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KOLEJ UNIVERSITI TEKNOLOGI TUN HUSSEIN ONN
BORANG PENGESAHAN STATUS TESIS
JUDUL: MECHANISTIC EVALUATION OF ASPHALTIC PAVEMENT BASED
ON BENKELMAN BEAM DEFLECTION
SESI PEl\"GAJIAl\" : 2003/2004
ROSNA'VATI BTE BUHARI
Saya
(HURUF BESAR)
mengaku membenarkan tesis (PS:M / Sm:iana; Doktor Falsafah )* ini disil11pan di Perpustakaan dengan syarat-syarat kegunaan seperti berihlt:
I. Tesis adalah hakmilik Kolej Uniyersiti Teknologi Tun Hussein Onn 2. Perpustakaan dibenarkan mel11buat salinan untuktujuan pengajian sahaja
3. Perpustakaan dibenarkan l11el11buat salin an tesis ini sebagai bahan pertukaran antara institusi pengajian tinggi.
4. ** Sila tandakan (,J)
D
D
D
SUUT lMengandungi maklul11at yang berdm:jah keselal11atan atau kepentingan JVlalaysia sepelti yang te!111U1.."tub di dalam AKT A RAHSIA RASMI 1972)
TERHAD (l\'Iengandungi maklumat TERHAD yang telah ditennlkan oleh organisasi/badan di mana penyelidikan dUalankan .
TIDAK TERHAD
Disahkan Oleh
(TANDATANGAN PENULIS) (T ANDAT ANGAN PENYELIA)
Alamat Tetap:
KG. PARIT BINGAN ,MK8,86400 PARIT RAJA. BATU PAHAT, JOHOR
DR. KEMAS AHMAD ZAMHARI
Nama Penyelia
Tarikh: It) APRIL 2004 Tarikh: 10 APRIL 2004
CATATAN: *
+
Poton g yang tidak berkenaan
Jika tesis ini SUUT atau TERHAD. sila lampirkan surat daripada pihak berkuasaiorganisasi berkenaan dengan meuyatnkan sekali sebab dan dikelaskan sebagai SULIT atau TERHAD
" I have read this proposal and it is my professional view that it fulfill the requirement of
Masters Degree in Civil Engineering in KUiTTHO ".
Signature
Name of Supervisor
Date
DR. KEMAS AHMAD ZAMHARI
MECHANISTIC EVALUATION OF ASPHALTIC PAVEMENT BASED
ON BENKELMAN BEAM DEFLECTION
ROSNA WA TI BTE BUHARI
This Project Report is present to fulfill apart from award condition
for Masters Degree of Civil Engineering.
Faculty Of Civil Engineering
Kolej Univesiti Teknologi Tun Hussein Onn
111
Especially To My Lovely
Father, Mother, Husband, Sister and Brother ... .
IV
ACKNOWLEDGEMENT
I am very grateful to those who have helped me in preparing this Thesis.
Firstly I want to express my gratitude to Dr Kemas Ahmad Zamhari as a Supervisor, for his
interest and simulating discussion and response during development of this project. I am also
grateful for his helpful comments, suggestion and criticisms.
I am also thankful to the instructors in helping the preparation of the instruments and
degree students for their assistance during field test. My sincere thanks also are extended to
the Department of Civil Engineering of KUiTTHO for the systematic management and
labatan Kerja Raya for the data given.
Finally, I am grateful with deep appreciation for the continued support, patience and
ABSTRACT
When empirical evaluation of pavement layers overlay was practiced, the
selection of layer thickness and properties was made without benefit of mechanistic
analysis. The application of elastic theory to the design of overlays on existing
pavement requires that the modulus of elasticity be assigned to the existing
structural system. Elastic moduli are determent from pavement surface deflection.
Benkelman Beam conducted under WASHO method to collect data in order to find
deflection condition of existing pavement. Based on present study, graphical
method which deflection dependent was developed to determine parameters of
elasticity. The objective of the present study are to find out the elastic/stiffness
modulus parameters for the layer of asphaltic pavement by using Benkelman beam
deflection and compare the remaining life of the existing pavement and to propose
overlay thickness based on conventional and mechanistic analysis approach. As
the conclusion, from the analysis I have determined that the elastic modulus can
obtained by interpretation of Benkelman Beam deflection test also have proved
that the mechanistic analysis is the available evaluation for existing pavement.
