STRENGTH AND DURABILITY OF ASPHALT
CONCRETE MODIFIED CRUMB RUBBER
D R A F T O F T H E S I S
Submitted to the Post Graduate of Civil Engineering Program in Partial Fulfillment of the Requirements for Third Seminar
By:
ALGALI A.M. ABAS
S941302044
MASTER OF CIVIL ENGINEERING
GRADUATE PROGRAM - SEBELAS MARET UNIVERSITY
2015
ii
STRENGTH AND DURABILITY OF ASPHALT
CONCRETE MODIFIED CRUMB RUBBER
By:
ALGALI A.M. ABAS
S941302044
Approved by Supervisor Team:
Position Name Signature Date
Supervisor I : Ir.Ary Setyawan, M.Sc(Eng).,Ph.D
NIP. 196905011995121001
... ...
Supervisor II : Dr. Ir. Arif Budiarto, M.T. NIP. 196304161997021001
... ...
Acknowledged by
Chairman of The Civil Engineering Master Program
iv
PRONOUNCEMENT
The person who signs here:
NAME :ALGALI A.M. ABAS NIM :S941302044
Certifies that the thesis entitled:
STRENGTH AND DURABILITY OF ASPHALT CONCRETE MODIFIED CRUMB RUBBER
Is really his own work. Anything related to others’ work is written in quotation, the source of which is listed on the bibliography.
If then, this pronouncement proves wrong, I am ready to accept any
academic punishment. Including the withdrawal of this thesis and my academic degree.
Surakarta, 19 June 2015 The person who makes this Pronouncement
ALGALI A.M. ABAS
v
ACKNOWLEDGEMENT
I am grateful to the Allah for the good health and wellbeing that
were
necessary to complete this research.
I wish to express my sincere thanks to Dr. Mamok Suprapto, M.
Eng,
Principal of the Faculty of Sebelas Maret University, for providing me
with all the
necessary facilities for the research.
I place on record, my sincere thank you to Dr. Eng. Ir. Syafi’I,
MT, Dean
of the Faculty, for continues encouragement.
I am also grateful to Ir.Ary Setyawan, M.Sc(Eng).,Ph.D, my
supervisor and
lecturer in the Department of Civil Engineering. I am extremely
thankful and indebted to him for sharing expertise, and sincere and
valuable guidance and encouragement extended to me.
I would like to express my sincere thanks and appreciation to
Dr. Ir. Arif Budiarto, MT
I take this opportunity to express gratitude to all of the
Department faculty
of civil engineering members for their help and support. I also thank
my mother
for the unceasing encouragement, support and attention. My dear
father Times are
hard. You always used to help me through everything. I am also
grateful to my
wife and my children who supported me through this venture.
I also place on record, my sense of gratitude to one and all, who
directly or
vi
ABSTRACT
Environmental problem becomes big problem if the trash is renewable and can not decompose. One of trashes which very dangerous to be neglected is tire rubber. Crumb rubber is an innovation for the development of asphalt concrete. The use of crumb rubber which is come from the recycle of tires is very beneficial on the environment and economic aspects. Based on the background, there are two research statements, namely: How is the influence of crumb rubber on asphalt concrete modification of strength aspect? How is the influence of crumb rubber on asphalt concrete modification on the durability aspect?
In the context of this research, the use of crumb rubber as asphalt modification to increase the strength and durability was depend on the asphalt content and percentages of crumb rubber itself. In terms of labolatory test, this research has been through many test for materials such as ITS, ITSM, UCS and OBC. All of the test were conducted to get the result about the influence of strength and durability on asphalt concrete modification with crumb rubber with several percentages, namely 0%, 3%, 4%, and 5%.
The existence of crumb rubber in asphalt mixture influenced the strength. The increased of the crumb rubber content, will influenced the decreased of the strength of mixture. It can be seen from the stability, ITS, UCS and ITSM. The score for those tests showed that the increased of crumb rubber would decreased the strength. The crumb rubber which can be recommended for the mixture was 4% with 5-5.5% of asphalt content. Then, the temperature also influenced the strength of the mixture. The higher of temperature would decreased the strength of mixture. The modification of asphalt with crumb rubber also influenced the durability. It can be seen from the density score, the maximum density was come from 4% crumb rubber content. Then, the increased of crumb rubber in the mixture (more than 4%) would decrease the density.
Keywords: crumb rubber, strength, durability
vii
ABSTRAK
Masalah lingkungan menjadi masalah besar jika sampah yang tidak dapat terbarukan tidak dapat terurai. Salah satu sampah yang sangat berbahaya adalah karet ban. Karet remah adalah sebuah inovasi untuk pengembangan beton aspal. Penggunaan karet remah yang berasal dari daur ulang ban sangat bermanfaat terhadap lingkungan dan aspek ekonomi. Berdasarkan latar belakang, ada dua pernyataan penelitian, yaitu: Bagaimana pengaruh karet remah pada beton aspal modifikasi dalam aspek kekuatan? Bagaimana pengaruh karet remah di aspal modifikasi beton pada aspek daya tahan?
Dalam konteks penelitian ini, penggunaan karet remah sebagai modifikasi aspal untuk meningkatkan kekuatan dan daya tahan adalah tergantung pada kadar aspal dan persentase karet remah sendiri. Dalam hal uji labolatorium, penelitian ini telah melalui banyak tes seperti ITS, ITSM, UCS dan OBC. Semua tes dilakukan untuk mendapatkan hasil tentang pengaruh kekuatan dan daya tahan di aspal modifikasi beton dengan karet remah dengan beberapa persentase, yaitu 0%, 3%, 4%, dan 5%.
Keberadaan karet remah dalam campuran aspal dipengaruhi kekuatan. Peningkatan remah kadar karet, akan mempengaruhi penurunan kekuatan campuran. Hal ini dapat dilihat dari stabilitas, ITS, UCS dan ITSM. Rata bagi mereka tes menunjukkan bahwa peningkatan karet remah akan menurun kekuatan. Karet remah yang dapat direkomendasikan untuk campuran adalah 4% dengan 5-5,5% dari kadar aspal. Kemudian, suhu juga mempengaruhi kekuatan campuran. Semakin tinggi suhu akan menurunkan kekuatan campuran. Modifikasi aspal dengan karet remah juga dipengaruhi daya tahan. Hal ini dapat dilihat dari nilai kerapatan, kepadatan maksimum berasal dari 4% kadar karet remah. Kemudian, peningkatan karet remah dalam campuran (lebih dari 4%) akan menurunkan kepadatan.
