NPTEL Course on Analysis and Design of Bituminous Pavements

Introduction

• Welcome to the NPTEL course on analysis and design of bituminous pavements.
• This course is offered by the same team that presented the earlier course on mechanical characterization of bituminous materials.

Course References

• Primary Text: Pavement Analysis and Design by Professor Huang (classic reference)
• Guidelines: IRC 37: 2008 (latest guidelines for pavement design)

Terminology

• Throughout the course, the terms "bituminous pavement" and "concrete pavement" will be used instead of "flexible pavement" or "rigid pavement".
• Stress analysis procedures differ between bituminous and concrete pavements.
  • Bituminous Pavement: Uses layered linear elastic theories.
  • Concrete Pavement: Uses models like the Winkler Foundation.

Course Outline

1. Cross Sections and Failure: Understanding different pavement cross sections and their failure mechanisms.
2. Overview of Design Process: Steps involved in pavement design.
3. Stress Analysis: Analyzing stresses and strains for design purposes.

Pavement Cross Sections

• Standard Cross Section:

  • Consists of multiple layers: subgrade, compacted subgrade, sub-base, base, binder, and surface.
  • Bituminous layers: binder and surface course.
  • Granular materials: sub-base, base.

• Types of Pavements:

  • Deep Strength Pavement: Thicker asphalt layers to support heavy loads.
  • Full Depth Pavement: Made entirely of asphalt layers.
  • Inverted Cross Sections: Higher modulus values in lower layers.

IRC 37 Cross Section

• Components:
  • Subgrade, base, and two bituminous layers.
  • Emphasis on fatigue resistance and vertical strain limits.
• Design aspects include:
  • Fatigue resistance layer.
  • Rut resistance layer.

Pavement Failures

• Common types of pavement failures:
  • Rutting: Wheel path depressions due to traffic loads.
  • Fatigue Damage: Cracking caused by repeated loading.
  • Low Temperature Cracking: Cracking from temperature fluctuations.
  • Moisture Induced Damage: Damage due to water infiltration.
• Two categories of cracking:
  • Load-induced cracking.
  • Non-load induced cracking.

Design Process Overview

1. Input Factors:

   • Traffic: Volume count and axle loads.
   • Foundation: Load carrying capacity of existing soil.
   • Climate: Variability across different regions affects material properties.
   • Material Properties: Type of bitumen and aggregate used.

2. Analysis:

   • Trial design strategy based on previous experience and empirical data.
   • Use pavement analysis models to compute stresses and strains.
   • Distress prediction models to estimate pavement life.

3. Strategy Selection:

   • Assess performance against design criteria and adjust as needed.
   • Iterative process to ensure the design meets expected traffic loads.

Conclusion

• The course will explore various pavement design methodologies, failure mechanisms, and stress analysis techniques.
• Future lectures will delve into specific design concepts and pavement analysis models.