MOHD KHAIRUL IDHAM BIN MOHD SATAR
REPEATABILITY OF RECLAIMED ASPHALT PAVEMENT
MOHD KHAIRUL IDHAM BIN MOHD SATAR
A thesis submitted in fulfilment of the requirements for the award of the degree of
Doctor of Philosophy (Civil Engineering)
Faculty of Civil Engineering Universiti Teknologi Malaysia
I would like to acknowledge the contributions and understanding of my main supervisor, Professor Dr. Mohd Rosli Hainin. Without his continuous academic guidance, encouragement, criticism and understanding, this thesis would not have been in this form. I wish to express my sincere appreciation to my co-supervisor, Dr. Haryati Yaacob, she has immensely contributed to the success of this work. Special thanks also to all my supervisors who spend valuable time in reading, reviewing and correcting the thesis. I am especially glad for their patience, tolerance and giving me ample freedom in conducting my research with full confidence. Their professionalism and dedication will certainly be a good example for me in my future undertakings.
Getting through this journey required more than academic support, and I have indeed many people to thank. Thanks for listening and for the way you tolerate me in the past few years. I would also like to thank my lab mates (Dr. Chang, Dr. Sola, Hanif, Kak Sya, Kak Azah, Doya, Eun, Naqi, Ibrahim, Yaya and Ijol) who have been working hard with me in the laboratory. The presence of you guys has actually created a happening environment in the working place. The continuous and fruitful discussions among us are especially beneficial and helpful in solving research related problems. It is an honour for me to thank the technicians (Mr. Azri, Mr. Azman, Mr.Sahak, and Mr. Suhaimi) in Transportation laboratory for immeasurable assistance rendered. Also, a special thanks to Ministry of Education for sponsoring this study through the SLAI Scholarship.
Last but not least, none of this could have happened without my family. To my wife, parents, brothers and sisters, I thank you so much for your understanding and support in my PhD journey. Certainly, there have been some challenges all the while.
Usage of fresh bitumen and aggregates in pavement construction and rehabilitation can be minimised by utilising reclaimed asphalt pavement (RAP). RAP is a waste material generated from old or damaged pavement surface. Although it has been practiced since 1970s and several suggestions on the usage of RAP in the new mixture have been introduced, there is a limited number of research has been found, discussing on the issue of second recycling of RAP (R2AP). Pavement made with RAP will reach the end of service life and there is a need to recycle again. This study focused on investigating the performance of mixtures incorporating RAP and R2AP. It was carried out in three phases. In the first phase, three ageing procedures consisted of eight laboratory ageing methods were conducted to select suitable method that produced most severe ageing effect. Ageing methods used were combination of rolling thin film oven (RTFO), pressure aging vessel (PAV), short term oven ageing (STOA) and long term oven ageing (LTOA). In the second phase, mixture tests were conducted to evaluate the performance of asphaltic concrete with 14 mm nominal maximum aggregate size (AC 14) mixture incorporating RAP and R2AP. Final phase involved the physical, rheological and chemical property tests of aged bitumen. Penetration, softening point, viscosity, dynamic shear, elemental analysis and Fourier transform infrared (FTIR) tests were performed on the bitumen which were extracted from the selected mixtures. Three mixtures consisted of 20, 40 and 60% RAP were evaluated in the first cycle and four mixtures consisted of 20, 40, 60 and 80% R2AP were evaluated in the second cycle. Results show that seven days of LTOA is the most suitable ageing method for AC 14. Mixture consisted of 40% RAP shows a better performance when it was mixed with 80-100 PEN (B1) bitumen whereas mixture with 60% RAP performed better with 60-70 PEN (B2) bitumen compared to other mixtures. After seven days of LTOA, mixture consisted of 40% R2AP mixed with B1 and 40% R2AP mixed with B2 show better performance compared to other recycled mixtures. Physical, rheological and chemical analyses of the extracted bitumen also indicated that there were acceptable differences between first and second cycle. Hence, it is proven that R2AP is suitable to be used as an alternative material to minimise the usage of fresh bitumen and aggregates. Based on regression model of aged bitumen properties, it can be concluded that RAP was suitable to be recycled up to second time.