Kata Kunci: karet remah, Kekuatan, daya tahan
viii
TABLE OF CONTENT
Page
Cover ... i
Table of Content ... ii
Chapter I Introduction ... 1
1.1 Background ... 1
1.2 Problem Formulation ... 3
1.3 Objectives of Research ... 4
1.4 Benefit of Research ... 4
Chapter II Literature Review and Basic Theory ... 5
2.1 Literature Review ... 5
2.1.1 Strength ... 5
2.1.2 Durability ... 6
2.2 Basic Theory ... 9
2.2.1 Strength ... 9
2.2.2 Durability ... 13
Chapter III Method of Research ... 14
3.1 Location and Type of Research... 14
3.2 Parameter and Variable ... 14
3.3 Data ... 15
3.3.1 Primary Data ... 16
3.3.2 Secondary Data ... 16
3.3.3 Sample Preparation of Material ... 17
3.3.4 Sample Production Of Bitumen Mixture ... 23
3.4 Analysis ... 24
3.4.1 Strength ... 25
3.4.2 Durability ... 25
ix
Chapter IV Result and Discussion ... 27
4.1 General ... 27
4.1.1 Asphalt ... 27
4.1.2 Aggregate ... 28
4.1.3 Crumb Rubber ... 30
4.1.4 Marshall Test of 60/70 Bitumen Mixture ... 30
4.2 Strength ... 54
4.2.1 Stability ... 54
4.2.2 Flow Test ... 59
4.2.3 VFWA ... 60
4.2.4 Void in Mixture (VIM) ... 62
4.2.5 Marshall Quotient (MQ) ... 64
4.2.6Void in Mineral Aggregate (VMA ... 67
4.2.7 Indirect Tensile Strength (ITS) Test ... 70
4.2.8 Unconfined Compressive Strength (UCS) Test ... 71
4.2.9 Indirect Tensile Stiffness Modulus Test (ITSM .. 74
4.3 Durability ... 76
4.4 Discussion ... 78
Chapter V Conclusion and Recommendation ... 80
5.1 Conclusion ... 80
5.2 Recommendation ... 80
x
LIST OF FIGURE
Page
Figure 3.1 Flow chart for laboratory process and analysis ... 27 Figure 4.1 Correlation Stability And ACWithout CR Toward Asphalt
Content ... 32 Figure 4.2 Correlation Flow And ACWithout CR Toward Asphalt
Content ... 33 Figure 4.3. Correlation VFWA And AC Without CR Toward Asphalt
Content ... 35 Figure 4.4. Correlation VIM And AC Without CR Toward Asphalt
Content ... 35 Figure 4.5. Correlation MQ And AC Without CR Toward Asphalt
Content ... 36 Figure 4.6. Correlation VMA And AC Without CR Toward Asphalt
Content ... 36 Figure 4.7. Correlation Marshall Properties Toward %
Bitumen... ... 37 Figure 4.8. Correlation Stability And AC With 3% CR Toward Asphalt
Content ... 38 Figure 4.9. Correlation Flow And AC With 3% CR Toward Asphalt
Content ... 39 figure 4.10. Correlation VFWA And AC With 3% CR Toward Asphalt
Content ... 40 Figure 4.11. Correlation VIM And AC With 3% CR Toward Asphalt
Content ... 40 Figure 4.12. Correlation MQ And AC With 3% CR Toward Asphalt
Content ... 41 Figure 4.13. Correlation VMA And AC With 3% CR Toward Asphalt
Content ... 42 Figure 4.14. Correlation Marshall Properties Toward 3% CR... .. 43
xi Figure 4.15. Correlation Stability And AC With 4% CR Toward Asphalt
Content ... 44
Figure 4.16. Correlation Flow And AC With 4% CR Toward Asphalt Content ... 45
Figure 4.17. Correlation VFWA And AC With 4% CR Toward Asphalt Content ... 45
Figure 4.18. Correlation VIM And AC With 4% CR Toward Asphalt Content ... 46
Figure 4.19. Correlation MQ And AC With 4% CR Toward Asphalt Content ... 46
Figure 4.20. Correlation VMA And AC With 4% CR Toward Asphalt Content ... 47
Figure 4.21. Correlation Marshall Properties Toward 4% CR ... 48
Figure 4.22. Correlation Stability And AC With 5% CR Toward Asphalt Content ... 49
Figure 4.23. Correlation Flow And AC With 5% CR Toward Asphalt Content ... 50
Figure 4.24. Correlation VFWA And AC With 5% CR Toward Asphalt Content ... 51
Figure 4.25. Correlation VIM And AC With 5% CR Toward Asphalt Content ... 52
Figure 4.26. Correlation MQ And AC With 5% CR Toward Asphalt Content ... 52
Figure 4.27. Correlation VMA And AC With 5% CR Toward Asphalt Content ... 53
Figure 4.28. Correlation Marshall Properties Toward 5% CR ... 54
Figure 4.29. Stability Test ... 57
Figure 4.30. Flow Test ... 59
Figure 4.31. VFWA ... 61
Figure 4.32. VIM Test ... ... 64
xii
Figure 4.35. ITS Test ... 71
Figure 4.36 UCS ... 73
Figure 4.37 ITSM Test ... 75
Figure 4.38. Density Test ... 78
xiii
LIST OF TABLE
page
Table 2.1 Resume OF Previous Research ... 8
Table 3.1 Parameter and Variable ... 14
Table 3.2 Gradation Limits for Wearing Course ... 19
Table 3.3 ITSM Test ... 23
Table 3.4 Number of Samples of Marshall Testing... 23
Table 3.5 The numbers of samples of UCS with different Temperatures 24 Table 3.6 The number of samples of ITS with different temperatures ... 24
Table 4.1 Properties of Asphalt ... 27
Table 4.2 Test Result For Course Aggregate, Fine Aggregate and Asphalt ... 29
Table 4.3 Coarse Aggregate Test ... 29
Table 4.4. Properties Of Asphalt Concrete Without Crumb Rubber (60/70) ... 31
Table 4.5. Marshall Properties Of Mixture AC-WC-CR3 ... 39
Table 4.6. Marshall Properties Of Mixture AC-WC-CR4 ... 44
Table 4.7. The Marshall Properties Of Mixture AC-WC-CR5 ... 49
Table 4.8. Stability... 57
Table 4.9. Flow Test ... 59
Table 4.10. VFWA ... 62
Table 4.11. VIM Test ... 63
Table 4.12. Marshall Quotient (MQ) ... 66
Table 4.13. Void in Mineral Aggregate (VMA) ... 69
Table 4.14. ITS ... 71
Table 4.15. Comparison of UCS Test at OBC at 30 , 40 And 60 ... 73
Table 4.16. ITSM... 74
Table 4.17. Density ... 77
xiv
List of Formula
Formula 2.1 Stability ……… 9
Formula 2.2 ITS………. 9
Formula 2.3 Flow ……….. 10
Formula 2.4 VFWA ……… 10
Formula 2.5 VIM ……… 10
Formula 2.6 Marshall Quotient ……….. 10
Formula 2.7 Bulk Specific Gravity ………. 11
Formula 2.8 Bulk Specific Gravity SSD ……… 11
Formula 2.9 Absorption……… 11
Formula 2.10 VMA ………. 12
Formula 2.11 OBC ………. 12
Formula 2.12 ITSM ………. 12
Formula 2.13 UCS ……….. 12
Formula 2.14 Density……….. 13
xv
Table Of Appendix
Appendix A
Appendix B
Appendix C
xvi
List of symbols
A = Weight of dry speciment in air
b = Volumetric flash + water + sand
B0 = Optimum Bitumen Content
B1 = % asphalt content at maximum unit weight.
B2 = % asphalt content at maximum stability.
B3 = % asphalt content at specified percent air voids in the total mix
Bsg = Bulk specific gravity
Bsg SSD = Bulk specific gravity SSD
c = Volumetric flash + water
d = Diameter of the specimen in mm to one decimal place.
d = Oven dry sand
D = The mean amplitude of the horizontal deformation obtained from 2 or more applications of the load pulse (mm),
F = Flow
have = Average height of the specimen in mm to one decimal place.
I = Volume of bitumen
ITS = Indirect Tensile Strength in KPa.
