affecting the riding quality.
What is a flexible pavement?
Flexible pavements are those which are surfaced with bituminous (or asphalt) materials . ... These types of pavements are called “flexible” since the total pavement structure “bends” or “deflects” due to traffic loads.
What are the methods to design flexible pavement?
- 2.1 Empirical design.
- 2.2 Mechanistic-Empirical Design.
- 3.1 Equivalent single wheel load.
- 3.2 Equivalent single axle load.
- 4.1 Resilient modulus of soil.
- 4.2 Dynamic complex modulus.
What is the designing life of flexible pavement?
It is recommended that a design period of 20 years may be adopted for the structural design of pavements for National Highways, State Highways and Urban Roads. For other categories of roads, a design period of 15 years is recommended.
Where is flexible pavement used?
Major highways constructed in the world are of bituminous surfacing. For example, 86 percent of rural highways and 78 percent of urban roads in the U.S. are of flexible type. Most of the runways in the world have flexible pavements, Autobahn in Germany is also with flexible pavement.
How many layers are in flexible pavement?
Lastly, it is important to protect the lower pavement layers and subgrade from any of the weakening effects of water. There are actually typically five or six layers in a flexible pavement, divided into two overlapping sections: the pavement section and the foundation section.
What is the main aim of the pavement design process?
What is the main aim of the pavement design process? Explanation: The pavement design mainly aims at determining the total thickness of the pavement . The thickness of each layer of the pavement is found out by designing it with proper inputs and then the total thickness is found out.
What are the factors in pavement design?
- Contact pressure: ...
- Wheel load: ...
- Axle configuration: ...
- Moving loads: ...
- Repetition of Loads: ...
- Layered elastic model:
How do you design pavement thickness?
The authors suggest the following computation method for obtaining pavement thickness using Gray’s formula: (1) carefully study the traffic mix likely to occur at a project site ; (2) calculate the total load and radius of the contact area on the basis of the proportions of vehicle types; (3) add an extra impact factor ...
What is difference between flexible and rigid pavement?
Flexible pavements tend to have more layers and are therefore much thicker by default. Rigid pavements have fewer layers and are thinner than flexible pavements , which makes them susceptible to more repairs over time.
What is the most commonly used overlay?
Explanation: The most commonly used overlay is flexible over flexible , rigid over flexible and rigid over rigid are also used but flexible is the most preferred and used pavement. Explanation: The commercial vehicles per day are considered as 150 to 1500 for pavement design studies.
Is code for flexible pavement design?
The Pavement designs given in the previous edition IRC:37-1984 were applicable to design traffic upto only 30 million standard axles (msa). ... Flexible pavements are considered to include the pavements which have bituminous surfacing and granular base and sub-base courses conforming to IRC/ MOST standards.
What is the most commonly used type of concrete pavement?
What is the most commonly used type of concrete pavement? Explanation: The most commonly used type is unreinforced , dowels and ties are not considered as reinforcements in slab.
Which layer of pavement should withstand stress?
The lower layers are the base courses. The surface course constitutes the top layer of the pavement and should be able to withstand high traffic- and environmentally-induced stresses without exhibiting unsatisfactory cracking and rutting.
What is CBR in road design?
The California Bearing Ratio (CBR) is a measure of the strength of the subgrade of a road or other paved area, and of the materials used in its construction.