Penggunaan bitumen dan agregat segar dalam pembinaan dan pemulihan turapan dapat diminimumkan dengan penggunaan turapan tebus guna (RAP). RAP adalah bahan buangan yang terhasil daripada permukaan turapan lama atau rosak. Walaupun ia telah dipraktikkan sejak 1970an dan pelbagai cadangan berkenaan penggunaan RAP di dalam campuran baru telah diperkenalkan, kajian membincangkan tentang isu kitar semula RAP kali kedua (R2AP) yang ditemui adalah terhad. Turapan yang diperbuat daripada RAP akan mencapai penghujung jangka hayat perkhidmatannya dan perlu dikitar semula sekali lagi. Kajian ini memberi tumpuan untuk menyiasat prestasi campuran yang mengandungi RAP dan R2AP. Ianya dijalankan dalam tiga fasa. Dalam fasa pertama, tiga prosedur penuaan yang terdiri daripada lapan kaedah penuaan di makmal telah dilaksanakan untuk memilih prosedur yang memberi kesan penuaan yang paling ketara. Kaedah penuaan yang digunakan adalah gabungan antara rolling thin film oven (RTFO), pressure ageing vessel (PAV), penuaan ketuhar jangka pendek (STOA) dan penuaan ketuhar jangka panjang (LTOA). Dalam fasa kedua, ujian campuran dilaksanakan untuk menilai prestasi campuran konkrit berasfalt dengan 14 mm saiz nominal maksimum agregat (AC 14) yang mengandungi RAP dan R2AP. Fasa terakhir melibatkan ujian ciri-ciri fizikal, reologikal dan kimia aged bitumen. Ujian penusukan, titik lembut, kelikatan, dynamic shear, analisis elemen dan Fourier transform infrared (FTIR) telah dilaksanakan ke atas bitumen yang diesktrak daripada campuran terpilih. Tiga campuran terdiri daripada 20, 40 dan 60% RAP dinilai dalam kitaran pertama dan empat campuran terdiri daripada 20, 40, 60, 80% R2AP telah dinilai dalam kitaran kedua. Keputusan menunjukkan tujuh hari LTOA adalah kaedah penuaan yang paling sesuai untuk AC 14. Campuran mengandungi 40% RAP menunjukkan prestasi yang lebih baik jika dicampur dengan bitumen 80-100 PEN (B1) sementara campuran dengan 60% RAP menunjukkan prestasi yang lebih baik jika dicampur dengan bitumen 60-70 PEN (B2) berbanding campuran lain. Selepas tujuh hari LTOA, campuran yang mengandungi 40% R2AP dicampur dengan B1 dan 40% R2AP dicampur dengan B2 telah menunjukkan prestasi yang lebih baik berbanding campuran lain. Analisis fizikal, reologikal dan kimia daripada bitumen yang diekstrak juga menunjukkan terdapat perbezaan yang boleh diterima antara kitaran pertama dan kedua. Oleh itu, ini membuktikan bahawa R2AP sesuai untuk digunakan sebagai bahan alternatif bagi meminimumkan penggunaan bitumen dan agregat segar. Daripada model regrasi ciri-ciri aged bitumen, dapat disimpulkan bahawa RAP sesuai dikitar semula untuk kali kedua.