ITSM = Indirect Tensile Stiffness Modulus
L = The peak value of the applied vertical load (N),
L = Volume of air voids
B = Marshall quotient
P = Maximum applied load in N.
P (Kn) = Maximum applied load in N
S = Weight of saturated surface dry speciment
t = The mean thickness of the test specimen (mm)
v = Poisson’s ratio (a value of .35 is normally used).
VIM = The average of VIM
W = Stability
1
CHAPTER I
INTRODUCTION
1.1. Background
Environmental problem is the big problem of human life. Environmental problem becomes big problem if the trash is renewable and can not decompose. One of trashes which very dangerous to be neglected is tire rubber. The tire rubber comes from many sources such as cars, busses, bicycle, motorcycle and so on. According to U.S. National Park Service, Mote Marine Lab, Sarasota, FL., rubber needs 50-80 years to be decomposed by the earth. The time which is needed to decompose the rubber is very long and the trash materials will influence the view of environment.
In New York State, an estimated 18-20 million waste tires are generated each year (approximately one tire-per-person-per-year). Management of waste tires is regulated by the New York State Department of Environmental Conservation (NYSDEC). In July 2004, NYSDEC released a comprehensive plan to abate noncompliant waste tire stockpiles. Enumeration and an assessment of each known noncompliant waste tire stockpile was conducted between August 2003 and May 2004, which identified approximately 95 locations, containing an estimated 29 million tires Four of the 95 identified sites are estimated to contain over one million waste tires each. Waste tires and piles of waste tires pose challenges and problems, including their potential as mosquito breeding locations and potential for fire(http://www.dec.ny.gov/ chemical/ 8792.html, 2013).
In Europe, scrap tires annually produce 2.2 million tons of which 34.4 % were not utilized. In United State nearly 300 million tires discarded a used car each year. While in Indonesia, the volume of waste vehicle tires from year to yearlong with an increase in the number of motor vehicles. Traditionally, most people use old tires as fuel manufacture of bricks or tiles.
Efforts destruction by burning turns produce harmful effects of pollution; in addition to the black smoke also contains rubber, carbon and other chemical elements adversely affect human health. Waste tires has become a global environmental problem developed countries, especially in developing countries (Hasballah, 2003). Many used tires
2 found piled up in the garage or tire place. These conditions give rise to the impression of a rundown on environment and the potential for mosquito breeding.
Crumb rubber, also referred to as ground rubber, is finely ground rubber derived from recycled or scrap tires. Over 20 million scrap tires are generated annually in New York State (NYS). The R.W. Beck consulting firm estimated that in 2004, about 22.5percent of NYS generated scrap tires were used to produce ground rubber (Beck, 2006).
Based on the increasing of waste rubber around the world, people should take care of the environment by practicing recycle program. The suggestion of the use of crumb rubber has been declared since 1980’s as a potential partial solution for environment in terms of waste problem (Papagiannakis., et al, 2000).
Crumb rubber is a common infill material for synthetic turf fields providing cushion and ballast for the playing surface. The benefits claimed for choosing crumb rubber over natural grass fields include reduced water needs and maintenance, avoided need for pesticides, herbicides or fertilizer, reduced injuries, and an “all-weather” playing surface. Out of the 850 synthetic turf fields in the United States, NYS has about 150 fields (Katz, 2007).
Crumb rubber asphalts are relatively uncommon in Australia although they have been used overseas. For example, in the U.S.A., various types of rubber asphalts are used and performance has been varied. This may be because, in some mixes, part of the coarse aggregate is replaced with rubber while, in others, it is the binder that is modified. The few trials carried out in Australia, where crumb rubber asphalt has been placed over badly cracked concrete and flexible pavements, have performed very well (APRG Technical Note 10, 2009).
3 portions and the wet process which modifies the bitumen binder. Initially, only the coarse rubber was used in the dry process method (Hassan et al, 2013).
Recycled waste tire rubber is a promising material in the construction industry due to its lightweight, elasticity, energy absorption, sound and heat insulating properties. The study of El Gammal et al (2010) has investigated that compressive strength (CS) of concrete utilizing waster tire rubber. According to the study crumb rubber is used as replace for fine and coarse aggregate by weight using different percentages. According to that study, there was a significant reduction in the compressive strength of concrete utilizing waste tire rubber than normal concrete, concrete utilizing waste tire rubber demonstrated a ductile, plastic failure rather than brittle failure. Moreover, according to Azmi et al (2008), although there is a reduction in strength for crumb rubber mixture, but slump values increase as the crumb rubber content increase from 0% to 30%. Meaning that crumb rubber mixture is more workable compare to normal concrete and can be acceptable to produce crumb rubber concretes. The results also indicated that inclusion crumb rubber in concrete reduced the static modulus elasticity (SME). Although there is a reduction in modulus elasticity but the deformability crumb rubber concrete increasing compared to normal concrete. Moreover, previous studies with the rubberised asphalt mixtures indicated better durability with an increase of fine rubber content (Hassan, 2013).
Based on the previous research, it can be known that crumb rubber for asphalt modification has many benefits such as environmental aspect because the use of crumb rubber can decrease the number of tyre garbage; moreover in terms of economic aspect the use of crumb rubber can substitute the use of fine and coarse aggregate therefore it can decrease the road construction budget; and quality improvement. Moreover, based on the benefit of crumb rubber modification, this research will investigate the influence of crumb rubber on asphalt concrete modification for strength and durability.
1.2. Problem Formulation
Based on the background, the focus of problem formulation are as follow:
a. How is the influence of crumb rubber on asphalt concrete modification of strength aspect?
b. How is the influence of crumb rubber on asphalt concrete modification on the durability aspect?
4
1.3. Objectives of Research
The objectives of this research are as follow:
a. To know the influence of crumb rubber for strength on asphalt concrete modification.
b. To know the influence of crumb rubber for durability on asphalt concrete modification.
1.4. Benefit of Research
The benefits of this research are as follow:
a. Theoretical Side
This research is expectedto give theoretical contribution for Civil Engineering Department especially in strength and durability of asphalt concrete modified crumb rubber.
b. Practical Side
This research is expected to give contribution on practical life which can be used to solve environment problem cause of the trash of tire rubber used in terms of asphalt concrete modification.
5
CHAPTER II
LITERATURE REVIEW & BASIC THEORY
2.1. Literature Review
The first used of asphalt pavement it was in the nineteenth century the different types of asphalt materials have been used in an attempt to reduce specific undesirable characteristics of the asphalt paving mixture or to improve the overall performance of pavement.
During the past several years many states experienced problems with amount and severity of permanent deformation in hot mix asphalt pavements. This problem with permanent deformation, or rutting, was attributed to an increase in truck tire pressures, axle loads, and volume of traffic (Brown, et al, 1990).
Today there are a number of serious asphalt pavement problem;and the significant economic impact of these problems, coupled with availability of numbers additives claimed by manufacturers to mitigate these problems to some degree, make it difficult for pavement engineers to make a sound judgment on which modifier to use (Zahran, 1988). Based on the problem due to asphalt quality, people should concern about asphalt quality on road construction. The strength and durability of asphalt on road construction should be care because those things relate with government budget on road construction and continuity of human’s life business.
2.1.1 Strength
According to ( Kennedy T.W. 1978), the elastic and viscoelastic properties of asphalt mixes are related to the basic distress modes of shrinkage cracking, fatigue cracking and rutting. The static indirect tensile strength stiffness values are typical and realistic for asphalt mixes where the strength generally varies from 200 to 400 kPa depending on the temperature of testing.
