AdvancedTopic 94 of 112Civil & Structural
Pavement design
Flexible and rigid pavements distribute wheel loads to subgrade.
In depth
Flexible pavements (asphalt layers on granular base) spread loads through layers; rigid pavements (concrete slabs) distribute loads by slab action. Design by AASHTO or mechanistic-empirical methods using traffic (ESALs), subgrade strength (CBR) and climate. Maintenance extends life.
Key points
- Rutting and fatigue cracking
- Joints and dowels
- Overlays
ExampleA highway pavement may have 50 mm wearing course, 100 mm binder, 250 mm base.
What is Pavement design?
Flexible and rigid pavements distribute wheel loads to subgrade.
Why is it important to understand pavement design?
Pavements spread wheel loads to the subgrade, so their design determines how long a road lasts before it needs repair.
What is the difference between flexible and rigid pavements?
Flexible pavements use asphalt layers that spread load through layers, while rigid pavements use concrete slabs that spread load over a wide area.
What is the subgrade?
The prepared soil layer below the pavement, whose strength strongly affects the required thickness of the layers above.
How is Pavement design used in practice?
Typical applications include designing a flexible pavement for a regional road with heavy trucks, choosing a concrete slab thickness for an airport apron and specifying a base layer to protect the subgrade from repeated loading.
What should I learn before Pavement design?
Study "Highway geometric design" first (topic 93 of 112 in Civil & Structural). It covers the groundwork this topic builds on.
What are the key points of Pavement design?
Rutting and fatigue cracking. Joints and dowels. Overlays.
Can you give an example of Pavement design?
A highway pavement may have 50 mm wearing course, 100 mm binder, 250 mm base.
What comes after Pavement design?
The next topic is "Traffic flow theory", which builds directly on this one.
How difficult is Pavement design?
It is classed as Advanced in Civil & Structural (topic 94 of 112). It is an advanced topic. It assumes you are comfortable with the intermediate topics in Civil & Structural.