TABLE OF CONTENT
CHAPTER TITLE PAGE
TABLE OF CONTENTS vii
LIST OF TABLES xii
LIST OF FIGURES xvi
LIST OF ABBREVIATIONS xxi
LIST OF APPENDICES xxiii
1 INTRODUCTION 1
1.1 Background of the Study 1
1.2 Statement of the Problem 3
1.3 Objective of the Study 4
1.4 Scope of the Study 5
1.5 Thesis Structure 5
2 LITERATURE REVIEW 7
2.1 Introduction 7
2.2 Pavement Ageing 7
2.2.1 Laboratory Ageing 10
184.108.40.206 Binder Ageing Method 13
2.2.2 Comparison between Ageing Methods 17
2.3 Pavement Recycling 19
2.4 Reclaimed Asphalt Pavement (RAP) 20
2.4.1 Mix Design of Recycled Mixture Incorporating
220.127.116.11 Determination of RAP Content in the Recycled Mixture
18.104.22.168 Estimation of RAP Specific Gravity 23 22.214.171.124 Preheating of RAP Materials 23 126.96.36.199 Calculation of Fresh Binder Content
24 188.8.131.52 Selection of Fresh Binder Grade 25 2.4.2 Performance of Recycled Mixture
Incorporating RAP 26
184.108.40.206 Strength and Stiffness Behaviour 26 220.127.116.11 Rutting Resistance Behaviour 29 18.104.22.168 Fatigue Resistance Behaviour 29
2.4.3 Properties of Aged Binder 34
22.214.171.124 Physical Properties 35 126.96.36.199 Rheological Properties 36 188.8.131.52 Chemical Properties 38 2.5 Summary 41 3 METHODOLOGY 43 3.1 Introduction 43 3.2 Materials 44
3.2.1 Binder and Aggregates 44
3.2.2 Reclaimed Asphalt Pavement (RAP) 45 3.3 Phase I: Selection of Appropriate Laboratory Ageing
3.3.1 Rolling Thin Film Oven (RTFO) 51 3.3.2 Pressurized Ageing Vessel (PAV) 52 3.3.3 Short Term Oven Ageing (STOA) 53
3.3.4 Long Term Oven Ageing (LTOA) 53
3.3.5 Mixture Performance Test 54
184.108.40.206 Marshall Stability and Flow Test 55 220.127.116.11 Theoretical Maximum Density (TMD) 56 18.104.22.168 Indirect Tensile Strength Test 57 22.214.171.124 Indirect Tensile Resilient Modulus
3.3.6 Grid Analysis Method 60
3.4 Phase II: Evaluation on the Performance of Bituminous Mixture Incorporating RAP and R2AP
3.4.1 Mixture Performance Test 66
126.96.36.199 Dynamic Creep Test 67
188.8.131.52 Four Point Beam Fatigue 68 3.5 Phase III: Evaluation on the Properties of Recovered
70 3.5.1 Extraction of Bituminous Mixture 71 3.5.2 Distillation of Extracted Solution 73
3.5.3 Binder Property Tests 74
184.108.40.206 Penetration Test 75
220.127.116.11 Softening Point Test 76
18.104.22.168 Viscosity Test 76
22.214.171.124 Dynamic Shear Rheometer (DSR) 77
126.96.36.199 Elemental Analysis 79
188.8.131.52 Fourier Transform Infrared (FTIR)
Spectroscopy Test 79
3.6 Summary 81
4 RESULTS AND DISCUSSIONS 82
4.1 Introduction 82
4.2 Phase I: Determination of Suitable Ageing Procedure 82 4.2.1 Tensile Strength of the Aged Mixtures 84 4.2.2 Resilient Modulus of the Aged Mixtures 85
4.3 Phase II: Performance of Recycled Mixture Incorporating RAP and R2AP
4.3.1 First Cycle (Incorporating RAP) 90 184.108.40.206 Marshall Stability and Flow Test 90 220.127.116.11 Tensile Strength Test 90 18.104.22.168 Resilient Modulus Test 93
22.214.171.124 Dynamic Creep Test 97
126.96.36.199 Grid Analysis 98
4.3.2 Second Cycle (Using R2AP) 100 188.8.131.52 Marshall Stability and Flow Test 101 184.108.40.206 Tensile Strength Test 101 220.127.116.11 Resilient Modulus Test 103
18.104.22.168 Dynamic Creep Test 107
22.214.171.124 Grid Analysis 108
4.3.3 Discussion on Overall Performance of
Recycled Mixtures 110
4.3.4 Beam Fatigue Test 115
4.4 Phase III: Evaluation on the Properties of the Aged
Bitumen Extracted from Recycled Mixture 117
4.4.1 Physical Property Tests 117