6 higher tensile strength corresponds to a stronger cracking resistance. At the same time, mixtures that are able to tolerate higher strain prior to failure are more likely to resist cracking than those unable to tolerate high strains (Tayfur et al., 2007).
A lot of research work has been reported on the performance of bituminous pavements relating the tensile strength of bituminous mixtures (Zhang et al., 2001; Behbani et al, 2009; Anderson et al., 2001). A higher tensile strength corresponds to a stronger low temperature cracking resistance (Huang et al., 2004). The test provides information on tensile strength, fatigue characteristics and permanent deformation characteristics of the pavement materials. The indirect tensile strength test comprises two vertically arranged compressive forces applying a single load parallel to and along the vertical diametral plane of the asphalt pats. This loading configuration develops a relatively uniform tensile stress perpendicular to the direction of the applied load and along the vertical diametral plane, which ultimately causes the specimen to fail by splitting along the vertical diameter. Ensuring the test was carried out in a consistent manner.
The values of indirect tensile strength may be used to evaluate the relative quality of bituminous mixtures in conjunction with laboratory mix design, testing and for estimating the resistance to cracking. The results can also be used to determine the resistance to field pavement moisture when results are obtained on both water conditioned and unconditioned specimens. Many researchers used this test (Wallace and Monismith, 1980; Kennedy and Hudson ,1968; Kandhal ,1979; Ibrahim, 2000).
2.1.2 Durability
Durability of an asphalt mixture is defined as its resistance to weathering and the abrasive action of traffic. In terms of its application to asphalt paving materials, durability can be defined as the ability of the materials in the asphalt pavement structure to withstand the effects of environmental conditions, such as water, ageing and temperature variations without any significant deterioration for an extended period for a given amount of traffic loading (Suparma, 2001).
In assessing durability, a mixture is subjected to environmental conditioning, and a mixture property associated with load-related or environmental distress is measured before and after the conditioning process. Abrasion characteristics of the aggregate in the mixture must also be considered in the assessment of durability. The greater the protection by asphalt concrete,
7 more durable the mix will be. The fewer air voids in the total mix, the slower will be the deterioration of the asphalt concrete itself.
Through the few last years, the use of asphalt in road building has gradually increased and reached its peak in 1979, it is concluded that the current annual worldwide consumption of asphalt is over 100 million tons (Tripathi, 2000).
In terms of strength and durability, the topic can not be avoided with asphalt as one of material in this research. Generally, the viscous properties of asphalt binder should be sufficiently fluid to permit it to be handled during construction and to coat and wet aggregate, viscous at high pavement temperatures so that it will not permanently deform under traffic and fluid at low temperatures to permit it to avoid fracture and cracks (Richard & Bent, 2004).
The selection of the grade and type of asphalt according to the type of construction and the climate of the area. However, the major problems with unmodified asphalt are the formation of wheel ruts by the repeated pressure exerted by vehicle tires. Further, hot climates in Libya, the plastic qualities of asphalt can lead to permanent deformation.
Usually in all weather conditions the asphalt used for paving roads must remain viscoelastic but this does not happen practically. All asphalts are known to soften up during summer and form rutting or permanent deformation. During winters, neutral molecules in the asphalt arrange themselves into more organized structural forms, which in turn harden the material leading to brittleness and the formation of cracks under high traffic loads. These processes are termed as fatigue and thermal cracking.The road surface deficiencies of concern are fatigue cracking, moisture damage, aging and rutting.
The most important property needed in this research in the objective of asphalt concrete mix design process is stability or resistance to permanent deformation under the action of traffic load, especially at high temperature (Mamlouk, et al, 2006). Due to the importance properties of asphalt concrete mix, the characteristic for each of component in asphalt concrete mix is presented as Penetration Grade Bitumen and Properties of Bitumen. Important properties of bitumen also presented areViscosity, Cohesion, Adhesion, Temperature susceptibility, Stiffness
8
Table 2.1 Resume Of Previous Research
No Author, Year Problem Method
1 Brown S.F, Rowlett R.D, and Boucher J.L (1990)
Asphalt Modification The use of modification to increase performance of asphalt
2 Zahran, G (1988) Asphalt quality Development of rubber and asphalt binder by
depolymerization and
devulcanistion of scrap tires in asphalt.
3 Kennedy, T.W. (1978) Performance of asphalt The research of elastic and viscoelastic properties of
6 Behbahani H Newbakht S, Fahadi H, Rahmani J
Asphalt binder Experiment for evaluation of fatigue criteria for asphalt binders
8 Huang, B, Li, G.
Vukosavljevic, D, Shu, X and Egan, B. (2004)
Hot mix asphalt Laboratory Investigation of Mixing Hot-Mix Asphalt
9 Wallace K, Monismith CL (1980)
10 P.S. Kandhal (1979) Asphalt Absorption as Related to Pore Characteristics of Aggregates
Experimental research on asphalt absorption.
Asphalt-9
13 Tripathi, R (2000) Asphalt modification Toner-Modified Asphalt Composition.
14 Richard, R., and Bent, T (2004)
Road engineering Experimental on strength and durability
Based on the previous study, it can be seen that this research also use modification in Crumb Rubber but in the low percentage. In the context of previous research, the score of strength and durability decreased inline with the added of Crumb Rubber, therefore this research will use low percentage of Crumb Rubber because this research will keep on determining the strength of asphalt will influence the lifetime of asphalt.
Stability = stability os sample*tool score of calibration*correction score*0.4536 ... (2.1) Where:
Tool of calibration = 40.40 lbs/div
ITS (Indirect Tensile Strength) is a method to determine the value of tensile strength of asphalt concrete mixtures. This test aims to determine the indications of cracking in the field. Testing is similar to the Marshall test, which distinguishes only the indirect tensile strength testing does not use test but using the ring-shaped concave plate with a width of 12.5 mm on the suppressant Marshall. Calculate the ITS for each specimen to the nearest 1 KPa using the following formula:
10 Where:
ITS = Indirect Tensile Strength in KPa. P = maximum applied load in N.
a ve
h Average height of the specimen in mm to one decimal place.
d = diameter of the specimen in mm to one decimal place.
Flow score is the total deformation of the sample (decrease in the vertical diameter) that occurs when it reaches the point of maximum load on the tool press marshall. The flow score is calculated with the following formula
Flow =
... (2.3)
VFWA is the percentage of voids in the asphalt aggregate filled or the ratio between the volume of asphalt in the mix and volume of pores in the aggregate. The formula of VFWA is as follow:
VFWA =
X 100 ... (2.4)
VIM is the percentage of air voids contained in the mixture, this number was obtained from the bulk specific gravity of each solid sample and mix pavement maximum specific gravity expressed in percent (%). The formula is as follow:
VIM = (100-(100*Bulk specific gravity/teory of compaction) ... (2.5) VIM = the average of VITM
Marshall Quotient (MQ) is stability inversely proportional to melting and can be used as an approach to the level of rigidity and flexibility mix.The calculation of MQ test is as follow:
MQ = W/F ... (2.6) Where:
MQ = marshall quotient W = stability
F = flow
11 Bsg=
... (2.7)
Where :
Bsg = bulk specific gravity
b = volumetric flash + water + sand d = oven dry sand
c = volumetric flash + water
Bulk Specific Gravity SSD can be calculate by:
Bsg SSD=
... (2.8)
Where:
b = volumetric flash + water + sand c = volumetric flash + water
Bsg SSD = Bulk specific gravity SSD Absorption can be calculate by:
Absorption= ... (2.9)
Where :
A = weight of dry speciment in air
S = weight of saturated surface dry speciment
Voids filled with bitumen is defined as the percent of the volume of voids in mineral aggregate that is filled with bitumen cement:
%VMA = (I/L) x 100 ... (2.10) Where :
I = volume of bitumen L = volume of air voids
12 Optimum bitumen content is needed to design the mix which gives maximum stability and density, flow and median air voids with aggregate filed with bitumen, and voids in the mix.
