flexible pavement introduction notes

CE3010: Transportation Engineering I

Atul Narayan, S. P.

IIT Madras

August 13, 2015

Outline

First-day information

Introduction to Pavement Design

Introduction to Flexible Pavement Materials

Introduction to Flexible Pavement Structure

Distresses of Flexible Pavements

Class timings

▸ Classes will be in the A slots on Monday, Thursday and Friday

▸ Additional classes on Tuesday A slot if required.

▸ Please keep yourself available for all the A slots of thesemester. Do not commit yourself to any activity on Aslots.

Contact Information

▸ My office is at 238H.

▸ You can contact me at [email protected] [email protected]

▸ For any questions or discussion, just stop by my office. Wewill fix an appointment if we cannot meet then.

▸ Your contact information?

Course contents and schedule

▸ Course contents and schedule will be mailed to you.

Reference Textbooks for course

▸ Chakroborthy and A. Das, Principles of Transportation Engineering,Prentice-Hall of India, 2003.

▸ C. S. Papacostas and P. D. Prevedouros, TransportationEngineering and Planning, Third Edition, Prentice Hall, 2001.

▸ Khanna and Justo Highway Engineering, Ninth Edition, Nemchand,2011

▸ J. H. Banks, Introduction to Transportation Engineering, Mc-GrawHill Book Company, 2002.

▸ P. H. Wright and K. K. Dixon, Highway Engineering, John Wiley &Sons, Seventh Edition, 2004.

▸ C. J. Khisty and B. K. Lall, Transportation Engineering AnIntroduction, Prentice- Hall of India, 2002.

▸ Yang Huang, Pavement Analysis and Design, Pearson, 2004.

▸ Yoder, E.J., and Witczak, Principles of Pavement Design, 2nd ed.John Wiley and Sons, 1975.

▸ R. Horonjeff and F. X. McKelvy, Planning and Design of Airports,Mc-Graw Hill International Editions, 1993.

▸ Appropriate IS codes on pavement and geometric design.

References for Pavement Design and Analsysis section

TextbookYang H. Huang (2004). Pavement Analysis and Design, Pearson.

Additional ReferencesYoder and Witczak (1975), Principles of Pavement Design, JohnWiley and Sons.IRC 37 (2012) and IRC 58 (2002)

Grading Policy

Assignments: 20%Mid-Semester Examination: 30%End-Semester Examination: 50%

Assignments

▸ Students can work on assignments in groups of maximum two.

▸ One submission per group is enough.

▸ Due dates are as listed in the calendar.

Classroom Policy

▸ Any form of misconduct including cheating, plagiarism,fabrication, etc. will not be tolerated. Any studentcaught doing so will be assured maximum punishment.

▸ If the submission of two or more groups have the samecontent with same mistakes, both groups will be given zerosfor that problem.

▸ Attendance rules of IIT Madras will be strictly followed.

▸ Please turn off all cell phones before coming to class.

▸ Please be courteous to fellow students. Do not disrupt theclass by talking, using your cell phone, etc.

Note-taking

▸ Attend all classes and write down notes whenever it appearsimportant.

▸ Reading materials will be sent to you once the lecture topic isfinished.

▸ Please use the reference textbooks for background reading.

Outline






Primary learning objectives

To design flexible and rigid pavements using the Indian RoadsCongress design methods

To evaluate when it would be necessary to modify the designmethods

Design Process

Source:MEPDG Flexible Pavement Design Guide

Subordinate learning objectives

▸ To analyze the stress-strain distribution in pavements forgiven loading conditions.

▸ To estimate pavement distresses based on stresses and strainsin pavement structure.

▸ To explain the effect of mechanical properties on pavementbehavior and performance.

▸ To analyze the stresses and distresses caused by vehicleloading.