4.4.2 Rheological Property Test 120
4.4.3 Chemical Property Tests 124
126.96.36.199 Elemental Analysis 125
188.8.131.52 Fourier Transform Infrared Test 127 4.4.4 Discussion on the Properties of Extracted
4.5 Summary 133
5 CONCLUSIONS AND RECOMMENDATIONS 135
5.1 Introduction 135
5.1.1 Binder and Mixture Ageing of Bituminous Mixture
5.1.2 Performance of Recycled Mixture Incorporating RAP and R2AP
5.1.3 Properties of the Aged Bitumen Extracted from Recycled Mixture
5.1.4 Recyclability of Bituminous Mixture 137 5.2 Recommendations for Future Research 137
LIST OF TABLES
TABLE NO. TITLE PAGE
2.1 Binder ageing methods. (Airey, 2003) 11
2.2 Mixture ageing methods (Airey, 2003) 12
2.3 Time of ageing with desired and obtained penetration
(Haneash, 2013) 17
2.4 Recommended binder grade based on RAP content
(AASHTO M323) 25
2.5 Viscosity readings (in Pa.s) at different rate of ageing at
135 °C. (Lee et al., 2008) 35
2.6 Failure temperature (ᵒC) at different rate of ageing. (Lee
et al., 2008) 37
2.7 Chemical composition of bitumen from different
sources. (Brown et al., 2009) 38
2.8 Recommended usage of RAP and R2AP 42
3.1 The bitumen properties 44
3.2 The physical and mechanical properties of granite
3.3 Summary of recovered RAP bitumen properties 45
3.4 Optimum bitumen content 49
3.5 Mixing and compaction temperature 50
3.7 List of test and corresponding number of samples in
Phase I 55
3.8 Marshall mixture specification for wearing course
(JabatanKerja Raya, 2008) 57
3.9 Optimum bitumen content 61
3.10 Mixing and compacting temperature 61
3.11 Designation of mixtures in Phase II (Cycle 1) 62
3.12 Fresh bitumen content of RAP mixture 62
3.13 Designation of mixtures in Phase II (Cycle 2) 65
3.14 Fresh bitumen content for R2AP mixture 66
3.15 List of test and corresponding number of samples in
Phase II 62
3.16 List of test and corresponding number of samples in
Phase III 75
4.1 AC 10 requirements at OBC 83
4.2 AC 14 requirements at OBC 83
4.3 AC 28 requirements at OBC 83
4.4 ANOVA test results for ITS of aged AC 10 mixture 85 4.5 ANOVA test results for ITS of aged AC 14 mixture 85 4.6 ANOVA test results for ITS of aged AC 28 mixture 85 4.7 ANOVA test results for resilient modulus of aged AC
10 mixture 86
4.8 ANOVA test results for resilient modulus of aged AC
14 mixture 86
4.9 ANOVA test results for resilient modulus of aged AC
28 mixture 87
4.10 Score and ranking of aged AC 10 88
4.11 Score and ranking of aged AC 14 88
4.13 Marshall mix design parameters of recycled mixture
blended with B1 (80-100 PEN) 91
4.14 Marshall mix design parameters of recycled mixture
blended with B2 (60-70 PEN) 91
4.15 ANOVA result for tensile strength of recycled mixture
blended with B1 (80-100 PEN) 93
4.16 ANOVA result for tensile strength of recycled mixture
blended with B2 (60-70 PEN) 93
4.17 ANOVA result for resilient modulus of recycled mixture blended with B1 (80-100 PEN) at 25 °C under
different pulse repetition period 95
4.18 ANOVA result for resilient modulus of recycled mixture blended with B2 (60-70 PEN) at 25 °C under
different pulse repetition period 96
4.19 ANOVA result for resilient modulus of recycled mixture blended with B1(80-100 PEN) at 40 °C under
different pulse repetition period 96
4.20 ANOVA result for resilient modulus of recycled mixture blended with B2 (60-70 PEN) at 40 °C under
different pulse repetition period 97
4.21 Dynamic creep test results of recycled mixture blended
with B1 (80-100 PEN) 98