... (2.11)
Where
B0 = Optimum Bitumen Content
B1 = % asphalt content at maximum unit weight. B2 = % asphalt content at maximum stability.
B3 = % asphalt content at specified percent air voids in the total mix
Indirect Tensile Modulus Test stiffness is a way of testing laboratories. The most conventional to calculate the stiffness modulus asphalt mixture. According tostandard, indirect tensile stiffness modulus of this test is defined as testand has been identified as a non-destructive method for calculating the averagestiffness modulus of the material
ITSM =
... (2.12)
Where:
ITSM = Indirect Tensile Stiffness Modulus
L = the peak value of the applied vertical load (N),
D = the mean amplitude of the horizontal deformation obtained from 2 or more applications of the load pulse (mm),
t = the mean thickness of the test specimen (mm) v = Poisson’s ratio (a value of .35 is normally used).
UCS or Unconfined Compressive Strength is used to determine the resistence to permanent deformation of bituminous mixtures and loads. The formula of UCS is as follow
UCS =
... (2.13)
Where:
13
2.2.2 Durability
In terms of durability, the result is presented from the result of density. The formula of density is as follow:
Density =
Water Inside Sample of
Weight
Sample of
e Dry Surfac of
Weight
Crush After
Sample of
Weight
... (2.14)
14
CHAPTER III
METHOD OF RESEARCH
3.1
Location and Type of ResearchThis research conducted in the Laboratory of University Muhamadiya Suarakarta (UMS). Then, this research was conducted with experimental research because this research use experiment variable and control variable of research.
3.2 Parameter and Variable
In the context of this research, there are two kinds of variables that will be used, namely dependent and independent variable. The dependent variable are strength and durability while the independent variable arecrumb rubber 3%, 4% and 5%, and bitumen content 4.5%, 5%, 5.5%, 6% and 6.5%. The desccription about variable and parameter will be discussed in Table 3.1
Table 3.1.Parameters and Variables
Analysis Value
Parameters Properties of asphalt concrete 60/70
- Los Angeles Abrasion - Apparent specific gravity - Absorption
- Apparent specific gravity - Absorption
Variables Asphalt concrete modified crumb rubber 3%, 4% and 5%
- Data Examination Asphalt.
- Data Marshall Properties Test.
- Data Indirect Tensile Strength Test (ITS).
15 Based on Table 3.1, it can be seen that the parameter of this research are aggregate, both coarse and fine; marshall properties. Moreover, this research is presented variable namely asphalt concrete modified crumb rubber 3%, 4% and 5% and bitumen content 4.5%, 5%, 5.5%, 6% and 6.5%.
3.3 Data
Based on Table 3.1 , it can be seen that this research use both coarse and fine aggregates. The coarse aggregate use should have rough surface, angular sharp and clean from other materials that could interfere with the binding process. Aggregates are used in the form of crush stone in the dry condition. The types of test conduct on aggregates are as follows.
a. Sieve Analysis
This examination is intended to determine the gradation, both coarse aggregate and fine aggregates. Examination procedures refer to AASHTO T27 - 88
b. Specific Gravity and Absorption
Investigation of procedures for coarse aggregate refers to AASHTO T84-88
c. Infinity of Aggregate to Asphalt
Examination procedures refer to the AASHTO T19-88
d. Abrasion with Los Angeles Machine
Examination procedures refer to the AASHTO T96-87
Then, in terms of fine aggregate using, fine aggregate consists of clean sand, fine materials results split stone or a combinationof both in the dry condition. Inspection types for fine aggregate are as follows:
a. Sieve Analysis
Examination procedures refer to the AASHTO T 27-88.
16
b. Specific gravity and absorption
Inspection of procedures for fine aggregate refers to AASHTO T84-88. Moreover, in terms of filler inspection, the examination of filler includes:
Absorption: Procedures for checking the sieve analysis for the filler refers to the Bina
Marga (2010) standard with > 3% for absorption.
Specific Gravity:Inspection of procedures for filler refers to Bina Marga (2010)
standard with > 2.5% gram/cc.
Data collection techniques implemented with an experimental method to several test specimens tested in the laboratory. The data used in this study include primary data and secondary data.
3.3.1 Primary Data
Primary data is data collected directly through a series of experiments conducted themselves with reference to the existing manual instructions, for example by conducting research testing directly.
The data included in primary data are as the follows: a. Data Examination Asphalt.
b. Data Marshall Properties Test.
c. Data Indirect Tensile Strength Test (ITS).
d. Data Unconfined Compressive Strength Test (UCS).
3.3.2 Secondary Data
Secondary data is data obtained indirectly (derived from research or other sources) for material same type. In many ways the researcher must receive secondary data according to what it is. Secondary data used in this study, namely:
a. Examination of aggregate data.
b. Testing ITS of AC mixture in previous studies. c. Testing UCS of AC mixture in previous studies.
17
3.3.3 Sample Preparation of Material
Aggregates used in this study consist of coarse aggregate, fine aggregate and filler. Coarse aggregate is defined as the aggregate retains on sieve size 4.75 mm (No.4) while fine aggregate is defined as the aggregate passing sieve size 4.75 mm (No.4) and retains on sieve size 75 μm (No.200).
A- Specific Gravity and Absorption of Aggregates.
a. Fine Aggregate
Specific gravity & water absorption test of fine aggregate according to these specifications (AASHTO T-84) for determination of specific gravity & water absorption of aggregates.
1. Apparatus
a) Balance (0 - 6 kg)
b) Pycnometer, (Figure 3.1). Volume content for the container needs to be reproduced within ± 100 mm.
c) Mold, metal in the form of a frustum of cone with acceptable dimensions of 40 ± 3 mm inside diameter at top, 90 ± 3 mm inside diameter at the bottom, and 75 ± 3 mm in height.
d) Tamper, metal having a mass of 340 ± 15g and having a flat circular tamping face of 25 ± 3 mm in diameter.
b. Coarse Aggregate
Specific gravity and water absorption test of coarse aggregate according to (AASHTO T 85), for determination of specific gravity & water absorption of aggregates.
1. Equipment's & Apparatus
a) Wire basket
b) Oven (300˚C)
c) Container for filling water and suspending the basket d) An air tight container
e) Balance (0-10 kg)
f) Shallow tray & absorbent clothes.
18
2. Preparation of sample
The sample to be tested is separated from the bulk by quartering or by using sample divider.