▸ To estimate the expected volume of traffic in design life

Levels of learning

▸ Remembering: Describing, identifying

▸ Understanding: Interpreting, explaining

▸ Applying: Executing, Implementing

▸ Analyzing: Comparing, Deconstructing

▸ Evaluating: Expringmenting, Judging

▸ Creating: Desiging, Constructing

Outline






Aggregates▸ Aggregates are granular materials such as river gravel, crushed

stone or sand.▸ It is the longest english word you can type with the left hand

(standard typing procedure)

(a) Sand (b) River Gravel (c) Granite

(d) Aggregate Mix

Bitumen

▸ Bitumen is a processed form of the residue obtained infractional distillation of petroleum.

▸ It is also known as asphalt or asphalt cement.

Bituminous concrete▸ Bituminous concrete is the compacted mixture of bitumen and

aggregates.▸ It is also known as bituminous mixture, asphalt concrete,

asphalt mixture and hot-mix asphalt (HMA).

(a) Loose Mix

(b) Compacted Concrete

Outline






Typical Pavement Structure

Surface Course

Binder Course

Base Course

Sub-base Course

Subgrade

Prime Coat

Tack Coat

Seal Coat

Seal Coat

▸ It is a thin layer of bitumen with or without crushedaggregates embedded in it.

▸ It is also known as chip seal or bituminous surface treatment.

▸ It is mainly useful in colder climates.32

▸ It is used for:

▸ Waterproofing the surface▸ Improving skid resistance▸ Improving surface finish and sealing surface cracks

Surface Course

▸ It is the top-most layer in an asphalt concrete pavement.

▸ The layer is usually made with dense-graded HMA.

▸ Open graded HMA with adequate porosity may also be used.

▸ It is also known as wearing course.

▸ Purpose:

▸ To provide resistance to frictional stresses caused bymoving vehicles

▸ To provide skid resistance▸ To waterproof the pavement structure

▸ It is meant to wear with repetitions of vehicle loading.

▸ It can be periodically rehabilitated during the design period.

Binder Course

▸ It is the layer below the surface course.

▸ Purpose:

▸ To distribute the stresses due to vehicle loading over alarge area

▸ To reduce the stresses and strains in the underlying layers▸ To reduce the cost of the pavement

▸ The binder course consists of HMA with larger aggregates andsmaller binder content.

Tack Coat and Prime Coat

▸ Both prime coat and tack coat are thin layers of bitumen.

▸ Hot bitumen, bituminous emulsion or cut-back asphalt issprayed on the surface for the coats.

▸ Their purpose is to ensure bond between pavement layers.

▸ Difference between tack coat and prime coat

▸ Since tack coat is between two HMA layers, it need notpenetrate either layers.

▸ Prime coat should penetrate the underlying layer to beeffective

Base and Sub-base Course

▸ Additional layers over the subgrade to reduce stresses on thesubgrade

▸ Both layers are similar. The subbase is usually constructedusing cheap and poorer quality material compared to the baselayer.

▸ Types of base layers:

▸ Untreated aggregate base▸ Asphalt treated base▸ Reclaimed asphalt pavement▸ Chemically treated base (with cement, lime, etc.)▸ Crushed slag

Subgrade

▸ Natural geological formation in the construction site overwhich the pavement is constructed.

▸ Sometimes the top of the subgrade is prepared throughcompaction.

Outline






Types of Distresses of Flexible Pavements

▸ Alligator cracking

▸ Longitudinal and transverse Cracking,

▸ Rutting

▸ Bleeding

▸ Joint reflection cracking

Alligator Cracking

▸ It is caused by fatigue

▸ “Bottom-up” mechanism of crack propogation

Source: PavementInteractive.org

Longitudinal cracking

▸ Possible causes include “top-down” fatigue and joint location


Transverse cracking▸ Caused by contraction of bituminous layers at low

temperatures


Rutting

▸ Permanent deformation along wheel path

▸ Rutting may be accompanied by swelling


Bleeding

▸ Bleeding is bitumen being squeezed out of the mixture

▸ Caused by poor mix design - lack of air voids


Reflection Cracking

▸ Occurs when HMA is overlayed on top of an existing PCCpavement


flexible pavement introduction notes

Documents

pavement designintroduction

pavement analysis

principles of pavement

design of airports

geometric design

justo highway engineering

prentice hall

additional classes