PRINCIPLES PAVEMENT DESIGN By Sri. A. Ramesh, (Ph.D)
PRINCIPLES PAVEMENT DESIGN
By
Sri. A. Ramesh, (Ph.D)
Objectives To understand the need for rational design
of Pavement To understand how pavements fail
functionally or structurally. Key parameters to be consider for design It makes us understand the differences of
different Pavement design approaches
For What Purpose Are Pavements Being Built And Where
Pavements is a structure which are intended to carry vehicular traffic
These pavements are provided atAir Ports Terminals Highways Terminals
Types of Pavements Un Surfaced
Earthen roads Gravel roads
Surfaced Bituminous Road Cement Concrete Road
Un Conventional Block Pavement
Flexible Pavements Earthen Roads Gravel Roads Bituminous Roads
Rigid Pavements Reinforced Concrete Plane Concrete Roads
Further Classification of Pavements
GRAVEL ROADS
Bituminous Pavement with Shoulder
Components of Flexible pavement
Load Dispersion in Flexible Pavements
Base
Black Topping
450
Sub Grade300mm
Sub Base
450
LOAD DISPERSION IN FLEXIBLE PAVEMENTS
Base
Black Topping
450
Sub Grade300mm
Sub Base
450
Base
Black Topping
450
Sub Grade300mm Sub Grade300mm
Sub Base
450450
LOAD DISPERSION IN FLEXIBLE PAVEMENTS
Rigid Pavement
Reinforced Cement Concrete Pavement Details
It is very challenging task compared to any other structure Complex loading
Complex behavior for various climatic condition
It is difficult in colleting information on performance modeling for various materials.
PAVEMENT DESIGN
DESIGN PARAMETER
Pavement Type No. Layers Layer Materials Joint Spacing for RCC
External Parameters
Sub grade Strength. Soil type, Strength, drainage Characteristics.
Traffic loading. No. Vehicles, type of vehicle, Speed, Load
Climatic Condition. Total Rainfall in year, Seasonal Distribution. Temperature (Max, Min, Daily Seasonal)
What Does Design means? For any given facility design is a process
of selecting appropriate values of parameters in such away that facility performs satisfactory.
Key words Design parameters Performance
PAVEMENT PERFORMANCE
Functional Performance Surface Characteristics eg. Pot holes,
Cracks, Rutting, Variation in longitudinal profile
“It is desirable to ensure that the surface characteristics are with in acceptable limits”
FATIGUE
Fatigue cracking
STRUCTURAL PERFORMANCE Mostly of the distress/ defects, Rutting are
caused by traffic loads
Some are also caused by non load associated factors Temperature, moisture, poor quality of
materials, inadequate maintenance. “ if the pavement shows load associated
distress it is considered to have failed structurally.”
Eg. Cracking, Rutting, Bleeding in Flexible Mud pumping, Blow up in CC Pavement
RUTTING
Rutting in wheel paths
Reflection cracking at PCC Joints
For What Pavement is to Be Design?
Functional Performance For road user FP is matter
Structural Performance For designer SP is matter
PERFORMANCE CRITERIA
Empirical Criteria Correlated to simple parameters like CBR,
Soil Index, Sub-grade. They do explain Load Vs Stress for different
materails. As result Empirical Methods cope up with
new materials Mechanistic Empirical Criteria
MECHANISTIC EMPIRICAL CRITERIA
Explain different phenomena (Stress, Strain Deflection) occurring in the pavement & the physical causes is explained using mathematical modeling.
Advantageous. Can Handel varying load condition, new materials. Contribution of different materials components is
better understood and thus optimal utilization is possible
More reliable and is called as rational.
Cannot cope with novel materials or pavement structures.
It is “like driving a car by only looking in the rear vision mirror, you could only be sure where you had been, but not where you were going”
Empirical Approach – Drawbacks
PERFORMANCE CRITERION IS HEART OF
PAVEMENT DESIGN
2. INPUT MATERIAL PROPERTIES CLIMATE INFORMATION
1. ASSUME PAVEMENT CONFIGURATION
3. CLIMATE MODELS HEAT TRANSFER MOISTURE EQUILIBRIUM INFILTRATION AND DRAINAGE
5. STRUCTURAL MODELS
4. INPUT TRAFFIC 6. PAVEMENT
RESPONSE
, , W
8. DISTRESS MODELS FATIGUE CRACKING, RUTTING, LOW TEMPERATURE CRACKING
7. DESIGN RELIABILITY
9. FINAL DESIGN
Figure 3.1: Calibrated mechanistic procedure for flexible pavement design.
SATISFACTORY
UN
SA
TIS
FA
CT
OR
Y
Design of Flexible Pavements
BUILDING BETTER ROADS-
BUILDING THE NATION