3. Procedure
a)About 2 kg of the aggregate sample is washed thoroughly to remove fines, drained and then placed in the wire basket and immersed in distilled water at a temperature between 22 to 32˚C with a cover of at least 50 mm of water above the top of the basket Immediately after the immersion the entrapped air is removed from the sample by lifting the basket containing it 25 mm above the base of the tank and allowing it to drop 25 times at the rate of about one drop per second. The basket and the aggregate should remain completely immersed in water for a period of 24 ± 0.5 hours afterwards.
b)The basket and the sample are then weighed while suspended in water at a temperature of 22 to 32 ˚C. The weight is noted while suspended in water (W1) g.
c)The basket and the aggregate are then removed from water and allowed
d)To drain for a few minutes, after which the aggregates are transferred to one of the dry absorbent clothes.
e)The empty basket is then returned to the tank of water, jolted 25 times and weights in water (W2) g.
f)The aggregates placed in the dry absorbent clothes are surface dried till no further moisture could be removed by this clothe.
g)Then the aggregate is transferred to the second dry cloth spread in a single layer, covered and allowed to dry for at least 10 minutes until the aggregates are completely surface dry. 10 to 60 minutes drying may be needed. The surface dried aggregate is then weighed W3 g.
19
B- Aggregate Gradation
The percentages of aggregates required for every sieve size were determined according to the Indonesian standards. Then the samples retained were calculated using the percent passing for every sample size. Table: 3.2 summaries the upper and lower limit According to Indonesian standards.
Table. 3.2. Gradation Limits For Wearing Course
SIEVE SIZE UPPER LIMIT
In this study will use three types of bitumen: Asphalt 60/70 pen, and crumb rubber modified (0%, 3%, 4%, and 5%) The bitumen contents for these samples will be rank as (4.5 to 6.5) % of the total weight according to ASTM 3515-96. It has been made the tests for bitumen to know the physical properties of bitumen.
1. Penetration Test
The penetration test is one of the oldest and most commonly-used tests on asphalt cements or residues from distillation of asphalt cutbacks or emulsions. The standardized procedure for this test can be found in ASTM D5 (ASTM, 2001). It is an empirical test which measures the consistency (hardness) of asphalt at a specified test condition. In the standard test condition, a standard needle of a total load of 100 gr is applied to the surface of an asphalt sample at a temperature of 25°C for 5 seconds. The amount of penetration of the needle at the end of 5 seconds is measured in units of 0.1 mm (or penetration unit). Figure 3.3 shows a penetration test for bitumen.
20 Softer asphalt will have a higher penetration; the penetration test can be used to designate grades of asphalt cement, and to measure changes in hardness due to age hardening or changes in temperature.
Penetration Test Setup
a. Pour the sample into the hood asphalt penetration, let stand 1-2 hours at room temperature soak in a tub of water 25 ° C, for 1-2 hours, clean the needle penetration and plug.
b. Put weight 50 ounces in the needle holder so that the total weight to 100gramsMove the following sample cup penetration into the tub of water with a temperature below 25°C penetration testers.
c. Set the needle to see the specimen surface (Asphalt) d. Remove the needle for 5 + 0.1 seconds.
e. Click and read bookmark penetration rate.
f. Lift the needle slowly, test at least 3 times on the same sample.
2. Softening Point Test
The ring and ball softening point test (ASTM D36) measures the temperature at which asphalt reaches a certain softness. When asphalt is at its softening point temperature, it has approximately a penetration of 800 or an absolute viscosity of 13,000 poises. This conversion is only approximate and can vary from asphalt to another, due to the non-Newtonian nature of asphalts and the different shear rates used by these different methods, Where the Figure 3.4 shows the Softening point Tools.
Testing steps:
a. Preheat asphalt + 25 gr up liquid.
b. Put 2 pieces of rings on the brass plate that has been smearedtalk-glycerol. c. Pour the sample into a ring mold, let stand at room temperature for 30minutes. d. Flatten the sample surface with a knife.
e. Attach the second specimen; Insert the glass vessel containing distilled water. f. Temperatures 5+1ºC Insert thermometer for determination of softening point.
g. Put the steel ball on the test objectSoak in water at 5°C for 15 minutes Heat the vessel with water temperature rise 5ºC/min.
21
3. Specific Gravity Test of Bitumen
The test method most often used to determine Gmm is AASHTO T 209. Within the method, there are several options for determining the Gmm but all utilize the same basic principle of measuring the mass and volume of the loose mix sample to determine its maximum specific gravity. The options within AASHTO T 209 differ by the type of sample container and whether the container is filled with water or submerged in a water bath. There are three container choices: bowl, flask, or pycnometer.An outline of the procedure is as follows:
a. The dry mass of the loose mix samples are first determined and the mix is then placed in a tare container of one of the types previously mentioned.
b. Water is added to the container to completely cover the sample and a vacuum is applied to remove entrapped air.
c. The container is then filled with water and the mass determined or it is placed in a water bath and the mass determined.
d. From these mass determinations, the volume of the loose mix and thereby its Gmm is determined.
4. Ductility Test
The ductility test (ASTM D113) measures the distance a standard asphalt sample will stretch without breaking under a standard testing condition (5 cm/min at 25°C). It is generally considered that asphalt with a very low ductility will have poor adhesive properties and thus poor performance in service. Specifications for asphalt cements normally contain requirements for minimum ductility, where figure 3.6 ductility test of bitumen machine.
Testing steps:
a. Heat until the liquid asphalt
b. Cover the mold with mold ductility glycerin attaches the base plate c. Pour the test material in the mold of the end to end untilfull
d. Refrigerate the mold at room temperature 30 - 40 minutes, and averaged e. Soak in the tub soaking temperature 25˚C, 30 minutes
f. Remove the specimen from the base plate and the sides of the mold. Attach thetest specimen and the tensile testing machine with a speed of 5 cm per minute until the specimen broke.
22
5. Indirect Tensile Strength Test
The crack width formation is dependent on the early tensile strength of concrete. The principle of critical steel ratio also applies in this situation. The amount of reinforcement required to control early thermal and shrinkage movement is determined by the capability of reinforcement to induce cracks on concrete structures. If an upper limit is set on the early tensile strength of immature concrete, then a range of tiny cracks would be formed by failing in concrete tension. However, if the strength of reinforcement is lower than immature concrete, then the subsequent yielding of reinforcement will produce isolated and wide cracks which are undesirable for water-retaining structures. Therefore, in order to control the formation of such wide crack widths, the concrete mix is specified to have a tensile strength (normally measured by Brazilian test) at 7 days not exceeding a certain value (e.g. 2.8N/mm2 for potable water).
A cylindrical specimen is loaded diametrically across the circular cross section. The loading causes a tensile deformation perpendicular to the loading direction, which yields a tensile failure. By registering the ultimate load and by knowing the dimensions of the specimen, the indirect tensile strength of the material can be computed. Below is a figure showing the load fixture and a principal picture of the loading. The detail of ITS formula is presented in formula 2.2.
6. Indirect Tensile Stiffness Modulus (ITSM)
The ITSM test is a non-destructive procedure for determining stiffness modulus using repeated load indirect tension. The results are used to assess:Load spreading, Temperature susceptibility, Durability (water sensitivity). The evaluation of the stiffness modulus of bituminous mixtures was done. On the basis of indirect tensile laboratory test results, a practical model for stiffness modulus prediction in pavement bearing capacity analysis was established and calibrated. The indirect tensile stiffness modulus is shown in Table 3.4 and can be calculate with formula 2.12.
Table 3.3.ITSM Test
Crumb Rubber 20oC 40 oC 50 oC
60/70 3 3 3
3% 3 3 3
4% 3 3 3
5% 3 3 3
23
3.3.4 Samples Production of Bitumen Mixtures
1. Samples for Marshall Stability Test
The numbers of samples required are:
Three samples for each Percentage of bitumen and 15 samples for each type of bitumen: Asphalt 60/70 pen and Crumb Rubber modified (0%, 3%, 4%, and 5%) According to Table 3.4. It is Shows the distribution and number of samples of Marshall testing for each type of bitumen.