VI
ABSTRAK
Kaedah penilaian empirical merupakan teknik untuk menentukan penindihan
semula lapisan permukaan turapan
yang dipraktik selama ini. Kaedah ini tidak
menggunakan analisis mekanistik dalam pemilihan ketebalan lapisan. Merekabentuk
lapisan penindihan semula dengan aplikasi keanjalan turapan memerlukan nilai elastic
modulus struktur turapan asal. Nilai elastic modulus ditentukan daripada lenturan
permukaan turapan. Ujian Benkelman Beam dijalankan dengan berpandukan kaedah
W ASHO bagi mendapatkan keadaan lenturan turapan yang asal. Nilai-nilai elastic
modulus bagi setiap lapisan turapan diperolehi daripada graf yang telah dibangunkan
dengan merujuk kepada nilai lenturan turapan yang telah dicerap serta bantuan
persamaan -persamaan yang telah dinyatakan pada kajian-kajian terdahulu. Kajian ini
adalah untuk mencapai objektif-objektif yang telah ditetapkan iaitu mendapatkan nilai
elastic modulus bagi lapisan turapan
asphaltdengan menggunakan nilai lenturan daripada
ujian Benkelman Beam dan membuat perbandingan nilai jangka hayat turapan asal yang
diperolehi dengan menggunakan kaedah konvensional dan mekanistik. Disamping itu
kajian juga dijalankan untuk mencadangkan ketebalan lapisan yang sesuai untuk
jangkahayat turapan dengan menggunakan kaedah konvensional dan analisis mekanistik.
Kesimpulannya daripada hasil analisis yang telah dijalankan, nilai elastic modulus boleh
diperolehi daripada ujian lenturan Benkelman beam dan analisis secara mekanistik
Vll
CONTENT
CHAPTER DISCRIPTION PAGE
TITLE SHEET I
DECLARATION SHEET 11
DEDICATION SHEET III
ACKNOWLEDGEMENT IV
ABSTRACT V
CONTENT VI
LIST OF TABLES x
LIST OF FIGURE Xl
SHORTFORM LIST XlI
LIST OF APPENDICES Xlll
CHAPTER I INTRODUCTION
1.1 Introduction 1
1.2 Problem Statement 2
1.3 Research Objectives 2
1.4 Scope Of The Proj ect 3
1.5 Finding 3
1.6 Performance Plan 4
CHAPTER II LITERATURE REVIEW
2.1 Pavement Structure 5
2.2 Benkelman Beam 6
2.3 Pavement type and Wheel Load 7
2.4 2.5 2.6 2.7
CHAPTER III
CHAPTER IV
2.3.2 Tire Pressure, Contact Pressure and
Tire Imprint
2.3.3 Distress, structural and functional
Flexible-Mechanistic Empirical Method
2.4.1 Deflection
2.4.2 Theory Of Elasticity
2.4.3 Subgrade Failure Criterion
2.4.4 Asphalt Fatigue Life
Stress in Flexible Pavement
2.5.1 Layered System Concept
2.5.2 Two Layer System
The Asphalt Institute Method
Mechanical Behaviour of Asphaltic Mechanistic
to Describe response
RESEARCH METHODOLOGY
3.1 Preparation Of Equipment
3.2 Test Location
3.3 Point condition
3.4 Test Procedure
3.5 Data Analysis
ANALYSIS
4.1 Introduction
4.2 Determinition Of Stiffness Modulus
4.3 Maximum Rebound Deflection Curve
4.4 Differential Deflection Curve
4.5 Elastic modulus parameters
IX
4.6
Comparison remaining life of the existing35
pavement using conventional and mechanistic
analysis
4.7
Comparison propose overlay for further38
design life.
4.8
Remaining life After Overlay Performance39
CHAPTER V
CONCLUSION AND RECOMMENDATION5.1
To find out the elastic modulus parametersbased on surface deflection by using
Benkelman beam test.
40
5.2
To compare remaining life at the existingpavement using conventional and mechanistic
analysis using Benkelman Beam Deflection.
41
5.3
To compare propose overlay for further layerDesign
41
5.4
Recommendation42
5.5
Recommendation for further research,43
BIBLIOGRAFI 44
TABLE NO.
2.1 4.1 4.2 4.3 4.4 4.5 4.6TABLE LIST
TITLECritical Analysis Locations in a Pavement Structure
Elastic modulus parameters:
Remaining life of the existing pavement using
conventional analysis:
Remaining life of the existing pavement using
mechanistic analysis
4 Year design life for Conventional Method
Comparison propose overlay for further
layer design life.
Remaining life after overlay performance
Xl
FIGURE LIST
FIGURE NO.