4.22 Dynamic creep test results of recycled mixture blended
with B2 (60-70 PEN) 98
4.23 Score and ranking of recycled mixture blended with B1
(80-100 PEN) 99
4.24 Score and ranking of recycled mixture blended with B2
(60-70 PEN) 100
4.25 Marshall mix design parameters of second recycled
4.26 Marshall mix design parameters of second recycled
mixture blended with B2 (60-70 PEN) 102
4.27 ANOVA result for tensile strength of second recycled
mixture blended with B1 (80-100 PEN) 103
4.28 ANOVA result for tensile strength of second recycled
mixture blended with B2 (60-70 PEN) 103
4.29 ANOVA result for resilient modulus of second recycled mixture blended with B1 (80-100 PEN) at 25 °C under
different pulse repetition period 105
4.30 ANOVA result for resilient modulus of second recycled mixture blended with B2 (60-70 PEN) at 25 °C under
different pulse repetition period 106
4.31 ANOVA result for resilient modulus of second recycled mixture blended with B1 (80-100 PEN)at 40 °C under
different pulse repetition period 106
4.32 ANOVA result for resilient modulus of second recycled mixture blended with B2 (60-70 PEN) at 40 °C under
different pulse repetition period 107
4.33 Dynamic creep test results second recycled mixture
blended with B1 (80-100 PEN) 107
4.34 Dynamic creep test results second recycled mixture
blended with B2 (60-70 PEN) 108
4.35 Score and ranking of second recycled mixture blended
with B1 (80-100 PEN) 109
4.36 Score and ranking of second recycled mixture blended
with B2 (60-70 PEN) 110
4.37 Recommended amount of recycles materials at each
4.38 Air void content of recycled mixture 115
4.39 Grid analysis on the suitable number of recycling
LIST OF FIGURES
FIGURE NO. TITLE PAGE
1.1 Average unit price of bitumen in Malaysia (Jabatan Perangkaan Malaysia, 2016a; Jabatan Perangkaan
Malaysia, 2016b) 2
1.2 Average unit price of aggregates in Malaysia (Jabatan Perangkaan Malaysia, 2016a; Jabatan Perangkaan
Malaysia, 2016b) 2
2.1 Bitumen penetration with respect to pavement life
(Brown et al., 2009) 9
2.2 Bitumen viscosity after few months of pavement service
life (Brown et al., 2009) 9
2.3 Change in penetration under different ageing procedure.
(Oke et al., 2010) 16
2.4 Ageing effect between RTFO and STOA samples. (Lee
et al., 2008) 18
2.5 Cored sample slices at different thickness.(Qin et al.,
2.6 Cold milling process 21
2.7 Effect of RAP preheating time on compression and indirect tensile strength (Stephens et al., 2001 cited after
Al-Qadi et al., 2007) 24
2.8 Effect of rejuvenator in the recycled mixture (Silva et al.
2.9 Effect of different binder interaction on the tensile
strength of recycled mixture (Chen et al. (2007) 27 2.10 Effect of different binder interaction on the resilient
modulus of recycled mixture (Chen et al. (2007) 28 2.11 Number of cycles to failed and plateau value of recycled
mixture incorporating RAP (Shu et al., 2008) 31 2.12 Effect of tensile strain on the repetitive loads (Tabakovic
et al., 2010) 32
2.13 Effect of stress on the cycle number based on (a) 50%
initial stiffness; (b) ER. (Ajideh et al., 2013) 32 2.14 Number of cycles to failure and cumulative dissipated
energy of RAP mixture (Huang et al., 2011) 33 2.15 Effect of tensile strain on the repetitive loads. (Silva et
al., 2013) 34
2.16 (a)Complex modulus of BA (pure bitumen) at high temperature; (b) complex modulus of BA at low temperature; (c) phase angle of BA at high temperature; (d) phase angle of BA at low temperature (Zeng et al.