Table 3.4. Number Of Samples Of Marshall Testing.
ASPHALT TYPE
PB -1 PB -0.5 PB PB +0.5 PB +1
4.5% 5% 5.5% 6% 6.5%
AC- Asphalt 60/70 Pen 3 3 3 3 3
AC (3% Crumb Rubber) 3 3 3 3 3
AC (4% Crumb Rubber) 3 3 3 3 3
AC (5% Crumb Rubber) 3 3 3 3 3
Total of samples =15 x 4= 60
2. Sample Testing for Unconfined Compressive Strength (UCS) at OBC
The Unconfined Compressive Strength (UCS) can be calculated with formula 2.13. The numbers of sample required are:
Two samples of each type of bitumen: Asphalt 60/70 pen and Crumb Rubber modified (0%, 3%, 4%, and 5%) at each different temperature at OBC; According to Table 3.5
Table 3.5.The Numbers Of Samples Of UCS With Different Temperatures.
ASPHALT TYPE TEMPERATURE TISTING
30 ºC 40 ºC 60 ºC
AC- Asphalt 60/70 Pen 3 3 3
AC (3% Crumb Rubber) 3 3 3
AC (4% Crumb Rubber) 3 3 3
AC (5% Crumb Rubber) 3 3 3
Total of samples = 3 x 3 x 4= 3
24
3. Sample Testing for Indirect Tensile Strength (ITS) at OBC
The numbers of sample required are:
Three samples of each type of bitumen: Asphalt 60/70 pen and Crumb Rubber modified (0%, 3%, 4%, 5%) at each different temperature at OBC; According to Table 3.6. It is shows the number of samples of ITS with different temperatures.
Table 3.6. The Number Of Samples Of ITS With Different Temperatures.
ASPHALT TYPE TEMPERATURE TISTING
30 ºC 40 ºC 60 ºC
AC- Asphalt 60/70 Pen 3 3 3
AC (3% Crumb Rubber) 3 3 3
AC (4% Crumb Rubber) 3 3 3
AC (5% Crumb Rubber) 3 3 3
Total of samples = 3 x 3 x 4= 36
3.4 Analysis
This research will be started with the sample preparation of materials, as follow: The researcher will conduct the research start from the problem of waste tire that getting higher than before. Then the researcher will prepare for sample materials, such as aggregate, asphalt 60/70 pen, and wet process crumb rubber. In the wet process, the straight binder is initially pre-heated to around 190oC in a tank under hermetic conditions and then transported to a blending tank, where crumb rubber is added. The digestion process, which is the incorporation of rubber in the conventional binder, continues for a period of 1 to 4 hours, at a temperature of 190oC. The process is facilitated by a mechanical agitation produced by a horizontal shaft (Visser, 2000). Then, the sieve analysis of crumb rubber is #300. Then, another material that should be tested is aggregate. In the context of this research, the researcher will test the sieve of aggregate, absorption, specific gravity, gradation and impact. Moreover, another material for this research is asphalt 60/70 pen. The asphalt will be mixed with crumb rubber with 0%, 3%, 4%, 5% combination. Then, the mixture will be test for penetration, softening point, ductility, coating and specific gravity.
In terms of penetration test, the standard that will be used is ASTM D5, for softening point is ASTM D36, for specific gravity is AASHTO T 209, for ductility is ASTM D113. Then, after all of the test meet the requirement, the next step is focusing on the asphalt mixture with Marshall Design. Then the test that will be conducted are permeability test, UCS with ITSM 15. Then, the researcher will do comparison between asphalt mixture in terms of strength and durability
25
3.4.1 Strength
Compressive Strength is measured on materials, components, and structures. By definition, the ultimate compressive strength of a material is that value of uniaxial compressive stress reached when the material fails completely. The compressive strength is usually obtained experimentally by means of a compressive test. The apparatus used for this experiment is the same as that used in a tensile test. However, rather than applying a uniaxial tensile load, a uniaxial compressive load is applied. As can be imagined, the specimen (usually cylindrical) is shortened as well as spread laterally. A Stress–strain curve is plotted by the instrument and would look similar to the following:
The compressive strength of the material would correspond to the stress at the red point shown on the curve. In a compression test, there is a linear region where the material follows Hooke's Law. Hence for this regionwhere this time E refers to the Young's Modulus for compression. In this region, the material deforms elastically and returns to its original length when the stress is removed.
3.4.2 Durability
Durability. In this study, regression models will be sought that would accurately predict Durability Factors by one or more aggregate and/or concrete mixture characteristics. Thus, Durability is the dependent variable and the aggregate/ concrete mixture characteristics are the independent variables. The dependent variable is also known as the “response variable”, and the independent variables are also known as “predictors” or “regressors”. If not included in an interaction, independent variables are also known as “main effects”. Several different types of regression models were desired, based on the sort of data that was to be included in each model. For instance, one type of model consisted of aggregate-only independent variables. Usually, model accuracy is sacrificed by using fewer orless definitive (but easier) test methods. In terms of durability, the calculation can be conducted with formula 2.14.
26
3.5 Flow Chart
The process framework for this study is summarized in Figure 3.1.
No
Yes
Yes
No START
Sample Preparation of Materials
Aggregate Asphalt 60/70
Impact Gradation
Absorption, SG Sieve Analysis
Wet Process Crumb Rubber
Sieve Analysis @ 16
Mix with Crumb Rubber @
(3%, 4%, 5%) Standards
Penetration Softening point Ductility Coating SG
Marshall Design to get OBC
[(UCS & ITS) tests @ OBC (30ºC, 40ºC, 60ºC)] [ITSM 20 ºC, 40 ºC, 50 ºC]
Comparison of results
AnalysisBitumen content Analysis of ITS, UCS
PermeabilityTest@ OBC
AC-Asphalt 60/70, Mix with Crumb Rubber @ (0%, 3%, 4%, 5%) Opt. Mixture Composition
Standards
END
27
CHAPTER IV
RESULT AND DISCUSSION
4.1General
The main materials used in this research were aggregate, asphalt and crumb rubber. All properties of the materials used were measured for further analysis consideration. Several tests were conducted in order to measure their properties according to the specification reffered were ASTM.
4.1.1 Asphalt
The properties of asphalt analysed were specific gravity, penetration, softening point and ductility as seen in the Table 4.1, the asphalt properties can fulfil all requirements.
Table 4.1. Properties Of Asphalt Type of
For the detail calculation see appendix (A2-A3-A4)
In terms of penetration, the calculation comes from all results of penetration for mixture on temperature 25oC. Based on the sample result, this research used 3 (three) samples for penetration with 68 mm, 65.8 mm and 62 mm for result. Then, the average for penetration score was 65.27 mm. Based on the research result, the penetration for asphalt is 65.27 mm, it means that the penetration met the standard from Bina Marga 2010 with 60-70 mm.
Then, in terms of specific gravity, the asphalt for this research also met the specification. The asphalt for this research has 1.061 for specific gravity, while specification of specific gravity from Bina Marga 2010 is Min.1.