TITLE
PAGE
1.1 Methodology Of The Study 4
2.1 Benkelman Beam Deflection Test 6
2.2 Critical Analysis location in a pavement structure 10
2.3 Deflection 12
2.4 Multilayered elastic system 17
2.5 Two-layers structure of of pavement 20
2.6 Material Model implemented in VEROAD 23
3.1 Position of Benkelman Beam for W ASHO Method. 26
4.1 Elastic modulus Curve 29
4.2 Maximum Rebound Deflection for Each Station. 30
4.3 Differential Deflection for Each Station. 31
4.3 Elastic Modulus of layer 1 33
AASHTO
NDT
RRD
ESAL
xu
SHORTFORM LIST
Association of State Highway and Transport Officials.
Non- Destructive Test
Representative Rebound Deflection
xiii
LIST OF APPENDICES
APPENDICS TITLE PAGE
APPENDICS A Full Calculation of El and E2 46
APPENDICS B Asphalt Institute Method 48
APPENDICS C Calculation for Propose overlay for further
layer design life 49
APPENDICS D Influences Of Deflection On Number Of
18-kip ESAL Application To Failure Curve 50
APPENDICS E Calculation of Remaining life at the existing
pavement using mechanistic analysis: 51
APPENDICS F Calculation of 4 year remaining life using
Conventional method 53
APPENDICS G Overlay Thickness Design Chart 54
APPENDICS H Nomograph For Determining The Stiffness
Modulus of Bitumen 55
APPENDICS I Nomograph For Predicting The Stiffness
CHAPTER I
INTRODUCTION
1.1 INTRODUCTION
In year of 1980s there has been increasing interest in the development of rational
design procedures for highway pavement. For example the Association of State
Highway and Transportation Officials (AASHTO) Guide for Design of Pavement
Structure (1986), and AUSTROAD, though still based on the empirical concept which
had previously experience been considered. Design the overlay to improve existing
pavement has become the major activity of almost highway agencies as a result of
increase awareness of the importance of maintaining the public infrastructure, together
a relative of scarcity of fund for new construction.
Although, in recent years attention has turned to the used offundamental
analyses of pavement response to load, including the evaluation of pavement
performance. This last method of pavement design evaluation is usually referred to as a
mechanistic evaluation procedures. The best mechanistic evaluation procedure use, to
find the pavement responses such as strain, stress and deflection at the critical point in
the pavement structure. The pavement response then relate with the empirical condition
on the field. Mechanistic evaluation procedure are perceived to have several advantage
over methods based on judgment or strictly empirical relationships.
Field testing method such as non-destructive testing (NDT) can provide
analyses. Around 1960-1970 Benkelman Beam is the most popular method for the
deflection measurement then interpretation it using empirical method. Falling Weight
deflection recently take over which is more simple.
1.2
PROBLEM STATEMENT
In empirical evaluation of overlay, the selection of layer thicknesses and
properties was made without benefit of mechanistic analysis. So that the mechanistic
evaluation method which considered layer elasticity need to improve the solution.
2
So that this study will focus on investigating of mechanistic variable such as
elastic modulus to improve the evaluation method also the application of elastic theory
to design of overlays on existing pavement by interpretation Benkelman Beam test
data. Falling Weight Deflection is an accurate method to find deflection but it needs
more investment compare Benkelman Beam. Benkelman Beam also use to find
deflection but until nowadays the interpretation of deflection data finding still using
empirical analysis.
1.3
RESEARCH OBJECTIVES
The objective of this study are:
1. To find out the elastic/stiffness modulus parameters based on surface
2. To compare remaining life at the existing pavement using conventional and
mechanistic analysis using Benkelman Beam Deflection.
3. To compare propose overlay for further layer design
1.4 SCOPE OF THE PROJECT
The scope of the project are:
This study is focused on Benkelman Beam method in order to find the
deflection and mechanistic variable/parameter of existing pavement.
Pavement structure: flexible pavement with specific to linear elastic
3
The parameter used are temperature, traffic volume and pavement structure.
1.5 EXPECTED RESULTS
1. Elastic modulus parameters
2. Comparison remaining life at the existing pavement using conventional and
mechanistic analysis using Benkelman Beam Deflection.