2.17 Change in asphaltene content under different ageing
procedure. (Oke et al., 2010) 39
2.18 Relationship between composition of ketones + sulfoxides with the ageing time. (Petersen & Glaser,
2.19 Percentage of oxygen and sulphur at different ageing rate.
(Siddiqui and Ali, 1999) 41
3.1 Research flow chart 43
3.2 Sieve analysis of RAP aggregate at ACW 20 gradation 46
3.3 Phase I experimental flow chart 47
3.4 AC 10 aggregate gradation 48
3.5 AC 14 aggregate gradation 48
3.7 Rolling thin film oven apparatus 52
3.8 Pressurized ageing vessel apparatus 52
3.9 Loose sample placed in the oven 53
3.10 Wrapped samples 54
3.11 Universal compression machine with Marshall loading
3.12 TMD Apparatus 56
3.13 Universal compression machine with ITS fixture 57 3.14 Universal Testing Machine (UTM-5)with resilient
modulus test fixture 59
3.15 Phase II experimental flow chart (cont’) 63
3.16 Universal Testing Machine (UTM-5) with dynamic
creep fixture 67
3.17 Universal Testing Machine (IPC UTM-5) with four
point beam fatigue set up 69
3.18 Phase III experimental flow chart 71
3.19 Extraction apparatus 72
3.20 Solvent (methylene chloride); (a) fresh; (b) with
extracted bitumen 73
3.21 Typical arrangement for distillation (binder recovery)
3.22 Penetration apparatus 75
3.23 Softening point test apparatus 76
3.24 Viscometer 77
3.25 Spindles and bitumen thickness 78
3.26 DSR apparatus 78
3.27 Elemental analysis equipment 79
3.28 FTIR apparatus 80
4.1 Indirect tensile strength of aged mixture at 25˚C 84
4.2 Resilient modulus of aged mixture at 25˚C 86
4.3 Tensile strength of recycled mixture 92
4.4 Resilient modulus of recycled mixture at 25°C 94 4.5 Resilient modulus of recycled mixture at 40°C 95
4.6 Tensile strength of second recycled mixture 101 4.7 Resilient modulus of second recycled mixture at 25 °C 104 4.8 Resilient modulus of second recycled mixture at 40 °C 105 4.9 Tensile strength of recycled mixture at different recycling
4.10 Resilient modulus of recycled mixture at different
recycling stages at (a) 25°C; and (b) 40 °C 113 4.11 Permanent strain of recycled mixture at different
recycling stages 114
4.12 Creep stiffness modulus and CSS of recycled mixture at
different recycling stages 115
4.13 Cycle to failure and initial stiffness of recycled mixture
at different recycling stages 116
4.14 Penetration of bitumen at different recycling cycles 118 4.15 Softening point of bitumen at different recycling stages 119 4.16 Viscosity of bitumen at different recycling stages 120 4.17 Complex shear modulus (G*) and phase angle(δ) at high
temperature (a) 60-70 PEN; (b) 80-100 PEN 121 4.18 Complex shear modulus (G*) and phase angle (δ) at
medium temperature (a) 80-100 PEN; (b) 60-70 PEN 122 4.19 High temperature failure at different recycling stages 123 4.20 Medium (fatigue) temperature failure at different
recycling stages 124
4.21 Carbon composition in bitumen at different recycling
4.22 Hydrogen composition in bitumen at different recycling
4.23 Nitrogen composition in bitumen at different recycling
4.24 Sulphur composition in bitumen at different recycling
4.25 FTIR spectra of bitumen blended with B1 (80-100 PEN)
4.26 FTIR spectra of bitumen blended with B2 (60-70 PEN)
at different recycling stages 130
4.27 Carbonyl index at different recycling stages 131 4.28 Sulfoxide index at different recycling stages 132
LIST OF ABBREVIATIONS
AASTHO - American Association of State Highway and TransportationOfficials
AC 10 - Asphaltic concrete of nominal maximum aggregate size 10 mm AC 14 - Asphaltic concrete of nominal maximum aggregate size 14 mm AC 28 - Asphaltic concrete of nominal maximum aggregate size 28 mm ANOVA - Analysis of Variance
ARRA - Asphalt Recycling and Reclaiming Association ASTM - American Society for Testing and Materials BS - British Standard
CSS - Creep strain slope C=O - Carbonyl band
DSR - Dynamic shear rheometer
ERTFOT - Extended rolling thin film oven test FHWA - Federal Highway Administration FTIR - Fourier Transform Infrared ITS - Indirect tensile strength JKR - Jabatan Kerja Raya LTOA - Long term oven ageing
LVDT - Linear Variable Displacement Transducer MS - Malaysia Standard
NCHRP - National Cooperative Highway Research Program NRTFOT - Nitrogen rolling thin film oven test
OBC - Optimum bitumen content OPC - Ordinary Portland cement
PAV - Pressurized ageing vessel RAP - Reclaimed asphalt pavement
R2AP - Second reclaimed asphalt pavement RCA - Recycled concrete aggregate
RCAT - Rotating cylinder ageing test RTFO - Rolling thin film oven test