The result of 1.061 gram from many factors, such as weight of asphalt, asphalt content, asphalt specific gravity. Take an example, the calculation for the first sample, weight of asphalt was calculated as follow:
The weight of asphalt = weight of picnometer filled with asphalt - weight of picnometer (with cover)
= 54 - 37 = 17 gram
28 Asphalt content = (weight of picnometer filled with water- weight of picnometer (with
cover))-(weight of picnometer filled with asphalt and water-weight of picnometer filled with asphalt)
= (60-37) - (61-54) = 16 gram
Asphalt specific gravity = weight of asphalt/asphalt content = 17/16 = 1.063
As we can se on formula (2.8)
Then, based on the result of asphalt specific gravity, the calculation of specific gravity was obtained from the mean between asphalt specific gravity sample I and II.
Moreover, in terms of softening point, the asphalt has softening point 52oC while specification of Bina Marga 2010 was ≥ 48o
C. In terms of softening point, the score was obtained from observation of 5oC to 60oC or 41oF to 140oF and from 0 second until 158 seconds for sample I and 280 seconds for sample II. Based on the observation, it was obtained that the score of softening point were 51oC for sample I and 53oC for sample II. The result of average between sample I and II was 5253oC, it means that the score was more than minimum standard of softening point in Bina Marga, namely ≥ 48oC. Moreover, the ductility score also met the specification of Bina Marga 2010 because the score was more than minimum standrad of ductility, namely ≥ 100 cm.
4.1.2 Aggregate
Aggregate size larger than 4.75 mm is defined as coarse aggregate whereas smaller than 4.75 mm is defined as fine aggregate and the specific gravity and absorption for each were analyzed. In the first stage, aggregates were sieved and separated according to the needed sizes based on the Indonesian National Standards for each sample; the total weight of aggregates needed was 1200g. The test results for coarse aggregate, fine aggregate and asphalt are presented in Table 4.2.
29
Table 4.2. Test Results For Coarse Aggregate, Fine Aggregate and Asphalt
No Test type Unit Specification Result
Coarse aggregatea)
For the detail calculation see appendix (A6-A9-A2-A4)
Based on the Indonesian National Standards, the aggregates were blended and sieved as in Table 4.2. The aggregate samples passing from each sieve size were collected based on the percentage of the weight. Then, it can be seen that the aggregate and asphalt can be used to support the research because the result is in line with the specification of BinaMarga.
At the preliminary stage, aggregate were sieved according to AASHTO T 27-88 and separated according to the size of sieves on the selected aggregate gradation. The aggregate gradation specification and the selected gradation used in this study are shown in Table 4.3.
Table 4.3. Coarse Aggregate Grading Test
Grading Test Number of Rounds = 500 Rounds
Sieve size I II
Through Sieve Not Through Sieve Sample (a) Sample (b) 76,2 (3") 63,5 (2,5")
Weight held by sieve No. 12 after research (b)
7935 3933
For the detail calculation see appendix (A7)
30 Based on Table 4.3, it can be concluded that the selected aggregate gradation used in this study can fulfil the gradation requirement specified by Bina Marga (2010).
Based on the result, it can be seen that the total weight (a) of sample I was 10000, the blocked sieve No. 12 after treatment (b) was 7935, so the result (a)-(b) = 10000-7935 = 2065; while the total weight (a) of sample II was 5000, the blocked sieve No. 12 after treatment (b) was 3933, so the result (a)-(b) = 5000-3933 = 1067.
Wearing I = ((a-b)/a) x 100 % = 20,65 %
Wearing II = ((a-b)/a) x 100 % = 21,34 %
Mean of Wearing = (Wearing I + Wearing II )/2 = 20,995
Based on the result it can be seen that it met the specification of Bina Marga 2010 with maximum 30%. The result of coarse aggregate wearing was 20.995%.
4.1.3 Crumb Rubber
In terms of crumb rubber, the specification of specific gravity was 1.09
4.1.4 Marshall Test of 60/70 Bitumen Mixture
In this study, the type of mixture used is Asphalt Concrete – Wearing Course (AC-WC). To determine the optimum asphalt content of the mixture, the performance of mixture was evaluated based on Marshall Test. Marshall Test has six parameters, those are, Marshall Stability, Flow, Marshall Quotient (MQ), Voids in Mineral Aggregate (VMA), Voids in the Mixture (VIM), and Voids Filled with Asphalt (VFA). The results of Marshall parameters evaluated in this study should comply with Indonesian specification (Bina Marga, 2010), as follows:
a. Marshall Stability, min. 800 kg. b. Flow, min. 3 mm.
c. Marshall Quotient (MQ), min.250 kg/mm. d. Void in Mineral Aggregate (VMA), min. 15%. e. Void in mixture (VIM), 3% - 5%.
f. Voids filled with Asphalt (VFA), min. 65%.
This research used two types of Marshall Test, namely asphalt concrete without rubber and asphalt concrete modified with rubber. Marshall Test for the 60/70 known as asphalt without
31 crumb rubber; while asphalt concrete modified with crumb rubber were divided into 3 parts namely Crumb Rubber 3%, Crumb Rubber 4% and Crumb Rubber 5%.
The results of the Properties of Asphalt Concrete Without Crumb Rubberis described in Table 4.4.
Table 4.4.Properties Of Asphalt Concrete Without Crumb Rubber (60/70)*)
Asphalt Content Stability Flow VFWA VIM MQ Density VMA
(%) Kg mm % % Kg/mm Gr/cm3 %
4,5 1321,81 3,20 61,90 6,11 413,72 2,44 16,00
5,0 1551,26 3,93 67,99 5,29 426,69 2,44 16,25
5,5 2031,00 3,90 73,32 4,98 527,73 2,43 16,94
6,0 1664,55 3,83 73,49 4,75 450,77 2,42 17,67
6,5 1357,78 3,50 75,31 4,78 392,38 2,41 18,62
Specification min 800 min 3 min 65 3.5-5 min 250 min 15
For the detail calculation see appendix (B4)
Based on Table 4.4, the result of properties of asphalt concrete without crumb rubber is presented in Figure 4.1.
The calculation of the optimum asphalt for stability (x) without Crumb Rubber is: y = -548.18 x2 + 6067 x – 14927
= -1096.36 x + 6076
= 0
x =
x = 5.53
Then, in terms of flow, the score was obtained from flow score divided by 100. Take and example, this research calculated mixture of 0% crumb rubber and 4.5% asphalt content. The result of flow calculation are 330/100 = 3.30 mm.
32
Figure 4.1 Correlation Stability And AC Without CR Toward Asphalt Content
33
Figure 4.2.Correlation Flows And AC Without CR Toward Asphalt Content
Flow (melting) is the total deformation of the sample (decrease in the vertical diameter) that occurs when it reaches the point of maximum load on the tool press marshal. The flow of asphalt also met the specification of Bina Marga 2010 with minimum 3, while this research result were more than 3 mm. Based on the data of Table 4.4, the added of asphalt content increased the score of flow. It can be seen when asphalt content added for 5%, the flow score was increased to 3.93 mm. Then, when asphalt content added into the mixture for 5.5%, the score of flow decreased to 3.90 mm. The score of flow kept on decreasing when asphalt content added to 6% and 6.5%. the added of asphalt content more than 5.5% decreased the flow score because the added more asphalt would influence the strength score, therefore the flow score would decreased also.
min limit = 3
0,00 1,00 2,00 3,00 4,00 5,00
4,0 4,5 5,0 5,5 6,0 6,5 7,0
F
lo
w
(
m
m
)
Asphalt Content (%)
AC-WC