1.6 PERFORMANCE PLAN
Scope Determ i nati on
Benkelman Beam Deflection Test Mechanistic analysis Research Title &
Method Finding
1
Literature Review
,
EqUipment and site Preparation
1
Test performance,
Data Collection,
Data Analysis,
ConclusIonFigure 1.1: Methodology Of The Study
4
W ASHO Method
[image:20.595.103.526.138.716.2]CHAPTER II
LITERA TURE REVIEW
2.1 PAVEMENT STRUCTURE
Flexible pavement structure consists of the surface course and the underlying
base and subbase courses. Each layer received the load from the above layer, spread
the out the passes on these loads to the next layer.
5
Surface course is the top layer and the layer that comes in contact with traffic. It
may be composed of one or several different sublayer. Base course plays a prominent
role in the support and dispersion of the traffic loads and surface course forms an
I
impermeable and flexible lining of high elastic modulus. Subbase course is the layers of
the specified material build up to the required designed thickness immediately over
laying the subgrade. It serve as an aid to disperse the load from the base course before
transmitting it to the subgrade. Subgrade is the upper most part of the soil, natural or
2.2 BENKELMAN BEAM
The Benkelman Beam Test is one of the Non Destructive Field Test which is
,
able to record the pavement surface deflection occurring under actual truck trafficloading at different discrete points along the pavement. The results of these
measurements can be used for analyzing the bearing capacity of an existing pavement
structure and to design the possibly required overlay.
[image:22.595.104.498.444.588.2]6
Figure 2.1 shows the beam developed by A. C. Benkelman in connection with
the WASHO Road Test. Mr. Benkelman devised the scheme whereby deflection at the
pavement surface is measured by means of a long beam; the deflections are recorded by
means ofa dial placed at one end of the beam. The Benkelman Beam is used with a
loaded truck -typically 80kN (18000 Ib) on a single axle with dual tyre inflated to 480
to 550 kPa (70-80 psi) .
/ : Deflections ore
J
.
measured by this probeA
.. 90.0"
sF
Reference~ / paints
"
!'~I
!fo
1
C E
>\-c'12.75""!< 35.75"
* .
-20.75-1
... _ _ ... _ ... - 159.25" ... -... . .. - _ ... -.... _._-_ ... >jBenkelman beam.
Figure 2.1 : Benkelman Beam Deflection Test
In Figure 2.1 the deflection at point A is measured by means of the deflection
dial at point F. The deflections are measured relative to the reference points at C and E.
The Benkelman beam principle has been mechanized so that a large number of readings
can be obtained by continuous reading of deflection under a loaded axle.
;
H.
I,'
The Benkelman Beam is low cost but is so slow, labor intensive and does not
provide a deflection basin.
2.3 Pavement type and Wheel Load
2.3.1 Type Of Pavement
7
The flexible pavement may consist of a relatively thin wearing surface built over
a base course and subbase course, and they rest upon the compacted subgrade. In
contrast, rigid pavements are made up of Portland cement concrete and mayor may not
have a base course between the pavement and subgrade.
The essential difference between the two types of pavements, is the manner in
which they distribute the load over the subgrade. The rigid pavement, because of its
rigidity and high modulus of elasticity, tends to distribute the load over a relatively wide
area of soil; thus, a major portion of the structural capacity is supplied by the slab itself.
The major factor considered in the design of rigid pavements is the structural strength of
the concrete. For this reason, minor variations in subgrade strength have little influence
upon the structural capacity of the pavement.
It should be noted at this point that the classical definition of flexible pavements
includes primarily those pavements that have an asphalt concrete surface. The load
carrying capacity of a truly flexible pavement is brought about by the load-distributing
8
with the highest-quality materials at or near the surface. Hence, the strength of a flexible
pavement is the result of building up thick layers and, thereby, distributing the load over
the subgrade, rather than by the bending action of the slab. The thickness design of the
pavement is influenced by the strength of the subgrade. If an asphalt pavement has high
stiffness, it may behave essentially as a rigid pavement and fatigue of the surface or of
any pavement component may become critical.
2.3.2 Tire Pressures, Contact Pressure and Tire Imprint
If the effect of the tyre wall is ignored, the contact pressure between the tyre and
pavement must be equal to the tyre pressure. For low-pressure tyres, however, contact
pressures under the tyre wall may be greater than at the center of the tyre. For
high-pressure tyres the reverse is true. For most problems, however, the assumption is made
that contact pressures are uniform over the imprint area.
In the majority of the problems, circular tyre imprint are assumed. Hence the
standard wheel loading as two circular vertical load (total) load 40kN uniform
vertical stress distribution in the range of 550-700 kPa center to center spacing of the
load 330 mm and radius of each load R=,f(Llnp) where L = load on one tire of the axle