SHRP - Strategic Highway Research Program STOA - Short term oven ageing
S=O - Sulfoxide band
TMD - Theoretical maximum density TFOT - Thin film oven test
VFB - Voids filled with bitumen VMA - Voids in mineral aggregates VTM - Voids in total mix
LIST OF APPENDICES
APPENDIX TITLE PAGE
A Sieve analysis of RAP aggregate 150
B Mixing & compaction temperature of aged bitumen 154 C Mixing & compaction temperature of fresh bitumen 155
D High temperature failure for B1 bitumen 156
E High temperature failure for B2 bitumen 159
F Medium temperature failure for B1 bitumen 162
G Medium temperature failure for B2 bitumen 165
H Average Permanent Strain Curve of Control B1 (80-100
PEN) Mixture 168
I Average Permanent Strain Curve of Control B2 (60-70
PEN) Mixture 169
J Average Permanent Strain Curve of Recycled Mixtures
Blended with B1 (80-100 PEN) Bitumen 170 K Average Permanent Strain Curve of Recycled Mixtures
Blended with B2 (60-70 PEN) Bitumen 172
L Average Permanent Strain Curve of Second Recycled
Mixtures Blended with B1 (80-100 PEN) Bitumen 174 M Average Permanent Strain Curve of Second Recycled
1.1 Background of the Study
In pavement design, flexible pavement is typically designed for about ten to fifteen years. During the service life, rehabilitation and maintenance activities are very crucial in order to ensure quality and improve serviceability of the particular road. Thus, demand on pavement materials is not only limited during the initial construction but it will continue throughout the service life. Nowadays, construction industry gives a greater attention on sustainability aspect. Sustainability issue in road construction focuses more in providing ways on how to reduce virgin materials, energy and waste in construction, without compromising the quality of the pavement itself. There are many factors contributing to the sustainable construction such as construction methods, design processes, machineries and materials used for the construction.
Furthermore, price of virgin or fresh construction materials keep on rising as a result of rapid development and depletion of natural recourses. Demand for bitumen and aggregate for road construction is reflected as well. Figure 1.1 shows the market price trend of bitumen for peninsular and east Malaysia. The price index is based on the price of bitumen 80-100 PEN. The same trend occurred in the market price of aggregate as in Figure 1.2. It shows the price of 10 mm, 20 mm and 40 mm aggregates which are commonly used for wearing and binder course of pavement in Malaysia. Due to the price increased, Malaysia government spends about RM 20 billion for road construction and maintenance in 2015 (Abdelfatah et al., 2015).
Figure 1.1: Average unit price of bitumen in Malaysia. (JabatanPerangkaan Malaysia, 2016a; JabatanPerangkaan Malaysia, 2016b)
Figure 1.2: Average unit price of aggregates in Malaysia. (Jabatan Perangkaan Malaysia, 2016a; JabatanPerangkaan Malaysia, 2016b)
Materials recycling is one of the best solution that support sustainability aspect at the same time reduce the construction and material cost. Recycling a bituminous pavement is not a new idea. Advancements in recycling technology and equipment
500 1000 1500 2000 2500 3000 P ri ce p er m et ri c T o n ( R M ) Date Peninsular Malaysia Sabah Sarawak 20 22 24 26 28 30 32 34 36 P ri ce p er m et ri c T o n ( R M ) Date 10mm 20mm 40mm
occurred in 1970s. It conserved energy and non-renewable natural resources, preserved environment, reduced the usage landfill, reduced cost for construction and improved the overall pavement performance (Asphalt Recycling and Reclaiming Association, 2001).
One of the common methods in bituminous recycling is by using reclaimed asphalt pavement (RAP). RAP consists of waste materials, obtained from the milling process of pavement surface (wearing course, binder course or both). RAP will be mixed with fresh aggregates, bitumen, with or without recycling agents to produce a recycled mixture. Although usage of RAP in the pavement has been established, the performance and properties of recycle RAP (R2AP) is unclear. Very few documented research on R2AP has been reported and the knowledge on this need to be further explored. Therefore, a study in this area is really needed in order to address the suitability and effectiveness of RAP and R2AP for a better implementation of sustainability in road construction. Furthermore,properties of aged bitumen extracted from the respective mixtures were evaluated to forecast the recyclability of the mixture.
1.2 Statement of the Problem
During the pavement service life, rehabilitation is required to optimize the performance by improving the serviceability of the road. It may involve reconstruction, recycling or overlay of the surface materials. However, the continuous demand on the construction materials lead to the depletion of natural resources and increase the waste materials. Recycling of bituminous pavement materials is found to be the best method to minimize the usage of natural resources and to solve the materials disposal issues.
Many studies have proved that RAP could be incorporated into the pavement mixture for the first time. Furthermore, it has been practiced since 1970s and several suggestions on usage of RAP have been established. For example, few places in the US have successfully used RAP in the pavement mixture on site (Federal Highway
Administration, 2016). However, there are still mixed findings on the performance of RAP were discovered among the researchers especially on the suitable amount of RAP to be incorporated in the mixture. For example Yang and Lee (2016) suggested that RAP should be less than 25% from the total mixture, but other researcher claimed that higher RAP content with proper handling is still capable to perform as good as conventional mixture (Poulikakos et al., 2014).
In addition, those pavements made with RAP will reach the end of service life. The same problem will occur during the second phase of rehabilitation on how to deal with milled RAP (R2AP) for the second time. Most of the existing research on RAP typically concentrate on evaluating the performance of mixture incorporating RAP while performance and properties of R2AP is very limited and still debatable. In R2AP study, Chen et al. (2009) suggested that up to 40% R2AP did not alter the mixture properties and performance, while Su et al. (2008) claimed that there are no distinct in certain parameter between conventional and second recycled mixture consists R2AP.
Issues on different materials and climate also have led to a motivation in conducting this study, where it will be more specifically suits for tropical region Furthermore, findings of this research are also essential to improve public perception on the usage of waste materials especially R2AP in road construction. It is also expected that the findings can be used as a fundamental guideline to recommend the suitable proportion of RAP in road construction. Overall, this research is very significant to encourage relevant parties to conduct more studies and practices on the usage of RAP in the road construction.
1.3 Objective of the Study
The aim of this study was to determine the recyclability of bituminous mixture. The aim was achieved through the following objectives:
a) To determine and select an appropriate method of laboratory ageing, which could produce most severe ageing effect on the mixture;
b) To evaluate the performance of bituminous mixtures incorporating RAP and R2AP (recycled mixtures) in term of rutting and cracking resistances;
c) To determine the physical, rheological and chemical properties of aged bitumen extracted from recycled mixtures;
d) To forecast recyclability of the mixture based on the properties of aged bitumen.
1.4 Scope of the Study
The scopes of the study were:
a) Recycled bituminous mixtures were designed by incorporating RAP and R2AP which are compatible with the conventional bituminous mixture.
b) Mixture gradations used in this study were design in accordance to JKR (JKR, 2008).
c) Four laboratory ageing methods were used in the first phase. Combinations of two ageing methods were then classified as a complete ageing process.
d) Three ageing processes were examined in first phase and the best process that produced the most severe ageing effect was used in second phase.
e) Two grades of fresh bitumen (80-100 PEN and 60-70 PEN) were utilized in this study.
f) Performance of the mixtures was evaluated based on laboratory samples and tests.
1.5 Thesis Structure
This thesis is organised into five chapters. Each chapter consists of several sections and sub-sections. The chapter details are explained as follows:
Chapter 1: Introduction
Chapter 1 briefly describes the overall perspectives of the research including background, problem statement, aim and objectives that need to be achieved.
Chapter 2: Literature Review
Chapter 2 provides a comprehensive review from previous research and experiences related to laboratory ageing process, usage of RAP in bituminous mixture and properties of extracted binder from aged mixtures.
Chapter 3: Research Methodology
Chapter 3 explains in details the process and methods used in this research. It includes materials, equipment, procedures and standards applied throughout the research. The research was designed and conducted in three different phases.
Chapter 4: Result and Discussion
Chapter 4 presents the findings from the experimental results. The results were organised in three sections in line with the phases described in Chapter 3.
Chapter 5: Conclusion and Recommendation
Chapter 5 summarises the findings with conclusions and several recommendations for future research.
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